Research Article S Nanosphere in Ferroelectric Liquid ...downloads.hindawi.com/journals/acmp/2013/250301.pdf · erties of liquid crystals due to the addition of nanomaterial is currently

Hindawi Publishing CorporationAdvances in Condensed Matter PhysicsVolume 2013 Article ID 250301 10 pageshttpdxdoiorg1011552013250301

Research ArticleZnO

1minus119909S119909

Nanosphere in Ferroelectric Liquid Crystal MatrixThe Effect of Aggregation and Defects on the Dielectric andElectro-Optical Properties

Dharmendra Pratap Singh Swadesh Kumar Gupta and Rajiv Manohar

Liquid Crystal Research Lab Physics Department University of Lucknow Lucknow 226007 India

Correspondence should be addressed to Rajiv Manohar rajivmanohargmailcom

Received 31 May 2013 Revised 20 July 2013 Accepted 20 July 2013

Academic Editor David Huber

Copyright copy 2013 Dharmendra Pratap Singh et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

High concentration (5wt) of ZnO1minus119909

S119909nanosphere (NS) has been dispersed in the ferroelectric liquid crystal (FLC) to analyze

the effect of high dopant concentration in the FLC matrix The FLC molecules actively interact with the NS The presence of NSenhances the photoluminescence of the pure FLC material due to the coupling of localized surface plasmon resonance from NSwith FLC molecules The high concentration of NS causes an aggregation in the FLC matrix and creates topological defects Thedefects and aggregation cause the change in electro-optical and dielectric properties of the pure FLC material The bigger size ofNS as compared to the smectic layer separation causes the warping in the smectic layer Semiconducting nature of NS also affectsthe conductivity of the pure FLC

1 Introduction

The scope of nanotechnology in the present age is notonly limited within the field of material science but alsoextended to all the fields of research and application Thefields like electronics condense matter and medical sciencesare benefited from the application point of view when usedwith nanoscience [1ndash3] The use of nanoscience in fieldsof liquid crystal has created some interesting and usefulproperties [4]

Ferroelectric liquid crystals (FLCs) have salient featuresover the trivial liquid crystals (LCs) because of their tiltedsmectic phase and the chirality of the molecules [5] Theyhave proved their applicability of showing faster responsetime and the instruments based on less threshold voltage[6] In addition to these properties they have also showntheir potential for the field effect transistors (FETs) spatiallight modulators (SLMs) switchable devices and nonvolatilememory effects [7 8] The prospective of tuning the prop-erties of liquid crystals due to the addition of nanomaterialis currently a hot topic in liquid crystal research [9ndash11]The composite system of the pure FLC and nanomaterial

has already shown its utility in the FLC-based devices withgreater efficiency [12]

In the present paper we report a comprehensive studyof the dielectric and electro-optical (E-O) properties ofa ferroelectric liquid crystal highly doped with ZnO

1minus119909S119909

nanospheres (NS) The present work has a motive to analyzethe effect of high concentration of the nanomaterial on theFLC matrix and also on the E-O and dielectric parametersThe ZnO

1minus119909S119909NS were added in 5wtwt concentration

to the pure FLC 16100 The results show that the dopingof NS alters the physical properties of the pure FLC Theinvestigated results are discussed and explained on the basisof the interactions taking place between the NS and FLCmolecules in the composite geometry effect of high dopingof NS on the pure FLC and molecular dynamics of NS andFLC molecules with their dipolar contributions

2 Experimental Details

A commercially available ferroelectric liquid crystal (FLC)16100 purchased from Clariant Chemicals Co Ltd Ger-many was used as host material in the present study

2 Advances in Condensed Matter Physics

The phase sequence of the FLC material is Cr SmClowast SmANlowast and Iso at minus20∘C 72∘C 82∘C and 90∘ndash94∘C For thepure FLC 16100 the standard values (as provided by themanufacturer) of spontaneous polarization (119875

119904) cone angle

(2120579) and rotational viscosity (120574119866) at 25∘Cwere minus105 nCcm2

5430∘ and 60m Pas respectivelyThe ZnO

1minus119909S119909nanospheres (NS) were added to the pure

FLC as a guest entity A typical coprecipitation method wasused to synthesize the present NS (nanocrystals of sphericalshape) taking CH

3OH as solvent The prepared NS were

characterized by X-ray diffraction (XRD) and transmissionelectronmicroscopy (TEM)Thediameter of the nanosphereswas found to be sim10ndash15 nm The detailed information aboutthe synthesis of the nanosphere (spherical shape nanoparti-cle) and the effect of small concentration of the NS on FLCparameters has already been published by Singh et al [13]

Highly conducting (sim 20Ω◻) indium tin oxide (ITO)coated glass plates were used to make sample cells Thedesired electrode pattern on the ITO substrates was achievedusing a photolithographic technique The active electrodearea was 7mm times 7mm The uniform thickness (6 120583m in ourcase) of both the sample cells was maintained by means ofMylar spacer The planar alignment was obtained by coatingpolymer (Nylon 66) on ITO glass plate and unidirectionalrubbing The empty sample cells were calibrated using ana-lytical reagent (AR) grade carbon tetrachloride (CCl

4) and

benzene (C6H6)

The nanosphere-ferroelectric liquid crystal (NS-FLC)composite system was prepared by the mixing of NS inthe 5wtwt ratio with pure FLC 16100 To prepare thecomposite system an appropriate amount (in the weightratio ie 50) of nanospheres was mixed into the pureFLC and then homogenized with an ultrasonic mixer at 90∘Cfor one hour and uniform dispersion of nanospheres wasensured but the high concentration of NS aggregates in thepure FLCmatrix which was clearly observed in the polarizingoptical microscope (POM) images

The pure FLC and the NS-doped FLC were filled in thesample cells at a temperature higher than the isotropic tem-perature by means of capillary action and then cooled grad-ually up to room temperature with the application of a smallac electric field The alignment of the samples was checkedby the polarizing microscope under the crossed polarizer-analyzer arrangement

The dielectric spectroscopy of the samples was per-formed by a computer-controlled impedancegain analyzer(Solartron SL1260) attached with a temperature controller forthe frequency interval 100Hzndash32MHz The dielectric mea-surements were carried out as a function of temperature byplacing the sample on a computer-controlled hot plate instec(HCS 302) The temperature stability was better than plusmn01∘CThe low- and high-frequency corrections were also made tothe experimental data

The FTIR spectra of the pure and the NS-doped FLC wasrecorded by the Fourier transform infrared spectrophotome-ter (IR Affinity-1 SHIMADZU) between 1500 to 3000 cmminus1The photoluminescence (PL) spectra of pure and NS-dopedFLC were recorded using Perkin Elmer LS 55 luminescence

spectrophotometer During the PL measurement all themeasuring parameters like slit width (4 nm in our case)excitation step and so forth were same for the entire samplesThe two excitation wavelengths that is 290 and 315 nm wereused to record the PL spectra of the pure and the NS-dopedFLC in the present investigation

The spontaneous polarization (119875119904) measurement was

performed using a triangular wave method at a voltage of20119881119875-119875 and 10Hz frequency 119875

119904was determined by using the

following relation [14]

119875119904=

1

2119860int 119894 (119905) 119889119905 (1)

where int 119894(119905)119889119905 is the area under the current bump and 119860

is the active area of the sample in sample holder For themeasurement of response time (120591res) a square wave signal of10Hz and 20119881

119875-119875 was used The rotational viscosity (120574119866) of

the Goldstone mode in SmClowast phase was calculated by therelation

120574119866= 119875119904times 120591res times 119864 = 119875

119904times11990510minus 11990590

18times 119864 (2)

where 119864 is the applied switching field and 11990510

and 11990590

arethe corresponding times for 10 and 90 of the maximumlevel of response time while other symbols have their usualmeaning [15]

The dielectric relaxation phenomena of the pure and theNS-doped FLC were analyzed using the Cole-Cole relation[16]

120576lowast= 1205761015840(infin) +

120575120576

1 + (119894120596120591)1minus120572

(3a)

where 120575120576 is the relaxation strength and 1205761015840(infin) is the high-

frequency limit of the dielectric permittivity data 120596 = 2120587119891where 119891 is the frequency 120591 is the relaxation time and 120572

is the distribution parameter The experimental data sufferslow- and high-frequency deviations in dielectric data andexceedingly require correction for low- and high-frequencyvalues On separating the real and imaginary parts of (3a)one may get

1205761015840= 1205761015840(119889119888) 119891

minus119899+ 1205761015840(infin)

+

120575120576 [1 + (2120587119891120591)(1minus120572) sin (1205721205872)]

1 + (2120587119891120591)2(1minus120572)

+ 2(2120587119891120591)(1minus120572) sin (1205721205872)

(3b)

12057610158401015840=

120590 (119889119888)

12057602120587119891119896

+120575120576(2120587119891120591)

(1minus120572) cos (1205721205872)

1 + (2120587119891120591)2(1minus120572)

+ 2(2120587119891120591)(1minus120572) sin (1205721205872)

+ 119860119891119898

(3c)

Here 120590(119889119888) is the 119889119888 ionic conductance 120576119900is the free space

permittivity and 119891 is the frequency while 119899 119898 and 119896 arethe fitting parametersThe terms 120576120484(119889119888)119891minus119899 and 120590(119889119888)120576

1199002120587119891119896

Advances in Condensed Matter Physics 3

20 nm

(a)

200 nm

(b)

Figure 1 (a) The scanning electron microscopic (SEM) image of the ZnO1minus119909

S119909nanosphere (NS) which represents a small agglomeration of

the NS (b) SEM image of the aggregation of NS

1600 1800 2000 2200 2400 2600 2800 30000

10

20

30

40

50

60

70

80

90

100

Wavenumber (cmminus1)

T(

)

(a)

Wavenumber (cmminus1)1600 1800 2000 2200 2400 2600 2800 3000

0

10

20

30

40

50

60

70

80

90

100

01500 1550 1600 1650 1700

10

20

30

40

50


T(

)

T(

)

(b)

Figure 2 FTIR spectra of the (a) pure FLC and (b) NS-doped FLC material The inset of Figure 2(b) shows the enlarged FTIR spectra of theNS-doped FLC material between the interval of 1500ndash1700 cmminus1

are added in (3b) and (3c) for correcting the low-frequencyeffect due to the electrode polarization capacitance and ionicconductance The 119860119891119898 term is added in (3c) for correctingthe high-frequency effect due to the ITO resistance and leadinductance [9] The other abbreviations are same as givenfor (3a) The experimental data have been fitted in theseequations and corrected for low- and high-frequency values[13]

3 Results and Discussions

Figures 1(a) and 1(b) represent the SEM image of theZnO1minus119909

S119909(NS) and aggregation of the NS respectively A

small agglomeration has been observed in the SEM image ofthe NS which is the basic problem of most of the nanomate-rial Due to the agglomeration property of NS it aggregates

in the FLC matrix as dispersed in high concentration Theaggregation and topological defects are the main factorswhich alter the physical properties of the pure FLC material

Fourier transform infrared (FTIR) spectroscopy is apowerful modern technique for the characterization of sam-ples This technique provides the information about theconcentration of the impurities their bonding with the hostmaterial and different types of vibrations occurring in thesamples The FTIR analysis for the wave number intervalsof 1500ndash3000 cmminus1 has been performed for the pure and theNS-doped FLCmaterial in Figures 2(a) and 2(b) respectivelyThe change in FTIR spectra for the NS-doped FLC system ismainly due to the aggregation of the NS in FLC matrix AsNS behaves like the ionic additive to the FLCmatrix the largeconcentration of the NS (or aggregation of NS) reflects in theFTIR spectra in the form of impurityThe inset of Figure 2(b)


350 375 400 425 450 475 500 525 5500

50

100

150

200

250

300

350

400

450

500

550

Wavelength (nm)

PL in

tens

ity (a

u)

388 nm

120582 = 315 nm120582 = 290 nm

ex

ex

(a)

Wavelength (nm)

PL in

tens

ity (a

u)

388 nm409 nm

432 nm

460 nm

= 290 nm= 315 nm

350 375 400 425 450 475 500 525 5500

100

200

300

400

500

600

700

120582ex120582ex

(b)

Figure 3 The photoluminescence (PL) spectra of the (a) pure FLC and the (b) NS-doped FLC at two different excitation wavelengths thatis 290 nm and 315 nm

shows the enlarged image of FTIR spectra from 1500 to1700 cmminus1 The transmission peaks in this region show thevibrations corresponding to impurity ions that is NS Thechange in percentage Transmission is due to the topologicaldefects and scattering of light from the aggregation of NSTherefore the change in FTIR spectra clearly indicates thepresence of a guest entity in a large concentration in the FLCmatrix

The PL spectra of the pure and the NS-doped FLC usingtwo different excitation wavelengths have been shown inFigure 3 The PL spectra of the pure FLC show a broademission peak centred at 388 nm corresponding to violetemissionThe PLmeasurement was performed on two differ-ent excitation wavelengths that is 290 nm and 315 nm Thechange in the excitation wavelength only alters the intensityof emission peak but it does not cause any shifting in theemission peak Due to the addition of NS the PL of thepure FLC materials has been enhanced This enhancementin the PL spectra of the pure FLC materials is attributed tothe coupling of localized surface plasmon resonance fromNSwith FLCmolecules [17] In addition to this someother feeblePL emission peaks centred at 409 432 and 460 nm havealso been observed These emission peaks lie in the spectralregion due to the self-activated PL centresThese centres haveoften been attributed to the crystal vacancies Thus feeble PLemission peaks centred at 409 432 and 460 nm arise fromthe crystal line incorporation of trace amount of Zn2+ in thecrystal lattice creating the oxygen and sulphur deficiency [18]The nonsmoothening of the PL spectra also suggests the sizedistribution of theNS in FLCmatrixThe change in excitationwavelength does not produce any change in the magnitudeof the PL emission peak of the NS-doped FLC system Thisshows that the aggregation of the NS in the pure FLC matrix

due to large amount of NS dominate over the intras FLCinteractions

With the help of triangular wave electrical response curve(also known as polarization reversal current method) thespontaneous polarization of the pure and the NS-dopedFLC has been calculated The behaviour of spontaneouspolarization (119875

119904) with the change in temperature is shown

in Figure 4(a) The value of 119875119904decreases with increasing

temperature for both the pure and the doped FLC but the 119875119904

value for the NS doped FLC system is higher than that of thepure FLC When a high concentration of the NS is dispersedin the FLC material it causes an aggregation of the NS TheNS behaves like an ionic additive in the FLC system At theplace of aggregation these ionic charges accumulate and forma local internal electric field This local internal electric fieldincreases the separation between polarization charges on theLC molecules which results in the increased dipole momentof the doped system The increased dipole moments resultthe increased spontaneous polarization of the NS-doped FLCsystem [19]

The response time (120591res) of the pure and the doped FLCsystem is plotted against the temperature scale in Figure 4(b)The response time of the pure and the doped systemdecreaseswith increasing temperature The response for the dopedsystem is slower as compared to the pure FLC due tothe presence of high concentration of NS The presence ofhigh quantity of NS creates additional constraints in themolecular motion of the FLC molecules under the influenceof applied field These constraints reduce the energy of thedoped FLC system therefore FLC molecules do not respondquickly with the applied field as compared to the pure FLCmolecules which results in a slower response for the NS-FLC system No noticeable shift in the SmClowast-SmA phase


25 30 35 40 45 50 55 60 65 70 75

0

1

2

3

4

5

6

7

8

9

10

Pure FLC 16100FLC doped with NS

Spon

tane

ous p

olar

izat

ion

(nC

cm2)

Temperature (∘C)

(a)


Temperature (∘C)25 30 35 40 45 50 55 60 65 70 75

9

12

15

18

21

24

27

30

33

36

Resp

onse

tim

e (m

s)(b)

Figure 4 The variation of (a) spontaneous polarization and (b) response time on the temperature scale for the pure and the NS-doped FLCsamples

25 30 35 40 45 50 55 60 65 70 750

01

02

03

04

05

06

07

08

09

1

11


Temperature (∘C)

Aggregation of NS

Actu

al la

yer s

paci

ng (d

)

Topological defectsnear aggregation

Alte

red

layer

spac

ing

(d998400 )

Rota

tiona

l visc

osity

(Pamiddot

s)

Figure 5 The change in rotational viscosity with the variation oftemperature for the pure and the NS-doped FLC whereas the insetof figure shows the paradigm of the warping of the smectic layersdue to the presence of aggregation of NS

transition temperature has been observed for the NS-FLCsystem

The rotational viscosity with the variation of temperatureis shown in Figure 5 Almost linear decrement in the value ofrotational viscosity on increasing the temperature has beenobserved for both the pure and the doped systems But thevalue of rotational viscosity for the NS-doped FLC systemis greater than that of the pure FLC system As rotational

viscosity (120574 = 119875119904sdot 120591res sdot 119864) is the product of spontaneous

polarization response time and effective electric field appliedon the sample cell therefore due to increase in the sponta-neous polarization and response time the rotational viscosityalso increases as compared to the pure FLC material Asdiscussed previously the NS aggregates in the FLC matrixand forms a local internal electric field near the aggregationThis field influences the smectic layer ordering which altersthe smectic layer spacing as shown in the inset of Figure 5This combined effect of disordering in smectic layers andaggregation produces the topological defects in FLC matrixThese two factors affect the rotational motion of FLCmolecules which results in the enhanced rotational viscosityof the doped FLC system The alteration in the smectic layerseparation due to spherical gold nanoparticle has alreadybeen reported by Pratibha et al [20]

In the molecular motion of the composite system fourtypes of interactions take place namely

(i) FLC molecule-molecule interaction(ii) FLC molecule-NS interaction(iii) NS-NS interaction(iv) FLC molecule-alignment layer interaction

In the presence of any guest entity (nanoparticles CNTsdyes polymers etc) the interaction of FLC molecules withthat of the guest material (NS in our case) takes place Theprobability of weak or strong NS-NS interaction dependsupon the concentration of NS in the composite system Inthe present work 5wtwt concentration ofNS causes strongNS-NS interactions in the composite systemThis strong NS-NS interaction causes the aggregation of NS in FLC matrixOne should notice that the size of the nanomaterial also


100120583m

P

A

(a)

100120583m

P

A

45∘

(b)

100120583m

P

A

(c)

100120583m

P

A

45∘

(d)

Figure 6 Polarizing optical microscopic (POM) texture in dark state (a) pure FLC (c) NS-doped FLC bright state (b) pure FLC and (d) NS-doped FLCThe dark state was achieved under the crossed polarizer-analyzer condition whereas the bright state was achieved by rotating thesample cell by 45∘ from the initial condition The aggregation of NS has been shown in the circle and topological defects are shown betweentwo dotted parallel lines Chevron or zig-zag defects are shown in Figure 6(a) in V-shaped dotted lines

plays a crucial role in determining the properties of thecomposite systems [21] The bigger size of NS and strong NS-NS interaction are mainly responsible for the modificationsin the properties of the pure FLC From the application pointof view FLC-NS interaction in the composite is accountabledepending on the nature characteristics size shape andquantity of NS

Mainly three types of events exist in theNS-FLC compos-ite system that is the presence of NS wraps the smectic layersaround it NS produces hindrance in the motion of the FLCmolecule and NS strongly interacts with the FLC moleculesThe presence of NS warps the smectic layers and alters thespacing between themThese warped smectic layers radicallyalter the neighbouring smectic layers In the cone motion ofthe FLCmolecules the factor 119889120593119889119905 in viscous torque (minusΓ

119911=

120574(119889120593119889119905) where Γ119911is the 119911 component of viscous torque and

120593 is the phase angle) is redistributed because of thewarping ofthe smectic layersThis results in a higher rotational viscosityfor the NS-doped FLC system

The polarizing opticalmicroscopic (POM) images in darkand bright states have been shown in Figure 6 Figures 6(a)

and 6(b) represent the POM images of the pure FLC in darkand bright states respectively whereas Figures 6(c) and 6(d)represent the NS-doped FLC in the dark and bright statesThe dark state POM image corresponds to undercrossedpolarizer-analyzer condition whereas the bright state wasachieved by rotating the sample cell by 45∘ from the initialcondition The high concentration of NS causes aggrega-tion and defects in the FLC medium which is clear fromFigure 6(c) Due to this aggregation of NS the molecularordering of the FLC molecules also impairs The increase inthe relaxation strength of the NS-doped FLC is compatiblewith the present result The study of the relaxation strengthwill be discussed later in the paper The high doping of theNS in the pure FLC also reduces the anchoring of the FLCsample which is also verified by the optical textures Theoccurrence of the intense chevron geometry can be seen inthe case of the pure FLC (Figures 6(a) and 6(b)) whereasin the doped FLC system the chevron geometry was notwell observed The presence of high concentration of the NScauses other topological defects in the FLC matrix causingthe scattering of transmitted light through NS which lowers


25 30 35 40 45 50 55 60 65 70 75

20

21

22

23

24

25

26

27

28

29

Die

lect

ric p

erm

ittiv

ity

At 100 Hz

Smectic Clowast phase


Temperature (∘C)

Figure 7 Temperature dependence of the dielectric permittivity at100Hz for the pure and the NS-doped FLC

the contrast of the NS-doped FLC system From applicationpoint of view the controlled addition of nanomaterial inliquid crystal enhances the contrast of the LC materialtherefore the determination of the suitable concentration ofany nanomaterial in host LC is vital factor

The change in response time can also be understood bythis observation For weak anchoring the relation can begiven as [22]

120591Res =4120578119889

1198821205872 (4)

where 119889 is the cell thickness and 119882 is the anchoring energycoefficientThe lower anchoring energy coefficient of the NS-doped FLC results in a higher response time

The temperature dependence of the dielectric permittiv-ity at 100Hz for both the pure and the NS-doped FLC isdepicted in Figure 7 The dielectric permittivity of the pureFLC increases slightly with increase in the temperature Themaximum value of dielectric permittivity for the pure FLChas been noticed at 45∘C Further increment in temperaturecauses a small decrease in the dielectric permittivity Asharp decrement in the value of dielectric permittivity hasbeen observed at the vicinity of SmClowast-SmA phase transitiontemperatureThis sharp decrease in the dielectric permittivityis due to the change in geometry at the SmClowast-SmA phasetransition temperature The dielectric permittivity measure-ment for the NS-doped FLC shows an increased value ofthis parameter as compared to the pure FLC This increasein the value of dielectric permittivity is due to the increasedpolarization (ie net dipole moment) of the NS-FLC system[23] The variation of dielectric permittivity on temperaturescale for the NS-doped FLC is not similar to that of thepure FLC For the NS doped FLC system the value ofdielectric permittivity increases almost linearly with increasein the temperature for the temperature interval of 30∘Cndash55∘C

25 30 35 40 45 50 55 60 65 70 75 80

20

25

30

35

40

45

50

55

60

Rela

xatio

n str

engt

h


Temperature (∘C)

Smectic Clowastphase

Figure 8 The variation of the relaxation strength with change intemperature for the pure and the NS-doped FLC

Beyond this temperature interval the dielectric permittivityshows a reducing trend on the temperature scale due to thechange in geometry of the LC phase

The relaxation strength (Δ120576) is plotted against the tem-perature in Figure 8 The relaxation strength for both thepure and the NS-doped FLC increases with increase in thetemperature The relaxation strength shows its maximumvalue near the temperature 55∘C and further increment intemperature causes a decrease in the value of Δ120576 because FLCsample approaches from SmClowast to SmA phaseThe relaxationstrength for the doped FLC system is greater than that of thepure FLC This greater value of Δ120576 for the doped system canbe explained by the following relation [24]

Δ120576 =1

21198701205760

sdot1198752

119904

11990221205792 (5)

where Δ120576 is the relaxation strength 119875119904the spontaneous

polarization 120579 the tilt angle 119902 the wave vector of helix and119870is the elastic constant The quantity 119875

119904120579 is a constant in the

first approximation and the variation of119870with temperature isalso very small therefore the variation of relaxation strengthmainly depends upon the wave vector of helix (119902) The wavevector of helix (119902 = 2120587119901 where 119901 is pitch) is decreased thus119901 increases due to aggregation of NS and defects formation inthe FLC matrix

A nonlinear increase in relaxation frequency (119891119877) has

been shown in Figure 9 In the whole SmClowast phase relaxationfrequency increases nonlinearly with increasing temperatureand attains its maximum value at SmClowast-SmA phase tran-sition temperature Further increment in the temperaturecauses a sharp decrease in the relaxation frequency valuedue to change in phase geometry and the removal of helicalstructure of the FLC molecules The value of relaxationfrequency for the doped FLC system is less as compared to


50

60

70

80

90

100

110

120

130

140

150

25 30 35 40 45 50 55

007

006

005

004

003

002

001

60 65 70 75 80


Temperature (∘C)

25 30 35 40 45 50 55 60 65 70 75 80Temperature (∘C)

Rela

xatio

n fre

quen

cy (H

z)


Dist

ribut

ion

para

met

er (120572

)

Figure 9 The variation of the relaxation frequency with change intemperature for the pure and the NS-doped FLC while the inset offigure shows the variation of the distribution parameter with changein temperature

the pure FLC system This behaviour of 119891119877can be explained

by the relation [25]

119891119877=1198701199022

2120587120574 (6)

where 120574 is the rotational viscosity and other symbols havetheir usual meaning

The above relation shows that relaxation frequency isinversely proportional to the rotational viscosity As therotational viscosity has greater value for the doped systema reduced value of the relaxation frequency is found for itIn addition to this the relaxation frequency also dependsupon the wave vector of helix It is assumed that the wavevector of helix has also decreased due to the presence of NSwhich results in the decrease in relaxation frequency Thereduction in the relaxation frequency has also verified by thedistribution parameter (120572) shown in the inset of Figure 9Thevalue of 120572 is higher for the NS-doped FLC sample thereforethe relaxation frequency of the NS-doped FLC get reducedThedistribution parameter of the pure FLC is almost constantfor the first four consecutive observations on temperaturescale (ie 30∘C to 45∘C) Beyond these observations distri-bution parameter increases with increase in the temperatureFor the NS doped FLC system distribution parameter alsoincreases with increase in the temperature In both cases thesmall value of distribution parameter (001ndash007) indicatesthat Goldstone mode predominates over the soft mode inthe SmClowast phase [26] and the doped FLC system completelyfollows the Cole-Cole-type relaxation process

Figure 10 represents the change in electrical conductivity[27] with the variation of temperature at 133Hz for boththe pure and the NS-doped FLC For the pure FLC systemthe electrical conductivity is almost temperature independent

01

02

03

04

05

06

07

08

3530 40 45 50 55 60 65 70 75


Temperature (∘C)

Elec

tric

al co

nduc

tivity

(lowast10

minus6

Sm

)

Figure 10 The change in the electrical conductivity with thevariation of temperature for the pure and the NS-doped FLC

whereas it strongly depends on temperature for the NS-doped FLC system Electrical conductivity sharply increaseswith increase in the temperature and shows its maximumvalue at 50∘C Further increment in the temperature causesa reduction in the electrical conductivity As NS behaveslike the ionic additives to the FLC materials it increasesthe electrical conductivity in the doped FLC system Inthe temperature range of 35∘Cndash50∘C the conductivity ismainly driven by the semiconducting nature of the NSand conductivity increases with increase in the temperatureBeyond 50∘C the FLC molecules get sufficient energy andmove with more kinetic energy which increases the numberof collisions of FLC molecules with NS Thus the resistiveforces increase in the NS-FLC system which results in thedecrement in the conductivity

4 Conclusions

The salient features of the present investigation can beconcluded as follows the addition of nanospheres (NS) in thepure FLCmaterial changes the dielectric and E-O parametersof the pure FLC The bigger size of NS occupies greatervolume as compared to the FLC molecule therefore theyproduce hindrance in the motion of the FLC molecules andwrap the smectic layer The high quantity of NS producesstrong NS-NS interaction (which causes the aggregation ofNS in the FLC matrix) which dominates other interactionstaking place in the composite system The presence of highconcentration of NS was confirmed by the FTIR analysisThechange in FTIR spectra clearly indicates the presence of aguest entity The change in percentage transmission in theNS-doped FLC system is due to the topological defects andscattering of the light from the aggregation of NS in FLCmatrix The enhanced PL in case of the NS-doped FLC hasbeen attributed to the surface Plasmon resonance between the


NS and FLC molecules Some other secondary PL emissionpeak has also been noticed due to the result of the oxygen andsulphur vacancies in the crystal structure The aggregationof NS supports the FLC molecular dipole moment whichincreases the net ferroelectricity (or net dipole moment) inthe composite The increased ferroelectricity increases thevalue of spontaneous polarization and dielectric permittivityThe variation of relaxation strength and relaxation frequencydepends upon the wave vector of helix and rotational viscos-ity The distribution parameter strongly recommends for theexistence of Cole-Cole relaxation phenomena in the compos-ite system The topological defects produced by NS createa slower response for the composite system but its order isstill important in case of constant rate video processing Highdopant concentration of the NS (ie 5) in FLC plays a roleas ionic additive which results in a higher conductivity for theNS-doped FLC system The better electrical response in theNS doped FLC system indicates its applicability in electronicdevice fabrication The intense chevron geometry in caseof the pure FLC has not been observed in the NS-dopedFLC system but the high concentration of NS produces thetopological defects in the composite system

Acknowledgments

The authors are thankful to the Department of Science andTechnology Government of India for the financial assistancefor present work in the form of projectThe authors (SwadeshKumar Gupta and Dharmendra Pratap Singh) are thankfulto CSIR for SRF Grant Authors are also very thankful toProfessor A C Pandey Nano Application Centre Universityof Allahabad for providing the nanospheres for presentstudy

References

[1] L J Yu andMM Labes ldquoFluorescent liquid-crystal display uti-lizing an electric-field-induced cholesteric-nematic transitionrdquoApplied Physics Letters vol 31 no 11 pp 719ndash720 1977

[2] R C Y King and F Roussel ldquoTransparent carbon nanotube-based driving electrodes for liquid crystal dispersion displaydevicesrdquo Applied Physics A vol 86 no 2 pp 159ndash163 2007

[3] L Calucci G Ciofani D de Marchi et al ldquoBoron nitridenanotubes as T

2-weighted MRI contrast agentsrdquo Journal of

Physical Chemistry Letters vol 1 no 17 pp 2561ndash2565 2010[4] D P Singh S K Gupta A Srivastava and R Manohar ldquoThe

phenomenon of induced photoluminescence in ferroelectricmesophaserdquo Journal of Luminescence vol 139 pp 60ndash63 2013

[5] R BMeyer L Liebert L Strzelecki and P Keller ldquoFerroelectricliquid crystalsrdquo Journal de Physique Lettres vol 36 no 3 pp 69ndash71 1975

[6] T Joshi A Kumar J Prakash and A M Biradar ldquoLow poweroperation of ferroelectric liquid crystal system dispersed withzinc oxide nanoparticlesrdquo Applied Physics Letters vol 96 no25 Article ID 253109 3 pages 2010

[7] R Martel V Derycke C Lavoie et al ldquoAmbipolar electricaltransport in semiconducting single-wall carbon nanotubesrdquoPhysical Review Letters vol 87 no 25 Article ID 256805 4pages 2001

[8] J Prakash A Choudhary A Kumar D S Mehta and A MBiradar ldquoNonvolatile memory effect based on gold nanoparti-cles doped ferroelectric liquid crystalrdquo Applied Physics Lettersvol 93 no 11 Article ID 112904 3 pages 2008

[9] D P Singh S K Gupta K K Pandey S P Yadav M C Variaand R Manohar ldquoFerroelectric liquid crystal matrix dispersedwith Cu doped ZnO nanoparticlesrdquo Journal of Non-CrystallineSolids vol 363 pp 178ndash186 2013

[10] V N Vijayakumar and M L N M Mohan ldquoEnhancementof the display parameters of 41015840-pentyl-4-cyanobiphenyl due tothe dispersion of functionalised gold nano particlesrdquo Journalof Dispersion Science and Technology vol 33 no 1 pp 111ndash1162012

[11] A Kumar G Singh T Joshi G K Rao A K Singh and A MBiradar ldquoTailoring of electro-optical properties of ferroelectricliquid crystals by doping Pd nanoparticlesrdquo Applied PhysicsLetters vol 100 no 5 Article ID 054102 4 pages 2012

[12] A K Srivastava E P Pozhidaev V G Chigrinov and RManohar ldquoSingle walled carbon nano-tube ferroelectric liquidcrystal composites excellent diffractive toolrdquo Applied PhysicsLetters vol 99 no 20 Article ID 201106 3 pages 2011

[13] D P Singh S P Yadav P K Tripathi et al ldquoConcentrationdependent physical parameters of ferroelectric liquid crystaland ZnOS nanomaterial composite systemrdquo SoftMaterials vol11 no 3 pp 305ndash314 2013

[14] R Manohar A K Srivastava P K Tripathi and D P SinghldquoDielectric and electro-optical study of ZnO nano rods dopedferroelectric liquid crystalsrdquo Journal of Materials Science vol46 no 18 pp 5969ndash5976 2011

[15] K Skarp and S T Lagerwall ldquoRotational viscosities in ferro-electric smectic liquid crystalsrdquo Ferroelectrics vol 84 no 1 pp119ndash142 1988

[16] K S Cole and R H Cole ldquoDispersion and absorption indielectrics I Alternating current characteristicsrdquoThe Journal ofChemical Physics vol 9 no 4 pp 341ndash351 1941

[17] A Kumar J Prakash D S Mehta A M Biradar andW HaaseldquoEnhanced photoluminescence in gold nanoparticles dopedferroelectric liquid crystalsrdquo Applied Physics Letters vol 95 no2 Article ID 023117 3 pages 2009

[18] A Kumar J Prakash A D Deshmukh D Haranath P Silotiaand A M Biradar ldquoEnhancing the photoluminescence offerroelectric liquid crystal by doping with ZnS quantum dotsrdquoApplied Physics Letters vol 100 no 13 Article ID 134101 4pages 2012

[19] P Malik A Chaudhary R Mehra and K K RainaldquoElectrooptic and dielectric studies in cadmium sulphidenanorodsferroelectric liquid crystal mixturesrdquo Advances inCondensed Matter Physics vol 2012 Article ID 853160 8 pages2012

[20] R Pratibha W Park and I I Smalyukh ldquoColloidal goldnanosphere dispersions in smectic liquid crystals and thinnanoparticle-decorated smectic filmsrdquo Journal of AppliedPhysics vol 107 no 6 Article ID 063511 5 pages 2010

[21] F V Podgornov A V Ryzhkova and W Haase ldquoInfluence ofgold nanorods size on electro-optical and dielectric propertiesof ferroelectric liquid crystalsrdquo Applied Physics Letters vol 97no 21 Article ID 212903 3 pages 2010

[22] X Nie R Lu H Xianyu T X Wu and S Wu ldquoAnchoringenergy and cell gap effects on liquid crystal response timerdquoJournal of Applied Physics vol 101 no 10 Article ID 103110 5pages 2007


[23] S K Gupta D P Singh and R Manohar ldquoSWCNT dopedferroelectric liquid crystal the electro-optical properties withenhanced dipolar contributionrdquoCurrent Applied Physics vol 13no 4 pp 684ndash687 2013

[24] T P Majumder M Mitra and S K Roy ldquoDielectric relaxationand rotational viscosity of a ferroelectric liquid crystal mixturerdquoPhysical Review E vol 50 no 6 pp 4796ndash4800 1994

[25] H S Kitzerow and C Bahr Chirality in Liquid CrystalsSpringer Berlin Germany 2001

[26] Y P Panarin Y P Kalmykov S T M Lughadha H Xu andJ K Vij ldquoDielectric response of surface stabilized ferroelectricliquid crystal cellsrdquo Physical Review E vol 50 no 6 pp 4763ndash4772 1994

[27] F Kremer and A Schonhals Broadband Dielectric SpectroscopySpringer Berlin Germany 2003

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


FluidsJournal of

Atomic and Molecular Physics

Journal of



Advances in Condensed Matter Physics

OpticsInternational Journal of



AstronomyAdvances in

International Journal of


Superconductivity


Statistical MechanicsInternational Journal of


GravityJournal of


AstrophysicsJournal of


Physics Research International


Solid State PhysicsJournal of

Computational Methods in Physics

Journal of



Soft MatterJournal of

Hindawi Publishing Corporationhttpwwwhindawicom

AerodynamicsJournal of

Volume 2014


PhotonicsJournal of


Journal of

Biophysics


ThermodynamicsJournal of


The phase sequence of the FLC material is Cr SmClowast SmANlowast and Iso at minus20∘C 72∘C 82∘C and 90∘ndash94∘C For thepure FLC 16100 the standard values (as provided by themanufacturer) of spontaneous polarization (119875

119904) cone angle

(2120579) and rotational viscosity (120574119866) at 25∘Cwere minus105 nCcm2

5430∘ and 60m Pas respectivelyThe ZnO

1minus119909S119909nanospheres (NS) were added to the pure

FLC as a guest entity A typical coprecipitation method wasused to synthesize the present NS (nanocrystals of sphericalshape) taking CH

3OH as solvent The prepared NS were

characterized by X-ray diffraction (XRD) and transmissionelectronmicroscopy (TEM)Thediameter of the nanosphereswas found to be sim10ndash15 nm The detailed information aboutthe synthesis of the nanosphere (spherical shape nanoparti-cle) and the effect of small concentration of the NS on FLCparameters has already been published by Singh et al [13]

Highly conducting (sim 20Ω◻) indium tin oxide (ITO)coated glass plates were used to make sample cells Thedesired electrode pattern on the ITO substrates was achievedusing a photolithographic technique The active electrodearea was 7mm times 7mm The uniform thickness (6 120583m in ourcase) of both the sample cells was maintained by means ofMylar spacer The planar alignment was obtained by coatingpolymer (Nylon 66) on ITO glass plate and unidirectionalrubbing The empty sample cells were calibrated using ana-lytical reagent (AR) grade carbon tetrachloride (CCl

4) and

benzene (C6H6)

The nanosphere-ferroelectric liquid crystal (NS-FLC)composite system was prepared by the mixing of NS inthe 5wtwt ratio with pure FLC 16100 To prepare thecomposite system an appropriate amount (in the weightratio ie 50) of nanospheres was mixed into the pureFLC and then homogenized with an ultrasonic mixer at 90∘Cfor one hour and uniform dispersion of nanospheres wasensured but the high concentration of NS aggregates in thepure FLCmatrix which was clearly observed in the polarizingoptical microscope (POM) images

The pure FLC and the NS-doped FLC were filled in thesample cells at a temperature higher than the isotropic tem-perature by means of capillary action and then cooled grad-ually up to room temperature with the application of a smallac electric field The alignment of the samples was checkedby the polarizing microscope under the crossed polarizer-analyzer arrangement

The dielectric spectroscopy of the samples was per-formed by a computer-controlled impedancegain analyzer(Solartron SL1260) attached with a temperature controller forthe frequency interval 100Hzndash32MHz The dielectric mea-surements were carried out as a function of temperature byplacing the sample on a computer-controlled hot plate instec(HCS 302) The temperature stability was better than plusmn01∘CThe low- and high-frequency corrections were also made tothe experimental data

The FTIR spectra of the pure and the NS-doped FLC wasrecorded by the Fourier transform infrared spectrophotome-ter (IR Affinity-1 SHIMADZU) between 1500 to 3000 cmminus1The photoluminescence (PL) spectra of pure and NS-dopedFLC were recorded using Perkin Elmer LS 55 luminescence

spectrophotometer During the PL measurement all themeasuring parameters like slit width (4 nm in our case)excitation step and so forth were same for the entire samplesThe two excitation wavelengths that is 290 and 315 nm wereused to record the PL spectra of the pure and the NS-dopedFLC in the present investigation

The spontaneous polarization (119875119904) measurement was

performed using a triangular wave method at a voltage of20119881119875-119875 and 10Hz frequency 119875

119904was determined by using the

following relation [14]

119875119904=

1

2119860int 119894 (119905) 119889119905 (1)

where int 119894(119905)119889119905 is the area under the current bump and 119860

is the active area of the sample in sample holder For themeasurement of response time (120591res) a square wave signal of10Hz and 20119881

119875-119875 was used The rotational viscosity (120574119866) of

the Goldstone mode in SmClowast phase was calculated by therelation

120574119866= 119875119904times 120591res times 119864 = 119875

119904times11990510minus 11990590

18times 119864 (2)

where 119864 is the applied switching field and 11990510

and 11990590

arethe corresponding times for 10 and 90 of the maximumlevel of response time while other symbols have their usualmeaning [15]

The dielectric relaxation phenomena of the pure and theNS-doped FLC were analyzed using the Cole-Cole relation[16]

120576lowast= 1205761015840(infin) +

120575120576

1 + (119894120596120591)1minus120572

(3a)

where 120575120576 is the relaxation strength and 1205761015840(infin) is the high-

frequency limit of the dielectric permittivity data 120596 = 2120587119891where 119891 is the frequency 120591 is the relaxation time and 120572

is the distribution parameter The experimental data sufferslow- and high-frequency deviations in dielectric data andexceedingly require correction for low- and high-frequencyvalues On separating the real and imaginary parts of (3a)one may get

1205761015840= 1205761015840(119889119888) 119891

minus119899+ 1205761015840(infin)

+

120575120576 [1 + (2120587119891120591)(1minus120572) sin (1205721205872)]

1 + (2120587119891120591)2(1minus120572)

+ 2(2120587119891120591)(1minus120572) sin (1205721205872)

(3b)

12057610158401015840=

120590 (119889119888)

12057602120587119891119896

+120575120576(2120587119891120591)

(1minus120572) cos (1205721205872)

1 + (2120587119891120591)2(1minus120572)

+ 2(2120587119891120591)(1minus120572) sin (1205721205872)

+ 119860119891119898

(3c)

Here 120590(119889119888) is the 119889119888 ionic conductance 120576119900is the free space

permittivity and 119891 is the frequency while 119899 119898 and 119896 arethe fitting parametersThe terms 120576120484(119889119888)119891minus119899 and 120590(119889119888)120576

1199002120587119891119896


20 nm

(a)

200 nm

(b)




1600 1800 2000 2200 2400 2600 2800 30000

10

20

30

40

50

60

70

80

90

100


T(

)

(a)


0

10

20

30

40

50

60

70

80

90

100

01500 1550 1600 1650 1700

10

20

30

40

50


T(

)

T(

)

(b)










350 375 400 425 450 475 500 525 5500

50

100

150

200

250

300

350

400

450

500

550

Wavelength (nm)

PL in

tens

ity (a

u)

388 nm

120582 = 315 nm120582 = 290 nm

ex

ex

(a)

Wavelength (nm)

PL in

tens

ity (a

u)

388 nm409 nm

432 nm

460 nm

= 290 nm= 315 nm

350 375 400 425 450 475 500 525 5500

100

200

300

400

500

600

700

120582ex120582ex

(b)












25 30 35 40 45 50 55 60 65 70 75

0

1

2

3

4

5

6

7

8

9

10


Spon

tane

ous p

olar

izat

ion

(nC

cm2)

Temperature (∘C)

(a)


Temperature (∘C)25 30 35 40 45 50 55 60 65 70 75

9

12

15

18

21

24

27

30

33

36

Resp

onse

tim

e (m

s)(b)


25 30 35 40 45 50 55 60 65 70 750

01

02

03

04

05

06

07

08

09

1

11


Temperature (∘C)

Aggregation of NS

Actu

al la

yer s

paci

ng (d

)


Alte

red

layer

spac

ing

(d998400 )

Rota

tiona

l visc

osity

(Pamiddot

s)










100120583m

P

A

(a)

100120583m

P

A

45∘

(b)

100120583m

P

A

(c)

100120583m

P

A

45∘

(d)




119911=






25 30 35 40 45 50 55 60 65 70 75

20

21

22

23

24

25

26

27

28

29

Die

lect

ric p

erm

ittiv

ity

At 100 Hz



Temperature (∘C)




120591Res =4120578119889

1198821205872 (4)



25 30 35 40 45 50 55 60 65 70 75 80

20

25

30

35

40

45

50

55

60

Rela

xatio

n str

engt

h


Temperature (∘C)





Δ120576 =1

21198701205760

sdot1198752

119904

11990221205792 (5)








50

60

70

80

90

100

110

120

130

140

150

25 30 35 40 45 50 55

007

006

005

004

003

002

001

60 65 70 75 80


Temperature (∘C)

25 30 35 40 45 50 55 60 65 70 75 80Temperature (∘C)

Rela

xatio

n fre

quen

cy (H

z)


Dist

ribut

ion

para

met

er (120572

)




119891119877=1198701199022

2120587120574 (6)




01

02

03

04

05

06

07

08

3530 40 45 50 55 60 65 70 75


Temperature (∘C)

Elec

tric

al co

nduc

tivity

(lowast10

minus6

Sm

)



4 Conclusions




Acknowledgments


References




































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




20 nm

(a)

200 nm

(b)




1600 1800 2000 2200 2400 2600 2800 30000

10

20

30

40

50

60

70

80

90

100


T(

)

(a)


0

10

20

30

40

50

60

70

80

90

100

01500 1550 1600 1650 1700

10

20

30

40

50


T(

)

T(

)

(b)










350 375 400 425 450 475 500 525 5500

50

100

150

200

250

300

350

400

450

500

550

Wavelength (nm)

PL in

tens

ity (a

u)

388 nm

120582 = 315 nm120582 = 290 nm

ex

ex

(a)

Wavelength (nm)

PL in

tens

ity (a

u)

388 nm409 nm

432 nm

460 nm

= 290 nm= 315 nm

350 375 400 425 450 475 500 525 5500

100

200

300

400

500

600

700

120582ex120582ex

(b)












25 30 35 40 45 50 55 60 65 70 75

0

1

2

3

4

5

6

7

8

9

10


Spon

tane

ous p

olar

izat

ion

(nC

cm2)

Temperature (∘C)

(a)


Temperature (∘C)25 30 35 40 45 50 55 60 65 70 75

9

12

15

18

21

24

27

30

33

36

Resp

onse

tim

e (m

s)(b)


25 30 35 40 45 50 55 60 65 70 750

01

02

03

04

05

06

07

08

09

1

11


Temperature (∘C)

Aggregation of NS

Actu

al la

yer s

paci

ng (d

)


Alte

red

layer

spac

ing

(d998400 )

Rota

tiona

l visc

osity

(Pamiddot

s)










100120583m

P

A

(a)

100120583m

P

A

45∘

(b)

100120583m

P

A

(c)

100120583m

P

A

45∘

(d)




119911=






25 30 35 40 45 50 55 60 65 70 75

20

21

22

23

24

25

26

27

28

29

Die

lect

ric p

erm

ittiv

ity

At 100 Hz



Temperature (∘C)




120591Res =4120578119889

1198821205872 (4)



25 30 35 40 45 50 55 60 65 70 75 80

20

25

30

35

40

45

50

55

60

Rela

xatio

n str

engt

h


Temperature (∘C)





Δ120576 =1

21198701205760

sdot1198752

119904

11990221205792 (5)








50

60

70

80

90

100

110

120

130

140

150

25 30 35 40 45 50 55

007

006

005

004

003

002

001

60 65 70 75 80


Temperature (∘C)

25 30 35 40 45 50 55 60 65 70 75 80Temperature (∘C)

Rela

xatio

n fre

quen

cy (H

z)


Dist

ribut

ion

para

met

er (120572

)




119891119877=1198701199022

2120587120574 (6)




01

02

03

04

05

06

07

08

3530 40 45 50 55 60 65 70 75


Temperature (∘C)

Elec

tric

al co

nduc

tivity

(lowast10

minus6

Sm

)



4 Conclusions




Acknowledgments


References




































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




350 375 400 425 450 475 500 525 5500

50

100

150

200

250

300

350

400

450

500

550

Wavelength (nm)

PL in

tens

ity (a

u)

388 nm

120582 = 315 nm120582 = 290 nm

ex

ex

(a)

Wavelength (nm)

PL in

tens

ity (a

u)

388 nm409 nm

432 nm

460 nm

= 290 nm= 315 nm

350 375 400 425 450 475 500 525 5500

100

200

300

400

500

600

700

120582ex120582ex

(b)












25 30 35 40 45 50 55 60 65 70 75

0

1

2

3

4

5

6

7

8

9

10


Spon

tane

ous p

olar

izat

ion

(nC

cm2)

Temperature (∘C)

(a)


Temperature (∘C)25 30 35 40 45 50 55 60 65 70 75

9

12

15

18

21

24

27

30

33

36

Resp

onse

tim

e (m

s)(b)


25 30 35 40 45 50 55 60 65 70 750

01

02

03

04

05

06

07

08

09

1

11


Temperature (∘C)

Aggregation of NS

Actu

al la

yer s

paci

ng (d

)


Alte

red

layer

spac

ing

(d998400 )

Rota

tiona

l visc

osity

(Pamiddot

s)










100120583m

P

A

(a)

100120583m

P

A

45∘

(b)

100120583m

P

A

(c)

100120583m

P

A

45∘

(d)




119911=






25 30 35 40 45 50 55 60 65 70 75

20

21

22

23

24

25

26

27

28

29

Die

lect

ric p

erm

ittiv

ity

At 100 Hz



Temperature (∘C)




120591Res =4120578119889

1198821205872 (4)



25 30 35 40 45 50 55 60 65 70 75 80

20

25

30

35

40

45

50

55

60

Rela

xatio

n str

engt

h


Temperature (∘C)





Δ120576 =1

21198701205760

sdot1198752

119904

11990221205792 (5)








50

60

70

80

90

100

110

120

130

140

150

25 30 35 40 45 50 55

007

006

005

004

003

002

001

60 65 70 75 80


Temperature (∘C)

25 30 35 40 45 50 55 60 65 70 75 80Temperature (∘C)

Rela

xatio

n fre

quen

cy (H

z)


Dist

ribut

ion

para

met

er (120572

)




119891119877=1198701199022

2120587120574 (6)




01

02

03

04

05

06

07

08

3530 40 45 50 55 60 65 70 75


Temperature (∘C)

Elec

tric

al co

nduc

tivity

(lowast10

minus6

Sm

)



4 Conclusions




Acknowledgments


References




































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




25 30 35 40 45 50 55 60 65 70 75

0

1

2

3

4

5

6

7

8

9

10


Spon

tane

ous p

olar

izat

ion

(nC

cm2)

Temperature (∘C)

(a)


Temperature (∘C)25 30 35 40 45 50 55 60 65 70 75

9

12

15

18

21

24

27

30

33

36

Resp

onse

tim

e (m

s)(b)


25 30 35 40 45 50 55 60 65 70 750

01

02

03

04

05

06

07

08

09

1

11


Temperature (∘C)

Aggregation of NS

Actu

al la

yer s

paci

ng (d

)


Alte

red

layer

spac

ing

(d998400 )

Rota

tiona

l visc

osity

(Pamiddot

s)










100120583m

P

A

(a)

100120583m

P

A

45∘

(b)

100120583m

P

A

(c)

100120583m

P

A

45∘

(d)




119911=






25 30 35 40 45 50 55 60 65 70 75

20

21

22

23

24

25

26

27

28

29

Die

lect

ric p

erm

ittiv

ity

At 100 Hz



Temperature (∘C)




120591Res =4120578119889

1198821205872 (4)



25 30 35 40 45 50 55 60 65 70 75 80

20

25

30

35

40

45

50

55

60

Rela

xatio

n str

engt

h


Temperature (∘C)





Δ120576 =1

21198701205760

sdot1198752

119904

11990221205792 (5)








50

60

70

80

90

100

110

120

130

140

150

25 30 35 40 45 50 55

007

006

005

004

003

002

001

60 65 70 75 80


Temperature (∘C)

25 30 35 40 45 50 55 60 65 70 75 80Temperature (∘C)

Rela

xatio

n fre

quen

cy (H

z)


Dist

ribut

ion

para

met

er (120572

)




119891119877=1198701199022

2120587120574 (6)




01

02

03

04

05

06

07

08

3530 40 45 50 55 60 65 70 75


Temperature (∘C)

Elec

tric

al co

nduc

tivity

(lowast10

minus6

Sm

)



4 Conclusions




Acknowledgments


References




































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




100120583m

P

A

(a)

100120583m

P

A

45∘

(b)

100120583m

P

A

(c)

100120583m

P

A

45∘

(d)




119911=






25 30 35 40 45 50 55 60 65 70 75

20

21

22

23

24

25

26

27

28

29

Die

lect

ric p

erm

ittiv

ity

At 100 Hz



Temperature (∘C)




120591Res =4120578119889

1198821205872 (4)



25 30 35 40 45 50 55 60 65 70 75 80

20

25

30

35

40

45

50

55

60

Rela

xatio

n str

engt

h


Temperature (∘C)





Δ120576 =1

21198701205760

sdot1198752

119904

11990221205792 (5)








50

60

70

80

90

100

110

120

130

140

150

25 30 35 40 45 50 55

007

006

005

004

003

002

001

60 65 70 75 80


Temperature (∘C)

25 30 35 40 45 50 55 60 65 70 75 80Temperature (∘C)

Rela

xatio

n fre

quen

cy (H

z)


Dist

ribut

ion

para

met

er (120572

)




119891119877=1198701199022

2120587120574 (6)




01

02

03

04

05

06

07

08

3530 40 45 50 55 60 65 70 75


Temperature (∘C)

Elec

tric

al co

nduc

tivity

(lowast10

minus6

Sm

)



4 Conclusions




Acknowledgments


References




































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




25 30 35 40 45 50 55 60 65 70 75

20

21

22

23

24

25

26

27

28

29

Die

lect

ric p

erm

ittiv

ity

At 100 Hz



Temperature (∘C)




120591Res =4120578119889

1198821205872 (4)



25 30 35 40 45 50 55 60 65 70 75 80

20

25

30

35

40

45

50

55

60

Rela

xatio

n str

engt

h


Temperature (∘C)





Δ120576 =1

21198701205760

sdot1198752

119904

11990221205792 (5)








50

60

70

80

90

100

110

120

130

140

150

25 30 35 40 45 50 55

007

006

005

004

003

002

001

60 65 70 75 80


Temperature (∘C)

25 30 35 40 45 50 55 60 65 70 75 80Temperature (∘C)

Rela

xatio

n fre

quen

cy (H

z)


Dist

ribut

ion

para

met

er (120572

)




119891119877=1198701199022

2120587120574 (6)




01

02

03

04

05

06

07

08

3530 40 45 50 55 60 65 70 75


Temperature (∘C)

Elec

tric

al co

nduc

tivity

(lowast10

minus6

Sm

)



4 Conclusions




Acknowledgments


References




































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics




50

60

70

80

90

100

110

120

130

140

150

25 30 35 40 45 50 55

007

006

005

004

003

002

001

60 65 70 75 80


Temperature (∘C)

25 30 35 40 45 50 55 60 65 70 75 80Temperature (∘C)

Rela

xatio

n fre

quen

cy (H

z)


Dist

ribut

ion

para

met

er (120572

)




119891119877=1198701199022

2120587120574 (6)




01

02

03

04

05

06

07

08

3530 40 45 50 55 60 65 70 75


Temperature (∘C)

Elec

tric

al co

nduc

tivity

(lowast10

minus6

Sm

)



4 Conclusions




Acknowledgments


References




































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics





Acknowledgments


References




































FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics














FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics








FluidsJournal of


Journal of










Superconductivity




GravityJournal of








Journal of






Volume 2014


PhotonicsJournal of


Journal of

Biophysics



Documents

Research Article S Nanosphere in Ferroelectric Liquid ...downloads.hindawi.com/journals/acmp/2013/250301.pdf · erties of liquid crystals due to the addition of nanomaterial is currently