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Research ArticleRaman Spectroscopy and Statistical Analysis ofthe Silicate Species and Group Connectivity in Cesium SilicateGlass Forming System
Armenak Osipov Leyla Osipova and Rimma Zainullina
Institute of Mineralogy of Ural Branch of RAS Miass Chelyabinsk Region 456317 Russia
Correspondence should be addressed to Armenak Osipov armikmineralogyru
Received 18 June 2015 Accepted 6 September 2015
Academic Editor Hans Riesen
Copyright copy 2015 Armenak Osipov et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited
TheRaman spectra of119909Cs2O-(100minus x)SiO
2(119909 = 17 22 27 33 and 37mol) glasses andmeltsweremeasured in the temperature
range of 293 to 1553KThe concentrations of the119876119899 species were calculated as a function of the composition and temperature basedon the deconvolution analysis of the spectra It was found that a dynamic equilibrium among structural units in the melts with119909 gt 17mol can be described by disproportionation reaction 119876
3hArr 1198764+ 1198762 The enthalpy of this reaction was found to be equal
to 32 plusmn 6 43 plusmn 8 56 plusmn 10 and 52 plusmn 9 for 119909 = 22 27 33 and 37mol respectively The nonideal entropy of mixing (Δ119878mix) dependson the melt temperature and increases almost linearly with increasing temperature The1198761198991198762ndash1198762 and119876
119899119894119895119896119897 distributions with 119909
ranging from 0 to 55mol were modeled using experimental data for the concentrations of the 119876119899 units
1 Introduction
Knowledge of the structure of amorphous materials is fun-damental for understanding of their physical and chemicalproperties Structure-properties correlations of the silicateglasses andmelts are ofmajor importance in geochemical andtechnological fieldsTherefore an adequate understanding ofthe composition and temperature dependencies of glass andmelt properties requires detailed information on their struc-ture Numerous studies of silicate glasses have demonstratedthat silicon-oxygen tetrahedra with various numbers ofbridging oxygen atoms are the fundamental structural blocksof these glasses The silicon-oxygen tetrahedra are called 119876
119899
units where 119899 = 0ndash4 is number of bridging oxygen atoms perSiO4tetrahedron Schematic 2-dimensional representation
of the 119876119899 species is shown in Figure 1(a) 119876119899 units form a
continuous random network of glasses or silicate anions inmelts via the Si-O-Si bridging linkages The random networkof SiO
2glass consists of SiO
4tetrahedra interconnected via
their oxygen apexes where all oxygen atoms are bridging(1198764 units) The addition of alkali oxides to SiO
2leads to
the breaking of the Si-O-Si linkages and the formation of
terminal oxygen atoms each of which belongs only to onesilicon atom that is the formation of119876119899 species with 119899 lt 4 inthe glass structure Schematic representation of the formationof 119876119899 species with nonbridging oxygen atoms (119899 lt 4) is
shown in Figure 1(b) 29Si MAS-NMR studies have shownthat the concentrations of various types of 119876119899 units dependon the concentration of the modifier oxide and the type ofalkali cation [1 2] Namely the equilibrium
2119876119899lArrrArr 119876
119899minus1+ 119876119899+1
(119899 = 3 2 1) (1)
is shifted to the right with increasing cationic power of themetal cation (119885119903 where 119885 is the valency and 119903 is the ionicradius Li+ gt Na+ gt K+) The Raman spectroscopy studies ofrubidium and cesium silicate glasses [3 4] allow the assertionthat the above-mentioned regularity is valid for all alkalications
As known equilibrium (1) (119899 = 3) is shifted to theright with increasing temperature in the case of the sodiumand potassium silicate melts [5ndash12] However no significantchanges in the local structure of lithium silicate melts werefound [5 12] Moreover thermodynamic calculations of
Hindawi Publishing CorporationInternational Journal of SpectroscopyVolume 2015 Article ID 572840 15 pageshttpdxdoiorg1011552015572840
2 International Journal of Spectroscopy
Q4 Q3 Q2 Q1 Q0
minus
minus
minus
minus
minus
minus minus
minus
minus
minus
Silicon atomBridging oxygen atomNonbridging oxygen atom
(a)
+ M2O rarr
2Q4 + M2Orarr2Q3
M+
M+
minus minus
Silicon atomBridging oxygen atomNonbridging oxygen atom
(b)
minus
Q3444
Silicon atomBridging oxygen atomNonbridging oxygen atom
Q3332
minus
minus
minus
minus
minus
Q3ndashQ4
Q3ndashQ4
Q3ndashQ4
Q3ndashQ3
Q3ndashQ3
Q3ndashQ2
(c)
Figure 1 Schematic 2-dimensional representations of the 119876119899 species (a) of the formation of 119876119899 species with nonbridging oxygen atoms (b)
and of some 119876119899119894119895119896119897 groups (c)
the 119876119899 distribution in the Li
2O-SiO
2system have shown
that equilibrium (1) is shifted to the left with increasingtemperature that is towards an increase in the concentrationof 1198763 units [7] To the best of our knowledge no data on the119876119899 distribution and its changes with temperature in cesium
silicatemelts can be found in the literatureTherefore the aimof this paper is a structural study of Cs
2O-SiO
2glasses and
melts by high-temperature Raman spectroscopyHigh-temperature Raman spectroscopy is a useful
method for investigating not only the glass structure but alsothe melt structure over a wide temperature range [5ndash15] Asis known the high-frequency region (800ndash1200 cmminus1) of thespectra of alkali silicate glasses and melts is characterizedby a series of Raman bands originating from the Si-Ominusstretching vibrations of various 119876
119899 units It is assumedthat the intensities of these bands are proportionate to theconcentrations of 119876
119899 species [3 5 7 8 10ndash15] Thereforethese bands can be used for the quantitative description ofthe structural changes of silicate glasses and melts dependingon both the composition and temperature
Although knowledge of the concentrations of 119876119899 speciesis important for describing the structure of silicate glassesand melts it does not provide a clear idea of their structurebecause the 119876
119899 distribution provides no information about
the interconnection between 119876119899 units Currently only a
limited number of publications address this problem and allof them focus on theNa
2O-SiO
2system [6 16ndash20]Therefore
this paper studies this problem for Cs2O-SiO
2glasses and
melts
2 Material and Methods
21 Sample Preparation Glass samples of the compositions119909Cs
2O-(100 minus x)SiO
2(119909 = 17 22 27 33 and 37mol)
were prepared by the conventional melting and quenchingmethod from reagent-grade SiO
2and Cs
2CO3 The initial
reagents were dried (120∘C for 2 h) weighed and mixed inthe required ratios The batch (5 g) was melted in a platinumcrucible at 119905 = 1000ndash1100∘C for 2ndash5 h (depending on themelt composition) to obtain a bubble-free meltThe obtainedmelt was cooled directly in a platinum crucible in air atroom temperature and then used for Raman measurementsat various temperatures To avoid glass hydration Ramanscattering measurements were started immediately after thesample preparation It should be noted that due to the highviscosity of the 17Cs
2O-83SiO
2melt we failed to prepare a
bubble-free glassy sample Thus this sample was only studiedin the glassy state
International Journal of Spectroscopy 3
22 Raman Experiments Raman scattering measurementswere performed on a specially designed high-temperatureapparatus based on a DFS-24 double monochromator Torecord the Raman spectra at different temperatures thesmall platinum crucible was placed into a vertical compactelectrical furnace Thus all spectra were recorded in 180∘geometry The operating temperature range was 20ndash1300∘Cand was controlled within plusmn1∘C The second-harmonic ofan LTI-701 solid-state pulsed laser (120582 = 532 nm ⟨119875⟩ =
500mW) operated at a modulation frequency of 87 kHzwas used as the excitation source The pulse duration ofthe acoustooptic switch was 2120583s An uncooled FEU-79photomultiplier was used to detect the Raman signal Agated photon counting system was applied to minimize thethermal radiation signal The spectral width of the slit was6 cmminus1 in all measurements A detailed description of theexperimental setup and recording conditions of the high-temperature Raman spectra can be found in [21ndash23]
To compare the spectra obtained at various temperaturesthey were reduced to obtain the temperature- and frequency-dependent scattering intensity
119868red (]) = 119868obs (]) [1 minus exp(
ℎ119888]119896119879
)]
]]30
(]0minus ])4
(2)
where 119868obs and 119868red are the observed and reduced Ramanintensities respectively ] and ]
0are the Raman shift and
wavenumber of the excitation source respectively and ℎ 119896119888 and 119879 represent Planckrsquos constant Boltzmannrsquos constantspeed of light and temperature respectively
23 Simulation of the 119876119899 119876119894ndash119876119895 and 119876
119899119894119895119896119897 DistributionsAs it is known Zachariasenrsquos rules [24] for glass formationare focused only on a local configuration of cation-oxygenpolyhedra and their connectivity to each other (via cornersnot edges or faces) Based on these rules it is possible toassume that the most important point in a modeling of alocal structure of silicate glasses is a coordination number ofglass-forming cations rather than a network dimensionalityand topology as a whole Any regular or random networkwhere each node has four linkages with the nearest nodesand each bond joins only two nodes reproduces completelythe 119876
119899 distribution in pure SiO2(all structural units are
1198764) Formally such network can be expressed in form of
the table consisting of five lines and 119873 columns when 119873
is a number of nodes in the system Top line contains theserial number of node and other four lines contain the serialnumbers of nodes which joined to the given in the top lineThus each column describes linkages between five nodesEach node in this table was interpreted as a silicon atom andhad four linkages with the nearest nodes The bond betweentwo nodes was interpreted as a Si-O-Si (hereafter we will usethe abbreviation 119876
119894ndash119876119895) bridging bond (some examples of119876119894ndash119876119895 bridging bonds are shown in Figure 1(c)) To calculate
the 119876119899 distribution it is necessary to break the preassigned
number of bonds (the number of the bonds that must bebroken is determined by the glass composition) and then theobtained configuration must be analyzed In this approach
eachnodewith 119899unbroken bonds and each broken bondwereinterpreted as a119876119899 unit and a Si-Ominus+MM+minusO-Si nonbridgingbond respectively Three parameters 1119908
1 11199082 and 1119908
3
were introduced into the modeling procedure to achieve thebest agreement between the experimental 119876119899 concentrationsand the calculated 119876
119899 distribution These parameters donot depend on the glass composition but do depend ontemperature and in addition to the concentration of varioustypes of nodes they determine the probability of the linkagebreak (Figure 2 demonstrates a role of these parameters in thecomputational algorithm) Taking into account the randomcharacter of the linkage choice and the table of linkages 50configurations were generated for each composition at a fixedtemperature The required concentrations of 119876119899 units wereobtained by averaging of all 50 configurations of the tableThe table was also analyzed to study the 119876
119894ndash119876119895 (bridgingbonds) and 119876
119899119894119895119896119897 (group connectivity) distributions basedon the 119876
119899 distribution data (eg schematic 2-dimensionalrepresentations of the 119876
3444 and 1198763332 groups are shown
in Figure 1(c)) Here 119899 is the number of bridging oxygenatoms and 119894 119895 119896 and 119897 indicate the type of connected 119876
119899
units The modeling was performed in a composition rangeof 0 to 55mol Cs
2O content at two fixed temperatures (293
and 1223K) A more detailed description of the modelingprocedure can be found in [25 26]
3 Results
31 Raman Spectra
311 Glass Spectra The Raman spectra of glasses with thecomposition 119909Cs
2O-(100 minus x)SiO
2(119909 = 17 22 27 33
and 37mol) are shown in Figure 3 in which the symbolicdesignations near the spectra (left side) indicate the Cs
2O
content The Raman spectra of glasses with relatively lowCs2O contents (119909 = 17 22 and 27mol) exhibit two bands
with peak intensities at 510 and 598 cmminus1 oneweakwide bandat approximately 785 cmminus1 and a line at 1100 cmminus1 havingthe highest intensity in each spectrum with a shoulder at1150 cmminus1 The peak position at 510 cmminus1 is gradually shiftedtoward higher frequencies and the 598 cmminus1 line is slightlyshifted toward lower frequencies with increasing Cs
2O con-
tent in the given composition range In addition the intensityof these bands increases whereas the intensity of the weakline at 785 cmminus1 decreases with the addition of cesium oxideFor the high-frequency envelope the shape of this contour ismost strongly affected by an increase in the modifier oxidecontent which causes a gradual resolution deterioration ofthe 1100 and 1150 cmminus1 bands and a drastic decrease inintensity for the high-frequency shoulder accompanied by anincrease in the intensity of the 1100 cmminus1 Raman band at 119909 gt
27mol The 1100 cmminus1 line becomes more symmetric andits width decreases A new band at approximately 930 cmminus1distinguishes the 33Cs and 37Cs spectra from the 119909 lt
33mol spectra The intensity of this band increases withincreasing 119909 It also should be noted that the intensity of the510ndash530 cmminus1 band is greater than that of the 598 cmminus1 bandat 119909 le 27mol and 119868
510ndash530 lt 119868598
at 119909 gt 27mol
4 International Journal of Spectroscopy
Searching
bond
All possiblechanges
No
Random number
(node choice)generator
Branchingpoint
Searching
bond
Searching
bond
Searching
bond
Branchingpoint
Branchingpoint
TrueTrueTrueTrue
NoNo No
False False FalseFalse
Exist Exist Exist Exist
1w1 1w2 1w3
n lt 4 n lt 3 n lt 2 n lt 1
2Q4rarr2Q3 2Q4rarr2Q3
Q4 + Q3rarrQ3 + Q2
2Q3rarr2Q2
2Q4rarr2Q3
Q4 + Q3rarrQ3 + Q2
2Q3rarr2Q2
Q4 + Q2rarrQ3 + Q1
Q3 + Q2rarrQ2 + Q1
2Q2rarr2Q1
for Q4ndashQ4 for Q43ndashQ43 for Q432ndashQ432 for Q4321ndashQ4321
1 minus 1w1 1 minus 1w2 1 minus 1w3
Figure 2 Block-diagram of simulation algorithm
312 High-Temperature Raman Spectra The Raman spectraof the 22Cs
2O-78SiO
2and 27Cs
2O-73SiO
2samples
measured at different temperatures are shown in Figures4(a) and 4(b) As seen in Figure 4(a) the peak intensityat 530 cmminus1 decreases slightly and its position is graduallyshifted toward lower frequencies with increasing tempera-ture The peak intensity at 598 cmminus1 in contrast to that of530 cmminus1 band increases with increasing temperature andremains at essentially the same frequency No significantchanges are observed in the peak intensity or the shape of thehigh-frequency envelope (1000ndash1200 cmminus1) at relatively lowtemperatures (up to sim898ndash1003K) Only one symmetric wideline with maximum near 1100 cmminus1 is observed in the high-frequency region at higher temperatures and the intensityof this line decreases with increasing temperature A newweak band at 930 cmminus1 that appeared in the Raman spectrameasured at temperatures above 1003K is another peculiarityof the high-temperature spectra All of the above-mentionedfeatures of the changes in the 22Cs spectra with temperatureare observed in the 27Cs spectra as well
The Raman spectra of glasses and melts with modifieroxide contents of 33 and 37mol are shown in Figures 5(a)and 5(b) respectively In contrast to the previous spectra the
line near 920ndash930 cmminus1 is observed at all temperatures and itsintensity increases with temperature This line is most clearlyobserved in the 37Cs spectra The peak intensity at 1100 cmminus1obviously decreases with increasing temperature and itsposition shifts slightly toward lower frequencies In additionthe width of this band increases The intensities of the low-frequency bands (520ndash530 and 598 cmminus1) depend weaklyon temperature but their width significantly increases withtemperature Finally the formation of another new Ramanline in the melt spectra with a maximum near 420 cmminus1should be noted (see Figure 5(b)) This line is observed inthe previous spectra only as an unresolved low-frequencyshoulder near the 530 cmminus1 band
32 Modeling Results The results of the modeling of the 119876119899
and 119876119894ndash119876119895 distributions in the Cs
2O-SiO
2system at two
different temperatures (293K solid lines 1223K dotted lines)are shown in Figures 6(a) and 6(b) respectively In additionto our experimental data the literature data [1 3 27] onthe concentrations of 119876
119899 units in the Cs2O-SiO
2glasses
and melts are also shown in Figure 6(a) As seen in thisfigure the modeled curves well describe the experimentaldata for both glasses and melts over a wide compositions
International Journal of Spectroscopy 5
1150
1100
930
785
598
530
51037Cs
33Cs
27Cs
22Cs17Cs
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
Figure 3 Raman spectra of 119909Cs2O-(100 minus x)SiO
2(119909 = 17 22 27
33 and 37mol) glasses
range Temperature changes have no significant effect onthe concentration of 119876
119899 units in glasses and melts withrelatively low Cs
2O contents (up to sim15mol) as well as in
a narrow composition interval near 40mol In turn mostconsiderable changes in the 119876
119899 distribution are observed forsamples with disilicate and metasilicate compositions Herethe concentrations of the dominant type of structural units(1198763 and119876
2 for disilicate andmetasilicate resp) decrease withincreasing temperature and are accompanied by an increasein the concentration of other structural units with 119899 differingby plusmn1 In the aggregate this phenomenon causes the curvesdescribing the dependences of the 119876
3 and 1198762 units on the
composition to be slightly wider for the melts than for theglasses but the positions of their maxima do not change withtemperature
As seen in Figure 6(b) only 119876119894ndash119876119895 bridging bonds with
|119894 minus 119895| = 0 or 1 may be observed in the system among allpossibilities (1198764ndash11987641198764ndash11987631198764ndash11987621198764ndash11987611198763ndash11987631198763ndash11987621198763ndash1198761 1198762ndash1198762 1198762ndash1198761 1198761ndash1198761) of 119876
119894ndash119876119895 bridging bondsThe maxima of the 119876
119894ndash119876119895 curves decrease with increasing|119894 minus 119895| and are approximately the same for the 119876
119894ndash119876119895 bondswith the same |119894 minus 119895| values The maxima of the 119876
4ndash1198763 and1198763ndash1198762 curves dependweakly on temperature (approximately
1) whereas the positions of thesemaxima are shifted towardhigher Cs
2O concentrations In addition an increase in the
width of these curves is also observedThewidth and positionof the peak of the1198763ndash1198763 and119876
2ndash1198762 curves behave similarlybut their maxima decreasemore dramatically with increasingtemperature (approximately 20)The119876119894ndash119876119895 curves with |119894minus
119895| = 2 are shown in the inset to Figure 6(b) As observed thedependence of the concentration of the given 119876
119894ndash119876119895 bridgeson temperature is opposite to that typical for119876119894ndash119876119895 bridgingbonds with |119894 minus 119895| = 0 In this case a significant increase
in the 1198764ndash1198762 and 119876
3ndash1198761 concentrations with increasingtemperature is observed Nevertheless the concentration ofthese Si-O-Si bonds is low in both glass and melt and is lessthan 1 and 4 at 293 and 1223K respectively
The modeling results of the concentrations of the 1198764119894119895119896119897
and 1198763119894119895119896 groups as a function of composition at different
temperatures (293 and 1223K) are shown in Figures 7(a)ndash7(d)The concentrations were calculated in two ways relativeto the concentration of the appropriate type of structural unit(Figures 7(a) and 7(c) for 1198764119894119895119896119897 and 119876
3119894119895119896 resp)
[119876119899119894119895119896119897
] =
119873119876119899119894119895119896119897
119873119876119899
times 100 (3)
and relative to the total concentration of 119876119899 units (Figures7(b) and 7(d) for 1198764119894119895119896119897 and 119876
3119894119895119896 resp)
[119876119899119894119895119896119897
] =
119873119876119899119894119895119896119897
sum4
119899=0119873119876119899
times 100 (4)
In these equations 119873119876119899119894119895119896119897 and 119873
119876119899 are the amounts of
different types of groups and structural units respectivelyAs seen in Figure 7(a) the gradual increase in concen-
tration of the modifier oxide leads to the following trans-formations of the 119876
4119894119895119896119897 groupings 11987644444 rarr 11987644443
rarr
11987644433
rarr 11987644333
rarr 11987643333
rarr 11987643332 In addition
11987644432 11987644332 and 119876
43322 groups are also formed in theglass structure As seen in the inset to Figure 7(a) howevertheir concentrations are lower than 7 Both the coexistenceregions and the variety of the 119876
4119894119895119896119897 groups are higher inmelts than in glasses The 119876
44332 11987643322 and 11987643222 groups
supplement the list of 1198764119894119895119896119897 groups at high temperature
(1223K) Their maximum concentration exceeds 7 in themelt structure and is low in the glasses The 119876
44322 1198764222211987643221 11987643331 and 119876
43321 groups may also appear in themelt structure but their concentration is less than 7 (seeFigure 7(a)) The shape of the 119876
44444(119909) 119876
44443(119909) and
11987644433
(119909) curves depends slightly on temperature whereasthe 119876
44333(119909) 11987643333(119909) and 119876
43332(119909) curves are subject
to dramatic changes An increase in the width of the curvesand a shift in the position of their maxima toward large 119909 aretypical for all of themThe ratio between the maxima of thesecurves at 293K is
11987211987643333 gt 119872
11987644333 asymp 119872
11987644332 (5)
and that at 1223K is
11987211987643332 gt 119872
11987644333 gt 119872
11987643333 (6)
The region of existence of the 1198763119894119895119896 groups is somewhat
broader than that of 1198764119894119895119896119897 and extends to 119909 asymp 52mol (seeFigure 7(c)) The transformation of 1198763119894119895119896 groups dependingon 119909 can be represented by the sequence1198763444 rarr 119876
3443rarr
1198763433
rarr 1198763333
rarr 1198763332
rarr 1198763322
rarr 1198763222
rarr 1198763221
In addition some amount of 1198763432 groups (less than 3 ofthe total amount of1198763 units) and119876
3321 groups (less than 4)can exist in the glass structure with disilicate andmetasilicate
6 International Journal of Spectroscopy
15531443
1223
1113
1003
898
793
683
473
293
530598
930
1100
1150
Raman shift (cmminus1)13001100900700500300
Ram
an in
tens
ity (a
u)
(a)
1223
1553
1338
1113
1003
898
793
293
530
573
683
598920
1100
1150
13001100900700500300
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)
(b)
Figure 4 Low- and high-temperature Raman spectra of the 22Cs2O-78SiO
2(a) and 27Cs
2O-73SiO
2(b) glasses andmelts (hereinafter
a temperature of the samples is shown in K)
1443
1338
1223
11131003
898
793
683
573
293
598530 920
1100
1150
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(a)
1443
1338
1223
1113
1003
573
293
420520 598
930
1100
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(b)
Figure 5 Low- and high-temperature Raman spectra of the 33Cs2O-67SiO
2(a) and 37Cs
2O-63SiO
2(b) glasses and melts
compositions respectively (see the inset in Figure 7(c))The region of coexistence of the 119876
3119894119895119896 groups increases bysim25 and reaches 55 as the temperature increases up to1223K It is also accompanied by an increase in the widthof the 119876
3119894119895119896(119909) curves a shift of the maxima of these curves
toward large 119909 values and the leveling of their maxima Theconcentration of the dominant type of structural group (ata given composition) decreases and the fraction of the 119876
3119894119895119896
groups that are untypical for glass increases with increasingtemperature As before no significant changes are observedin the 1198763119894119895119896 distribution at 119909 lt 20mol
The1198762119894119895 and1198761119894 distributions calculated according to (3)
and (4) are shown in Figures 7(a)ndash7(d) Figures 8(a) and 8(c)represent the1198762119894119895 and119876
1119894 distributions relative to the1198762 and1198761 contents respectively and Figures 8(b) and 8(d) represent
the concentrations of the 1198762119894119895 and 119876
1119894 groups relative to the
International Journal of Spectroscopy 7
10 20 30 40 5000
20
40
60
80
100
Q4
Q3Q2
Q1
Q0
[Qn]
()
Cs2O (mol)
(a)
20 25 30 35 40 45 50 55
0
1
2
3
4
0 10 20 30 40 500
20
40
60
80
100
Qi ndashQ
j(
)
Q4ndashQ4
Q4ndashQ3
Q3ndashQ3 Q2ndashQ2
Q3ndashQ2
Q2ndashQ1
Q4ndashQ2
Q3ndashQ1
Q1ndashQ1
Cs2O (mol)
(b)
Figure 6 119876119899 (a) and 119876119894ndash119876119895 (b) distributions for glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 = 1223K) of Cs
2O-SiO
2system
Symbols are experimental data (◻ [1] ⃝ [3] [27] andM this work)
total amount of119876119899 units respectively As seen in Figure 8(a)an increase in concentration in themodifier oxide leads to thetransformation of the 1198762119894119895 groups in the following sequence119876244
rarr 119876243
rarr 119876233
rarr 119876232
rarr 119876222
rarr 119876221
rarr
119876211 It should be noted that the concentration of the 119876
244
and 119876243 groups relative to 119876
119899 units in the glass structureis low at 119909 gt 15mol (less than 15 see Figure 8(b))although their fraction relative to the total amount of 1198762119894119895
groups exceeds 40 Moreover the 1198762119894119895 groups are only
formed in the glass structure in an amount exceeding 1at 119909 gt 28mol as follows from Figure 8(b) As beforean increase in the width of the 119876
2119894119895(119909) curves and a shift
in the position of their maxima toward large 119909 values areobserved with increasing temperature The 119876
2119894119895(119909) maxima
change such that the difference between maxima decreaseswith increasing temperature
The 1198761119894 distribution has the simplest form which is
evidently related to the low variety of such groups (A changein 119894 from 4 to 1 gives only four types of 119876
1119894 groups) Theconcentration of the 119876
14 groups is negligible in the glassstructure Therefore a consequence of the transformationsof the 119876
1119894 groups looks similar to 11987613
rarr 11987612
rarr 11987611
The data presented in Figures 8(c) and 8(d) support theassumption that the changes in the 119876
1119894(119909) curves will be
similar to those described above
4 Discussion
41 Raman Spectra and Structure of the119909Cs2O-(100minus x)SiO2(x = 17 22 27 33 and 37mol) Glasses It is rational todivide the overall frequency range into low-frequency (400ndash700 cmminus1) and high-frequency (800ndash1200 cmminus1) intervals toanalyze the obtained Raman spectra The low-frequencyinterval is related to the stretching and some of the bending
vibrations of Si-O-Si linkages Two narrow lines (490 cmminus1(D1) and 602 cmminus1 (D
2)) along with a broad intense line
(sim450 cmminus1) are observed in the Raman spectrum of g-SiO2
(eg [28]) It is accepted that the D1and D
2lines can be
related to the symmetric oxygen breathing vibration of three-(D2) and four-membered (D
1) siloxane rings consisting of
SiO4tetrahedra [28ndash32] The investigation of the Raman
spectra of alkali silicate glasses with high SiO2content [33]
has shown that the bands near 490 and 602 cmminus1 are graduallyshifted toward higher and lower frequencies respectivelywith increasing Cs
2O content Thus it can be assumed that
the Raman bands near 510ndash530 and 598 cmminus1 in our spectrahave the same origin as the D
1and D
2lines respectively The
change in the intensity of these lines as a function of glasscomposition (see Figure 3) shows that the increase in mod-ifier oxide concentrations leads to changes in the statisticaldistribution of 119899-membered rings wherein the concentrationof three-membered rings gradually increases This obser-vation is in accordance with the results published in [27]where an increase in concentrations of three-membered ringswith increasing Cs
2O was shown based on NMR data The
concentration of the four-membered rings changes weakly at17 lt 119909 lt 22 and decreases at higher Cs
2O content
The Raman bands originating from the symmetricstretching vibration of the Si-Ominus terminal groups of various119876119899 (119899 lt 4) units are located in the high-frequency range of
spectra of alkali silicate glasses [34](i) the band at 1050ndash1100 cmminus1 is due to the symmetric
stretching vibrations of the terminal oxygen atoms ofSiO4tetrahedra with one nonbridging oxygen (NBO)
atom that is 1198763 units(ii) the band at 920ndash950 cmminus1 results from the Si-Ominus
stretching of SiO4tetrahedra with two NBO (1198762
units)
8 International Journal of Spectroscopy
15 20 25 30 35 40 45
0
1
2
3
4
5
6
7
10 200 30 400
20
40
60
80
100
Q43321
Q43221
Q44322
Q42222
Q43331Q44432
Q44332
Q43322
Q43222
Q43322
Q43332
Q43333
Q44333
Q44433
Q44443
Q44444
Q44332
[Q4ijk]
()
Cs2O (mol)
(a)
5
4
3
2
1
0
15 20 25 30 35 40 45
100 20 30 400
20
40
60
80
100
Q43332
Q43333Q44333
Q43333
Q44433
Q44443
Q44432
Q44332
Q44444
[Q4ijkl ]998400
()
Cs2O (mol)
(b)
100
80
60
40
20
00 10 20 30 40 50
15 20 30 40 50
0
2
4
6
8
10
[Q3ijk]
()
Q3311
Q3211
Q3111
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3221
Cs2O (mol)
(c)
100 20 30 40 50
20
10
0
30
40
50
60
70
80
2
0
1
3
4
5
6
10 20 30 40 50[Q3ijk]998400
()
Q3311
Q3221Q3331
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3222
Cs2O (mol)
(d)
Figure 7 1198764119894119895119896119897 ((a) and (b)) and 1198763119894119895119896 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines
119879 = 1223K) ((a) and (c) equation (3) (b) and (d) equation (4))
(iii) the Raman band near 900 cmminus1 is attributed to thestretching vibration of the 119876
1 units (SiO4tetrahedra
with three NBO)(iv) finally the line at 850 cmminus1 is related to the symmetric
stretching mode of 1198760 anionsAs seen in Figure 3 only the 1050ndash1100 and 930 cmminus1
bands are observed in the Raman spectra of studied glassesIt should be noted that the 1050ndash1100 cmminus1 band exists inall spectra whereas the 930 cmminus1 band is only observed inthe spectra of glasses with relatively high Cs
2O contents
(33Cs and 37Cs) In addition a high-frequency shoulderwith maximum at approximately 1150 cmminus1 is observed inthe Raman spectra of the 17Cs 22Cs and 27Cs samplesAlthough alkali silicate glasses have been studied for a longtime a review of the literature revealed that the origin of thisshoulder is still controversial In one series of publications[12 13 35] the 1150 cmminus1 line was attributed to the Si-Ostretching vibration in fully polymerized structural species
that is the vibrations of 1198764 units However based on a studyof the Raman spectra of alkali silicate glasses with variouscompositions Matson et al [33] have suggested that this linemay be assigned to the vibrations of the 119876
31015840 units whichare structurally and vibrationally distinguished from thoseof the 119876
3 units producing the 1050ndash1100 cmminus1 band Theyargued that the 1150 cmminus1 shoulder has significantly greaterintensity than could reasonably be assigned to residual g-SiO2spectral features In addition they found no correlation
between the intensity of this band and other bands (eg450 cmminus1) characteristic of the g-SiO
2spectrum Based on
these conclusions the 1150 cmminus1 shoulder was attributed to11987631015840 units which have slightly stronger (shorter) Si-Ominus bond
than the one producing the 1100 cmminus1 line [33]Matson et alrsquos assumption concerning the origin of the
1150 cmminus1 shoulder was confirmed later on by You with co-authors [6] The correlation between the Raman shift andconnecting topology of adjacent 119876119899 units was found based
International Journal of Spectroscopy 9
0
20
40
100
60
80
5 10 20 30 40 50
5
7
8
6
4
3
2
1
0
10 20 30 40 50
[Q2ij]
()
Cs2O (mol)
Q211
Q231
Q242
Q244
Q243
Q233
Q232
Q221
Q222
(a)
0
20
40
60
10
30
70
50
5 10 20 30 40 50
4
3
2
1
0
2010 30 40 50
[Q2ij]998400
()
Cs2O (mol)
Q211
Q231
Q244
Q243
Q233
Q232
Q221
Q222
(b)
36 38 44 48 5240 42 46 50 540
40
60
20
80
100
[Q1i ]
()
Cs2O (mol)
Q13Q12
Q11
Q14
(c)
0
15
20
10
25
30
5
36 38 44 48 5240 42 46 50 54
[Q1i ]998400
()
Cs2O (mol)
Q13
Q12
Q11
(d)
Figure 8 1198762119894119897 ((a) and (b)) and 1198761119894 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 =
1223K) ((a) and (c) equation (2) (b) and (d) equation (3))
on the quantum chemical calculation of the characteristicfrequencies of 119876
119899 species In other words it was demon-strated that the Raman shift of the symmetric stretchingvibration of 119876
119899 units decreases as the number of bridgingoxygen atoms of the nearest-neighbor 119876119899 species adjacent tothe given 119876
119899 unit decreases For example the Raman shiftof the 119876
3444 group is higher than that of the 1198763333 group
In our opinion the conclusions in [6] are strong evidenceof Matsonrsquos assumption Thus we will rely on Matsonrsquosinterpretation of the origin of 1150 cmminus1 band in our paper
The qualitative examination of the Raman spectra ofCs2O-SiO
2glasses (Figure 3) confirms that the structure of
glasses with a Cs2Ocontent below 33mol consists of1198764 and
1198763 units (the existence of1198764 units is obvious and requires no
evidence although the 1150 cmminus1 shoulder indirectly provesthe presence of such structural units) and that the 1198763 speciesare present at the least in the form of 119876
3444 and 1198763333
groups The Raman band at 930 cmminus1 shows that 1198762 units
are formed in the 33Cs and 37Cs glasses The presence of1198764 units in the structure of disilicate glasses is a result of
satisfying the charge balance (NBOSi = 1) Regarding the37Cs glass the presence of 1198764 species can be identified onlyby the quantitative analysis of the corresponding spectrum
The high-frequency envelope (800ndash1300 cmminus1) of theregistered Raman spectra was simulated as a superpositionof the Gaussian lines to estimate the 119876
119899 concentrationsThe number of Gaussian lines was sufficient to reproducethe original spectra with a correlation factor of ge098 Theinterpretation of the Raman bands described above was alsotaken into account In addition some results published in [6]were also taken into account 119876119899 species with equal 119899 givemore than one band and peak position of individual banddepends on the structural position of 119876119899 units For examplewavenumbers of NBO symmetric stretching vibration of 1198763species are located in the range of 1050 to 1150 cmminus1 whereas1198762 units give a set of the individual peaks in the range of
10 International Journal of Spectroscopy
60160260360460560660
H5
H4H3
22Cs
Ram
an in
tens
ity (a
u)
minus40
1443K
H1lowastH2lowast
50150250350450550650
H4H3
H5
27Cs
minus50
1553K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5
33Cs
minus40
1443K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5H6
37Cs
minus40
H2lowast
H1lowast
1443K
70170270370470570670770
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
793K
minus30
70170270370470570670
H4
H3
H5
Ram
an in
tens
ity (a
u)
1113K
minus30
H1lowastH2lowast
60160260360460560660
H4H3
H5
1113K
minus40
H1lowastH2lowast
70170270370470570670770
H4
H3H5
1223K
minus30
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1223K
minus30
H1lowastH2lowast
70170270370470570670770
H4H3
H5
898K
minus30
H1lowastH2lowast
60160260360460560660760860960
H4H3H5
793K
minus40
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1003K
minus30
H1lowastH2lowast
70170270370470570670770870
850 950 1050 1150 1250
H4
H3
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
70170270370470570670770
800 900 1000 1100 1200 1300
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
293K
minus30
Raman shift (cmminus1)
70170270370470570670770870970
800 900 1000 1100 1200 1300
H3H4
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
170370570770970
1170
800 900 1000 1100 1200 1300
H5H3 H4
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
Figure 9 Examples of the band deconvolution of Cs2O-SiO
2glasses and melts Raman spectra between 800 and 1300 cmminus1
930 to 1050 cmminus1 [6] Several examples of the deconvolutionresults of the Raman signal of the studied samples in the high-frequency region are shown in Figure 9 Four Gaussian lineswere sufficient to reproduce the low-temperature (293K)Raman spectra of the 17Cs and 22Cs glasses whereas five lineswere needed to simulate the 27Cs 33Cs and 37Cs spectraThe H3 and H4 bands were attributed to the 119876
3 speciesBecause the 17Cs and 22Cs glasses consist of1198764 and119876
3 unitsit is possible to assume that only four types of structuralgroups (119876344411987634431198763433 and119876
3333) can exist in structureof these glasses Considering the dependence of the Ramanshift of 1198763119894119895119896 groups on the 119894 119895 and 119896 indexes established in[6] it was assumed that the 119876
3444 and 1198763443 groups are the
main contributors to the intensity of the H4 band and thatthe vibrations of the 119876
3433 and 1198763333 groups are the main
contributors to the intensity of theH3 bandThis qualitativelyagrees with the simulation results of the 119876
3119894119895119896 distributionrepresented in Figures 7(c) and 7(d) The H2 band is mostlikely due to the stretching vibrations of the Si-O-Si linkages[3 31] The origin of the H1 line is unclear It is possible thatthis line is a result of the assumption of the Gaussian shape ofthe elementary bands in the spectra of glasses with relativelylow Cs
2O concentrations (17Cs and 22Cs) that is this line
is an error in the choice of the type of elementary bands
The relative area of the H1 band is the same for the 17Cs and22Cs spectra (002) and its intensity increases with furtherincreases in the Cs
2O content The H2 line behaves similarly
An increase in intensity of both H1 and H2 lines begins fromthe appearance of a new H5 line in the deconvolution of theRaman spectra The H5 line indicates the formation of 1198762species in the structure of the samples According to [6] itis possible to assume that the vibrations of the 119876
3119894119895119896 groupsconnected with one or two 119876
2 units for example 1198763332 and1198763322 groups also contribute to the intensity of the H2 band
at higher concentrations of the modifier oxide Thus the1060 cmminus1 line was designated as H2
lowast in the deconvolutionof the 27Cs 33Cs and 37Cs spectra In turn the H1
lowast linecan be attributed to the vibrations of the 119876
244 119876243 and119876233 groups according to the 119876
2119894119895 distribution representedin Figures 8(a) and 8(b) Finally the H5 line was ascribed to119876232 groupsThe localized nature of the silicon-oxygen stretching
motions of silicate units containing SiO4tetrahedra with
one two three or four nonbridging oxygen atoms [34 36]allows us to use the relative integral intensities of theGaussiancomponents to calculate the 119876119899 concentrations
If three types (1198764 1198763 1198762) of 119876
119899 species coexistin a structure simultaneously then their concentrations
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
2 International Journal of Spectroscopy
Q4 Q3 Q2 Q1 Q0
minus
minus
minus
minus
minus
minus minus
minus
minus
minus
Silicon atomBridging oxygen atomNonbridging oxygen atom
(a)
+ M2O rarr
2Q4 + M2Orarr2Q3
M+
M+
minus minus
Silicon atomBridging oxygen atomNonbridging oxygen atom
(b)
minus
Q3444
Silicon atomBridging oxygen atomNonbridging oxygen atom
Q3332
minus
minus
minus
minus
minus
Q3ndashQ4
Q3ndashQ4
Q3ndashQ4
Q3ndashQ3
Q3ndashQ3
Q3ndashQ2
(c)
Figure 1 Schematic 2-dimensional representations of the 119876119899 species (a) of the formation of 119876119899 species with nonbridging oxygen atoms (b)
and of some 119876119899119894119895119896119897 groups (c)
the 119876119899 distribution in the Li
2O-SiO
2system have shown
that equilibrium (1) is shifted to the left with increasingtemperature that is towards an increase in the concentrationof 1198763 units [7] To the best of our knowledge no data on the119876119899 distribution and its changes with temperature in cesium
silicatemelts can be found in the literatureTherefore the aimof this paper is a structural study of Cs
2O-SiO
2glasses and
melts by high-temperature Raman spectroscopyHigh-temperature Raman spectroscopy is a useful
method for investigating not only the glass structure but alsothe melt structure over a wide temperature range [5ndash15] Asis known the high-frequency region (800ndash1200 cmminus1) of thespectra of alkali silicate glasses and melts is characterizedby a series of Raman bands originating from the Si-Ominusstretching vibrations of various 119876
119899 units It is assumedthat the intensities of these bands are proportionate to theconcentrations of 119876
119899 species [3 5 7 8 10ndash15] Thereforethese bands can be used for the quantitative description ofthe structural changes of silicate glasses and melts dependingon both the composition and temperature
Although knowledge of the concentrations of 119876119899 speciesis important for describing the structure of silicate glassesand melts it does not provide a clear idea of their structurebecause the 119876
119899 distribution provides no information about
the interconnection between 119876119899 units Currently only a
limited number of publications address this problem and allof them focus on theNa
2O-SiO
2system [6 16ndash20]Therefore
this paper studies this problem for Cs2O-SiO
2glasses and
melts
2 Material and Methods
21 Sample Preparation Glass samples of the compositions119909Cs
2O-(100 minus x)SiO
2(119909 = 17 22 27 33 and 37mol)
were prepared by the conventional melting and quenchingmethod from reagent-grade SiO
2and Cs
2CO3 The initial
reagents were dried (120∘C for 2 h) weighed and mixed inthe required ratios The batch (5 g) was melted in a platinumcrucible at 119905 = 1000ndash1100∘C for 2ndash5 h (depending on themelt composition) to obtain a bubble-free meltThe obtainedmelt was cooled directly in a platinum crucible in air atroom temperature and then used for Raman measurementsat various temperatures To avoid glass hydration Ramanscattering measurements were started immediately after thesample preparation It should be noted that due to the highviscosity of the 17Cs
2O-83SiO
2melt we failed to prepare a
bubble-free glassy sample Thus this sample was only studiedin the glassy state
International Journal of Spectroscopy 3
22 Raman Experiments Raman scattering measurementswere performed on a specially designed high-temperatureapparatus based on a DFS-24 double monochromator Torecord the Raman spectra at different temperatures thesmall platinum crucible was placed into a vertical compactelectrical furnace Thus all spectra were recorded in 180∘geometry The operating temperature range was 20ndash1300∘Cand was controlled within plusmn1∘C The second-harmonic ofan LTI-701 solid-state pulsed laser (120582 = 532 nm ⟨119875⟩ =
500mW) operated at a modulation frequency of 87 kHzwas used as the excitation source The pulse duration ofthe acoustooptic switch was 2120583s An uncooled FEU-79photomultiplier was used to detect the Raman signal Agated photon counting system was applied to minimize thethermal radiation signal The spectral width of the slit was6 cmminus1 in all measurements A detailed description of theexperimental setup and recording conditions of the high-temperature Raman spectra can be found in [21ndash23]
To compare the spectra obtained at various temperaturesthey were reduced to obtain the temperature- and frequency-dependent scattering intensity
119868red (]) = 119868obs (]) [1 minus exp(
ℎ119888]119896119879
)]
]]30
(]0minus ])4
(2)
where 119868obs and 119868red are the observed and reduced Ramanintensities respectively ] and ]
0are the Raman shift and
wavenumber of the excitation source respectively and ℎ 119896119888 and 119879 represent Planckrsquos constant Boltzmannrsquos constantspeed of light and temperature respectively
23 Simulation of the 119876119899 119876119894ndash119876119895 and 119876
119899119894119895119896119897 DistributionsAs it is known Zachariasenrsquos rules [24] for glass formationare focused only on a local configuration of cation-oxygenpolyhedra and their connectivity to each other (via cornersnot edges or faces) Based on these rules it is possible toassume that the most important point in a modeling of alocal structure of silicate glasses is a coordination number ofglass-forming cations rather than a network dimensionalityand topology as a whole Any regular or random networkwhere each node has four linkages with the nearest nodesand each bond joins only two nodes reproduces completelythe 119876
119899 distribution in pure SiO2(all structural units are
1198764) Formally such network can be expressed in form of
the table consisting of five lines and 119873 columns when 119873
is a number of nodes in the system Top line contains theserial number of node and other four lines contain the serialnumbers of nodes which joined to the given in the top lineThus each column describes linkages between five nodesEach node in this table was interpreted as a silicon atom andhad four linkages with the nearest nodes The bond betweentwo nodes was interpreted as a Si-O-Si (hereafter we will usethe abbreviation 119876
119894ndash119876119895) bridging bond (some examples of119876119894ndash119876119895 bridging bonds are shown in Figure 1(c)) To calculate
the 119876119899 distribution it is necessary to break the preassigned
number of bonds (the number of the bonds that must bebroken is determined by the glass composition) and then theobtained configuration must be analyzed In this approach
eachnodewith 119899unbroken bonds and each broken bondwereinterpreted as a119876119899 unit and a Si-Ominus+MM+minusO-Si nonbridgingbond respectively Three parameters 1119908
1 11199082 and 1119908
3
were introduced into the modeling procedure to achieve thebest agreement between the experimental 119876119899 concentrationsand the calculated 119876
119899 distribution These parameters donot depend on the glass composition but do depend ontemperature and in addition to the concentration of varioustypes of nodes they determine the probability of the linkagebreak (Figure 2 demonstrates a role of these parameters in thecomputational algorithm) Taking into account the randomcharacter of the linkage choice and the table of linkages 50configurations were generated for each composition at a fixedtemperature The required concentrations of 119876119899 units wereobtained by averaging of all 50 configurations of the tableThe table was also analyzed to study the 119876
119894ndash119876119895 (bridgingbonds) and 119876
119899119894119895119896119897 (group connectivity) distributions basedon the 119876
119899 distribution data (eg schematic 2-dimensionalrepresentations of the 119876
3444 and 1198763332 groups are shown
in Figure 1(c)) Here 119899 is the number of bridging oxygenatoms and 119894 119895 119896 and 119897 indicate the type of connected 119876
119899
units The modeling was performed in a composition rangeof 0 to 55mol Cs
2O content at two fixed temperatures (293
and 1223K) A more detailed description of the modelingprocedure can be found in [25 26]
3 Results
31 Raman Spectra
311 Glass Spectra The Raman spectra of glasses with thecomposition 119909Cs
2O-(100 minus x)SiO
2(119909 = 17 22 27 33
and 37mol) are shown in Figure 3 in which the symbolicdesignations near the spectra (left side) indicate the Cs
2O
content The Raman spectra of glasses with relatively lowCs2O contents (119909 = 17 22 and 27mol) exhibit two bands
with peak intensities at 510 and 598 cmminus1 oneweakwide bandat approximately 785 cmminus1 and a line at 1100 cmminus1 havingthe highest intensity in each spectrum with a shoulder at1150 cmminus1 The peak position at 510 cmminus1 is gradually shiftedtoward higher frequencies and the 598 cmminus1 line is slightlyshifted toward lower frequencies with increasing Cs
2O con-
tent in the given composition range In addition the intensityof these bands increases whereas the intensity of the weakline at 785 cmminus1 decreases with the addition of cesium oxideFor the high-frequency envelope the shape of this contour ismost strongly affected by an increase in the modifier oxidecontent which causes a gradual resolution deterioration ofthe 1100 and 1150 cmminus1 bands and a drastic decrease inintensity for the high-frequency shoulder accompanied by anincrease in the intensity of the 1100 cmminus1 Raman band at 119909 gt
27mol The 1100 cmminus1 line becomes more symmetric andits width decreases A new band at approximately 930 cmminus1distinguishes the 33Cs and 37Cs spectra from the 119909 lt
33mol spectra The intensity of this band increases withincreasing 119909 It also should be noted that the intensity of the510ndash530 cmminus1 band is greater than that of the 598 cmminus1 bandat 119909 le 27mol and 119868
510ndash530 lt 119868598
at 119909 gt 27mol
4 International Journal of Spectroscopy
Searching
bond
All possiblechanges
No
Random number
(node choice)generator
Branchingpoint
Searching
bond
Searching
bond
Searching
bond
Branchingpoint
Branchingpoint
TrueTrueTrueTrue
NoNo No
False False FalseFalse
Exist Exist Exist Exist
1w1 1w2 1w3
n lt 4 n lt 3 n lt 2 n lt 1
2Q4rarr2Q3 2Q4rarr2Q3
Q4 + Q3rarrQ3 + Q2
2Q3rarr2Q2
2Q4rarr2Q3
Q4 + Q3rarrQ3 + Q2
2Q3rarr2Q2
Q4 + Q2rarrQ3 + Q1
Q3 + Q2rarrQ2 + Q1
2Q2rarr2Q1
for Q4ndashQ4 for Q43ndashQ43 for Q432ndashQ432 for Q4321ndashQ4321
1 minus 1w1 1 minus 1w2 1 minus 1w3
Figure 2 Block-diagram of simulation algorithm
312 High-Temperature Raman Spectra The Raman spectraof the 22Cs
2O-78SiO
2and 27Cs
2O-73SiO
2samples
measured at different temperatures are shown in Figures4(a) and 4(b) As seen in Figure 4(a) the peak intensityat 530 cmminus1 decreases slightly and its position is graduallyshifted toward lower frequencies with increasing tempera-ture The peak intensity at 598 cmminus1 in contrast to that of530 cmminus1 band increases with increasing temperature andremains at essentially the same frequency No significantchanges are observed in the peak intensity or the shape of thehigh-frequency envelope (1000ndash1200 cmminus1) at relatively lowtemperatures (up to sim898ndash1003K) Only one symmetric wideline with maximum near 1100 cmminus1 is observed in the high-frequency region at higher temperatures and the intensityof this line decreases with increasing temperature A newweak band at 930 cmminus1 that appeared in the Raman spectrameasured at temperatures above 1003K is another peculiarityof the high-temperature spectra All of the above-mentionedfeatures of the changes in the 22Cs spectra with temperatureare observed in the 27Cs spectra as well
The Raman spectra of glasses and melts with modifieroxide contents of 33 and 37mol are shown in Figures 5(a)and 5(b) respectively In contrast to the previous spectra the
line near 920ndash930 cmminus1 is observed at all temperatures and itsintensity increases with temperature This line is most clearlyobserved in the 37Cs spectra The peak intensity at 1100 cmminus1obviously decreases with increasing temperature and itsposition shifts slightly toward lower frequencies In additionthe width of this band increases The intensities of the low-frequency bands (520ndash530 and 598 cmminus1) depend weaklyon temperature but their width significantly increases withtemperature Finally the formation of another new Ramanline in the melt spectra with a maximum near 420 cmminus1should be noted (see Figure 5(b)) This line is observed inthe previous spectra only as an unresolved low-frequencyshoulder near the 530 cmminus1 band
32 Modeling Results The results of the modeling of the 119876119899
and 119876119894ndash119876119895 distributions in the Cs
2O-SiO
2system at two
different temperatures (293K solid lines 1223K dotted lines)are shown in Figures 6(a) and 6(b) respectively In additionto our experimental data the literature data [1 3 27] onthe concentrations of 119876
119899 units in the Cs2O-SiO
2glasses
and melts are also shown in Figure 6(a) As seen in thisfigure the modeled curves well describe the experimentaldata for both glasses and melts over a wide compositions
International Journal of Spectroscopy 5
1150
1100
930
785
598
530
51037Cs
33Cs
27Cs
22Cs17Cs
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
Figure 3 Raman spectra of 119909Cs2O-(100 minus x)SiO
2(119909 = 17 22 27
33 and 37mol) glasses
range Temperature changes have no significant effect onthe concentration of 119876
119899 units in glasses and melts withrelatively low Cs
2O contents (up to sim15mol) as well as in
a narrow composition interval near 40mol In turn mostconsiderable changes in the 119876
119899 distribution are observed forsamples with disilicate and metasilicate compositions Herethe concentrations of the dominant type of structural units(1198763 and119876
2 for disilicate andmetasilicate resp) decrease withincreasing temperature and are accompanied by an increasein the concentration of other structural units with 119899 differingby plusmn1 In the aggregate this phenomenon causes the curvesdescribing the dependences of the 119876
3 and 1198762 units on the
composition to be slightly wider for the melts than for theglasses but the positions of their maxima do not change withtemperature
As seen in Figure 6(b) only 119876119894ndash119876119895 bridging bonds with
|119894 minus 119895| = 0 or 1 may be observed in the system among allpossibilities (1198764ndash11987641198764ndash11987631198764ndash11987621198764ndash11987611198763ndash11987631198763ndash11987621198763ndash1198761 1198762ndash1198762 1198762ndash1198761 1198761ndash1198761) of 119876
119894ndash119876119895 bridging bondsThe maxima of the 119876
119894ndash119876119895 curves decrease with increasing|119894 minus 119895| and are approximately the same for the 119876
119894ndash119876119895 bondswith the same |119894 minus 119895| values The maxima of the 119876
4ndash1198763 and1198763ndash1198762 curves dependweakly on temperature (approximately
1) whereas the positions of thesemaxima are shifted towardhigher Cs
2O concentrations In addition an increase in the
width of these curves is also observedThewidth and positionof the peak of the1198763ndash1198763 and119876
2ndash1198762 curves behave similarlybut their maxima decreasemore dramatically with increasingtemperature (approximately 20)The119876119894ndash119876119895 curves with |119894minus
119895| = 2 are shown in the inset to Figure 6(b) As observed thedependence of the concentration of the given 119876
119894ndash119876119895 bridgeson temperature is opposite to that typical for119876119894ndash119876119895 bridgingbonds with |119894 minus 119895| = 0 In this case a significant increase
in the 1198764ndash1198762 and 119876
3ndash1198761 concentrations with increasingtemperature is observed Nevertheless the concentration ofthese Si-O-Si bonds is low in both glass and melt and is lessthan 1 and 4 at 293 and 1223K respectively
The modeling results of the concentrations of the 1198764119894119895119896119897
and 1198763119894119895119896 groups as a function of composition at different
temperatures (293 and 1223K) are shown in Figures 7(a)ndash7(d)The concentrations were calculated in two ways relativeto the concentration of the appropriate type of structural unit(Figures 7(a) and 7(c) for 1198764119894119895119896119897 and 119876
3119894119895119896 resp)
[119876119899119894119895119896119897
] =
119873119876119899119894119895119896119897
119873119876119899
times 100 (3)
and relative to the total concentration of 119876119899 units (Figures7(b) and 7(d) for 1198764119894119895119896119897 and 119876
3119894119895119896 resp)
[119876119899119894119895119896119897
] =
119873119876119899119894119895119896119897
sum4
119899=0119873119876119899
times 100 (4)
In these equations 119873119876119899119894119895119896119897 and 119873
119876119899 are the amounts of
different types of groups and structural units respectivelyAs seen in Figure 7(a) the gradual increase in concen-
tration of the modifier oxide leads to the following trans-formations of the 119876
4119894119895119896119897 groupings 11987644444 rarr 11987644443
rarr
11987644433
rarr 11987644333
rarr 11987643333
rarr 11987643332 In addition
11987644432 11987644332 and 119876
43322 groups are also formed in theglass structure As seen in the inset to Figure 7(a) howevertheir concentrations are lower than 7 Both the coexistenceregions and the variety of the 119876
4119894119895119896119897 groups are higher inmelts than in glasses The 119876
44332 11987643322 and 11987643222 groups
supplement the list of 1198764119894119895119896119897 groups at high temperature
(1223K) Their maximum concentration exceeds 7 in themelt structure and is low in the glasses The 119876
44322 1198764222211987643221 11987643331 and 119876
43321 groups may also appear in themelt structure but their concentration is less than 7 (seeFigure 7(a)) The shape of the 119876
44444(119909) 119876
44443(119909) and
11987644433
(119909) curves depends slightly on temperature whereasthe 119876
44333(119909) 11987643333(119909) and 119876
43332(119909) curves are subject
to dramatic changes An increase in the width of the curvesand a shift in the position of their maxima toward large 119909 aretypical for all of themThe ratio between the maxima of thesecurves at 293K is
11987211987643333 gt 119872
11987644333 asymp 119872
11987644332 (5)
and that at 1223K is
11987211987643332 gt 119872
11987644333 gt 119872
11987643333 (6)
The region of existence of the 1198763119894119895119896 groups is somewhat
broader than that of 1198764119894119895119896119897 and extends to 119909 asymp 52mol (seeFigure 7(c)) The transformation of 1198763119894119895119896 groups dependingon 119909 can be represented by the sequence1198763444 rarr 119876
3443rarr
1198763433
rarr 1198763333
rarr 1198763332
rarr 1198763322
rarr 1198763222
rarr 1198763221
In addition some amount of 1198763432 groups (less than 3 ofthe total amount of1198763 units) and119876
3321 groups (less than 4)can exist in the glass structure with disilicate andmetasilicate
6 International Journal of Spectroscopy
15531443
1223
1113
1003
898
793
683
473
293
530598
930
1100
1150
Raman shift (cmminus1)13001100900700500300
Ram
an in
tens
ity (a
u)
(a)
1223
1553
1338
1113
1003
898
793
293
530
573
683
598920
1100
1150
13001100900700500300
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)
(b)
Figure 4 Low- and high-temperature Raman spectra of the 22Cs2O-78SiO
2(a) and 27Cs
2O-73SiO
2(b) glasses andmelts (hereinafter
a temperature of the samples is shown in K)
1443
1338
1223
11131003
898
793
683
573
293
598530 920
1100
1150
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(a)
1443
1338
1223
1113
1003
573
293
420520 598
930
1100
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(b)
Figure 5 Low- and high-temperature Raman spectra of the 33Cs2O-67SiO
2(a) and 37Cs
2O-63SiO
2(b) glasses and melts
compositions respectively (see the inset in Figure 7(c))The region of coexistence of the 119876
3119894119895119896 groups increases bysim25 and reaches 55 as the temperature increases up to1223K It is also accompanied by an increase in the widthof the 119876
3119894119895119896(119909) curves a shift of the maxima of these curves
toward large 119909 values and the leveling of their maxima Theconcentration of the dominant type of structural group (ata given composition) decreases and the fraction of the 119876
3119894119895119896
groups that are untypical for glass increases with increasingtemperature As before no significant changes are observedin the 1198763119894119895119896 distribution at 119909 lt 20mol
The1198762119894119895 and1198761119894 distributions calculated according to (3)
and (4) are shown in Figures 7(a)ndash7(d) Figures 8(a) and 8(c)represent the1198762119894119895 and119876
1119894 distributions relative to the1198762 and1198761 contents respectively and Figures 8(b) and 8(d) represent
the concentrations of the 1198762119894119895 and 119876
1119894 groups relative to the
International Journal of Spectroscopy 7
10 20 30 40 5000
20
40
60
80
100
Q4
Q3Q2
Q1
Q0
[Qn]
()
Cs2O (mol)
(a)
20 25 30 35 40 45 50 55
0
1
2
3
4
0 10 20 30 40 500
20
40
60
80
100
Qi ndashQ
j(
)
Q4ndashQ4
Q4ndashQ3
Q3ndashQ3 Q2ndashQ2
Q3ndashQ2
Q2ndashQ1
Q4ndashQ2
Q3ndashQ1
Q1ndashQ1
Cs2O (mol)
(b)
Figure 6 119876119899 (a) and 119876119894ndash119876119895 (b) distributions for glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 = 1223K) of Cs
2O-SiO
2system
Symbols are experimental data (◻ [1] ⃝ [3] [27] andM this work)
total amount of119876119899 units respectively As seen in Figure 8(a)an increase in concentration in themodifier oxide leads to thetransformation of the 1198762119894119895 groups in the following sequence119876244
rarr 119876243
rarr 119876233
rarr 119876232
rarr 119876222
rarr 119876221
rarr
119876211 It should be noted that the concentration of the 119876
244
and 119876243 groups relative to 119876
119899 units in the glass structureis low at 119909 gt 15mol (less than 15 see Figure 8(b))although their fraction relative to the total amount of 1198762119894119895
groups exceeds 40 Moreover the 1198762119894119895 groups are only
formed in the glass structure in an amount exceeding 1at 119909 gt 28mol as follows from Figure 8(b) As beforean increase in the width of the 119876
2119894119895(119909) curves and a shift
in the position of their maxima toward large 119909 values areobserved with increasing temperature The 119876
2119894119895(119909) maxima
change such that the difference between maxima decreaseswith increasing temperature
The 1198761119894 distribution has the simplest form which is
evidently related to the low variety of such groups (A changein 119894 from 4 to 1 gives only four types of 119876
1119894 groups) Theconcentration of the 119876
14 groups is negligible in the glassstructure Therefore a consequence of the transformationsof the 119876
1119894 groups looks similar to 11987613
rarr 11987612
rarr 11987611
The data presented in Figures 8(c) and 8(d) support theassumption that the changes in the 119876
1119894(119909) curves will be
similar to those described above
4 Discussion
41 Raman Spectra and Structure of the119909Cs2O-(100minus x)SiO2(x = 17 22 27 33 and 37mol) Glasses It is rational todivide the overall frequency range into low-frequency (400ndash700 cmminus1) and high-frequency (800ndash1200 cmminus1) intervals toanalyze the obtained Raman spectra The low-frequencyinterval is related to the stretching and some of the bending
vibrations of Si-O-Si linkages Two narrow lines (490 cmminus1(D1) and 602 cmminus1 (D
2)) along with a broad intense line
(sim450 cmminus1) are observed in the Raman spectrum of g-SiO2
(eg [28]) It is accepted that the D1and D
2lines can be
related to the symmetric oxygen breathing vibration of three-(D2) and four-membered (D
1) siloxane rings consisting of
SiO4tetrahedra [28ndash32] The investigation of the Raman
spectra of alkali silicate glasses with high SiO2content [33]
has shown that the bands near 490 and 602 cmminus1 are graduallyshifted toward higher and lower frequencies respectivelywith increasing Cs
2O content Thus it can be assumed that
the Raman bands near 510ndash530 and 598 cmminus1 in our spectrahave the same origin as the D
1and D
2lines respectively The
change in the intensity of these lines as a function of glasscomposition (see Figure 3) shows that the increase in mod-ifier oxide concentrations leads to changes in the statisticaldistribution of 119899-membered rings wherein the concentrationof three-membered rings gradually increases This obser-vation is in accordance with the results published in [27]where an increase in concentrations of three-membered ringswith increasing Cs
2O was shown based on NMR data The
concentration of the four-membered rings changes weakly at17 lt 119909 lt 22 and decreases at higher Cs
2O content
The Raman bands originating from the symmetricstretching vibration of the Si-Ominus terminal groups of various119876119899 (119899 lt 4) units are located in the high-frequency range of
spectra of alkali silicate glasses [34](i) the band at 1050ndash1100 cmminus1 is due to the symmetric
stretching vibrations of the terminal oxygen atoms ofSiO4tetrahedra with one nonbridging oxygen (NBO)
atom that is 1198763 units(ii) the band at 920ndash950 cmminus1 results from the Si-Ominus
stretching of SiO4tetrahedra with two NBO (1198762
units)
8 International Journal of Spectroscopy
15 20 25 30 35 40 45
0
1
2
3
4
5
6
7
10 200 30 400
20
40
60
80
100
Q43321
Q43221
Q44322
Q42222
Q43331Q44432
Q44332
Q43322
Q43222
Q43322
Q43332
Q43333
Q44333
Q44433
Q44443
Q44444
Q44332
[Q4ijk]
()
Cs2O (mol)
(a)
5
4
3
2
1
0
15 20 25 30 35 40 45
100 20 30 400
20
40
60
80
100
Q43332
Q43333Q44333
Q43333
Q44433
Q44443
Q44432
Q44332
Q44444
[Q4ijkl ]998400
()
Cs2O (mol)
(b)
100
80
60
40
20
00 10 20 30 40 50
15 20 30 40 50
0
2
4
6
8
10
[Q3ijk]
()
Q3311
Q3211
Q3111
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3221
Cs2O (mol)
(c)
100 20 30 40 50
20
10
0
30
40
50
60
70
80
2
0
1
3
4
5
6
10 20 30 40 50[Q3ijk]998400
()
Q3311
Q3221Q3331
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3222
Cs2O (mol)
(d)
Figure 7 1198764119894119895119896119897 ((a) and (b)) and 1198763119894119895119896 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines
119879 = 1223K) ((a) and (c) equation (3) (b) and (d) equation (4))
(iii) the Raman band near 900 cmminus1 is attributed to thestretching vibration of the 119876
1 units (SiO4tetrahedra
with three NBO)(iv) finally the line at 850 cmminus1 is related to the symmetric
stretching mode of 1198760 anionsAs seen in Figure 3 only the 1050ndash1100 and 930 cmminus1
bands are observed in the Raman spectra of studied glassesIt should be noted that the 1050ndash1100 cmminus1 band exists inall spectra whereas the 930 cmminus1 band is only observed inthe spectra of glasses with relatively high Cs
2O contents
(33Cs and 37Cs) In addition a high-frequency shoulderwith maximum at approximately 1150 cmminus1 is observed inthe Raman spectra of the 17Cs 22Cs and 27Cs samplesAlthough alkali silicate glasses have been studied for a longtime a review of the literature revealed that the origin of thisshoulder is still controversial In one series of publications[12 13 35] the 1150 cmminus1 line was attributed to the Si-Ostretching vibration in fully polymerized structural species
that is the vibrations of 1198764 units However based on a studyof the Raman spectra of alkali silicate glasses with variouscompositions Matson et al [33] have suggested that this linemay be assigned to the vibrations of the 119876
31015840 units whichare structurally and vibrationally distinguished from thoseof the 119876
3 units producing the 1050ndash1100 cmminus1 band Theyargued that the 1150 cmminus1 shoulder has significantly greaterintensity than could reasonably be assigned to residual g-SiO2spectral features In addition they found no correlation
between the intensity of this band and other bands (eg450 cmminus1) characteristic of the g-SiO
2spectrum Based on
these conclusions the 1150 cmminus1 shoulder was attributed to11987631015840 units which have slightly stronger (shorter) Si-Ominus bond
than the one producing the 1100 cmminus1 line [33]Matson et alrsquos assumption concerning the origin of the
1150 cmminus1 shoulder was confirmed later on by You with co-authors [6] The correlation between the Raman shift andconnecting topology of adjacent 119876119899 units was found based
International Journal of Spectroscopy 9
0
20
40
100
60
80
5 10 20 30 40 50
5
7
8
6
4
3
2
1
0
10 20 30 40 50
[Q2ij]
()
Cs2O (mol)
Q211
Q231
Q242
Q244
Q243
Q233
Q232
Q221
Q222
(a)
0
20
40
60
10
30
70
50
5 10 20 30 40 50
4
3
2
1
0
2010 30 40 50
[Q2ij]998400
()
Cs2O (mol)
Q211
Q231
Q244
Q243
Q233
Q232
Q221
Q222
(b)
36 38 44 48 5240 42 46 50 540
40
60
20
80
100
[Q1i ]
()
Cs2O (mol)
Q13Q12
Q11
Q14
(c)
0
15
20
10
25
30
5
36 38 44 48 5240 42 46 50 54
[Q1i ]998400
()
Cs2O (mol)
Q13
Q12
Q11
(d)
Figure 8 1198762119894119897 ((a) and (b)) and 1198761119894 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 =
1223K) ((a) and (c) equation (2) (b) and (d) equation (3))
on the quantum chemical calculation of the characteristicfrequencies of 119876
119899 species In other words it was demon-strated that the Raman shift of the symmetric stretchingvibration of 119876
119899 units decreases as the number of bridgingoxygen atoms of the nearest-neighbor 119876119899 species adjacent tothe given 119876
119899 unit decreases For example the Raman shiftof the 119876
3444 group is higher than that of the 1198763333 group
In our opinion the conclusions in [6] are strong evidenceof Matsonrsquos assumption Thus we will rely on Matsonrsquosinterpretation of the origin of 1150 cmminus1 band in our paper
The qualitative examination of the Raman spectra ofCs2O-SiO
2glasses (Figure 3) confirms that the structure of
glasses with a Cs2Ocontent below 33mol consists of1198764 and
1198763 units (the existence of1198764 units is obvious and requires no
evidence although the 1150 cmminus1 shoulder indirectly provesthe presence of such structural units) and that the 1198763 speciesare present at the least in the form of 119876
3444 and 1198763333
groups The Raman band at 930 cmminus1 shows that 1198762 units
are formed in the 33Cs and 37Cs glasses The presence of1198764 units in the structure of disilicate glasses is a result of
satisfying the charge balance (NBOSi = 1) Regarding the37Cs glass the presence of 1198764 species can be identified onlyby the quantitative analysis of the corresponding spectrum
The high-frequency envelope (800ndash1300 cmminus1) of theregistered Raman spectra was simulated as a superpositionof the Gaussian lines to estimate the 119876
119899 concentrationsThe number of Gaussian lines was sufficient to reproducethe original spectra with a correlation factor of ge098 Theinterpretation of the Raman bands described above was alsotaken into account In addition some results published in [6]were also taken into account 119876119899 species with equal 119899 givemore than one band and peak position of individual banddepends on the structural position of 119876119899 units For examplewavenumbers of NBO symmetric stretching vibration of 1198763species are located in the range of 1050 to 1150 cmminus1 whereas1198762 units give a set of the individual peaks in the range of
10 International Journal of Spectroscopy
60160260360460560660
H5
H4H3
22Cs
Ram
an in
tens
ity (a
u)
minus40
1443K
H1lowastH2lowast
50150250350450550650
H4H3
H5
27Cs
minus50
1553K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5
33Cs
minus40
1443K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5H6
37Cs
minus40
H2lowast
H1lowast
1443K
70170270370470570670770
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
793K
minus30
70170270370470570670
H4
H3
H5
Ram
an in
tens
ity (a
u)
1113K
minus30
H1lowastH2lowast
60160260360460560660
H4H3
H5
1113K
minus40
H1lowastH2lowast
70170270370470570670770
H4
H3H5
1223K
minus30
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1223K
minus30
H1lowastH2lowast
70170270370470570670770
H4H3
H5
898K
minus30
H1lowastH2lowast
60160260360460560660760860960
H4H3H5
793K
minus40
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1003K
minus30
H1lowastH2lowast
70170270370470570670770870
850 950 1050 1150 1250
H4
H3
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
70170270370470570670770
800 900 1000 1100 1200 1300
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
293K
minus30
Raman shift (cmminus1)
70170270370470570670770870970
800 900 1000 1100 1200 1300
H3H4
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
170370570770970
1170
800 900 1000 1100 1200 1300
H5H3 H4
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
Figure 9 Examples of the band deconvolution of Cs2O-SiO
2glasses and melts Raman spectra between 800 and 1300 cmminus1
930 to 1050 cmminus1 [6] Several examples of the deconvolutionresults of the Raman signal of the studied samples in the high-frequency region are shown in Figure 9 Four Gaussian lineswere sufficient to reproduce the low-temperature (293K)Raman spectra of the 17Cs and 22Cs glasses whereas five lineswere needed to simulate the 27Cs 33Cs and 37Cs spectraThe H3 and H4 bands were attributed to the 119876
3 speciesBecause the 17Cs and 22Cs glasses consist of1198764 and119876
3 unitsit is possible to assume that only four types of structuralgroups (119876344411987634431198763433 and119876
3333) can exist in structureof these glasses Considering the dependence of the Ramanshift of 1198763119894119895119896 groups on the 119894 119895 and 119896 indexes established in[6] it was assumed that the 119876
3444 and 1198763443 groups are the
main contributors to the intensity of the H4 band and thatthe vibrations of the 119876
3433 and 1198763333 groups are the main
contributors to the intensity of theH3 bandThis qualitativelyagrees with the simulation results of the 119876
3119894119895119896 distributionrepresented in Figures 7(c) and 7(d) The H2 band is mostlikely due to the stretching vibrations of the Si-O-Si linkages[3 31] The origin of the H1 line is unclear It is possible thatthis line is a result of the assumption of the Gaussian shape ofthe elementary bands in the spectra of glasses with relativelylow Cs
2O concentrations (17Cs and 22Cs) that is this line
is an error in the choice of the type of elementary bands
The relative area of the H1 band is the same for the 17Cs and22Cs spectra (002) and its intensity increases with furtherincreases in the Cs
2O content The H2 line behaves similarly
An increase in intensity of both H1 and H2 lines begins fromthe appearance of a new H5 line in the deconvolution of theRaman spectra The H5 line indicates the formation of 1198762species in the structure of the samples According to [6] itis possible to assume that the vibrations of the 119876
3119894119895119896 groupsconnected with one or two 119876
2 units for example 1198763332 and1198763322 groups also contribute to the intensity of the H2 band
at higher concentrations of the modifier oxide Thus the1060 cmminus1 line was designated as H2
lowast in the deconvolutionof the 27Cs 33Cs and 37Cs spectra In turn the H1
lowast linecan be attributed to the vibrations of the 119876
244 119876243 and119876233 groups according to the 119876
2119894119895 distribution representedin Figures 8(a) and 8(b) Finally the H5 line was ascribed to119876232 groupsThe localized nature of the silicon-oxygen stretching
motions of silicate units containing SiO4tetrahedra with
one two three or four nonbridging oxygen atoms [34 36]allows us to use the relative integral intensities of theGaussiancomponents to calculate the 119876119899 concentrations
If three types (1198764 1198763 1198762) of 119876
119899 species coexistin a structure simultaneously then their concentrations
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
International Journal of Spectroscopy 3
22 Raman Experiments Raman scattering measurementswere performed on a specially designed high-temperatureapparatus based on a DFS-24 double monochromator Torecord the Raman spectra at different temperatures thesmall platinum crucible was placed into a vertical compactelectrical furnace Thus all spectra were recorded in 180∘geometry The operating temperature range was 20ndash1300∘Cand was controlled within plusmn1∘C The second-harmonic ofan LTI-701 solid-state pulsed laser (120582 = 532 nm ⟨119875⟩ =
500mW) operated at a modulation frequency of 87 kHzwas used as the excitation source The pulse duration ofthe acoustooptic switch was 2120583s An uncooled FEU-79photomultiplier was used to detect the Raman signal Agated photon counting system was applied to minimize thethermal radiation signal The spectral width of the slit was6 cmminus1 in all measurements A detailed description of theexperimental setup and recording conditions of the high-temperature Raman spectra can be found in [21ndash23]
To compare the spectra obtained at various temperaturesthey were reduced to obtain the temperature- and frequency-dependent scattering intensity
119868red (]) = 119868obs (]) [1 minus exp(
ℎ119888]119896119879
)]
]]30
(]0minus ])4
(2)
where 119868obs and 119868red are the observed and reduced Ramanintensities respectively ] and ]
0are the Raman shift and
wavenumber of the excitation source respectively and ℎ 119896119888 and 119879 represent Planckrsquos constant Boltzmannrsquos constantspeed of light and temperature respectively
23 Simulation of the 119876119899 119876119894ndash119876119895 and 119876
119899119894119895119896119897 DistributionsAs it is known Zachariasenrsquos rules [24] for glass formationare focused only on a local configuration of cation-oxygenpolyhedra and their connectivity to each other (via cornersnot edges or faces) Based on these rules it is possible toassume that the most important point in a modeling of alocal structure of silicate glasses is a coordination number ofglass-forming cations rather than a network dimensionalityand topology as a whole Any regular or random networkwhere each node has four linkages with the nearest nodesand each bond joins only two nodes reproduces completelythe 119876
119899 distribution in pure SiO2(all structural units are
1198764) Formally such network can be expressed in form of
the table consisting of five lines and 119873 columns when 119873
is a number of nodes in the system Top line contains theserial number of node and other four lines contain the serialnumbers of nodes which joined to the given in the top lineThus each column describes linkages between five nodesEach node in this table was interpreted as a silicon atom andhad four linkages with the nearest nodes The bond betweentwo nodes was interpreted as a Si-O-Si (hereafter we will usethe abbreviation 119876
119894ndash119876119895) bridging bond (some examples of119876119894ndash119876119895 bridging bonds are shown in Figure 1(c)) To calculate
the 119876119899 distribution it is necessary to break the preassigned
number of bonds (the number of the bonds that must bebroken is determined by the glass composition) and then theobtained configuration must be analyzed In this approach
eachnodewith 119899unbroken bonds and each broken bondwereinterpreted as a119876119899 unit and a Si-Ominus+MM+minusO-Si nonbridgingbond respectively Three parameters 1119908
1 11199082 and 1119908
3
were introduced into the modeling procedure to achieve thebest agreement between the experimental 119876119899 concentrationsand the calculated 119876
119899 distribution These parameters donot depend on the glass composition but do depend ontemperature and in addition to the concentration of varioustypes of nodes they determine the probability of the linkagebreak (Figure 2 demonstrates a role of these parameters in thecomputational algorithm) Taking into account the randomcharacter of the linkage choice and the table of linkages 50configurations were generated for each composition at a fixedtemperature The required concentrations of 119876119899 units wereobtained by averaging of all 50 configurations of the tableThe table was also analyzed to study the 119876
119894ndash119876119895 (bridgingbonds) and 119876
119899119894119895119896119897 (group connectivity) distributions basedon the 119876
119899 distribution data (eg schematic 2-dimensionalrepresentations of the 119876
3444 and 1198763332 groups are shown
in Figure 1(c)) Here 119899 is the number of bridging oxygenatoms and 119894 119895 119896 and 119897 indicate the type of connected 119876
119899
units The modeling was performed in a composition rangeof 0 to 55mol Cs
2O content at two fixed temperatures (293
and 1223K) A more detailed description of the modelingprocedure can be found in [25 26]
3 Results
31 Raman Spectra
311 Glass Spectra The Raman spectra of glasses with thecomposition 119909Cs
2O-(100 minus x)SiO
2(119909 = 17 22 27 33
and 37mol) are shown in Figure 3 in which the symbolicdesignations near the spectra (left side) indicate the Cs
2O
content The Raman spectra of glasses with relatively lowCs2O contents (119909 = 17 22 and 27mol) exhibit two bands
with peak intensities at 510 and 598 cmminus1 oneweakwide bandat approximately 785 cmminus1 and a line at 1100 cmminus1 havingthe highest intensity in each spectrum with a shoulder at1150 cmminus1 The peak position at 510 cmminus1 is gradually shiftedtoward higher frequencies and the 598 cmminus1 line is slightlyshifted toward lower frequencies with increasing Cs
2O con-
tent in the given composition range In addition the intensityof these bands increases whereas the intensity of the weakline at 785 cmminus1 decreases with the addition of cesium oxideFor the high-frequency envelope the shape of this contour ismost strongly affected by an increase in the modifier oxidecontent which causes a gradual resolution deterioration ofthe 1100 and 1150 cmminus1 bands and a drastic decrease inintensity for the high-frequency shoulder accompanied by anincrease in the intensity of the 1100 cmminus1 Raman band at 119909 gt
27mol The 1100 cmminus1 line becomes more symmetric andits width decreases A new band at approximately 930 cmminus1distinguishes the 33Cs and 37Cs spectra from the 119909 lt
33mol spectra The intensity of this band increases withincreasing 119909 It also should be noted that the intensity of the510ndash530 cmminus1 band is greater than that of the 598 cmminus1 bandat 119909 le 27mol and 119868
510ndash530 lt 119868598
at 119909 gt 27mol
4 International Journal of Spectroscopy
Searching
bond
All possiblechanges
No
Random number
(node choice)generator
Branchingpoint
Searching
bond
Searching
bond
Searching
bond
Branchingpoint
Branchingpoint
TrueTrueTrueTrue
NoNo No
False False FalseFalse
Exist Exist Exist Exist
1w1 1w2 1w3
n lt 4 n lt 3 n lt 2 n lt 1
2Q4rarr2Q3 2Q4rarr2Q3
Q4 + Q3rarrQ3 + Q2
2Q3rarr2Q2
2Q4rarr2Q3
Q4 + Q3rarrQ3 + Q2
2Q3rarr2Q2
Q4 + Q2rarrQ3 + Q1
Q3 + Q2rarrQ2 + Q1
2Q2rarr2Q1
for Q4ndashQ4 for Q43ndashQ43 for Q432ndashQ432 for Q4321ndashQ4321
1 minus 1w1 1 minus 1w2 1 minus 1w3
Figure 2 Block-diagram of simulation algorithm
312 High-Temperature Raman Spectra The Raman spectraof the 22Cs
2O-78SiO
2and 27Cs
2O-73SiO
2samples
measured at different temperatures are shown in Figures4(a) and 4(b) As seen in Figure 4(a) the peak intensityat 530 cmminus1 decreases slightly and its position is graduallyshifted toward lower frequencies with increasing tempera-ture The peak intensity at 598 cmminus1 in contrast to that of530 cmminus1 band increases with increasing temperature andremains at essentially the same frequency No significantchanges are observed in the peak intensity or the shape of thehigh-frequency envelope (1000ndash1200 cmminus1) at relatively lowtemperatures (up to sim898ndash1003K) Only one symmetric wideline with maximum near 1100 cmminus1 is observed in the high-frequency region at higher temperatures and the intensityof this line decreases with increasing temperature A newweak band at 930 cmminus1 that appeared in the Raman spectrameasured at temperatures above 1003K is another peculiarityof the high-temperature spectra All of the above-mentionedfeatures of the changes in the 22Cs spectra with temperatureare observed in the 27Cs spectra as well
The Raman spectra of glasses and melts with modifieroxide contents of 33 and 37mol are shown in Figures 5(a)and 5(b) respectively In contrast to the previous spectra the
line near 920ndash930 cmminus1 is observed at all temperatures and itsintensity increases with temperature This line is most clearlyobserved in the 37Cs spectra The peak intensity at 1100 cmminus1obviously decreases with increasing temperature and itsposition shifts slightly toward lower frequencies In additionthe width of this band increases The intensities of the low-frequency bands (520ndash530 and 598 cmminus1) depend weaklyon temperature but their width significantly increases withtemperature Finally the formation of another new Ramanline in the melt spectra with a maximum near 420 cmminus1should be noted (see Figure 5(b)) This line is observed inthe previous spectra only as an unresolved low-frequencyshoulder near the 530 cmminus1 band
32 Modeling Results The results of the modeling of the 119876119899
and 119876119894ndash119876119895 distributions in the Cs
2O-SiO
2system at two
different temperatures (293K solid lines 1223K dotted lines)are shown in Figures 6(a) and 6(b) respectively In additionto our experimental data the literature data [1 3 27] onthe concentrations of 119876
119899 units in the Cs2O-SiO
2glasses
and melts are also shown in Figure 6(a) As seen in thisfigure the modeled curves well describe the experimentaldata for both glasses and melts over a wide compositions
International Journal of Spectroscopy 5
1150
1100
930
785
598
530
51037Cs
33Cs
27Cs
22Cs17Cs
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
Figure 3 Raman spectra of 119909Cs2O-(100 minus x)SiO
2(119909 = 17 22 27
33 and 37mol) glasses
range Temperature changes have no significant effect onthe concentration of 119876
119899 units in glasses and melts withrelatively low Cs
2O contents (up to sim15mol) as well as in
a narrow composition interval near 40mol In turn mostconsiderable changes in the 119876
119899 distribution are observed forsamples with disilicate and metasilicate compositions Herethe concentrations of the dominant type of structural units(1198763 and119876
2 for disilicate andmetasilicate resp) decrease withincreasing temperature and are accompanied by an increasein the concentration of other structural units with 119899 differingby plusmn1 In the aggregate this phenomenon causes the curvesdescribing the dependences of the 119876
3 and 1198762 units on the
composition to be slightly wider for the melts than for theglasses but the positions of their maxima do not change withtemperature
As seen in Figure 6(b) only 119876119894ndash119876119895 bridging bonds with
|119894 minus 119895| = 0 or 1 may be observed in the system among allpossibilities (1198764ndash11987641198764ndash11987631198764ndash11987621198764ndash11987611198763ndash11987631198763ndash11987621198763ndash1198761 1198762ndash1198762 1198762ndash1198761 1198761ndash1198761) of 119876
119894ndash119876119895 bridging bondsThe maxima of the 119876
119894ndash119876119895 curves decrease with increasing|119894 minus 119895| and are approximately the same for the 119876
119894ndash119876119895 bondswith the same |119894 minus 119895| values The maxima of the 119876
4ndash1198763 and1198763ndash1198762 curves dependweakly on temperature (approximately
1) whereas the positions of thesemaxima are shifted towardhigher Cs
2O concentrations In addition an increase in the
width of these curves is also observedThewidth and positionof the peak of the1198763ndash1198763 and119876
2ndash1198762 curves behave similarlybut their maxima decreasemore dramatically with increasingtemperature (approximately 20)The119876119894ndash119876119895 curves with |119894minus
119895| = 2 are shown in the inset to Figure 6(b) As observed thedependence of the concentration of the given 119876
119894ndash119876119895 bridgeson temperature is opposite to that typical for119876119894ndash119876119895 bridgingbonds with |119894 minus 119895| = 0 In this case a significant increase
in the 1198764ndash1198762 and 119876
3ndash1198761 concentrations with increasingtemperature is observed Nevertheless the concentration ofthese Si-O-Si bonds is low in both glass and melt and is lessthan 1 and 4 at 293 and 1223K respectively
The modeling results of the concentrations of the 1198764119894119895119896119897
and 1198763119894119895119896 groups as a function of composition at different
temperatures (293 and 1223K) are shown in Figures 7(a)ndash7(d)The concentrations were calculated in two ways relativeto the concentration of the appropriate type of structural unit(Figures 7(a) and 7(c) for 1198764119894119895119896119897 and 119876
3119894119895119896 resp)
[119876119899119894119895119896119897
] =
119873119876119899119894119895119896119897
119873119876119899
times 100 (3)
and relative to the total concentration of 119876119899 units (Figures7(b) and 7(d) for 1198764119894119895119896119897 and 119876
3119894119895119896 resp)
[119876119899119894119895119896119897
] =
119873119876119899119894119895119896119897
sum4
119899=0119873119876119899
times 100 (4)
In these equations 119873119876119899119894119895119896119897 and 119873
119876119899 are the amounts of
different types of groups and structural units respectivelyAs seen in Figure 7(a) the gradual increase in concen-
tration of the modifier oxide leads to the following trans-formations of the 119876
4119894119895119896119897 groupings 11987644444 rarr 11987644443
rarr
11987644433
rarr 11987644333
rarr 11987643333
rarr 11987643332 In addition
11987644432 11987644332 and 119876
43322 groups are also formed in theglass structure As seen in the inset to Figure 7(a) howevertheir concentrations are lower than 7 Both the coexistenceregions and the variety of the 119876
4119894119895119896119897 groups are higher inmelts than in glasses The 119876
44332 11987643322 and 11987643222 groups
supplement the list of 1198764119894119895119896119897 groups at high temperature
(1223K) Their maximum concentration exceeds 7 in themelt structure and is low in the glasses The 119876
44322 1198764222211987643221 11987643331 and 119876
43321 groups may also appear in themelt structure but their concentration is less than 7 (seeFigure 7(a)) The shape of the 119876
44444(119909) 119876
44443(119909) and
11987644433
(119909) curves depends slightly on temperature whereasthe 119876
44333(119909) 11987643333(119909) and 119876
43332(119909) curves are subject
to dramatic changes An increase in the width of the curvesand a shift in the position of their maxima toward large 119909 aretypical for all of themThe ratio between the maxima of thesecurves at 293K is
11987211987643333 gt 119872
11987644333 asymp 119872
11987644332 (5)
and that at 1223K is
11987211987643332 gt 119872
11987644333 gt 119872
11987643333 (6)
The region of existence of the 1198763119894119895119896 groups is somewhat
broader than that of 1198764119894119895119896119897 and extends to 119909 asymp 52mol (seeFigure 7(c)) The transformation of 1198763119894119895119896 groups dependingon 119909 can be represented by the sequence1198763444 rarr 119876
3443rarr
1198763433
rarr 1198763333
rarr 1198763332
rarr 1198763322
rarr 1198763222
rarr 1198763221
In addition some amount of 1198763432 groups (less than 3 ofthe total amount of1198763 units) and119876
3321 groups (less than 4)can exist in the glass structure with disilicate andmetasilicate
6 International Journal of Spectroscopy
15531443
1223
1113
1003
898
793
683
473
293
530598
930
1100
1150
Raman shift (cmminus1)13001100900700500300
Ram
an in
tens
ity (a
u)
(a)
1223
1553
1338
1113
1003
898
793
293
530
573
683
598920
1100
1150
13001100900700500300
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)
(b)
Figure 4 Low- and high-temperature Raman spectra of the 22Cs2O-78SiO
2(a) and 27Cs
2O-73SiO
2(b) glasses andmelts (hereinafter
a temperature of the samples is shown in K)
1443
1338
1223
11131003
898
793
683
573
293
598530 920
1100
1150
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(a)
1443
1338
1223
1113
1003
573
293
420520 598
930
1100
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(b)
Figure 5 Low- and high-temperature Raman spectra of the 33Cs2O-67SiO
2(a) and 37Cs
2O-63SiO
2(b) glasses and melts
compositions respectively (see the inset in Figure 7(c))The region of coexistence of the 119876
3119894119895119896 groups increases bysim25 and reaches 55 as the temperature increases up to1223K It is also accompanied by an increase in the widthof the 119876
3119894119895119896(119909) curves a shift of the maxima of these curves
toward large 119909 values and the leveling of their maxima Theconcentration of the dominant type of structural group (ata given composition) decreases and the fraction of the 119876
3119894119895119896
groups that are untypical for glass increases with increasingtemperature As before no significant changes are observedin the 1198763119894119895119896 distribution at 119909 lt 20mol
The1198762119894119895 and1198761119894 distributions calculated according to (3)
and (4) are shown in Figures 7(a)ndash7(d) Figures 8(a) and 8(c)represent the1198762119894119895 and119876
1119894 distributions relative to the1198762 and1198761 contents respectively and Figures 8(b) and 8(d) represent
the concentrations of the 1198762119894119895 and 119876
1119894 groups relative to the
International Journal of Spectroscopy 7
10 20 30 40 5000
20
40
60
80
100
Q4
Q3Q2
Q1
Q0
[Qn]
()
Cs2O (mol)
(a)
20 25 30 35 40 45 50 55
0
1
2
3
4
0 10 20 30 40 500
20
40
60
80
100
Qi ndashQ
j(
)
Q4ndashQ4
Q4ndashQ3
Q3ndashQ3 Q2ndashQ2
Q3ndashQ2
Q2ndashQ1
Q4ndashQ2
Q3ndashQ1
Q1ndashQ1
Cs2O (mol)
(b)
Figure 6 119876119899 (a) and 119876119894ndash119876119895 (b) distributions for glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 = 1223K) of Cs
2O-SiO
2system
Symbols are experimental data (◻ [1] ⃝ [3] [27] andM this work)
total amount of119876119899 units respectively As seen in Figure 8(a)an increase in concentration in themodifier oxide leads to thetransformation of the 1198762119894119895 groups in the following sequence119876244
rarr 119876243
rarr 119876233
rarr 119876232
rarr 119876222
rarr 119876221
rarr
119876211 It should be noted that the concentration of the 119876
244
and 119876243 groups relative to 119876
119899 units in the glass structureis low at 119909 gt 15mol (less than 15 see Figure 8(b))although their fraction relative to the total amount of 1198762119894119895
groups exceeds 40 Moreover the 1198762119894119895 groups are only
formed in the glass structure in an amount exceeding 1at 119909 gt 28mol as follows from Figure 8(b) As beforean increase in the width of the 119876
2119894119895(119909) curves and a shift
in the position of their maxima toward large 119909 values areobserved with increasing temperature The 119876
2119894119895(119909) maxima
change such that the difference between maxima decreaseswith increasing temperature
The 1198761119894 distribution has the simplest form which is
evidently related to the low variety of such groups (A changein 119894 from 4 to 1 gives only four types of 119876
1119894 groups) Theconcentration of the 119876
14 groups is negligible in the glassstructure Therefore a consequence of the transformationsof the 119876
1119894 groups looks similar to 11987613
rarr 11987612
rarr 11987611
The data presented in Figures 8(c) and 8(d) support theassumption that the changes in the 119876
1119894(119909) curves will be
similar to those described above
4 Discussion
41 Raman Spectra and Structure of the119909Cs2O-(100minus x)SiO2(x = 17 22 27 33 and 37mol) Glasses It is rational todivide the overall frequency range into low-frequency (400ndash700 cmminus1) and high-frequency (800ndash1200 cmminus1) intervals toanalyze the obtained Raman spectra The low-frequencyinterval is related to the stretching and some of the bending
vibrations of Si-O-Si linkages Two narrow lines (490 cmminus1(D1) and 602 cmminus1 (D
2)) along with a broad intense line
(sim450 cmminus1) are observed in the Raman spectrum of g-SiO2
(eg [28]) It is accepted that the D1and D
2lines can be
related to the symmetric oxygen breathing vibration of three-(D2) and four-membered (D
1) siloxane rings consisting of
SiO4tetrahedra [28ndash32] The investigation of the Raman
spectra of alkali silicate glasses with high SiO2content [33]
has shown that the bands near 490 and 602 cmminus1 are graduallyshifted toward higher and lower frequencies respectivelywith increasing Cs
2O content Thus it can be assumed that
the Raman bands near 510ndash530 and 598 cmminus1 in our spectrahave the same origin as the D
1and D
2lines respectively The
change in the intensity of these lines as a function of glasscomposition (see Figure 3) shows that the increase in mod-ifier oxide concentrations leads to changes in the statisticaldistribution of 119899-membered rings wherein the concentrationof three-membered rings gradually increases This obser-vation is in accordance with the results published in [27]where an increase in concentrations of three-membered ringswith increasing Cs
2O was shown based on NMR data The
concentration of the four-membered rings changes weakly at17 lt 119909 lt 22 and decreases at higher Cs
2O content
The Raman bands originating from the symmetricstretching vibration of the Si-Ominus terminal groups of various119876119899 (119899 lt 4) units are located in the high-frequency range of
spectra of alkali silicate glasses [34](i) the band at 1050ndash1100 cmminus1 is due to the symmetric
stretching vibrations of the terminal oxygen atoms ofSiO4tetrahedra with one nonbridging oxygen (NBO)
atom that is 1198763 units(ii) the band at 920ndash950 cmminus1 results from the Si-Ominus
stretching of SiO4tetrahedra with two NBO (1198762
units)
8 International Journal of Spectroscopy
15 20 25 30 35 40 45
0
1
2
3
4
5
6
7
10 200 30 400
20
40
60
80
100
Q43321
Q43221
Q44322
Q42222
Q43331Q44432
Q44332
Q43322
Q43222
Q43322
Q43332
Q43333
Q44333
Q44433
Q44443
Q44444
Q44332
[Q4ijk]
()
Cs2O (mol)
(a)
5
4
3
2
1
0
15 20 25 30 35 40 45
100 20 30 400
20
40
60
80
100
Q43332
Q43333Q44333
Q43333
Q44433
Q44443
Q44432
Q44332
Q44444
[Q4ijkl ]998400
()
Cs2O (mol)
(b)
100
80
60
40
20
00 10 20 30 40 50
15 20 30 40 50
0
2
4
6
8
10
[Q3ijk]
()
Q3311
Q3211
Q3111
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3221
Cs2O (mol)
(c)
100 20 30 40 50
20
10
0
30
40
50
60
70
80
2
0
1
3
4
5
6
10 20 30 40 50[Q3ijk]998400
()
Q3311
Q3221Q3331
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3222
Cs2O (mol)
(d)
Figure 7 1198764119894119895119896119897 ((a) and (b)) and 1198763119894119895119896 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines
119879 = 1223K) ((a) and (c) equation (3) (b) and (d) equation (4))
(iii) the Raman band near 900 cmminus1 is attributed to thestretching vibration of the 119876
1 units (SiO4tetrahedra
with three NBO)(iv) finally the line at 850 cmminus1 is related to the symmetric
stretching mode of 1198760 anionsAs seen in Figure 3 only the 1050ndash1100 and 930 cmminus1
bands are observed in the Raman spectra of studied glassesIt should be noted that the 1050ndash1100 cmminus1 band exists inall spectra whereas the 930 cmminus1 band is only observed inthe spectra of glasses with relatively high Cs
2O contents
(33Cs and 37Cs) In addition a high-frequency shoulderwith maximum at approximately 1150 cmminus1 is observed inthe Raman spectra of the 17Cs 22Cs and 27Cs samplesAlthough alkali silicate glasses have been studied for a longtime a review of the literature revealed that the origin of thisshoulder is still controversial In one series of publications[12 13 35] the 1150 cmminus1 line was attributed to the Si-Ostretching vibration in fully polymerized structural species
that is the vibrations of 1198764 units However based on a studyof the Raman spectra of alkali silicate glasses with variouscompositions Matson et al [33] have suggested that this linemay be assigned to the vibrations of the 119876
31015840 units whichare structurally and vibrationally distinguished from thoseof the 119876
3 units producing the 1050ndash1100 cmminus1 band Theyargued that the 1150 cmminus1 shoulder has significantly greaterintensity than could reasonably be assigned to residual g-SiO2spectral features In addition they found no correlation
between the intensity of this band and other bands (eg450 cmminus1) characteristic of the g-SiO
2spectrum Based on
these conclusions the 1150 cmminus1 shoulder was attributed to11987631015840 units which have slightly stronger (shorter) Si-Ominus bond
than the one producing the 1100 cmminus1 line [33]Matson et alrsquos assumption concerning the origin of the
1150 cmminus1 shoulder was confirmed later on by You with co-authors [6] The correlation between the Raman shift andconnecting topology of adjacent 119876119899 units was found based
International Journal of Spectroscopy 9
0
20
40
100
60
80
5 10 20 30 40 50
5
7
8
6
4
3
2
1
0
10 20 30 40 50
[Q2ij]
()
Cs2O (mol)
Q211
Q231
Q242
Q244
Q243
Q233
Q232
Q221
Q222
(a)
0
20
40
60
10
30
70
50
5 10 20 30 40 50
4
3
2
1
0
2010 30 40 50
[Q2ij]998400
()
Cs2O (mol)
Q211
Q231
Q244
Q243
Q233
Q232
Q221
Q222
(b)
36 38 44 48 5240 42 46 50 540
40
60
20
80
100
[Q1i ]
()
Cs2O (mol)
Q13Q12
Q11
Q14
(c)
0
15
20
10
25
30
5
36 38 44 48 5240 42 46 50 54
[Q1i ]998400
()
Cs2O (mol)
Q13
Q12
Q11
(d)
Figure 8 1198762119894119897 ((a) and (b)) and 1198761119894 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 =
1223K) ((a) and (c) equation (2) (b) and (d) equation (3))
on the quantum chemical calculation of the characteristicfrequencies of 119876
119899 species In other words it was demon-strated that the Raman shift of the symmetric stretchingvibration of 119876
119899 units decreases as the number of bridgingoxygen atoms of the nearest-neighbor 119876119899 species adjacent tothe given 119876
119899 unit decreases For example the Raman shiftof the 119876
3444 group is higher than that of the 1198763333 group
In our opinion the conclusions in [6] are strong evidenceof Matsonrsquos assumption Thus we will rely on Matsonrsquosinterpretation of the origin of 1150 cmminus1 band in our paper
The qualitative examination of the Raman spectra ofCs2O-SiO
2glasses (Figure 3) confirms that the structure of
glasses with a Cs2Ocontent below 33mol consists of1198764 and
1198763 units (the existence of1198764 units is obvious and requires no
evidence although the 1150 cmminus1 shoulder indirectly provesthe presence of such structural units) and that the 1198763 speciesare present at the least in the form of 119876
3444 and 1198763333
groups The Raman band at 930 cmminus1 shows that 1198762 units
are formed in the 33Cs and 37Cs glasses The presence of1198764 units in the structure of disilicate glasses is a result of
satisfying the charge balance (NBOSi = 1) Regarding the37Cs glass the presence of 1198764 species can be identified onlyby the quantitative analysis of the corresponding spectrum
The high-frequency envelope (800ndash1300 cmminus1) of theregistered Raman spectra was simulated as a superpositionof the Gaussian lines to estimate the 119876
119899 concentrationsThe number of Gaussian lines was sufficient to reproducethe original spectra with a correlation factor of ge098 Theinterpretation of the Raman bands described above was alsotaken into account In addition some results published in [6]were also taken into account 119876119899 species with equal 119899 givemore than one band and peak position of individual banddepends on the structural position of 119876119899 units For examplewavenumbers of NBO symmetric stretching vibration of 1198763species are located in the range of 1050 to 1150 cmminus1 whereas1198762 units give a set of the individual peaks in the range of
10 International Journal of Spectroscopy
60160260360460560660
H5
H4H3
22Cs
Ram
an in
tens
ity (a
u)
minus40
1443K
H1lowastH2lowast
50150250350450550650
H4H3
H5
27Cs
minus50
1553K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5
33Cs
minus40
1443K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5H6
37Cs
minus40
H2lowast
H1lowast
1443K
70170270370470570670770
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
793K
minus30
70170270370470570670
H4
H3
H5
Ram
an in
tens
ity (a
u)
1113K
minus30
H1lowastH2lowast
60160260360460560660
H4H3
H5
1113K
minus40
H1lowastH2lowast
70170270370470570670770
H4
H3H5
1223K
minus30
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1223K
minus30
H1lowastH2lowast
70170270370470570670770
H4H3
H5
898K
minus30
H1lowastH2lowast
60160260360460560660760860960
H4H3H5
793K
minus40
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1003K
minus30
H1lowastH2lowast
70170270370470570670770870
850 950 1050 1150 1250
H4
H3
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
70170270370470570670770
800 900 1000 1100 1200 1300
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
293K
minus30
Raman shift (cmminus1)
70170270370470570670770870970
800 900 1000 1100 1200 1300
H3H4
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
170370570770970
1170
800 900 1000 1100 1200 1300
H5H3 H4
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
Figure 9 Examples of the band deconvolution of Cs2O-SiO
2glasses and melts Raman spectra between 800 and 1300 cmminus1
930 to 1050 cmminus1 [6] Several examples of the deconvolutionresults of the Raman signal of the studied samples in the high-frequency region are shown in Figure 9 Four Gaussian lineswere sufficient to reproduce the low-temperature (293K)Raman spectra of the 17Cs and 22Cs glasses whereas five lineswere needed to simulate the 27Cs 33Cs and 37Cs spectraThe H3 and H4 bands were attributed to the 119876
3 speciesBecause the 17Cs and 22Cs glasses consist of1198764 and119876
3 unitsit is possible to assume that only four types of structuralgroups (119876344411987634431198763433 and119876
3333) can exist in structureof these glasses Considering the dependence of the Ramanshift of 1198763119894119895119896 groups on the 119894 119895 and 119896 indexes established in[6] it was assumed that the 119876
3444 and 1198763443 groups are the
main contributors to the intensity of the H4 band and thatthe vibrations of the 119876
3433 and 1198763333 groups are the main
contributors to the intensity of theH3 bandThis qualitativelyagrees with the simulation results of the 119876
3119894119895119896 distributionrepresented in Figures 7(c) and 7(d) The H2 band is mostlikely due to the stretching vibrations of the Si-O-Si linkages[3 31] The origin of the H1 line is unclear It is possible thatthis line is a result of the assumption of the Gaussian shape ofthe elementary bands in the spectra of glasses with relativelylow Cs
2O concentrations (17Cs and 22Cs) that is this line
is an error in the choice of the type of elementary bands
The relative area of the H1 band is the same for the 17Cs and22Cs spectra (002) and its intensity increases with furtherincreases in the Cs
2O content The H2 line behaves similarly
An increase in intensity of both H1 and H2 lines begins fromthe appearance of a new H5 line in the deconvolution of theRaman spectra The H5 line indicates the formation of 1198762species in the structure of the samples According to [6] itis possible to assume that the vibrations of the 119876
3119894119895119896 groupsconnected with one or two 119876
2 units for example 1198763332 and1198763322 groups also contribute to the intensity of the H2 band
at higher concentrations of the modifier oxide Thus the1060 cmminus1 line was designated as H2
lowast in the deconvolutionof the 27Cs 33Cs and 37Cs spectra In turn the H1
lowast linecan be attributed to the vibrations of the 119876
244 119876243 and119876233 groups according to the 119876
2119894119895 distribution representedin Figures 8(a) and 8(b) Finally the H5 line was ascribed to119876232 groupsThe localized nature of the silicon-oxygen stretching
motions of silicate units containing SiO4tetrahedra with
one two three or four nonbridging oxygen atoms [34 36]allows us to use the relative integral intensities of theGaussiancomponents to calculate the 119876119899 concentrations
If three types (1198764 1198763 1198762) of 119876
119899 species coexistin a structure simultaneously then their concentrations
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
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Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
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Journal of
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Analytical ChemistryInternational Journal of
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Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
4 International Journal of Spectroscopy
Searching
bond
All possiblechanges
No
Random number
(node choice)generator
Branchingpoint
Searching
bond
Searching
bond
Searching
bond
Branchingpoint
Branchingpoint
TrueTrueTrueTrue
NoNo No
False False FalseFalse
Exist Exist Exist Exist
1w1 1w2 1w3
n lt 4 n lt 3 n lt 2 n lt 1
2Q4rarr2Q3 2Q4rarr2Q3
Q4 + Q3rarrQ3 + Q2
2Q3rarr2Q2
2Q4rarr2Q3
Q4 + Q3rarrQ3 + Q2
2Q3rarr2Q2
Q4 + Q2rarrQ3 + Q1
Q3 + Q2rarrQ2 + Q1
2Q2rarr2Q1
for Q4ndashQ4 for Q43ndashQ43 for Q432ndashQ432 for Q4321ndashQ4321
1 minus 1w1 1 minus 1w2 1 minus 1w3
Figure 2 Block-diagram of simulation algorithm
312 High-Temperature Raman Spectra The Raman spectraof the 22Cs
2O-78SiO
2and 27Cs
2O-73SiO
2samples
measured at different temperatures are shown in Figures4(a) and 4(b) As seen in Figure 4(a) the peak intensityat 530 cmminus1 decreases slightly and its position is graduallyshifted toward lower frequencies with increasing tempera-ture The peak intensity at 598 cmminus1 in contrast to that of530 cmminus1 band increases with increasing temperature andremains at essentially the same frequency No significantchanges are observed in the peak intensity or the shape of thehigh-frequency envelope (1000ndash1200 cmminus1) at relatively lowtemperatures (up to sim898ndash1003K) Only one symmetric wideline with maximum near 1100 cmminus1 is observed in the high-frequency region at higher temperatures and the intensityof this line decreases with increasing temperature A newweak band at 930 cmminus1 that appeared in the Raman spectrameasured at temperatures above 1003K is another peculiarityof the high-temperature spectra All of the above-mentionedfeatures of the changes in the 22Cs spectra with temperatureare observed in the 27Cs spectra as well
The Raman spectra of glasses and melts with modifieroxide contents of 33 and 37mol are shown in Figures 5(a)and 5(b) respectively In contrast to the previous spectra the
line near 920ndash930 cmminus1 is observed at all temperatures and itsintensity increases with temperature This line is most clearlyobserved in the 37Cs spectra The peak intensity at 1100 cmminus1obviously decreases with increasing temperature and itsposition shifts slightly toward lower frequencies In additionthe width of this band increases The intensities of the low-frequency bands (520ndash530 and 598 cmminus1) depend weaklyon temperature but their width significantly increases withtemperature Finally the formation of another new Ramanline in the melt spectra with a maximum near 420 cmminus1should be noted (see Figure 5(b)) This line is observed inthe previous spectra only as an unresolved low-frequencyshoulder near the 530 cmminus1 band
32 Modeling Results The results of the modeling of the 119876119899
and 119876119894ndash119876119895 distributions in the Cs
2O-SiO
2system at two
different temperatures (293K solid lines 1223K dotted lines)are shown in Figures 6(a) and 6(b) respectively In additionto our experimental data the literature data [1 3 27] onthe concentrations of 119876
119899 units in the Cs2O-SiO
2glasses
and melts are also shown in Figure 6(a) As seen in thisfigure the modeled curves well describe the experimentaldata for both glasses and melts over a wide compositions
International Journal of Spectroscopy 5
1150
1100
930
785
598
530
51037Cs
33Cs
27Cs
22Cs17Cs
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
Figure 3 Raman spectra of 119909Cs2O-(100 minus x)SiO
2(119909 = 17 22 27
33 and 37mol) glasses
range Temperature changes have no significant effect onthe concentration of 119876
119899 units in glasses and melts withrelatively low Cs
2O contents (up to sim15mol) as well as in
a narrow composition interval near 40mol In turn mostconsiderable changes in the 119876
119899 distribution are observed forsamples with disilicate and metasilicate compositions Herethe concentrations of the dominant type of structural units(1198763 and119876
2 for disilicate andmetasilicate resp) decrease withincreasing temperature and are accompanied by an increasein the concentration of other structural units with 119899 differingby plusmn1 In the aggregate this phenomenon causes the curvesdescribing the dependences of the 119876
3 and 1198762 units on the
composition to be slightly wider for the melts than for theglasses but the positions of their maxima do not change withtemperature
As seen in Figure 6(b) only 119876119894ndash119876119895 bridging bonds with
|119894 minus 119895| = 0 or 1 may be observed in the system among allpossibilities (1198764ndash11987641198764ndash11987631198764ndash11987621198764ndash11987611198763ndash11987631198763ndash11987621198763ndash1198761 1198762ndash1198762 1198762ndash1198761 1198761ndash1198761) of 119876
119894ndash119876119895 bridging bondsThe maxima of the 119876
119894ndash119876119895 curves decrease with increasing|119894 minus 119895| and are approximately the same for the 119876
119894ndash119876119895 bondswith the same |119894 minus 119895| values The maxima of the 119876
4ndash1198763 and1198763ndash1198762 curves dependweakly on temperature (approximately
1) whereas the positions of thesemaxima are shifted towardhigher Cs
2O concentrations In addition an increase in the
width of these curves is also observedThewidth and positionof the peak of the1198763ndash1198763 and119876
2ndash1198762 curves behave similarlybut their maxima decreasemore dramatically with increasingtemperature (approximately 20)The119876119894ndash119876119895 curves with |119894minus
119895| = 2 are shown in the inset to Figure 6(b) As observed thedependence of the concentration of the given 119876
119894ndash119876119895 bridgeson temperature is opposite to that typical for119876119894ndash119876119895 bridgingbonds with |119894 minus 119895| = 0 In this case a significant increase
in the 1198764ndash1198762 and 119876
3ndash1198761 concentrations with increasingtemperature is observed Nevertheless the concentration ofthese Si-O-Si bonds is low in both glass and melt and is lessthan 1 and 4 at 293 and 1223K respectively
The modeling results of the concentrations of the 1198764119894119895119896119897
and 1198763119894119895119896 groups as a function of composition at different
temperatures (293 and 1223K) are shown in Figures 7(a)ndash7(d)The concentrations were calculated in two ways relativeto the concentration of the appropriate type of structural unit(Figures 7(a) and 7(c) for 1198764119894119895119896119897 and 119876
3119894119895119896 resp)
[119876119899119894119895119896119897
] =
119873119876119899119894119895119896119897
119873119876119899
times 100 (3)
and relative to the total concentration of 119876119899 units (Figures7(b) and 7(d) for 1198764119894119895119896119897 and 119876
3119894119895119896 resp)
[119876119899119894119895119896119897
] =
119873119876119899119894119895119896119897
sum4
119899=0119873119876119899
times 100 (4)
In these equations 119873119876119899119894119895119896119897 and 119873
119876119899 are the amounts of
different types of groups and structural units respectivelyAs seen in Figure 7(a) the gradual increase in concen-
tration of the modifier oxide leads to the following trans-formations of the 119876
4119894119895119896119897 groupings 11987644444 rarr 11987644443
rarr
11987644433
rarr 11987644333
rarr 11987643333
rarr 11987643332 In addition
11987644432 11987644332 and 119876
43322 groups are also formed in theglass structure As seen in the inset to Figure 7(a) howevertheir concentrations are lower than 7 Both the coexistenceregions and the variety of the 119876
4119894119895119896119897 groups are higher inmelts than in glasses The 119876
44332 11987643322 and 11987643222 groups
supplement the list of 1198764119894119895119896119897 groups at high temperature
(1223K) Their maximum concentration exceeds 7 in themelt structure and is low in the glasses The 119876
44322 1198764222211987643221 11987643331 and 119876
43321 groups may also appear in themelt structure but their concentration is less than 7 (seeFigure 7(a)) The shape of the 119876
44444(119909) 119876
44443(119909) and
11987644433
(119909) curves depends slightly on temperature whereasthe 119876
44333(119909) 11987643333(119909) and 119876
43332(119909) curves are subject
to dramatic changes An increase in the width of the curvesand a shift in the position of their maxima toward large 119909 aretypical for all of themThe ratio between the maxima of thesecurves at 293K is
11987211987643333 gt 119872
11987644333 asymp 119872
11987644332 (5)
and that at 1223K is
11987211987643332 gt 119872
11987644333 gt 119872
11987643333 (6)
The region of existence of the 1198763119894119895119896 groups is somewhat
broader than that of 1198764119894119895119896119897 and extends to 119909 asymp 52mol (seeFigure 7(c)) The transformation of 1198763119894119895119896 groups dependingon 119909 can be represented by the sequence1198763444 rarr 119876
3443rarr
1198763433
rarr 1198763333
rarr 1198763332
rarr 1198763322
rarr 1198763222
rarr 1198763221
In addition some amount of 1198763432 groups (less than 3 ofthe total amount of1198763 units) and119876
3321 groups (less than 4)can exist in the glass structure with disilicate andmetasilicate
6 International Journal of Spectroscopy
15531443
1223
1113
1003
898
793
683
473
293
530598
930
1100
1150
Raman shift (cmminus1)13001100900700500300
Ram
an in
tens
ity (a
u)
(a)
1223
1553
1338
1113
1003
898
793
293
530
573
683
598920
1100
1150
13001100900700500300
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)
(b)
Figure 4 Low- and high-temperature Raman spectra of the 22Cs2O-78SiO
2(a) and 27Cs
2O-73SiO
2(b) glasses andmelts (hereinafter
a temperature of the samples is shown in K)
1443
1338
1223
11131003
898
793
683
573
293
598530 920
1100
1150
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(a)
1443
1338
1223
1113
1003
573
293
420520 598
930
1100
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(b)
Figure 5 Low- and high-temperature Raman spectra of the 33Cs2O-67SiO
2(a) and 37Cs
2O-63SiO
2(b) glasses and melts
compositions respectively (see the inset in Figure 7(c))The region of coexistence of the 119876
3119894119895119896 groups increases bysim25 and reaches 55 as the temperature increases up to1223K It is also accompanied by an increase in the widthof the 119876
3119894119895119896(119909) curves a shift of the maxima of these curves
toward large 119909 values and the leveling of their maxima Theconcentration of the dominant type of structural group (ata given composition) decreases and the fraction of the 119876
3119894119895119896
groups that are untypical for glass increases with increasingtemperature As before no significant changes are observedin the 1198763119894119895119896 distribution at 119909 lt 20mol
The1198762119894119895 and1198761119894 distributions calculated according to (3)
and (4) are shown in Figures 7(a)ndash7(d) Figures 8(a) and 8(c)represent the1198762119894119895 and119876
1119894 distributions relative to the1198762 and1198761 contents respectively and Figures 8(b) and 8(d) represent
the concentrations of the 1198762119894119895 and 119876
1119894 groups relative to the
International Journal of Spectroscopy 7
10 20 30 40 5000
20
40
60
80
100
Q4
Q3Q2
Q1
Q0
[Qn]
()
Cs2O (mol)
(a)
20 25 30 35 40 45 50 55
0
1
2
3
4
0 10 20 30 40 500
20
40
60
80
100
Qi ndashQ
j(
)
Q4ndashQ4
Q4ndashQ3
Q3ndashQ3 Q2ndashQ2
Q3ndashQ2
Q2ndashQ1
Q4ndashQ2
Q3ndashQ1
Q1ndashQ1
Cs2O (mol)
(b)
Figure 6 119876119899 (a) and 119876119894ndash119876119895 (b) distributions for glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 = 1223K) of Cs
2O-SiO
2system
Symbols are experimental data (◻ [1] ⃝ [3] [27] andM this work)
total amount of119876119899 units respectively As seen in Figure 8(a)an increase in concentration in themodifier oxide leads to thetransformation of the 1198762119894119895 groups in the following sequence119876244
rarr 119876243
rarr 119876233
rarr 119876232
rarr 119876222
rarr 119876221
rarr
119876211 It should be noted that the concentration of the 119876
244
and 119876243 groups relative to 119876
119899 units in the glass structureis low at 119909 gt 15mol (less than 15 see Figure 8(b))although their fraction relative to the total amount of 1198762119894119895
groups exceeds 40 Moreover the 1198762119894119895 groups are only
formed in the glass structure in an amount exceeding 1at 119909 gt 28mol as follows from Figure 8(b) As beforean increase in the width of the 119876
2119894119895(119909) curves and a shift
in the position of their maxima toward large 119909 values areobserved with increasing temperature The 119876
2119894119895(119909) maxima
change such that the difference between maxima decreaseswith increasing temperature
The 1198761119894 distribution has the simplest form which is
evidently related to the low variety of such groups (A changein 119894 from 4 to 1 gives only four types of 119876
1119894 groups) Theconcentration of the 119876
14 groups is negligible in the glassstructure Therefore a consequence of the transformationsof the 119876
1119894 groups looks similar to 11987613
rarr 11987612
rarr 11987611
The data presented in Figures 8(c) and 8(d) support theassumption that the changes in the 119876
1119894(119909) curves will be
similar to those described above
4 Discussion
41 Raman Spectra and Structure of the119909Cs2O-(100minus x)SiO2(x = 17 22 27 33 and 37mol) Glasses It is rational todivide the overall frequency range into low-frequency (400ndash700 cmminus1) and high-frequency (800ndash1200 cmminus1) intervals toanalyze the obtained Raman spectra The low-frequencyinterval is related to the stretching and some of the bending
vibrations of Si-O-Si linkages Two narrow lines (490 cmminus1(D1) and 602 cmminus1 (D
2)) along with a broad intense line
(sim450 cmminus1) are observed in the Raman spectrum of g-SiO2
(eg [28]) It is accepted that the D1and D
2lines can be
related to the symmetric oxygen breathing vibration of three-(D2) and four-membered (D
1) siloxane rings consisting of
SiO4tetrahedra [28ndash32] The investigation of the Raman
spectra of alkali silicate glasses with high SiO2content [33]
has shown that the bands near 490 and 602 cmminus1 are graduallyshifted toward higher and lower frequencies respectivelywith increasing Cs
2O content Thus it can be assumed that
the Raman bands near 510ndash530 and 598 cmminus1 in our spectrahave the same origin as the D
1and D
2lines respectively The
change in the intensity of these lines as a function of glasscomposition (see Figure 3) shows that the increase in mod-ifier oxide concentrations leads to changes in the statisticaldistribution of 119899-membered rings wherein the concentrationof three-membered rings gradually increases This obser-vation is in accordance with the results published in [27]where an increase in concentrations of three-membered ringswith increasing Cs
2O was shown based on NMR data The
concentration of the four-membered rings changes weakly at17 lt 119909 lt 22 and decreases at higher Cs
2O content
The Raman bands originating from the symmetricstretching vibration of the Si-Ominus terminal groups of various119876119899 (119899 lt 4) units are located in the high-frequency range of
spectra of alkali silicate glasses [34](i) the band at 1050ndash1100 cmminus1 is due to the symmetric
stretching vibrations of the terminal oxygen atoms ofSiO4tetrahedra with one nonbridging oxygen (NBO)
atom that is 1198763 units(ii) the band at 920ndash950 cmminus1 results from the Si-Ominus
stretching of SiO4tetrahedra with two NBO (1198762
units)
8 International Journal of Spectroscopy
15 20 25 30 35 40 45
0
1
2
3
4
5
6
7
10 200 30 400
20
40
60
80
100
Q43321
Q43221
Q44322
Q42222
Q43331Q44432
Q44332
Q43322
Q43222
Q43322
Q43332
Q43333
Q44333
Q44433
Q44443
Q44444
Q44332
[Q4ijk]
()
Cs2O (mol)
(a)
5
4
3
2
1
0
15 20 25 30 35 40 45
100 20 30 400
20
40
60
80
100
Q43332
Q43333Q44333
Q43333
Q44433
Q44443
Q44432
Q44332
Q44444
[Q4ijkl ]998400
()
Cs2O (mol)
(b)
100
80
60
40
20
00 10 20 30 40 50
15 20 30 40 50
0
2
4
6
8
10
[Q3ijk]
()
Q3311
Q3211
Q3111
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3221
Cs2O (mol)
(c)
100 20 30 40 50
20
10
0
30
40
50
60
70
80
2
0
1
3
4
5
6
10 20 30 40 50[Q3ijk]998400
()
Q3311
Q3221Q3331
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3222
Cs2O (mol)
(d)
Figure 7 1198764119894119895119896119897 ((a) and (b)) and 1198763119894119895119896 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines
119879 = 1223K) ((a) and (c) equation (3) (b) and (d) equation (4))
(iii) the Raman band near 900 cmminus1 is attributed to thestretching vibration of the 119876
1 units (SiO4tetrahedra
with three NBO)(iv) finally the line at 850 cmminus1 is related to the symmetric
stretching mode of 1198760 anionsAs seen in Figure 3 only the 1050ndash1100 and 930 cmminus1
bands are observed in the Raman spectra of studied glassesIt should be noted that the 1050ndash1100 cmminus1 band exists inall spectra whereas the 930 cmminus1 band is only observed inthe spectra of glasses with relatively high Cs
2O contents
(33Cs and 37Cs) In addition a high-frequency shoulderwith maximum at approximately 1150 cmminus1 is observed inthe Raman spectra of the 17Cs 22Cs and 27Cs samplesAlthough alkali silicate glasses have been studied for a longtime a review of the literature revealed that the origin of thisshoulder is still controversial In one series of publications[12 13 35] the 1150 cmminus1 line was attributed to the Si-Ostretching vibration in fully polymerized structural species
that is the vibrations of 1198764 units However based on a studyof the Raman spectra of alkali silicate glasses with variouscompositions Matson et al [33] have suggested that this linemay be assigned to the vibrations of the 119876
31015840 units whichare structurally and vibrationally distinguished from thoseof the 119876
3 units producing the 1050ndash1100 cmminus1 band Theyargued that the 1150 cmminus1 shoulder has significantly greaterintensity than could reasonably be assigned to residual g-SiO2spectral features In addition they found no correlation
between the intensity of this band and other bands (eg450 cmminus1) characteristic of the g-SiO
2spectrum Based on
these conclusions the 1150 cmminus1 shoulder was attributed to11987631015840 units which have slightly stronger (shorter) Si-Ominus bond
than the one producing the 1100 cmminus1 line [33]Matson et alrsquos assumption concerning the origin of the
1150 cmminus1 shoulder was confirmed later on by You with co-authors [6] The correlation between the Raman shift andconnecting topology of adjacent 119876119899 units was found based
International Journal of Spectroscopy 9
0
20
40
100
60
80
5 10 20 30 40 50
5
7
8
6
4
3
2
1
0
10 20 30 40 50
[Q2ij]
()
Cs2O (mol)
Q211
Q231
Q242
Q244
Q243
Q233
Q232
Q221
Q222
(a)
0
20
40
60
10
30
70
50
5 10 20 30 40 50
4
3
2
1
0
2010 30 40 50
[Q2ij]998400
()
Cs2O (mol)
Q211
Q231
Q244
Q243
Q233
Q232
Q221
Q222
(b)
36 38 44 48 5240 42 46 50 540
40
60
20
80
100
[Q1i ]
()
Cs2O (mol)
Q13Q12
Q11
Q14
(c)
0
15
20
10
25
30
5
36 38 44 48 5240 42 46 50 54
[Q1i ]998400
()
Cs2O (mol)
Q13
Q12
Q11
(d)
Figure 8 1198762119894119897 ((a) and (b)) and 1198761119894 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 =
1223K) ((a) and (c) equation (2) (b) and (d) equation (3))
on the quantum chemical calculation of the characteristicfrequencies of 119876
119899 species In other words it was demon-strated that the Raman shift of the symmetric stretchingvibration of 119876
119899 units decreases as the number of bridgingoxygen atoms of the nearest-neighbor 119876119899 species adjacent tothe given 119876
119899 unit decreases For example the Raman shiftof the 119876
3444 group is higher than that of the 1198763333 group
In our opinion the conclusions in [6] are strong evidenceof Matsonrsquos assumption Thus we will rely on Matsonrsquosinterpretation of the origin of 1150 cmminus1 band in our paper
The qualitative examination of the Raman spectra ofCs2O-SiO
2glasses (Figure 3) confirms that the structure of
glasses with a Cs2Ocontent below 33mol consists of1198764 and
1198763 units (the existence of1198764 units is obvious and requires no
evidence although the 1150 cmminus1 shoulder indirectly provesthe presence of such structural units) and that the 1198763 speciesare present at the least in the form of 119876
3444 and 1198763333
groups The Raman band at 930 cmminus1 shows that 1198762 units
are formed in the 33Cs and 37Cs glasses The presence of1198764 units in the structure of disilicate glasses is a result of
satisfying the charge balance (NBOSi = 1) Regarding the37Cs glass the presence of 1198764 species can be identified onlyby the quantitative analysis of the corresponding spectrum
The high-frequency envelope (800ndash1300 cmminus1) of theregistered Raman spectra was simulated as a superpositionof the Gaussian lines to estimate the 119876
119899 concentrationsThe number of Gaussian lines was sufficient to reproducethe original spectra with a correlation factor of ge098 Theinterpretation of the Raman bands described above was alsotaken into account In addition some results published in [6]were also taken into account 119876119899 species with equal 119899 givemore than one band and peak position of individual banddepends on the structural position of 119876119899 units For examplewavenumbers of NBO symmetric stretching vibration of 1198763species are located in the range of 1050 to 1150 cmminus1 whereas1198762 units give a set of the individual peaks in the range of
10 International Journal of Spectroscopy
60160260360460560660
H5
H4H3
22Cs
Ram
an in
tens
ity (a
u)
minus40
1443K
H1lowastH2lowast
50150250350450550650
H4H3
H5
27Cs
minus50
1553K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5
33Cs
minus40
1443K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5H6
37Cs
minus40
H2lowast
H1lowast
1443K
70170270370470570670770
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
793K
minus30
70170270370470570670
H4
H3
H5
Ram
an in
tens
ity (a
u)
1113K
minus30
H1lowastH2lowast
60160260360460560660
H4H3
H5
1113K
minus40
H1lowastH2lowast
70170270370470570670770
H4
H3H5
1223K
minus30
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1223K
minus30
H1lowastH2lowast
70170270370470570670770
H4H3
H5
898K
minus30
H1lowastH2lowast
60160260360460560660760860960
H4H3H5
793K
minus40
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1003K
minus30
H1lowastH2lowast
70170270370470570670770870
850 950 1050 1150 1250
H4
H3
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
70170270370470570670770
800 900 1000 1100 1200 1300
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
293K
minus30
Raman shift (cmminus1)
70170270370470570670770870970
800 900 1000 1100 1200 1300
H3H4
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
170370570770970
1170
800 900 1000 1100 1200 1300
H5H3 H4
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
Figure 9 Examples of the band deconvolution of Cs2O-SiO
2glasses and melts Raman spectra between 800 and 1300 cmminus1
930 to 1050 cmminus1 [6] Several examples of the deconvolutionresults of the Raman signal of the studied samples in the high-frequency region are shown in Figure 9 Four Gaussian lineswere sufficient to reproduce the low-temperature (293K)Raman spectra of the 17Cs and 22Cs glasses whereas five lineswere needed to simulate the 27Cs 33Cs and 37Cs spectraThe H3 and H4 bands were attributed to the 119876
3 speciesBecause the 17Cs and 22Cs glasses consist of1198764 and119876
3 unitsit is possible to assume that only four types of structuralgroups (119876344411987634431198763433 and119876
3333) can exist in structureof these glasses Considering the dependence of the Ramanshift of 1198763119894119895119896 groups on the 119894 119895 and 119896 indexes established in[6] it was assumed that the 119876
3444 and 1198763443 groups are the
main contributors to the intensity of the H4 band and thatthe vibrations of the 119876
3433 and 1198763333 groups are the main
contributors to the intensity of theH3 bandThis qualitativelyagrees with the simulation results of the 119876
3119894119895119896 distributionrepresented in Figures 7(c) and 7(d) The H2 band is mostlikely due to the stretching vibrations of the Si-O-Si linkages[3 31] The origin of the H1 line is unclear It is possible thatthis line is a result of the assumption of the Gaussian shape ofthe elementary bands in the spectra of glasses with relativelylow Cs
2O concentrations (17Cs and 22Cs) that is this line
is an error in the choice of the type of elementary bands
The relative area of the H1 band is the same for the 17Cs and22Cs spectra (002) and its intensity increases with furtherincreases in the Cs
2O content The H2 line behaves similarly
An increase in intensity of both H1 and H2 lines begins fromthe appearance of a new H5 line in the deconvolution of theRaman spectra The H5 line indicates the formation of 1198762species in the structure of the samples According to [6] itis possible to assume that the vibrations of the 119876
3119894119895119896 groupsconnected with one or two 119876
2 units for example 1198763332 and1198763322 groups also contribute to the intensity of the H2 band
at higher concentrations of the modifier oxide Thus the1060 cmminus1 line was designated as H2
lowast in the deconvolutionof the 27Cs 33Cs and 37Cs spectra In turn the H1
lowast linecan be attributed to the vibrations of the 119876
244 119876243 and119876233 groups according to the 119876
2119894119895 distribution representedin Figures 8(a) and 8(b) Finally the H5 line was ascribed to119876232 groupsThe localized nature of the silicon-oxygen stretching
motions of silicate units containing SiO4tetrahedra with
one two three or four nonbridging oxygen atoms [34 36]allows us to use the relative integral intensities of theGaussiancomponents to calculate the 119876119899 concentrations
If three types (1198764 1198763 1198762) of 119876
119899 species coexistin a structure simultaneously then their concentrations
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Journal of
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Analytical ChemistryInternational Journal of
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Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
International Journal of Spectroscopy 5
1150
1100
930
785
598
530
51037Cs
33Cs
27Cs
22Cs17Cs
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
Figure 3 Raman spectra of 119909Cs2O-(100 minus x)SiO
2(119909 = 17 22 27
33 and 37mol) glasses
range Temperature changes have no significant effect onthe concentration of 119876
119899 units in glasses and melts withrelatively low Cs
2O contents (up to sim15mol) as well as in
a narrow composition interval near 40mol In turn mostconsiderable changes in the 119876
119899 distribution are observed forsamples with disilicate and metasilicate compositions Herethe concentrations of the dominant type of structural units(1198763 and119876
2 for disilicate andmetasilicate resp) decrease withincreasing temperature and are accompanied by an increasein the concentration of other structural units with 119899 differingby plusmn1 In the aggregate this phenomenon causes the curvesdescribing the dependences of the 119876
3 and 1198762 units on the
composition to be slightly wider for the melts than for theglasses but the positions of their maxima do not change withtemperature
As seen in Figure 6(b) only 119876119894ndash119876119895 bridging bonds with
|119894 minus 119895| = 0 or 1 may be observed in the system among allpossibilities (1198764ndash11987641198764ndash11987631198764ndash11987621198764ndash11987611198763ndash11987631198763ndash11987621198763ndash1198761 1198762ndash1198762 1198762ndash1198761 1198761ndash1198761) of 119876
119894ndash119876119895 bridging bondsThe maxima of the 119876
119894ndash119876119895 curves decrease with increasing|119894 minus 119895| and are approximately the same for the 119876
119894ndash119876119895 bondswith the same |119894 minus 119895| values The maxima of the 119876
4ndash1198763 and1198763ndash1198762 curves dependweakly on temperature (approximately
1) whereas the positions of thesemaxima are shifted towardhigher Cs
2O concentrations In addition an increase in the
width of these curves is also observedThewidth and positionof the peak of the1198763ndash1198763 and119876
2ndash1198762 curves behave similarlybut their maxima decreasemore dramatically with increasingtemperature (approximately 20)The119876119894ndash119876119895 curves with |119894minus
119895| = 2 are shown in the inset to Figure 6(b) As observed thedependence of the concentration of the given 119876
119894ndash119876119895 bridgeson temperature is opposite to that typical for119876119894ndash119876119895 bridgingbonds with |119894 minus 119895| = 0 In this case a significant increase
in the 1198764ndash1198762 and 119876
3ndash1198761 concentrations with increasingtemperature is observed Nevertheless the concentration ofthese Si-O-Si bonds is low in both glass and melt and is lessthan 1 and 4 at 293 and 1223K respectively
The modeling results of the concentrations of the 1198764119894119895119896119897
and 1198763119894119895119896 groups as a function of composition at different
temperatures (293 and 1223K) are shown in Figures 7(a)ndash7(d)The concentrations were calculated in two ways relativeto the concentration of the appropriate type of structural unit(Figures 7(a) and 7(c) for 1198764119894119895119896119897 and 119876
3119894119895119896 resp)
[119876119899119894119895119896119897
] =
119873119876119899119894119895119896119897
119873119876119899
times 100 (3)
and relative to the total concentration of 119876119899 units (Figures7(b) and 7(d) for 1198764119894119895119896119897 and 119876
3119894119895119896 resp)
[119876119899119894119895119896119897
] =
119873119876119899119894119895119896119897
sum4
119899=0119873119876119899
times 100 (4)
In these equations 119873119876119899119894119895119896119897 and 119873
119876119899 are the amounts of
different types of groups and structural units respectivelyAs seen in Figure 7(a) the gradual increase in concen-
tration of the modifier oxide leads to the following trans-formations of the 119876
4119894119895119896119897 groupings 11987644444 rarr 11987644443
rarr
11987644433
rarr 11987644333
rarr 11987643333
rarr 11987643332 In addition
11987644432 11987644332 and 119876
43322 groups are also formed in theglass structure As seen in the inset to Figure 7(a) howevertheir concentrations are lower than 7 Both the coexistenceregions and the variety of the 119876
4119894119895119896119897 groups are higher inmelts than in glasses The 119876
44332 11987643322 and 11987643222 groups
supplement the list of 1198764119894119895119896119897 groups at high temperature
(1223K) Their maximum concentration exceeds 7 in themelt structure and is low in the glasses The 119876
44322 1198764222211987643221 11987643331 and 119876
43321 groups may also appear in themelt structure but their concentration is less than 7 (seeFigure 7(a)) The shape of the 119876
44444(119909) 119876
44443(119909) and
11987644433
(119909) curves depends slightly on temperature whereasthe 119876
44333(119909) 11987643333(119909) and 119876
43332(119909) curves are subject
to dramatic changes An increase in the width of the curvesand a shift in the position of their maxima toward large 119909 aretypical for all of themThe ratio between the maxima of thesecurves at 293K is
11987211987643333 gt 119872
11987644333 asymp 119872
11987644332 (5)
and that at 1223K is
11987211987643332 gt 119872
11987644333 gt 119872
11987643333 (6)
The region of existence of the 1198763119894119895119896 groups is somewhat
broader than that of 1198764119894119895119896119897 and extends to 119909 asymp 52mol (seeFigure 7(c)) The transformation of 1198763119894119895119896 groups dependingon 119909 can be represented by the sequence1198763444 rarr 119876
3443rarr
1198763433
rarr 1198763333
rarr 1198763332
rarr 1198763322
rarr 1198763222
rarr 1198763221
In addition some amount of 1198763432 groups (less than 3 ofthe total amount of1198763 units) and119876
3321 groups (less than 4)can exist in the glass structure with disilicate andmetasilicate
6 International Journal of Spectroscopy
15531443
1223
1113
1003
898
793
683
473
293
530598
930
1100
1150
Raman shift (cmminus1)13001100900700500300
Ram
an in
tens
ity (a
u)
(a)
1223
1553
1338
1113
1003
898
793
293
530
573
683
598920
1100
1150
13001100900700500300
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)
(b)
Figure 4 Low- and high-temperature Raman spectra of the 22Cs2O-78SiO
2(a) and 27Cs
2O-73SiO
2(b) glasses andmelts (hereinafter
a temperature of the samples is shown in K)
1443
1338
1223
11131003
898
793
683
573
293
598530 920
1100
1150
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(a)
1443
1338
1223
1113
1003
573
293
420520 598
930
1100
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(b)
Figure 5 Low- and high-temperature Raman spectra of the 33Cs2O-67SiO
2(a) and 37Cs
2O-63SiO
2(b) glasses and melts
compositions respectively (see the inset in Figure 7(c))The region of coexistence of the 119876
3119894119895119896 groups increases bysim25 and reaches 55 as the temperature increases up to1223K It is also accompanied by an increase in the widthof the 119876
3119894119895119896(119909) curves a shift of the maxima of these curves
toward large 119909 values and the leveling of their maxima Theconcentration of the dominant type of structural group (ata given composition) decreases and the fraction of the 119876
3119894119895119896
groups that are untypical for glass increases with increasingtemperature As before no significant changes are observedin the 1198763119894119895119896 distribution at 119909 lt 20mol
The1198762119894119895 and1198761119894 distributions calculated according to (3)
and (4) are shown in Figures 7(a)ndash7(d) Figures 8(a) and 8(c)represent the1198762119894119895 and119876
1119894 distributions relative to the1198762 and1198761 contents respectively and Figures 8(b) and 8(d) represent
the concentrations of the 1198762119894119895 and 119876
1119894 groups relative to the
International Journal of Spectroscopy 7
10 20 30 40 5000
20
40
60
80
100
Q4
Q3Q2
Q1
Q0
[Qn]
()
Cs2O (mol)
(a)
20 25 30 35 40 45 50 55
0
1
2
3
4
0 10 20 30 40 500
20
40
60
80
100
Qi ndashQ
j(
)
Q4ndashQ4
Q4ndashQ3
Q3ndashQ3 Q2ndashQ2
Q3ndashQ2
Q2ndashQ1
Q4ndashQ2
Q3ndashQ1
Q1ndashQ1
Cs2O (mol)
(b)
Figure 6 119876119899 (a) and 119876119894ndash119876119895 (b) distributions for glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 = 1223K) of Cs
2O-SiO
2system
Symbols are experimental data (◻ [1] ⃝ [3] [27] andM this work)
total amount of119876119899 units respectively As seen in Figure 8(a)an increase in concentration in themodifier oxide leads to thetransformation of the 1198762119894119895 groups in the following sequence119876244
rarr 119876243
rarr 119876233
rarr 119876232
rarr 119876222
rarr 119876221
rarr
119876211 It should be noted that the concentration of the 119876
244
and 119876243 groups relative to 119876
119899 units in the glass structureis low at 119909 gt 15mol (less than 15 see Figure 8(b))although their fraction relative to the total amount of 1198762119894119895
groups exceeds 40 Moreover the 1198762119894119895 groups are only
formed in the glass structure in an amount exceeding 1at 119909 gt 28mol as follows from Figure 8(b) As beforean increase in the width of the 119876
2119894119895(119909) curves and a shift
in the position of their maxima toward large 119909 values areobserved with increasing temperature The 119876
2119894119895(119909) maxima
change such that the difference between maxima decreaseswith increasing temperature
The 1198761119894 distribution has the simplest form which is
evidently related to the low variety of such groups (A changein 119894 from 4 to 1 gives only four types of 119876
1119894 groups) Theconcentration of the 119876
14 groups is negligible in the glassstructure Therefore a consequence of the transformationsof the 119876
1119894 groups looks similar to 11987613
rarr 11987612
rarr 11987611
The data presented in Figures 8(c) and 8(d) support theassumption that the changes in the 119876
1119894(119909) curves will be
similar to those described above
4 Discussion
41 Raman Spectra and Structure of the119909Cs2O-(100minus x)SiO2(x = 17 22 27 33 and 37mol) Glasses It is rational todivide the overall frequency range into low-frequency (400ndash700 cmminus1) and high-frequency (800ndash1200 cmminus1) intervals toanalyze the obtained Raman spectra The low-frequencyinterval is related to the stretching and some of the bending
vibrations of Si-O-Si linkages Two narrow lines (490 cmminus1(D1) and 602 cmminus1 (D
2)) along with a broad intense line
(sim450 cmminus1) are observed in the Raman spectrum of g-SiO2
(eg [28]) It is accepted that the D1and D
2lines can be
related to the symmetric oxygen breathing vibration of three-(D2) and four-membered (D
1) siloxane rings consisting of
SiO4tetrahedra [28ndash32] The investigation of the Raman
spectra of alkali silicate glasses with high SiO2content [33]
has shown that the bands near 490 and 602 cmminus1 are graduallyshifted toward higher and lower frequencies respectivelywith increasing Cs
2O content Thus it can be assumed that
the Raman bands near 510ndash530 and 598 cmminus1 in our spectrahave the same origin as the D
1and D
2lines respectively The
change in the intensity of these lines as a function of glasscomposition (see Figure 3) shows that the increase in mod-ifier oxide concentrations leads to changes in the statisticaldistribution of 119899-membered rings wherein the concentrationof three-membered rings gradually increases This obser-vation is in accordance with the results published in [27]where an increase in concentrations of three-membered ringswith increasing Cs
2O was shown based on NMR data The
concentration of the four-membered rings changes weakly at17 lt 119909 lt 22 and decreases at higher Cs
2O content
The Raman bands originating from the symmetricstretching vibration of the Si-Ominus terminal groups of various119876119899 (119899 lt 4) units are located in the high-frequency range of
spectra of alkali silicate glasses [34](i) the band at 1050ndash1100 cmminus1 is due to the symmetric
stretching vibrations of the terminal oxygen atoms ofSiO4tetrahedra with one nonbridging oxygen (NBO)
atom that is 1198763 units(ii) the band at 920ndash950 cmminus1 results from the Si-Ominus
stretching of SiO4tetrahedra with two NBO (1198762
units)
8 International Journal of Spectroscopy
15 20 25 30 35 40 45
0
1
2
3
4
5
6
7
10 200 30 400
20
40
60
80
100
Q43321
Q43221
Q44322
Q42222
Q43331Q44432
Q44332
Q43322
Q43222
Q43322
Q43332
Q43333
Q44333
Q44433
Q44443
Q44444
Q44332
[Q4ijk]
()
Cs2O (mol)
(a)
5
4
3
2
1
0
15 20 25 30 35 40 45
100 20 30 400
20
40
60
80
100
Q43332
Q43333Q44333
Q43333
Q44433
Q44443
Q44432
Q44332
Q44444
[Q4ijkl ]998400
()
Cs2O (mol)
(b)
100
80
60
40
20
00 10 20 30 40 50
15 20 30 40 50
0
2
4
6
8
10
[Q3ijk]
()
Q3311
Q3211
Q3111
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3221
Cs2O (mol)
(c)
100 20 30 40 50
20
10
0
30
40
50
60
70
80
2
0
1
3
4
5
6
10 20 30 40 50[Q3ijk]998400
()
Q3311
Q3221Q3331
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3222
Cs2O (mol)
(d)
Figure 7 1198764119894119895119896119897 ((a) and (b)) and 1198763119894119895119896 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines
119879 = 1223K) ((a) and (c) equation (3) (b) and (d) equation (4))
(iii) the Raman band near 900 cmminus1 is attributed to thestretching vibration of the 119876
1 units (SiO4tetrahedra
with three NBO)(iv) finally the line at 850 cmminus1 is related to the symmetric
stretching mode of 1198760 anionsAs seen in Figure 3 only the 1050ndash1100 and 930 cmminus1
bands are observed in the Raman spectra of studied glassesIt should be noted that the 1050ndash1100 cmminus1 band exists inall spectra whereas the 930 cmminus1 band is only observed inthe spectra of glasses with relatively high Cs
2O contents
(33Cs and 37Cs) In addition a high-frequency shoulderwith maximum at approximately 1150 cmminus1 is observed inthe Raman spectra of the 17Cs 22Cs and 27Cs samplesAlthough alkali silicate glasses have been studied for a longtime a review of the literature revealed that the origin of thisshoulder is still controversial In one series of publications[12 13 35] the 1150 cmminus1 line was attributed to the Si-Ostretching vibration in fully polymerized structural species
that is the vibrations of 1198764 units However based on a studyof the Raman spectra of alkali silicate glasses with variouscompositions Matson et al [33] have suggested that this linemay be assigned to the vibrations of the 119876
31015840 units whichare structurally and vibrationally distinguished from thoseof the 119876
3 units producing the 1050ndash1100 cmminus1 band Theyargued that the 1150 cmminus1 shoulder has significantly greaterintensity than could reasonably be assigned to residual g-SiO2spectral features In addition they found no correlation
between the intensity of this band and other bands (eg450 cmminus1) characteristic of the g-SiO
2spectrum Based on
these conclusions the 1150 cmminus1 shoulder was attributed to11987631015840 units which have slightly stronger (shorter) Si-Ominus bond
than the one producing the 1100 cmminus1 line [33]Matson et alrsquos assumption concerning the origin of the
1150 cmminus1 shoulder was confirmed later on by You with co-authors [6] The correlation between the Raman shift andconnecting topology of adjacent 119876119899 units was found based
International Journal of Spectroscopy 9
0
20
40
100
60
80
5 10 20 30 40 50
5
7
8
6
4
3
2
1
0
10 20 30 40 50
[Q2ij]
()
Cs2O (mol)
Q211
Q231
Q242
Q244
Q243
Q233
Q232
Q221
Q222
(a)
0
20
40
60
10
30
70
50
5 10 20 30 40 50
4
3
2
1
0
2010 30 40 50
[Q2ij]998400
()
Cs2O (mol)
Q211
Q231
Q244
Q243
Q233
Q232
Q221
Q222
(b)
36 38 44 48 5240 42 46 50 540
40
60
20
80
100
[Q1i ]
()
Cs2O (mol)
Q13Q12
Q11
Q14
(c)
0
15
20
10
25
30
5
36 38 44 48 5240 42 46 50 54
[Q1i ]998400
()
Cs2O (mol)
Q13
Q12
Q11
(d)
Figure 8 1198762119894119897 ((a) and (b)) and 1198761119894 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 =
1223K) ((a) and (c) equation (2) (b) and (d) equation (3))
on the quantum chemical calculation of the characteristicfrequencies of 119876
119899 species In other words it was demon-strated that the Raman shift of the symmetric stretchingvibration of 119876
119899 units decreases as the number of bridgingoxygen atoms of the nearest-neighbor 119876119899 species adjacent tothe given 119876
119899 unit decreases For example the Raman shiftof the 119876
3444 group is higher than that of the 1198763333 group
In our opinion the conclusions in [6] are strong evidenceof Matsonrsquos assumption Thus we will rely on Matsonrsquosinterpretation of the origin of 1150 cmminus1 band in our paper
The qualitative examination of the Raman spectra ofCs2O-SiO
2glasses (Figure 3) confirms that the structure of
glasses with a Cs2Ocontent below 33mol consists of1198764 and
1198763 units (the existence of1198764 units is obvious and requires no
evidence although the 1150 cmminus1 shoulder indirectly provesthe presence of such structural units) and that the 1198763 speciesare present at the least in the form of 119876
3444 and 1198763333
groups The Raman band at 930 cmminus1 shows that 1198762 units
are formed in the 33Cs and 37Cs glasses The presence of1198764 units in the structure of disilicate glasses is a result of
satisfying the charge balance (NBOSi = 1) Regarding the37Cs glass the presence of 1198764 species can be identified onlyby the quantitative analysis of the corresponding spectrum
The high-frequency envelope (800ndash1300 cmminus1) of theregistered Raman spectra was simulated as a superpositionof the Gaussian lines to estimate the 119876
119899 concentrationsThe number of Gaussian lines was sufficient to reproducethe original spectra with a correlation factor of ge098 Theinterpretation of the Raman bands described above was alsotaken into account In addition some results published in [6]were also taken into account 119876119899 species with equal 119899 givemore than one band and peak position of individual banddepends on the structural position of 119876119899 units For examplewavenumbers of NBO symmetric stretching vibration of 1198763species are located in the range of 1050 to 1150 cmminus1 whereas1198762 units give a set of the individual peaks in the range of
10 International Journal of Spectroscopy
60160260360460560660
H5
H4H3
22Cs
Ram
an in
tens
ity (a
u)
minus40
1443K
H1lowastH2lowast
50150250350450550650
H4H3
H5
27Cs
minus50
1553K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5
33Cs
minus40
1443K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5H6
37Cs
minus40
H2lowast
H1lowast
1443K
70170270370470570670770
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
793K
minus30
70170270370470570670
H4
H3
H5
Ram
an in
tens
ity (a
u)
1113K
minus30
H1lowastH2lowast
60160260360460560660
H4H3
H5
1113K
minus40
H1lowastH2lowast
70170270370470570670770
H4
H3H5
1223K
minus30
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1223K
minus30
H1lowastH2lowast
70170270370470570670770
H4H3
H5
898K
minus30
H1lowastH2lowast
60160260360460560660760860960
H4H3H5
793K
minus40
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1003K
minus30
H1lowastH2lowast
70170270370470570670770870
850 950 1050 1150 1250
H4
H3
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
70170270370470570670770
800 900 1000 1100 1200 1300
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
293K
minus30
Raman shift (cmminus1)
70170270370470570670770870970
800 900 1000 1100 1200 1300
H3H4
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
170370570770970
1170
800 900 1000 1100 1200 1300
H5H3 H4
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
Figure 9 Examples of the band deconvolution of Cs2O-SiO
2glasses and melts Raman spectra between 800 and 1300 cmminus1
930 to 1050 cmminus1 [6] Several examples of the deconvolutionresults of the Raman signal of the studied samples in the high-frequency region are shown in Figure 9 Four Gaussian lineswere sufficient to reproduce the low-temperature (293K)Raman spectra of the 17Cs and 22Cs glasses whereas five lineswere needed to simulate the 27Cs 33Cs and 37Cs spectraThe H3 and H4 bands were attributed to the 119876
3 speciesBecause the 17Cs and 22Cs glasses consist of1198764 and119876
3 unitsit is possible to assume that only four types of structuralgroups (119876344411987634431198763433 and119876
3333) can exist in structureof these glasses Considering the dependence of the Ramanshift of 1198763119894119895119896 groups on the 119894 119895 and 119896 indexes established in[6] it was assumed that the 119876
3444 and 1198763443 groups are the
main contributors to the intensity of the H4 band and thatthe vibrations of the 119876
3433 and 1198763333 groups are the main
contributors to the intensity of theH3 bandThis qualitativelyagrees with the simulation results of the 119876
3119894119895119896 distributionrepresented in Figures 7(c) and 7(d) The H2 band is mostlikely due to the stretching vibrations of the Si-O-Si linkages[3 31] The origin of the H1 line is unclear It is possible thatthis line is a result of the assumption of the Gaussian shape ofthe elementary bands in the spectra of glasses with relativelylow Cs
2O concentrations (17Cs and 22Cs) that is this line
is an error in the choice of the type of elementary bands
The relative area of the H1 band is the same for the 17Cs and22Cs spectra (002) and its intensity increases with furtherincreases in the Cs
2O content The H2 line behaves similarly
An increase in intensity of both H1 and H2 lines begins fromthe appearance of a new H5 line in the deconvolution of theRaman spectra The H5 line indicates the formation of 1198762species in the structure of the samples According to [6] itis possible to assume that the vibrations of the 119876
3119894119895119896 groupsconnected with one or two 119876
2 units for example 1198763332 and1198763322 groups also contribute to the intensity of the H2 band
at higher concentrations of the modifier oxide Thus the1060 cmminus1 line was designated as H2
lowast in the deconvolutionof the 27Cs 33Cs and 37Cs spectra In turn the H1
lowast linecan be attributed to the vibrations of the 119876
244 119876243 and119876233 groups according to the 119876
2119894119895 distribution representedin Figures 8(a) and 8(b) Finally the H5 line was ascribed to119876232 groupsThe localized nature of the silicon-oxygen stretching
motions of silicate units containing SiO4tetrahedra with
one two three or four nonbridging oxygen atoms [34 36]allows us to use the relative integral intensities of theGaussiancomponents to calculate the 119876119899 concentrations
If three types (1198764 1198763 1198762) of 119876
119899 species coexistin a structure simultaneously then their concentrations
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
6 International Journal of Spectroscopy
15531443
1223
1113
1003
898
793
683
473
293
530598
930
1100
1150
Raman shift (cmminus1)13001100900700500300
Ram
an in
tens
ity (a
u)
(a)
1223
1553
1338
1113
1003
898
793
293
530
573
683
598920
1100
1150
13001100900700500300
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)
(b)
Figure 4 Low- and high-temperature Raman spectra of the 22Cs2O-78SiO
2(a) and 27Cs
2O-73SiO
2(b) glasses andmelts (hereinafter
a temperature of the samples is shown in K)
1443
1338
1223
11131003
898
793
683
573
293
598530 920
1100
1150
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(a)
1443
1338
1223
1113
1003
573
293
420520 598
930
1100
Ram
an in
tens
ity (a
u)
Raman shift (cmminus1)13001100900700500300
(b)
Figure 5 Low- and high-temperature Raman spectra of the 33Cs2O-67SiO
2(a) and 37Cs
2O-63SiO
2(b) glasses and melts
compositions respectively (see the inset in Figure 7(c))The region of coexistence of the 119876
3119894119895119896 groups increases bysim25 and reaches 55 as the temperature increases up to1223K It is also accompanied by an increase in the widthof the 119876
3119894119895119896(119909) curves a shift of the maxima of these curves
toward large 119909 values and the leveling of their maxima Theconcentration of the dominant type of structural group (ata given composition) decreases and the fraction of the 119876
3119894119895119896
groups that are untypical for glass increases with increasingtemperature As before no significant changes are observedin the 1198763119894119895119896 distribution at 119909 lt 20mol
The1198762119894119895 and1198761119894 distributions calculated according to (3)
and (4) are shown in Figures 7(a)ndash7(d) Figures 8(a) and 8(c)represent the1198762119894119895 and119876
1119894 distributions relative to the1198762 and1198761 contents respectively and Figures 8(b) and 8(d) represent
the concentrations of the 1198762119894119895 and 119876
1119894 groups relative to the
International Journal of Spectroscopy 7
10 20 30 40 5000
20
40
60
80
100
Q4
Q3Q2
Q1
Q0
[Qn]
()
Cs2O (mol)
(a)
20 25 30 35 40 45 50 55
0
1
2
3
4
0 10 20 30 40 500
20
40
60
80
100
Qi ndashQ
j(
)
Q4ndashQ4
Q4ndashQ3
Q3ndashQ3 Q2ndashQ2
Q3ndashQ2
Q2ndashQ1
Q4ndashQ2
Q3ndashQ1
Q1ndashQ1
Cs2O (mol)
(b)
Figure 6 119876119899 (a) and 119876119894ndash119876119895 (b) distributions for glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 = 1223K) of Cs
2O-SiO
2system
Symbols are experimental data (◻ [1] ⃝ [3] [27] andM this work)
total amount of119876119899 units respectively As seen in Figure 8(a)an increase in concentration in themodifier oxide leads to thetransformation of the 1198762119894119895 groups in the following sequence119876244
rarr 119876243
rarr 119876233
rarr 119876232
rarr 119876222
rarr 119876221
rarr
119876211 It should be noted that the concentration of the 119876
244
and 119876243 groups relative to 119876
119899 units in the glass structureis low at 119909 gt 15mol (less than 15 see Figure 8(b))although their fraction relative to the total amount of 1198762119894119895
groups exceeds 40 Moreover the 1198762119894119895 groups are only
formed in the glass structure in an amount exceeding 1at 119909 gt 28mol as follows from Figure 8(b) As beforean increase in the width of the 119876
2119894119895(119909) curves and a shift
in the position of their maxima toward large 119909 values areobserved with increasing temperature The 119876
2119894119895(119909) maxima
change such that the difference between maxima decreaseswith increasing temperature
The 1198761119894 distribution has the simplest form which is
evidently related to the low variety of such groups (A changein 119894 from 4 to 1 gives only four types of 119876
1119894 groups) Theconcentration of the 119876
14 groups is negligible in the glassstructure Therefore a consequence of the transformationsof the 119876
1119894 groups looks similar to 11987613
rarr 11987612
rarr 11987611
The data presented in Figures 8(c) and 8(d) support theassumption that the changes in the 119876
1119894(119909) curves will be
similar to those described above
4 Discussion
41 Raman Spectra and Structure of the119909Cs2O-(100minus x)SiO2(x = 17 22 27 33 and 37mol) Glasses It is rational todivide the overall frequency range into low-frequency (400ndash700 cmminus1) and high-frequency (800ndash1200 cmminus1) intervals toanalyze the obtained Raman spectra The low-frequencyinterval is related to the stretching and some of the bending
vibrations of Si-O-Si linkages Two narrow lines (490 cmminus1(D1) and 602 cmminus1 (D
2)) along with a broad intense line
(sim450 cmminus1) are observed in the Raman spectrum of g-SiO2
(eg [28]) It is accepted that the D1and D
2lines can be
related to the symmetric oxygen breathing vibration of three-(D2) and four-membered (D
1) siloxane rings consisting of
SiO4tetrahedra [28ndash32] The investigation of the Raman
spectra of alkali silicate glasses with high SiO2content [33]
has shown that the bands near 490 and 602 cmminus1 are graduallyshifted toward higher and lower frequencies respectivelywith increasing Cs
2O content Thus it can be assumed that
the Raman bands near 510ndash530 and 598 cmminus1 in our spectrahave the same origin as the D
1and D
2lines respectively The
change in the intensity of these lines as a function of glasscomposition (see Figure 3) shows that the increase in mod-ifier oxide concentrations leads to changes in the statisticaldistribution of 119899-membered rings wherein the concentrationof three-membered rings gradually increases This obser-vation is in accordance with the results published in [27]where an increase in concentrations of three-membered ringswith increasing Cs
2O was shown based on NMR data The
concentration of the four-membered rings changes weakly at17 lt 119909 lt 22 and decreases at higher Cs
2O content
The Raman bands originating from the symmetricstretching vibration of the Si-Ominus terminal groups of various119876119899 (119899 lt 4) units are located in the high-frequency range of
spectra of alkali silicate glasses [34](i) the band at 1050ndash1100 cmminus1 is due to the symmetric
stretching vibrations of the terminal oxygen atoms ofSiO4tetrahedra with one nonbridging oxygen (NBO)
atom that is 1198763 units(ii) the band at 920ndash950 cmminus1 results from the Si-Ominus
stretching of SiO4tetrahedra with two NBO (1198762
units)
8 International Journal of Spectroscopy
15 20 25 30 35 40 45
0
1
2
3
4
5
6
7
10 200 30 400
20
40
60
80
100
Q43321
Q43221
Q44322
Q42222
Q43331Q44432
Q44332
Q43322
Q43222
Q43322
Q43332
Q43333
Q44333
Q44433
Q44443
Q44444
Q44332
[Q4ijk]
()
Cs2O (mol)
(a)
5
4
3
2
1
0
15 20 25 30 35 40 45
100 20 30 400
20
40
60
80
100
Q43332
Q43333Q44333
Q43333
Q44433
Q44443
Q44432
Q44332
Q44444
[Q4ijkl ]998400
()
Cs2O (mol)
(b)
100
80
60
40
20
00 10 20 30 40 50
15 20 30 40 50
0
2
4
6
8
10
[Q3ijk]
()
Q3311
Q3211
Q3111
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3221
Cs2O (mol)
(c)
100 20 30 40 50
20
10
0
30
40
50
60
70
80
2
0
1
3
4
5
6
10 20 30 40 50[Q3ijk]998400
()
Q3311
Q3221Q3331
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3222
Cs2O (mol)
(d)
Figure 7 1198764119894119895119896119897 ((a) and (b)) and 1198763119894119895119896 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines
119879 = 1223K) ((a) and (c) equation (3) (b) and (d) equation (4))
(iii) the Raman band near 900 cmminus1 is attributed to thestretching vibration of the 119876
1 units (SiO4tetrahedra
with three NBO)(iv) finally the line at 850 cmminus1 is related to the symmetric
stretching mode of 1198760 anionsAs seen in Figure 3 only the 1050ndash1100 and 930 cmminus1
bands are observed in the Raman spectra of studied glassesIt should be noted that the 1050ndash1100 cmminus1 band exists inall spectra whereas the 930 cmminus1 band is only observed inthe spectra of glasses with relatively high Cs
2O contents
(33Cs and 37Cs) In addition a high-frequency shoulderwith maximum at approximately 1150 cmminus1 is observed inthe Raman spectra of the 17Cs 22Cs and 27Cs samplesAlthough alkali silicate glasses have been studied for a longtime a review of the literature revealed that the origin of thisshoulder is still controversial In one series of publications[12 13 35] the 1150 cmminus1 line was attributed to the Si-Ostretching vibration in fully polymerized structural species
that is the vibrations of 1198764 units However based on a studyof the Raman spectra of alkali silicate glasses with variouscompositions Matson et al [33] have suggested that this linemay be assigned to the vibrations of the 119876
31015840 units whichare structurally and vibrationally distinguished from thoseof the 119876
3 units producing the 1050ndash1100 cmminus1 band Theyargued that the 1150 cmminus1 shoulder has significantly greaterintensity than could reasonably be assigned to residual g-SiO2spectral features In addition they found no correlation
between the intensity of this band and other bands (eg450 cmminus1) characteristic of the g-SiO
2spectrum Based on
these conclusions the 1150 cmminus1 shoulder was attributed to11987631015840 units which have slightly stronger (shorter) Si-Ominus bond
than the one producing the 1100 cmminus1 line [33]Matson et alrsquos assumption concerning the origin of the
1150 cmminus1 shoulder was confirmed later on by You with co-authors [6] The correlation between the Raman shift andconnecting topology of adjacent 119876119899 units was found based
International Journal of Spectroscopy 9
0
20
40
100
60
80
5 10 20 30 40 50
5
7
8
6
4
3
2
1
0
10 20 30 40 50
[Q2ij]
()
Cs2O (mol)
Q211
Q231
Q242
Q244
Q243
Q233
Q232
Q221
Q222
(a)
0
20
40
60
10
30
70
50
5 10 20 30 40 50
4
3
2
1
0
2010 30 40 50
[Q2ij]998400
()
Cs2O (mol)
Q211
Q231
Q244
Q243
Q233
Q232
Q221
Q222
(b)
36 38 44 48 5240 42 46 50 540
40
60
20
80
100
[Q1i ]
()
Cs2O (mol)
Q13Q12
Q11
Q14
(c)
0
15
20
10
25
30
5
36 38 44 48 5240 42 46 50 54
[Q1i ]998400
()
Cs2O (mol)
Q13
Q12
Q11
(d)
Figure 8 1198762119894119897 ((a) and (b)) and 1198761119894 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 =
1223K) ((a) and (c) equation (2) (b) and (d) equation (3))
on the quantum chemical calculation of the characteristicfrequencies of 119876
119899 species In other words it was demon-strated that the Raman shift of the symmetric stretchingvibration of 119876
119899 units decreases as the number of bridgingoxygen atoms of the nearest-neighbor 119876119899 species adjacent tothe given 119876
119899 unit decreases For example the Raman shiftof the 119876
3444 group is higher than that of the 1198763333 group
In our opinion the conclusions in [6] are strong evidenceof Matsonrsquos assumption Thus we will rely on Matsonrsquosinterpretation of the origin of 1150 cmminus1 band in our paper
The qualitative examination of the Raman spectra ofCs2O-SiO
2glasses (Figure 3) confirms that the structure of
glasses with a Cs2Ocontent below 33mol consists of1198764 and
1198763 units (the existence of1198764 units is obvious and requires no
evidence although the 1150 cmminus1 shoulder indirectly provesthe presence of such structural units) and that the 1198763 speciesare present at the least in the form of 119876
3444 and 1198763333
groups The Raman band at 930 cmminus1 shows that 1198762 units
are formed in the 33Cs and 37Cs glasses The presence of1198764 units in the structure of disilicate glasses is a result of
satisfying the charge balance (NBOSi = 1) Regarding the37Cs glass the presence of 1198764 species can be identified onlyby the quantitative analysis of the corresponding spectrum
The high-frequency envelope (800ndash1300 cmminus1) of theregistered Raman spectra was simulated as a superpositionof the Gaussian lines to estimate the 119876
119899 concentrationsThe number of Gaussian lines was sufficient to reproducethe original spectra with a correlation factor of ge098 Theinterpretation of the Raman bands described above was alsotaken into account In addition some results published in [6]were also taken into account 119876119899 species with equal 119899 givemore than one band and peak position of individual banddepends on the structural position of 119876119899 units For examplewavenumbers of NBO symmetric stretching vibration of 1198763species are located in the range of 1050 to 1150 cmminus1 whereas1198762 units give a set of the individual peaks in the range of
10 International Journal of Spectroscopy
60160260360460560660
H5
H4H3
22Cs
Ram
an in
tens
ity (a
u)
minus40
1443K
H1lowastH2lowast
50150250350450550650
H4H3
H5
27Cs
minus50
1553K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5
33Cs
minus40
1443K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5H6
37Cs
minus40
H2lowast
H1lowast
1443K
70170270370470570670770
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
793K
minus30
70170270370470570670
H4
H3
H5
Ram
an in
tens
ity (a
u)
1113K
minus30
H1lowastH2lowast
60160260360460560660
H4H3
H5
1113K
minus40
H1lowastH2lowast
70170270370470570670770
H4
H3H5
1223K
minus30
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1223K
minus30
H1lowastH2lowast
70170270370470570670770
H4H3
H5
898K
minus30
H1lowastH2lowast
60160260360460560660760860960
H4H3H5
793K
minus40
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1003K
minus30
H1lowastH2lowast
70170270370470570670770870
850 950 1050 1150 1250
H4
H3
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
70170270370470570670770
800 900 1000 1100 1200 1300
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
293K
minus30
Raman shift (cmminus1)
70170270370470570670770870970
800 900 1000 1100 1200 1300
H3H4
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
170370570770970
1170
800 900 1000 1100 1200 1300
H5H3 H4
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
Figure 9 Examples of the band deconvolution of Cs2O-SiO
2glasses and melts Raman spectra between 800 and 1300 cmminus1
930 to 1050 cmminus1 [6] Several examples of the deconvolutionresults of the Raman signal of the studied samples in the high-frequency region are shown in Figure 9 Four Gaussian lineswere sufficient to reproduce the low-temperature (293K)Raman spectra of the 17Cs and 22Cs glasses whereas five lineswere needed to simulate the 27Cs 33Cs and 37Cs spectraThe H3 and H4 bands were attributed to the 119876
3 speciesBecause the 17Cs and 22Cs glasses consist of1198764 and119876
3 unitsit is possible to assume that only four types of structuralgroups (119876344411987634431198763433 and119876
3333) can exist in structureof these glasses Considering the dependence of the Ramanshift of 1198763119894119895119896 groups on the 119894 119895 and 119896 indexes established in[6] it was assumed that the 119876
3444 and 1198763443 groups are the
main contributors to the intensity of the H4 band and thatthe vibrations of the 119876
3433 and 1198763333 groups are the main
contributors to the intensity of theH3 bandThis qualitativelyagrees with the simulation results of the 119876
3119894119895119896 distributionrepresented in Figures 7(c) and 7(d) The H2 band is mostlikely due to the stretching vibrations of the Si-O-Si linkages[3 31] The origin of the H1 line is unclear It is possible thatthis line is a result of the assumption of the Gaussian shape ofthe elementary bands in the spectra of glasses with relativelylow Cs
2O concentrations (17Cs and 22Cs) that is this line
is an error in the choice of the type of elementary bands
The relative area of the H1 band is the same for the 17Cs and22Cs spectra (002) and its intensity increases with furtherincreases in the Cs
2O content The H2 line behaves similarly
An increase in intensity of both H1 and H2 lines begins fromthe appearance of a new H5 line in the deconvolution of theRaman spectra The H5 line indicates the formation of 1198762species in the structure of the samples According to [6] itis possible to assume that the vibrations of the 119876
3119894119895119896 groupsconnected with one or two 119876
2 units for example 1198763332 and1198763322 groups also contribute to the intensity of the H2 band
at higher concentrations of the modifier oxide Thus the1060 cmminus1 line was designated as H2
lowast in the deconvolutionof the 27Cs 33Cs and 37Cs spectra In turn the H1
lowast linecan be attributed to the vibrations of the 119876
244 119876243 and119876233 groups according to the 119876
2119894119895 distribution representedin Figures 8(a) and 8(b) Finally the H5 line was ascribed to119876232 groupsThe localized nature of the silicon-oxygen stretching
motions of silicate units containing SiO4tetrahedra with
one two three or four nonbridging oxygen atoms [34 36]allows us to use the relative integral intensities of theGaussiancomponents to calculate the 119876119899 concentrations
If three types (1198764 1198763 1198762) of 119876
119899 species coexistin a structure simultaneously then their concentrations
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
International Journal of Spectroscopy 7
10 20 30 40 5000
20
40
60
80
100
Q4
Q3Q2
Q1
Q0
[Qn]
()
Cs2O (mol)
(a)
20 25 30 35 40 45 50 55
0
1
2
3
4
0 10 20 30 40 500
20
40
60
80
100
Qi ndashQ
j(
)
Q4ndashQ4
Q4ndashQ3
Q3ndashQ3 Q2ndashQ2
Q3ndashQ2
Q2ndashQ1
Q4ndashQ2
Q3ndashQ1
Q1ndashQ1
Cs2O (mol)
(b)
Figure 6 119876119899 (a) and 119876119894ndash119876119895 (b) distributions for glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 = 1223K) of Cs
2O-SiO
2system
Symbols are experimental data (◻ [1] ⃝ [3] [27] andM this work)
total amount of119876119899 units respectively As seen in Figure 8(a)an increase in concentration in themodifier oxide leads to thetransformation of the 1198762119894119895 groups in the following sequence119876244
rarr 119876243
rarr 119876233
rarr 119876232
rarr 119876222
rarr 119876221
rarr
119876211 It should be noted that the concentration of the 119876
244
and 119876243 groups relative to 119876
119899 units in the glass structureis low at 119909 gt 15mol (less than 15 see Figure 8(b))although their fraction relative to the total amount of 1198762119894119895
groups exceeds 40 Moreover the 1198762119894119895 groups are only
formed in the glass structure in an amount exceeding 1at 119909 gt 28mol as follows from Figure 8(b) As beforean increase in the width of the 119876
2119894119895(119909) curves and a shift
in the position of their maxima toward large 119909 values areobserved with increasing temperature The 119876
2119894119895(119909) maxima
change such that the difference between maxima decreaseswith increasing temperature
The 1198761119894 distribution has the simplest form which is
evidently related to the low variety of such groups (A changein 119894 from 4 to 1 gives only four types of 119876
1119894 groups) Theconcentration of the 119876
14 groups is negligible in the glassstructure Therefore a consequence of the transformationsof the 119876
1119894 groups looks similar to 11987613
rarr 11987612
rarr 11987611
The data presented in Figures 8(c) and 8(d) support theassumption that the changes in the 119876
1119894(119909) curves will be
similar to those described above
4 Discussion
41 Raman Spectra and Structure of the119909Cs2O-(100minus x)SiO2(x = 17 22 27 33 and 37mol) Glasses It is rational todivide the overall frequency range into low-frequency (400ndash700 cmminus1) and high-frequency (800ndash1200 cmminus1) intervals toanalyze the obtained Raman spectra The low-frequencyinterval is related to the stretching and some of the bending
vibrations of Si-O-Si linkages Two narrow lines (490 cmminus1(D1) and 602 cmminus1 (D
2)) along with a broad intense line
(sim450 cmminus1) are observed in the Raman spectrum of g-SiO2
(eg [28]) It is accepted that the D1and D
2lines can be
related to the symmetric oxygen breathing vibration of three-(D2) and four-membered (D
1) siloxane rings consisting of
SiO4tetrahedra [28ndash32] The investigation of the Raman
spectra of alkali silicate glasses with high SiO2content [33]
has shown that the bands near 490 and 602 cmminus1 are graduallyshifted toward higher and lower frequencies respectivelywith increasing Cs
2O content Thus it can be assumed that
the Raman bands near 510ndash530 and 598 cmminus1 in our spectrahave the same origin as the D
1and D
2lines respectively The
change in the intensity of these lines as a function of glasscomposition (see Figure 3) shows that the increase in mod-ifier oxide concentrations leads to changes in the statisticaldistribution of 119899-membered rings wherein the concentrationof three-membered rings gradually increases This obser-vation is in accordance with the results published in [27]where an increase in concentrations of three-membered ringswith increasing Cs
2O was shown based on NMR data The
concentration of the four-membered rings changes weakly at17 lt 119909 lt 22 and decreases at higher Cs
2O content
The Raman bands originating from the symmetricstretching vibration of the Si-Ominus terminal groups of various119876119899 (119899 lt 4) units are located in the high-frequency range of
spectra of alkali silicate glasses [34](i) the band at 1050ndash1100 cmminus1 is due to the symmetric
stretching vibrations of the terminal oxygen atoms ofSiO4tetrahedra with one nonbridging oxygen (NBO)
atom that is 1198763 units(ii) the band at 920ndash950 cmminus1 results from the Si-Ominus
stretching of SiO4tetrahedra with two NBO (1198762
units)
8 International Journal of Spectroscopy
15 20 25 30 35 40 45
0
1
2
3
4
5
6
7
10 200 30 400
20
40
60
80
100
Q43321
Q43221
Q44322
Q42222
Q43331Q44432
Q44332
Q43322
Q43222
Q43322
Q43332
Q43333
Q44333
Q44433
Q44443
Q44444
Q44332
[Q4ijk]
()
Cs2O (mol)
(a)
5
4
3
2
1
0
15 20 25 30 35 40 45
100 20 30 400
20
40
60
80
100
Q43332
Q43333Q44333
Q43333
Q44433
Q44443
Q44432
Q44332
Q44444
[Q4ijkl ]998400
()
Cs2O (mol)
(b)
100
80
60
40
20
00 10 20 30 40 50
15 20 30 40 50
0
2
4
6
8
10
[Q3ijk]
()
Q3311
Q3211
Q3111
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3221
Cs2O (mol)
(c)
100 20 30 40 50
20
10
0
30
40
50
60
70
80
2
0
1
3
4
5
6
10 20 30 40 50[Q3ijk]998400
()
Q3311
Q3221Q3331
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3222
Cs2O (mol)
(d)
Figure 7 1198764119894119895119896119897 ((a) and (b)) and 1198763119894119895119896 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines
119879 = 1223K) ((a) and (c) equation (3) (b) and (d) equation (4))
(iii) the Raman band near 900 cmminus1 is attributed to thestretching vibration of the 119876
1 units (SiO4tetrahedra
with three NBO)(iv) finally the line at 850 cmminus1 is related to the symmetric
stretching mode of 1198760 anionsAs seen in Figure 3 only the 1050ndash1100 and 930 cmminus1
bands are observed in the Raman spectra of studied glassesIt should be noted that the 1050ndash1100 cmminus1 band exists inall spectra whereas the 930 cmminus1 band is only observed inthe spectra of glasses with relatively high Cs
2O contents
(33Cs and 37Cs) In addition a high-frequency shoulderwith maximum at approximately 1150 cmminus1 is observed inthe Raman spectra of the 17Cs 22Cs and 27Cs samplesAlthough alkali silicate glasses have been studied for a longtime a review of the literature revealed that the origin of thisshoulder is still controversial In one series of publications[12 13 35] the 1150 cmminus1 line was attributed to the Si-Ostretching vibration in fully polymerized structural species
that is the vibrations of 1198764 units However based on a studyof the Raman spectra of alkali silicate glasses with variouscompositions Matson et al [33] have suggested that this linemay be assigned to the vibrations of the 119876
31015840 units whichare structurally and vibrationally distinguished from thoseof the 119876
3 units producing the 1050ndash1100 cmminus1 band Theyargued that the 1150 cmminus1 shoulder has significantly greaterintensity than could reasonably be assigned to residual g-SiO2spectral features In addition they found no correlation
between the intensity of this band and other bands (eg450 cmminus1) characteristic of the g-SiO
2spectrum Based on
these conclusions the 1150 cmminus1 shoulder was attributed to11987631015840 units which have slightly stronger (shorter) Si-Ominus bond
than the one producing the 1100 cmminus1 line [33]Matson et alrsquos assumption concerning the origin of the
1150 cmminus1 shoulder was confirmed later on by You with co-authors [6] The correlation between the Raman shift andconnecting topology of adjacent 119876119899 units was found based
International Journal of Spectroscopy 9
0
20
40
100
60
80
5 10 20 30 40 50
5
7
8
6
4
3
2
1
0
10 20 30 40 50
[Q2ij]
()
Cs2O (mol)
Q211
Q231
Q242
Q244
Q243
Q233
Q232
Q221
Q222
(a)
0
20
40
60
10
30
70
50
5 10 20 30 40 50
4
3
2
1
0
2010 30 40 50
[Q2ij]998400
()
Cs2O (mol)
Q211
Q231
Q244
Q243
Q233
Q232
Q221
Q222
(b)
36 38 44 48 5240 42 46 50 540
40
60
20
80
100
[Q1i ]
()
Cs2O (mol)
Q13Q12
Q11
Q14
(c)
0
15
20
10
25
30
5
36 38 44 48 5240 42 46 50 54
[Q1i ]998400
()
Cs2O (mol)
Q13
Q12
Q11
(d)
Figure 8 1198762119894119897 ((a) and (b)) and 1198761119894 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 =
1223K) ((a) and (c) equation (2) (b) and (d) equation (3))
on the quantum chemical calculation of the characteristicfrequencies of 119876
119899 species In other words it was demon-strated that the Raman shift of the symmetric stretchingvibration of 119876
119899 units decreases as the number of bridgingoxygen atoms of the nearest-neighbor 119876119899 species adjacent tothe given 119876
119899 unit decreases For example the Raman shiftof the 119876
3444 group is higher than that of the 1198763333 group
In our opinion the conclusions in [6] are strong evidenceof Matsonrsquos assumption Thus we will rely on Matsonrsquosinterpretation of the origin of 1150 cmminus1 band in our paper
The qualitative examination of the Raman spectra ofCs2O-SiO
2glasses (Figure 3) confirms that the structure of
glasses with a Cs2Ocontent below 33mol consists of1198764 and
1198763 units (the existence of1198764 units is obvious and requires no
evidence although the 1150 cmminus1 shoulder indirectly provesthe presence of such structural units) and that the 1198763 speciesare present at the least in the form of 119876
3444 and 1198763333
groups The Raman band at 930 cmminus1 shows that 1198762 units
are formed in the 33Cs and 37Cs glasses The presence of1198764 units in the structure of disilicate glasses is a result of
satisfying the charge balance (NBOSi = 1) Regarding the37Cs glass the presence of 1198764 species can be identified onlyby the quantitative analysis of the corresponding spectrum
The high-frequency envelope (800ndash1300 cmminus1) of theregistered Raman spectra was simulated as a superpositionof the Gaussian lines to estimate the 119876
119899 concentrationsThe number of Gaussian lines was sufficient to reproducethe original spectra with a correlation factor of ge098 Theinterpretation of the Raman bands described above was alsotaken into account In addition some results published in [6]were also taken into account 119876119899 species with equal 119899 givemore than one band and peak position of individual banddepends on the structural position of 119876119899 units For examplewavenumbers of NBO symmetric stretching vibration of 1198763species are located in the range of 1050 to 1150 cmminus1 whereas1198762 units give a set of the individual peaks in the range of
10 International Journal of Spectroscopy
60160260360460560660
H5
H4H3
22Cs
Ram
an in
tens
ity (a
u)
minus40
1443K
H1lowastH2lowast
50150250350450550650
H4H3
H5
27Cs
minus50
1553K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5
33Cs
minus40
1443K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5H6
37Cs
minus40
H2lowast
H1lowast
1443K
70170270370470570670770
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
793K
minus30
70170270370470570670
H4
H3
H5
Ram
an in
tens
ity (a
u)
1113K
minus30
H1lowastH2lowast
60160260360460560660
H4H3
H5
1113K
minus40
H1lowastH2lowast
70170270370470570670770
H4
H3H5
1223K
minus30
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1223K
minus30
H1lowastH2lowast
70170270370470570670770
H4H3
H5
898K
minus30
H1lowastH2lowast
60160260360460560660760860960
H4H3H5
793K
minus40
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1003K
minus30
H1lowastH2lowast
70170270370470570670770870
850 950 1050 1150 1250
H4
H3
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
70170270370470570670770
800 900 1000 1100 1200 1300
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
293K
minus30
Raman shift (cmminus1)
70170270370470570670770870970
800 900 1000 1100 1200 1300
H3H4
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
170370570770970
1170
800 900 1000 1100 1200 1300
H5H3 H4
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
Figure 9 Examples of the band deconvolution of Cs2O-SiO
2glasses and melts Raman spectra between 800 and 1300 cmminus1
930 to 1050 cmminus1 [6] Several examples of the deconvolutionresults of the Raman signal of the studied samples in the high-frequency region are shown in Figure 9 Four Gaussian lineswere sufficient to reproduce the low-temperature (293K)Raman spectra of the 17Cs and 22Cs glasses whereas five lineswere needed to simulate the 27Cs 33Cs and 37Cs spectraThe H3 and H4 bands were attributed to the 119876
3 speciesBecause the 17Cs and 22Cs glasses consist of1198764 and119876
3 unitsit is possible to assume that only four types of structuralgroups (119876344411987634431198763433 and119876
3333) can exist in structureof these glasses Considering the dependence of the Ramanshift of 1198763119894119895119896 groups on the 119894 119895 and 119896 indexes established in[6] it was assumed that the 119876
3444 and 1198763443 groups are the
main contributors to the intensity of the H4 band and thatthe vibrations of the 119876
3433 and 1198763333 groups are the main
contributors to the intensity of theH3 bandThis qualitativelyagrees with the simulation results of the 119876
3119894119895119896 distributionrepresented in Figures 7(c) and 7(d) The H2 band is mostlikely due to the stretching vibrations of the Si-O-Si linkages[3 31] The origin of the H1 line is unclear It is possible thatthis line is a result of the assumption of the Gaussian shape ofthe elementary bands in the spectra of glasses with relativelylow Cs
2O concentrations (17Cs and 22Cs) that is this line
is an error in the choice of the type of elementary bands
The relative area of the H1 band is the same for the 17Cs and22Cs spectra (002) and its intensity increases with furtherincreases in the Cs
2O content The H2 line behaves similarly
An increase in intensity of both H1 and H2 lines begins fromthe appearance of a new H5 line in the deconvolution of theRaman spectra The H5 line indicates the formation of 1198762species in the structure of the samples According to [6] itis possible to assume that the vibrations of the 119876
3119894119895119896 groupsconnected with one or two 119876
2 units for example 1198763332 and1198763322 groups also contribute to the intensity of the H2 band
at higher concentrations of the modifier oxide Thus the1060 cmminus1 line was designated as H2
lowast in the deconvolutionof the 27Cs 33Cs and 37Cs spectra In turn the H1
lowast linecan be attributed to the vibrations of the 119876
244 119876243 and119876233 groups according to the 119876
2119894119895 distribution representedin Figures 8(a) and 8(b) Finally the H5 line was ascribed to119876232 groupsThe localized nature of the silicon-oxygen stretching
motions of silicate units containing SiO4tetrahedra with
one two three or four nonbridging oxygen atoms [34 36]allows us to use the relative integral intensities of theGaussiancomponents to calculate the 119876119899 concentrations
If three types (1198764 1198763 1198762) of 119876
119899 species coexistin a structure simultaneously then their concentrations
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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CatalystsJournal of
8 International Journal of Spectroscopy
15 20 25 30 35 40 45
0
1
2
3
4
5
6
7
10 200 30 400
20
40
60
80
100
Q43321
Q43221
Q44322
Q42222
Q43331Q44432
Q44332
Q43322
Q43222
Q43322
Q43332
Q43333
Q44333
Q44433
Q44443
Q44444
Q44332
[Q4ijk]
()
Cs2O (mol)
(a)
5
4
3
2
1
0
15 20 25 30 35 40 45
100 20 30 400
20
40
60
80
100
Q43332
Q43333Q44333
Q43333
Q44433
Q44443
Q44432
Q44332
Q44444
[Q4ijkl ]998400
()
Cs2O (mol)
(b)
100
80
60
40
20
00 10 20 30 40 50
15 20 30 40 50
0
2
4
6
8
10
[Q3ijk]
()
Q3311
Q3211
Q3111
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3221
Cs2O (mol)
(c)
100 20 30 40 50
20
10
0
30
40
50
60
70
80
2
0
1
3
4
5
6
10 20 30 40 50[Q3ijk]998400
()
Q3311
Q3221Q3331
Q3321
Q3432
Q3442
Q3322
Q3222
Q3332
Q3333
Q3433
Q3444
Q3443
Q3222
Cs2O (mol)
(d)
Figure 7 1198764119894119895119896119897 ((a) and (b)) and 1198763119894119895119896 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines
119879 = 1223K) ((a) and (c) equation (3) (b) and (d) equation (4))
(iii) the Raman band near 900 cmminus1 is attributed to thestretching vibration of the 119876
1 units (SiO4tetrahedra
with three NBO)(iv) finally the line at 850 cmminus1 is related to the symmetric
stretching mode of 1198760 anionsAs seen in Figure 3 only the 1050ndash1100 and 930 cmminus1
bands are observed in the Raman spectra of studied glassesIt should be noted that the 1050ndash1100 cmminus1 band exists inall spectra whereas the 930 cmminus1 band is only observed inthe spectra of glasses with relatively high Cs
2O contents
(33Cs and 37Cs) In addition a high-frequency shoulderwith maximum at approximately 1150 cmminus1 is observed inthe Raman spectra of the 17Cs 22Cs and 27Cs samplesAlthough alkali silicate glasses have been studied for a longtime a review of the literature revealed that the origin of thisshoulder is still controversial In one series of publications[12 13 35] the 1150 cmminus1 line was attributed to the Si-Ostretching vibration in fully polymerized structural species
that is the vibrations of 1198764 units However based on a studyof the Raman spectra of alkali silicate glasses with variouscompositions Matson et al [33] have suggested that this linemay be assigned to the vibrations of the 119876
31015840 units whichare structurally and vibrationally distinguished from thoseof the 119876
3 units producing the 1050ndash1100 cmminus1 band Theyargued that the 1150 cmminus1 shoulder has significantly greaterintensity than could reasonably be assigned to residual g-SiO2spectral features In addition they found no correlation
between the intensity of this band and other bands (eg450 cmminus1) characteristic of the g-SiO
2spectrum Based on
these conclusions the 1150 cmminus1 shoulder was attributed to11987631015840 units which have slightly stronger (shorter) Si-Ominus bond
than the one producing the 1100 cmminus1 line [33]Matson et alrsquos assumption concerning the origin of the
1150 cmminus1 shoulder was confirmed later on by You with co-authors [6] The correlation between the Raman shift andconnecting topology of adjacent 119876119899 units was found based
International Journal of Spectroscopy 9
0
20
40
100
60
80
5 10 20 30 40 50
5
7
8
6
4
3
2
1
0
10 20 30 40 50
[Q2ij]
()
Cs2O (mol)
Q211
Q231
Q242
Q244
Q243
Q233
Q232
Q221
Q222
(a)
0
20
40
60
10
30
70
50
5 10 20 30 40 50
4
3
2
1
0
2010 30 40 50
[Q2ij]998400
()
Cs2O (mol)
Q211
Q231
Q244
Q243
Q233
Q232
Q221
Q222
(b)
36 38 44 48 5240 42 46 50 540
40
60
20
80
100
[Q1i ]
()
Cs2O (mol)
Q13Q12
Q11
Q14
(c)
0
15
20
10
25
30
5
36 38 44 48 5240 42 46 50 54
[Q1i ]998400
()
Cs2O (mol)
Q13
Q12
Q11
(d)
Figure 8 1198762119894119897 ((a) and (b)) and 1198761119894 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 =
1223K) ((a) and (c) equation (2) (b) and (d) equation (3))
on the quantum chemical calculation of the characteristicfrequencies of 119876
119899 species In other words it was demon-strated that the Raman shift of the symmetric stretchingvibration of 119876
119899 units decreases as the number of bridgingoxygen atoms of the nearest-neighbor 119876119899 species adjacent tothe given 119876
119899 unit decreases For example the Raman shiftof the 119876
3444 group is higher than that of the 1198763333 group
In our opinion the conclusions in [6] are strong evidenceof Matsonrsquos assumption Thus we will rely on Matsonrsquosinterpretation of the origin of 1150 cmminus1 band in our paper
The qualitative examination of the Raman spectra ofCs2O-SiO
2glasses (Figure 3) confirms that the structure of
glasses with a Cs2Ocontent below 33mol consists of1198764 and
1198763 units (the existence of1198764 units is obvious and requires no
evidence although the 1150 cmminus1 shoulder indirectly provesthe presence of such structural units) and that the 1198763 speciesare present at the least in the form of 119876
3444 and 1198763333
groups The Raman band at 930 cmminus1 shows that 1198762 units
are formed in the 33Cs and 37Cs glasses The presence of1198764 units in the structure of disilicate glasses is a result of
satisfying the charge balance (NBOSi = 1) Regarding the37Cs glass the presence of 1198764 species can be identified onlyby the quantitative analysis of the corresponding spectrum
The high-frequency envelope (800ndash1300 cmminus1) of theregistered Raman spectra was simulated as a superpositionof the Gaussian lines to estimate the 119876
119899 concentrationsThe number of Gaussian lines was sufficient to reproducethe original spectra with a correlation factor of ge098 Theinterpretation of the Raman bands described above was alsotaken into account In addition some results published in [6]were also taken into account 119876119899 species with equal 119899 givemore than one band and peak position of individual banddepends on the structural position of 119876119899 units For examplewavenumbers of NBO symmetric stretching vibration of 1198763species are located in the range of 1050 to 1150 cmminus1 whereas1198762 units give a set of the individual peaks in the range of
10 International Journal of Spectroscopy
60160260360460560660
H5
H4H3
22Cs
Ram
an in
tens
ity (a
u)
minus40
1443K
H1lowastH2lowast
50150250350450550650
H4H3
H5
27Cs
minus50
1553K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5
33Cs
minus40
1443K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5H6
37Cs
minus40
H2lowast
H1lowast
1443K
70170270370470570670770
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
793K
minus30
70170270370470570670
H4
H3
H5
Ram
an in
tens
ity (a
u)
1113K
minus30
H1lowastH2lowast
60160260360460560660
H4H3
H5
1113K
minus40
H1lowastH2lowast
70170270370470570670770
H4
H3H5
1223K
minus30
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1223K
minus30
H1lowastH2lowast
70170270370470570670770
H4H3
H5
898K
minus30
H1lowastH2lowast
60160260360460560660760860960
H4H3H5
793K
minus40
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1003K
minus30
H1lowastH2lowast
70170270370470570670770870
850 950 1050 1150 1250
H4
H3
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
70170270370470570670770
800 900 1000 1100 1200 1300
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
293K
minus30
Raman shift (cmminus1)
70170270370470570670770870970
800 900 1000 1100 1200 1300
H3H4
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
170370570770970
1170
800 900 1000 1100 1200 1300
H5H3 H4
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
Figure 9 Examples of the band deconvolution of Cs2O-SiO
2glasses and melts Raman spectra between 800 and 1300 cmminus1
930 to 1050 cmminus1 [6] Several examples of the deconvolutionresults of the Raman signal of the studied samples in the high-frequency region are shown in Figure 9 Four Gaussian lineswere sufficient to reproduce the low-temperature (293K)Raman spectra of the 17Cs and 22Cs glasses whereas five lineswere needed to simulate the 27Cs 33Cs and 37Cs spectraThe H3 and H4 bands were attributed to the 119876
3 speciesBecause the 17Cs and 22Cs glasses consist of1198764 and119876
3 unitsit is possible to assume that only four types of structuralgroups (119876344411987634431198763433 and119876
3333) can exist in structureof these glasses Considering the dependence of the Ramanshift of 1198763119894119895119896 groups on the 119894 119895 and 119896 indexes established in[6] it was assumed that the 119876
3444 and 1198763443 groups are the
main contributors to the intensity of the H4 band and thatthe vibrations of the 119876
3433 and 1198763333 groups are the main
contributors to the intensity of theH3 bandThis qualitativelyagrees with the simulation results of the 119876
3119894119895119896 distributionrepresented in Figures 7(c) and 7(d) The H2 band is mostlikely due to the stretching vibrations of the Si-O-Si linkages[3 31] The origin of the H1 line is unclear It is possible thatthis line is a result of the assumption of the Gaussian shape ofthe elementary bands in the spectra of glasses with relativelylow Cs
2O concentrations (17Cs and 22Cs) that is this line
is an error in the choice of the type of elementary bands
The relative area of the H1 band is the same for the 17Cs and22Cs spectra (002) and its intensity increases with furtherincreases in the Cs
2O content The H2 line behaves similarly
An increase in intensity of both H1 and H2 lines begins fromthe appearance of a new H5 line in the deconvolution of theRaman spectra The H5 line indicates the formation of 1198762species in the structure of the samples According to [6] itis possible to assume that the vibrations of the 119876
3119894119895119896 groupsconnected with one or two 119876
2 units for example 1198763332 and1198763322 groups also contribute to the intensity of the H2 band
at higher concentrations of the modifier oxide Thus the1060 cmminus1 line was designated as H2
lowast in the deconvolutionof the 27Cs 33Cs and 37Cs spectra In turn the H1
lowast linecan be attributed to the vibrations of the 119876
244 119876243 and119876233 groups according to the 119876
2119894119895 distribution representedin Figures 8(a) and 8(b) Finally the H5 line was ascribed to119876232 groupsThe localized nature of the silicon-oxygen stretching
motions of silicate units containing SiO4tetrahedra with
one two three or four nonbridging oxygen atoms [34 36]allows us to use the relative integral intensities of theGaussiancomponents to calculate the 119876119899 concentrations
If three types (1198764 1198763 1198762) of 119876
119899 species coexistin a structure simultaneously then their concentrations
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
International Journal of Spectroscopy 9
0
20
40
100
60
80
5 10 20 30 40 50
5
7
8
6
4
3
2
1
0
10 20 30 40 50
[Q2ij]
()
Cs2O (mol)
Q211
Q231
Q242
Q244
Q243
Q233
Q232
Q221
Q222
(a)
0
20
40
60
10
30
70
50
5 10 20 30 40 50
4
3
2
1
0
2010 30 40 50
[Q2ij]998400
()
Cs2O (mol)
Q211
Q231
Q244
Q243
Q233
Q232
Q221
Q222
(b)
36 38 44 48 5240 42 46 50 540
40
60
20
80
100
[Q1i ]
()
Cs2O (mol)
Q13Q12
Q11
Q14
(c)
0
15
20
10
25
30
5
36 38 44 48 5240 42 46 50 54
[Q1i ]998400
()
Cs2O (mol)
Q13
Q12
Q11
(d)
Figure 8 1198762119894119897 ((a) and (b)) and 1198761119894 ((c) and (d)) distributions in Cs
2O-SiO
2glasses (solid lines 119879 = 293K) and melts (dotted lines 119879 =
1223K) ((a) and (c) equation (2) (b) and (d) equation (3))
on the quantum chemical calculation of the characteristicfrequencies of 119876
119899 species In other words it was demon-strated that the Raman shift of the symmetric stretchingvibration of 119876
119899 units decreases as the number of bridgingoxygen atoms of the nearest-neighbor 119876119899 species adjacent tothe given 119876
119899 unit decreases For example the Raman shiftof the 119876
3444 group is higher than that of the 1198763333 group
In our opinion the conclusions in [6] are strong evidenceof Matsonrsquos assumption Thus we will rely on Matsonrsquosinterpretation of the origin of 1150 cmminus1 band in our paper
The qualitative examination of the Raman spectra ofCs2O-SiO
2glasses (Figure 3) confirms that the structure of
glasses with a Cs2Ocontent below 33mol consists of1198764 and
1198763 units (the existence of1198764 units is obvious and requires no
evidence although the 1150 cmminus1 shoulder indirectly provesthe presence of such structural units) and that the 1198763 speciesare present at the least in the form of 119876
3444 and 1198763333
groups The Raman band at 930 cmminus1 shows that 1198762 units
are formed in the 33Cs and 37Cs glasses The presence of1198764 units in the structure of disilicate glasses is a result of
satisfying the charge balance (NBOSi = 1) Regarding the37Cs glass the presence of 1198764 species can be identified onlyby the quantitative analysis of the corresponding spectrum
The high-frequency envelope (800ndash1300 cmminus1) of theregistered Raman spectra was simulated as a superpositionof the Gaussian lines to estimate the 119876
119899 concentrationsThe number of Gaussian lines was sufficient to reproducethe original spectra with a correlation factor of ge098 Theinterpretation of the Raman bands described above was alsotaken into account In addition some results published in [6]were also taken into account 119876119899 species with equal 119899 givemore than one band and peak position of individual banddepends on the structural position of 119876119899 units For examplewavenumbers of NBO symmetric stretching vibration of 1198763species are located in the range of 1050 to 1150 cmminus1 whereas1198762 units give a set of the individual peaks in the range of
10 International Journal of Spectroscopy
60160260360460560660
H5
H4H3
22Cs
Ram
an in
tens
ity (a
u)
minus40
1443K
H1lowastH2lowast
50150250350450550650
H4H3
H5
27Cs
minus50
1553K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5
33Cs
minus40
1443K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5H6
37Cs
minus40
H2lowast
H1lowast
1443K
70170270370470570670770
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
793K
minus30
70170270370470570670
H4
H3
H5
Ram
an in
tens
ity (a
u)
1113K
minus30
H1lowastH2lowast
60160260360460560660
H4H3
H5
1113K
minus40
H1lowastH2lowast
70170270370470570670770
H4
H3H5
1223K
minus30
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1223K
minus30
H1lowastH2lowast
70170270370470570670770
H4H3
H5
898K
minus30
H1lowastH2lowast
60160260360460560660760860960
H4H3H5
793K
minus40
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1003K
minus30
H1lowastH2lowast
70170270370470570670770870
850 950 1050 1150 1250
H4
H3
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
70170270370470570670770
800 900 1000 1100 1200 1300
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
293K
minus30
Raman shift (cmminus1)
70170270370470570670770870970
800 900 1000 1100 1200 1300
H3H4
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
170370570770970
1170
800 900 1000 1100 1200 1300
H5H3 H4
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
Figure 9 Examples of the band deconvolution of Cs2O-SiO
2glasses and melts Raman spectra between 800 and 1300 cmminus1
930 to 1050 cmminus1 [6] Several examples of the deconvolutionresults of the Raman signal of the studied samples in the high-frequency region are shown in Figure 9 Four Gaussian lineswere sufficient to reproduce the low-temperature (293K)Raman spectra of the 17Cs and 22Cs glasses whereas five lineswere needed to simulate the 27Cs 33Cs and 37Cs spectraThe H3 and H4 bands were attributed to the 119876
3 speciesBecause the 17Cs and 22Cs glasses consist of1198764 and119876
3 unitsit is possible to assume that only four types of structuralgroups (119876344411987634431198763433 and119876
3333) can exist in structureof these glasses Considering the dependence of the Ramanshift of 1198763119894119895119896 groups on the 119894 119895 and 119896 indexes established in[6] it was assumed that the 119876
3444 and 1198763443 groups are the
main contributors to the intensity of the H4 band and thatthe vibrations of the 119876
3433 and 1198763333 groups are the main
contributors to the intensity of theH3 bandThis qualitativelyagrees with the simulation results of the 119876
3119894119895119896 distributionrepresented in Figures 7(c) and 7(d) The H2 band is mostlikely due to the stretching vibrations of the Si-O-Si linkages[3 31] The origin of the H1 line is unclear It is possible thatthis line is a result of the assumption of the Gaussian shape ofthe elementary bands in the spectra of glasses with relativelylow Cs
2O concentrations (17Cs and 22Cs) that is this line
is an error in the choice of the type of elementary bands
The relative area of the H1 band is the same for the 17Cs and22Cs spectra (002) and its intensity increases with furtherincreases in the Cs
2O content The H2 line behaves similarly
An increase in intensity of both H1 and H2 lines begins fromthe appearance of a new H5 line in the deconvolution of theRaman spectra The H5 line indicates the formation of 1198762species in the structure of the samples According to [6] itis possible to assume that the vibrations of the 119876
3119894119895119896 groupsconnected with one or two 119876
2 units for example 1198763332 and1198763322 groups also contribute to the intensity of the H2 band
at higher concentrations of the modifier oxide Thus the1060 cmminus1 line was designated as H2
lowast in the deconvolutionof the 27Cs 33Cs and 37Cs spectra In turn the H1
lowast linecan be attributed to the vibrations of the 119876
244 119876243 and119876233 groups according to the 119876
2119894119895 distribution representedin Figures 8(a) and 8(b) Finally the H5 line was ascribed to119876232 groupsThe localized nature of the silicon-oxygen stretching
motions of silicate units containing SiO4tetrahedra with
one two three or four nonbridging oxygen atoms [34 36]allows us to use the relative integral intensities of theGaussiancomponents to calculate the 119876119899 concentrations
If three types (1198764 1198763 1198762) of 119876
119899 species coexistin a structure simultaneously then their concentrations
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
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Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
10 International Journal of Spectroscopy
60160260360460560660
H5
H4H3
22Cs
Ram
an in
tens
ity (a
u)
minus40
1443K
H1lowastH2lowast
50150250350450550650
H4H3
H5
27Cs
minus50
1553K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5
33Cs
minus40
1443K
H2lowast
H1lowast
60160260360460560660
H4
H3
H5H6
37Cs
minus40
H2lowast
H1lowast
1443K
70170270370470570670770
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
793K
minus30
70170270370470570670
H4
H3
H5
Ram
an in
tens
ity (a
u)
1113K
minus30
H1lowastH2lowast
60160260360460560660
H4H3
H5
1113K
minus40
H1lowastH2lowast
70170270370470570670770
H4
H3H5
1223K
minus30
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1223K
minus30
H1lowastH2lowast
70170270370470570670770
H4H3
H5
898K
minus30
H1lowastH2lowast
60160260360460560660760860960
H4H3H5
793K
minus40
H1lowastH2lowast
70170270370470570670770870
H6H5 H3 H4
1003K
minus30
H1lowastH2lowast
70170270370470570670770870
850 950 1050 1150 1250
H4
H3
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
70170270370470570670770
800 900 1000 1100 1200 1300
H4
H3
H2H1
Ram
an in
tens
ity (a
u)
293K
minus30
Raman shift (cmminus1)
70170270370470570670770870970
800 900 1000 1100 1200 1300
H3H4
H5
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
170370570770970
1170
800 900 1000 1100 1200 1300
H5H3 H4
293K
minus30
H1lowastH2lowast
Raman shift (cmminus1)
Figure 9 Examples of the band deconvolution of Cs2O-SiO
2glasses and melts Raman spectra between 800 and 1300 cmminus1
930 to 1050 cmminus1 [6] Several examples of the deconvolutionresults of the Raman signal of the studied samples in the high-frequency region are shown in Figure 9 Four Gaussian lineswere sufficient to reproduce the low-temperature (293K)Raman spectra of the 17Cs and 22Cs glasses whereas five lineswere needed to simulate the 27Cs 33Cs and 37Cs spectraThe H3 and H4 bands were attributed to the 119876
3 speciesBecause the 17Cs and 22Cs glasses consist of1198764 and119876
3 unitsit is possible to assume that only four types of structuralgroups (119876344411987634431198763433 and119876
3333) can exist in structureof these glasses Considering the dependence of the Ramanshift of 1198763119894119895119896 groups on the 119894 119895 and 119896 indexes established in[6] it was assumed that the 119876
3444 and 1198763443 groups are the
main contributors to the intensity of the H4 band and thatthe vibrations of the 119876
3433 and 1198763333 groups are the main
contributors to the intensity of theH3 bandThis qualitativelyagrees with the simulation results of the 119876
3119894119895119896 distributionrepresented in Figures 7(c) and 7(d) The H2 band is mostlikely due to the stretching vibrations of the Si-O-Si linkages[3 31] The origin of the H1 line is unclear It is possible thatthis line is a result of the assumption of the Gaussian shape ofthe elementary bands in the spectra of glasses with relativelylow Cs
2O concentrations (17Cs and 22Cs) that is this line
is an error in the choice of the type of elementary bands
The relative area of the H1 band is the same for the 17Cs and22Cs spectra (002) and its intensity increases with furtherincreases in the Cs
2O content The H2 line behaves similarly
An increase in intensity of both H1 and H2 lines begins fromthe appearance of a new H5 line in the deconvolution of theRaman spectra The H5 line indicates the formation of 1198762species in the structure of the samples According to [6] itis possible to assume that the vibrations of the 119876
3119894119895119896 groupsconnected with one or two 119876
2 units for example 1198763332 and1198763322 groups also contribute to the intensity of the H2 band
at higher concentrations of the modifier oxide Thus the1060 cmminus1 line was designated as H2
lowast in the deconvolutionof the 27Cs 33Cs and 37Cs spectra In turn the H1
lowast linecan be attributed to the vibrations of the 119876
244 119876243 and119876233 groups according to the 119876
2119894119895 distribution representedin Figures 8(a) and 8(b) Finally the H5 line was ascribed to119876232 groupsThe localized nature of the silicon-oxygen stretching
motions of silicate units containing SiO4tetrahedra with
one two three or four nonbridging oxygen atoms [34 36]allows us to use the relative integral intensities of theGaussiancomponents to calculate the 119876119899 concentrations
If three types (1198764 1198763 1198762) of 119876
119899 species coexistin a structure simultaneously then their concentrations
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
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Journal of
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Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
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Analytical ChemistryInternational Journal of
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Quantum Chemistry
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ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
International Journal of Spectroscopy 11
([1198764] [1198763] [1198762]) can be obtained from the following systemof equations
[1198764] + [119876
3] + [119876
2] = 1
[1198763] + 2 [119876
2] =
2119909
1 minus 119909
[
1198763
1198762] = 119886
119868H2lowast + 119868H3 + 119868H4119868H1lowast + 119868H5
(7)
The coefficient proportionality 119886 was chosen to achieve abest accordance with data published in other papers [3 4]Furthermore if there is reason to believe that 119876
2 unitsare absent in the glass structure (as in the 17Cs and 22Csglasses) then the final equation does not make sense and the[1198764] and [1198763] concentrations can be calculated analyticallyfrom the first two equations without any experimental dataConsidering the complicated nature of the H1
lowast and H2lowast
bands two scenarios were calculated In the first variant the119868H2lowast and 119868H1lowast values were equal to the areas of the H2
lowast andH1lowast components respectively The integral intensity of the
H1lowast and H2
lowast bands was reduced on the ⟨119868H1⟩ and ⟨119868H2⟩values in the second scenario Here ⟨119868H1⟩ and ⟨119868H2⟩ arethe average values of the integral intensities of the H1 andH2 bands respectively measured from the deconvolutionresults of the high-frequency range of the Raman spectraof low-alkali glasses (17Cs and 22Cs) The peak positionsrelative areas of the partial bands and the [119876119899] concentrationscalculated according to system (4) are summarized in Table 1The peak positions and FWHM values were establishedwithin plusmn5 cmminus1 As seen in the table the first calculationvariant yields slightly higher [1198764] and [1198762] concentrationsand a somewhat lower [1198763] value The calculation results ofthe second scenario yields the opposite trend Accountingfor the ⟨119868H1⟩ and ⟨119868H2⟩ values produces higher [1198763] valuesand somewhat lower concentrations of 1198764 and 119876
2 units Thegreatest difference between the calculation results is observedfor the 27Cs glass and is asymp3 for the [1198763] concentration
42 High-Temperature Raman Spectra and Structure of theCs2O-SiO2 Glasses andMelts TheRaman spectra of the 22Cssample measured in the temperature range of 293 to 1553Kare shown in Figure 4(a) As seen from this figure the changein temperature results in changes in the spectra in bothlow- and high-frequency ranges According to the above-mentioned structural interpretation of the Raman bandsthe significantly greater intensity of the 598 cmminus1 band andsignificantly lower intensity of the 530 cmminus1 band in themelt spectra in comparison with the glass spectra indicatea considerable influence of temperature on the distributionof 119899-membered rings These data support the assumptionthat the fraction of 4-membered rings decreases and fractionof 3-membered rings increases with increasing temperatureIn turn the changes in the shape of the high-frequencyenvelope and the appearance of a weak Raman signal at930 cmminus1 in the melt spectra (this band is absent in the glassspectrum) point to a structural transformation in the local
structure of the sample It can be argued at a qualitativelevel that the list of structural units for glasses and meltswill differ The local structure of the glassy sample includesonly two structural units 1198764 and 119876
3 whereas that of meltscontains significant amounts of 119876
2 units (930 cmminus1 line)The same conclusions may be drawn from the 27Cs spectra(Figure 4(b)) Changes in the 119868
598119868530
ratio and the gradualincrease in the intensity of the 920ndash930 cmminus1 band also occurSuch obvious changes in the low-frequency range are notobserved in the Raman spectra of samples with higher Cs
2O
contents (see Figures 5(a) and 5(b)) In this case it is difficultto derive well-defined conclusions about dependence of thedistribution of the 119899-membered rings on temperature At thesame time an increase in the intensity of the 920ndash930 cmminus1band and a decrease in the intensity of the 1090ndash1100 cmminus1band are observed with increasing temperature as beforeThus an increase in temperature leads to a decrease in theconcentration of the 119876
3 units and an increase in the fractionof the 1198762 species in all studied samples
The high-frequency range of the Raman spectra mea-sured at different temperatures was simulated as a superpo-sition of the Gaussian lines to study the influence of tem-perature on the concentrations of 119876119899 species (see Figure 9)The parameters of the partial bands obtained from themodeling of glass spectra were used in the deconvolutionof the spectra measured at different temperatures Thus theband designation and origin correspond to those accepted inthe previous section It was found that the low-temperaturespectra of the 22Cs samples are well reproduced by the sameset of partial bands as the glass spectra However the low-temperature set of partial bands is insufficient for modelingof the high-temperature spectra and a new H5 componentappears in deconvolution of these spectra One more H6 lineappears in the modeling of the spectra of the sample with thehighest Cs
2O content (37Cs) Both H5 and H6 bands were
assigned to the 1198762 units The H6 line is more likely due to
119876222 groups according to Figures 8(a) and 8(b)The [119876119899](119879) dependences calculated according to system
(7) are summarized in Table 1 (an additional item 119868H6 wasadded to the denominator of the last equation of system (7)in the calculation of the local structure of the 37Cs sample)According to the obtained data the local structure of thestudied glasses does not change under a moderate increasein temperature Further increases in temperature lead to adecrease in the concentration of 1198763 species and an increasein concentrations of 1198764 and 119876
2 units These changes can beexplained by the shift of the equilibrium
21198763lArrrArr 119876
4+ 1198762 (8)
to the right with increasing temperatureThe temperature of the beginning of the shift of equilib-
rium (8) to the right depends on the sample compositionand most likely corresponds to the glass-transition (119879
119892)
temperature The dynamic equilibrium (8) is ldquofrozenrdquo attemperatures below 119879
119892
The [119876119899] data can be used to determine the Δ119867
enthalpy of the reaction (8) The equilibrium constant of the
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
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Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Journal of
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Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
12 International Journal of Spectroscopy
Table 1 The peak positions (cmminus1) relative intensities and fractions of 119876119899 species () in investigated glasses and melts
119879 K H1 (H1lowast) H2 (H2lowast) H3 H4 H5 H6 [1198764] [119876
3] [119876
2]
17Cs2O-83SiO
2
293 10080020 10600072 10980325 11440583 mdash mdash 59 41 mdash22Cs
2O-78SiO
2
293 10100020 10650068 11000352 11450560 mdash mdash 44 56 mdash473 10070021 10630074 10990328 11420577 mdash mdash 44 56 mdash683 10060019 10600074 10970333 11400574 mdash mdash 44 56 mdash793 10060025 10600081 10960323 11380571 mdash mdash 44 56 mdash898 10060031 10590093 10950315 11350555 9350006 mdash 4645 5254 211003 10040035 10590108 10950308 11330540 9370009 mdash 4645 5254 211113 10040038 10560128 10920304 11290517 9310013 mdash 4645 5153 321223 10010049 10530143 10910285 11270500 9260023 mdash 4747 4950 431443 9980062 10520167 10910259 11240479 9200033 mdash 4848 4748 541553 9980067 10500191 10880249 11230452 9220041 mdash 4949 4546 65
27Cs2O-73SiO
2
293 10060024 10620105 10970361 11390505 9290005 mdash 2827 7073 2lt1573 10050022 10620144 10970354 11370474 9320006 mdash 2827 7073 2lt1683 10050022 10620134 10960350 11350490 9350004 mdash 2827 7073 2lt1793 10050024 10600155 10940344 11330469 9360008 mdash 2827 7072 21898 10020024 10600151 10940340 11290477 9320008 mdash 2827 7072 211003 10030026 10580158 10920335 11270471 9290010 mdash 2927 6971 221113 10020036 10570168 10930324 11250452 9260020 mdash 3029 6668 431223 10000044 10550188 10920307 11220433 9230028 mdash 3130 6466 541338 10010051 10550194 10900285 11200428 9200042 mdash 3232 6163 751553 10000070 10520209 10880237 11190426 9160058 mdash 3434 5758 98
33Cs2O-67SiO
2
293 10010042 10600177 11030569 11430184 9340028 mdash 76 8789 76573 9960043 10590177 11010566 11410183 9300031 mdash 76 8689 76683 9920042 10580179 10980563 11370184 9270032 mdash 76 8689 76793 9890046 10570188 10960539 11340193 9250034 mdash 87 8587 87898 9880043 10560185 10940548 11300191 9220033 mdash 76 8688 761003 9890056 10570240 10920434 11280225 9180045 mdash 98 8284 981113 9910064 10560233 10950412 11300238 9170053 mdash 1110 7981 11101223 9920075 10570240 10960374 11300245 9180066 mdash 1312 7576 13121338 9890093 10540258 10920299 11260262 9160088 mdash 1515 6970 15151443 9900123 10570266 10890243 11230275 9150093 mdash 1818 6464 1818
37Cs2O-63SiO
2
293 10050088 10630189 10990579 11360055 9280089 mdash lt1 8283 1817573 10060089 10620176 10990586 11370057 9270092 mdash lt1 8182 18181003 10010086 10600186 10950553 11340083 9220083 8710009 lt1 8283 18171113 10040113 10620216 10920439 11300120 9190091 8720021 44 7474 22221223 9980117 10570236 10890409 11270114 9120105 8670019 55 7272 23231338 9940125 10520270 10850344 11220126 9060107 8600028 77 6968 24251443 9910134 10550263 10860308 11210139 9030128 8550028 99 6564 2627
disproportional reaction (7) expressed using the concentra-tions of the 119876119899 units is defined as
119870 =
[1198764] [1198762]
[1198763]2
(9)
In turn theΔ119867 enthalpy of equilibrium (8) is calculated fromthe Vanrsquot Hoff equation
Δ119867 = minus119877
119889 (ln119870)
119889 (1119879)
(10)
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
International Journal of Spectroscopy 13
6 7 8 9 10 11
22Csminus20
minus15
minus25
minus30
minus35
minus40
minus45
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus38304
T+ 03482
R2 = 0951
6 11 16 21 26 31
33Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus66904
T+ 19729
R2 = 0974
6 7 8 109
37Csminus25
minus30
minus35
minus40
minus45
minus50
1T times 10minus4 (Kminus1)
ln(K
)ln K = minus
62039
T+ 13689
R2 = 0975
5 10 15 20 25 30 35
27Csminus20
minus25
minus30
minus35
minus40
minus45
minus50
minus55
minus60
1T times 10minus4 (Kminus1)
ln(K
)
ln K = minus52033
T+ 08734
R2 = 0989
Figure 10 Relationship between equilibrium constant for equilibrium (7) ln119870 and 1119879 (Kminus1) The lines were obtained by least squaresfitting
Assuming that Δ119867 is independent of temperature above119879119892 it is possible to calculate the enthalpy values using
the slope of the ln (119870) versus (1119879) line from the high-temperature experimental data The ln (119870)(1119879) data areshown in Figure 10 Thus the Δ119867 values for 22Cs 27Cs33Cs and 37Cs are obtained as 32 plusmn 6 43 plusmn 8 56 plusmn 10and 52 plusmn 9 kJmol respectively These results show that Δ119867
value depends on the melt composition and is highest at33mol Cs
2O A similar trend has been observed for the
sodium silicate system [8] However one should be advisedand understand that there are a number of other reasons fordecreasing of Δ119867 with increasing SiO
2content choice of
the individual bands to modeling of poorly resolved high-frequency spectral envelope Gaussian shape of individualpeaks an increase in experimental error at determinationof the integral intensity of the weak bands ascribed to the1198762 units and so forth Thus we can assert unambiguously
that Δ119867 is constant for the melts with 119909 close to 33mol(25 le 119909 le 40) Based on this conclusion one can see that thereis a quite clear tendency for increase in Δ119867 with increasingalkali cation radius Δ119867 is approximately equal to 0 [7 37]20 [11 22 37 38] 30 [10 39] and 50 kJmol (this work)for lithium sodium potassium and cesium silicate meltsrespectively
Maehara et al [8] have shown that [119876119899] data can be usedto calculate the nonideal entropy of mixing (Δ119878mix) for thesilicate glasses and melts
Δ119878mix = minus119896119860 ([1198762] ln [119876
2] + [119876
3] ln [119876
3]
+ [1198764] ln [119876
4])
(11)
where 119860 = (1 minus 119909100)119873119860 119873119860is the Avogadro constant
and 119896 is Boltzmannrsquos constant As follows from Figure 6(a)the change in temperature does not significantly changethe Δ119878mix in glasses and melts with high SiO
2contents
(119909 lt 20mol) A similar situation would be typical forglasses with lower SiO
2contents but only at relatively low
temperatures (less than 119879119892) As seen in Table 1 the local
structure of the 22Cs 27Cs 33Cs and 37Cs samples signif-icantly changes at higher temperatures Hence considerablechanges in Δ119878mix values are expected in this case The Δ119878mixvalues as a function of temperature for the above-mentionedsamples calculated by (11) are shown in Figure 11 As onecan see the entropy increases almost linearly with increasingtemperature in the studied temperature range for all samplesThe entropy change depends on the melt composition theentropy increasingwithmodifier oxide content up to 33moland then beginning to decrease
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
14 International Journal of Spectroscopy
850 1000 1150 1300 1450 160025
30
35
40
45
50
55
60
65
T (K)
ΔS m
ix(J
mol
K)
22Cs R2 = 0969
27Cs R2 = 0991
33Cs R2 = 0998
37Cs R2 = 0989
Figure 11 Plots Δ119878mix versus 119879 for compositions indicated Regres-sion lines are through solid data points (above glass-transitioninterval)
5 Conclusion
The structure of the 119909Cs2O-(100 minus x)SiO
2glasses and melts
was studied by high-temperature Raman spectroscopy Itwas found that the concentration of 119876
4 species graduallydecreases with increasing modifier oxide content In turnthe fraction of 119876
3 units increases reaches a maximum at119909 = 33mol and then starts to decrease The 119876
2 speciesare observed in the glass structure at 119909 ge 27mol Theirconcentration increases with increasing Cs
2O content The
concentrations of 1198764 and 119876
2 units are higher in the meltstructure than in the corresponding glasses The increasein the concentration of these structural units is explainedby the shift of equilibrium (8) to the right with increasingtemperature The enthalpy of equilibrium (8) depends on themelt composition and was found to be equal to 32 plusmn 6 43plusmn 8 56 plusmn 10 and 52 plusmn 9 kJmol for 22Cs 27Cs 33Cs and37Cs respectively The nonideal entropy of mixing Δ119878mixdepends on the melt composition and increases linearly withincreasing temperature at 119879 gt 119879
119892 The Δ119878mixΔ119879 value also
depends on the melt composition increasing with the Cs2O
content up to 33mol and then beginning to decreaseThe [119876119899] experimental data were used to model the 119876
119899
distribution in Cs2O-SiO
2glasses and melts The developed
approach allows us to describe the experimental data overa wide composition range for both glasses and melts Theconfigurations of the random linkages generated during themodeling were analyzed for the identification of 119876119894ndash119876119895 and119876119899119894119895119896119897 distributions The results support the assumption that
temperature changes weakly influence the 119876119894ndash119876119895 and 119876
119899119894119895119896119897
distributions at relatively low Cs2O contents (less than 15 divide
20mol) At higher Cs2O contents119876119894ndash119876119895 bridges with 119894 = 119895
aremost sensitive to temperatureThe direction of the change(increasedecrease) in concentration of the bridging bondsbetween one-type structural units depends on the glass (melt)composition except for 119876
4ndash1198764 bridges the concentration
which always increases with increasing temperature at 119909 gt
20molAs for the119876119899119894119895119896119897 groups it was found that increasingtemperature widens the variety of coexisting119876
119899119894119895119896119897 groups inthe meltThe greatest change in the distribution of1198764119894119895119896119897 and1198763119894119895119896 groups is expected in melts with 119909 asymp 33mol whereas
the 1198762119894119895 and 119876
1119894 distributions are more prone to changes inthe melts with 119909 asymp 50mol
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgment
Partial support by the RFBR (Project no 14-08-00323 a) isgratefully acknowledged
References
[1] R Dupree D Holland and D S Williams ldquoThe structure ofbinary alkali silicate glassesrdquo Journal of Non-Crystalline Solidsvol 81 no 1-2 pp 185ndash200 1986
[2] H Maekawa T Maekawa K Kawamura and T YokokawaldquoThe structural groups of alkali silicate glasses determined from29Si MAS-NMRrdquo Journal of Non-Crystalline Solids vol 127 no1 pp 53ndash64 1991
[3] V N Bykov A A Osipov andVN Anfilogov ldquoStructural studyof rubidium and caesium silicate glasses by Raman spectro-scopyrdquo Physics and Chemistry of Glasses vol 41 no 1 pp 10ndash11 2000
[4] W J Malfait ldquoQuantitative Raman spectroscopy speciation ofcesium silicate glassesrdquo Journal of Raman Spectroscopy vol 40no 12 pp 1895ndash1901 2009
[5] B O Mysen and J D Frantz ldquoRaman spectroscopy of silicatemelts at magmatic temperatures Na
2O-SiO
2 K2O-SiO
2and
Li2O-SiO
2binary composition in the temperature range 25-
1475 Crdquo Chemical Geology vol 96 no 3-4 pp 321ndash332 1992[6] J-L You G-C Jiang H-Y Hou H Chen Y-Q Wu and K-D
Xu ldquoQuantum chemistry study on superstructure and Ramanspectra of binary sodium silicatesrdquo Journal of Raman Spectro-scopy vol 36 no 3 pp 237ndash249 2005
[7] V N Bykov O N Koroleva and A A Osipov ldquoStructure ofsilicate melts Raman spectroscopic data and thermodynamicsimulation resultsrdquo Geochemistry International vol 47 no 11pp 1067ndash1074 2009
[8] T Maehara T Yano and S Shibata ldquoStructural rules of phaseseparation in alkali silicate melts analyzed by high-temperatureRaman spectroscopyrdquo Journal of Non-Crystalline Solids vol 351no 49-51 pp 3685ndash3692 2005
[9] W E Halter and B O Mysen ldquoMelt speciation in the systemNa2O-SiO
2rdquo Chemical Geology vol 213 no 1ndash3 pp 115ndash123
2004[10] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-
titative Raman spectroscopy principles and application topotassium silicate meltsrdquo Journal of Non-Crystalline Solids vol353 no 44ndash46 pp 4029ndash4042 2007
[11] W J Malfait V P Zakaznova-Herzog andW E Halter ldquoQuan-titative Raman spectroscopy speciation of Na-silicate glassesandmeltsrdquoAmericanMineralogist vol 93 no 10 pp 1505ndash15182008
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
International Journal of Spectroscopy 15
[12] B O Mysen and J D Frantz ldquoSilicate melts at magmatic tem-peratures in-situ structure determination to 1651∘C and effectof temperature and bulk composition on the mixing behaviorof structural unitsrdquo Contributions to Mineralogy and Petrologyvol 117 no 1 pp 1ndash14 1994
[13] J D Frantz and B O Mysen ldquoRaman spectra and strucuture ofBaO-SiO
2 SrO-SiO
2and CaO-SiO
2melts to 1600∘ CrdquoChemical
Geology vol 121 no 1ndash4 pp 155ndash176 1995[14] P F McMillan G H Wolf and B T Poe ldquoVibrational spec-
troscopy of silicate liquids and glassesrdquo Chemical Geology vol96 no 3-4 pp 351ndash366 1992
[15] N Umesaki M Takahashi M Tatsumisago and T MinamildquoRaman spectroscopic study of alkali silicate glasses and meltsrdquoJournal of Non-Crystalline Solids vol 205-207 no 1 pp 225ndash230 1996
[16] L Olivier X Yuan A N Cormack and C Jager ldquoCombined29Si double quantum NMR and MD simulation studies of net-work connectivities of binary Na
2OsdotSiO
2glasses new prospects
and problemsrdquo Journal of Non-Crystalline Solids vol 293ndash295no 1 pp 53ndash66 2001
[17] O Gedeon M Liska and J Machacek ldquoConnectivity of Q-species in binary sodium-silicate glassesrdquo Journal of Non-Crys-talline Solids vol 354 no 12-13 pp 1133ndash1136 2008
[18] J Machacek and O Gedeon ldquoGroup connectivity in binarysilicate glasses a quasi-chemical approach and moleculardynamics simulationrdquo Journal of Non-Crystalline Solids vol354 no 2-9 pp 138ndash142 2008
[19] J Du and A N Cormack ldquoThe medium range structure ofsodium silicate glasses a molecular dynamics simulationrdquo Jour-nal of Non-Crystalline Solids vol 349 pp 66ndash79 2004
[20] D Sprenger H Bach W Meisel and P Gutlich ldquoDiscrete bondmodel (DBM) of sodium silicate glasses derived from XPSRaman and NMR measurementsrdquo Journal of Non-CrystallineSolids vol 159 no 3 pp 187ndash203 1993
[21] V N Bykov A A Osipov and V N Anfilogov ldquoHigh-temper-ature device for registration of Raman spectra of meltsrdquo Ras-plavy no 4 pp 28ndash31 1997 (Russian)
[22] V N Anfilogov V N Bykov and A A Osipov Silicate MeltsNauka Moscow Russia 2005
[23] A A Osipov and L M Osipova ldquoStructure of lithium borateglasses and melts investigation by high temperature Ramanspectroscopyrdquo Physics and Chemistry of Glasses European Jour-nal of Glass Science and Technology Part B vol 50 no 6 pp343ndash354 2009
[24] W H Zachariasen ldquoThe atomic arrangement in glassrdquo Journalof the American Chemical Society vol 54 no 10 pp 3841ndash38511932
[25] A A Osipov and L M Osipova ldquoQn distribution in silicatesalkali silicate glasses and meltsrdquo Advanced Materials Researchvol 560-561 pp 254ndash258 2012
[26] A A Osipov and LM Osipova ldquoNew approach tomodeling ofa local structure of silicate glasses and meltsrdquo Journal of PhysicsConference Series vol 410 no 1 Article ID 012019 2013
[27] W J Malfait W E Halter Y Morizet B H Meier and R VerelldquoStructural control on bulk melt properties single and doublequantum 29Si NMR spectroscopy on alkali-silicate glassesrdquoGeochimica et Cosmochimica Acta vol 71 no 24 pp 6002ndash6018 2007
[28] B Boizot S Agnello B Reynard R Boscaino and G PetiteldquoRaman spectroscopy study of 120573-irradiated silica glassrdquo Journalof Non-Crystalline Solids vol 325 no 1ndash3 pp 22ndash28 2003
[29] R J Hemley H K Mao P M Bell and B O Mysen ldquoRamanspectroscopy of SiO
2glass at high pressurerdquo Physical Review
Letters vol 57 no 6 pp 747ndash750 1986[30] F Ruiz J R Martınez and J Gonzalez-Hernandez ldquoA simple
model to analyze vibrationally decoupled modes on SiO2
glassesrdquo Journal of Molecular Structure vol 641 no 2-3 pp243ndash250 2002
[31] S K Sharma T F Cooney Z Wang and S van der LaanldquoRaman band assignments of silicate and germanate glassesusing high-pressure and high-temperature spectral datardquo Jour-nal of Raman Spectroscopy vol 28 no 9 pp 697ndash709 1997
[32] V Martinez C Martinet B Champagnon and R Le ParcldquoLight scattering in SiO
2-GeO
2glasses quantitative compari-
son of Rayleigh Brillouin and Raman effectsrdquo Journal of Non-Crystalline Solids vol 345-346 pp 315ndash318 2004
[33] D W Matson S K Sharma and J A Philpotts ldquoThe structureof high-silica alkali-silicate glasses A Raman spectroscopicinvestigationrdquo Journal of Non-Crystalline Solids vol 58 no 2-3 pp 323ndash352 1983
[34] P McMillan ldquoStructural studies of silicate glasses and meltsmdashapplications and limitations of Raman spectroscopyrdquo AmericanMineralogist vol 69 no 7-8 pp 622ndash644 1984
[35] B G Parkinson D Holland M E Smith et al ldquoQuantitativemeasurement of Q3 species in silicate and borosilicate glassesusing Raman spectroscopyrdquo Journal of Non-Crystalline Solidsvol 354 no 17 pp 1936ndash1942 2008
[36] T Furukawa K E Fox andW BWhite ldquoRaman spectroscopicinvestigation of the structure of silicate glasses III Ramanintensities and structural units in sodium silicate glassesrdquo TheJournal of Chemical Physics vol 75 no 7 pp 3226ndash3237 1981
[37] B O Mysen and J D Frantz ldquoStructure and properties of alkalisilicate melts at magmatic temperaturesrdquo European Journal ofMineralogy vol 5 no 3 pp 393ndash407 1993
[38] V N Bykov A A Osipov and V I Anfilogov ldquoRaman spec-troscopy of melts and glasses in Na
2O-SiO
2systemrdquo Rasplavy
no 6 pp 86ndash91 1998 (Russian)[39] V N Bykov O N Koroleva and A A Osipov ldquoStructure
of K2O-SiO
2melts Raman spectroscopic data and thermo-
dynamic simulation resultsrdquo Rasplavy no 3 pp 50ndash59 2008(Russian)
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of