H. Giefers, Universität Paderborn
Einleitung
Hochdruck-Kristallographie und Synthese28. August 2003
Reaktionskinetik der Disproportionierung von SnO unter Druck
Hubertus Giefers
Universität PaderbornDepartment Physik
AG Wortmann
H. Giefers, Universität Paderborn
Survey
1. The system tin – oxide
2. The disproportionation of SnO at ambient pressure- set up- analysis of the spectra
3. The disproportionation of SnO under pressure
4. Summary
5. Acknowledgement
H. Giefers, Universität Paderborn
1. The system tin and tin oxide
Sn SnO Sn2O3 SnO2
thermodyn. stable
thermodyn.
metastablethermodyn.
metastablethermodyn.
stable
7.31 g/cm³ 6.4 g/cm³ 7.03 g/cm³5.9 g/cm³
0 - 10 GPabct Sn-I
10 - 45 GPa bct Sn-II
45 - >120 GPabcc Sn-III
under hydrostaticpressure tetragonal
-PbOat least to 60 GPa
under nonhydrostatic compression orthorhombic
splitting
triclinic structure
a phase transition
at ca. 9 GPato unkown
structure
two low pressure phases:
tetragonal and orthorhombic
high pressure phase (>10 GPa)
fcc
H. Giefers, Universität Paderborn
1. The system tin and tin oxyde under pressure
our high pressurestudy on:
SnO to 50 GPatetragonal + orth. splittingz(Sn) was determined with EXAFS
Sn2O3 to 30 GPatriclinic, unkown
SnO2 to 50 GPatetragonal, orthorhomic,cubic
0 5 10 15 20 25 30 35 40 45 50 550.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
snoz_p.opj
p (GPa)
V/V
0
Sn-I + Sn-II (bct) SnO (st) SnO
x (triclinic)
SnO2 (st)
H. Giefers, Universität Paderborn
2. Disproportionation of SnO at ambient pressure
SnO
Sn2O3 + Sn
SnO2 + Sn
T > ca. 250 °C
SnO is metastable and disproportionates to the 2 stablematerials SnO2 and Sn at elevated temperatures.
Depending on temperature and alsoon the synthesis condition of SnO, the metastable compound Sn2O3 is formed in the disproportionation reaction, which decomposes to SnO2 and Snat higher temperature.
H. Giefers, Universität Paderborn
2. Disproportionation of SnO at ambient pressure
The disproportionation of SnO was studied ex situ and in situ withEnergy Dispersive X-Ray Diffraction (EDXRD) at beamline F3 at HASYLAB/DESY in Hamburg.
2
H. Giefers, Universität Paderborn
2. Disproportionation of SnO at ambient pressure
←heating band
ceramic spacer →
collimator ↓
HP cell →←thermocouple
↓ Al foil
H. Giefers, Universität Paderborn
2. Disproportionation of SnO at ambient pressure
irradiated SnO at 131 °C & 0 GPa after 15 h
GasketSnOdecomposed SnO(shape of SR beam)
Sample environment
0.2 mm
H. Giefers, Universität Paderborn
25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 300 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 3000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 6000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 9000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 12000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 15000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 18000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 21000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 24000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 27000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 30000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 33000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 36000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 39000 s
Inte
nsity
Energy (keV)25 30 35 40 45 50 55 60 65
SnO T = 370 °C
t = 42000 s
Inte
nsity
Energy (keV)
2. Disproportionation of SnO at ambient pressure
We analysed the normalized diffractionline intensities of the 3 samples SnO, Sn2O3
and SnO2. Sn was liquid or showed no reproducibleline intensities.
We used the fluoreszence lines of Sn to normalize the bragg peaks. This is an advantage of EDXRD. A time resolution of 100 s was achieved.
H. Giefers, Universität Paderborn
0 5000 10000 15000 20000 25000 30000 350000.0
0.2
0.4
0.6
0.8
1.0
1.2
T = 297 °C
Yie
ld fr
actio
n
Time (s)0 10000 20000 30000 40000
0.0
0.2
0.4
0.6
0.8
1.0
1.2
T = 370 °C
SnO SnO
2
SnOx
Yie
ld fr
actio
n
Time (s)
2. Disproportionation of SnO at ambient pressure
At low T (< 250 °C) SnOdecomposes due to the synchrotron radiation(!) tonanocrystalline SnO2 and Sn.
No Sn2O3 is produced.
At high T (>370 °C) the reaction is dominated by thermal disproportionation.
Sn2O3 is produced.
H. Giefers, Universität Paderborn
2. Disproportionation of SnO at ambient pressure
5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
avramib.opj
= 0.2 .. 0.63 from SnO
2+Sn
2O
3
ln( t(s) )
in °C 434 434 425 416 407 388 370 333 296 268 241 186 131
5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 10.5 11.0-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
= 0.2 .. 0.63 from SnO
SnO
Avrami-Erofe'ev Plot
ln(-
ln(1
-))
ln( t(s) )
Sharp-Hancock plot of the reaction progress
H. Giefers, Universität Paderborn
„activation energy EA“ radiation induced range : 27(2) kJ/molthermal induced range: 225(32) kJ/mol
Arrhenius:k = A exp(-EA/RT)
2. Disproportionation of SnO at ambient pressure
0 50 100 150 200 250 300 350 400 450 5000.4
0.8
1.2
1.6
2.0
2.4
avramib.opj
A2 : Avrami-Erofe'evF0 : Reaktionskinetik 0. OrdnungF1 : Reaktionskinetik 1. Ordnung D2 : 2D Diffusion (Zylinder)D3 : 3D Diffusion (Kugel)
A2
F0
F1
D2D3
Avrami-Erofe'evSnO, SnO2, Sn2O3
ln(-ln(1-)) = C + m*ln(t)mit C = m*ln(k) = 0.2 .. 0.63
m
Temperature (°C)0.00016 0.00018 0.00020 0.00022 0.00024 0.00026
-12
-10
-8
-6
-4
avramib.opj
Disproportionation of SnO from SnO and Sn
2O
3 + SnO
2 radiation induced thermal induced
EA,r
= 25(7) kJ/molln(A
r) = -6.0(2)
EA,t
= 166(19) kJ/molln(A
t) = 21(3)
359 °C
1/RT (mol/J)
ln( k(
s-1)
)
450 400 350 300 250 200
Temperature (°C)
1E-5
1E-4
1E-3
0.01
k (s-1)
- up to ca. 275 °C the in situ reaction is radiation induced- above 370 °C the in situ reaction is mainly thermal induced
H. Giefers, Universität Paderborn
2. Disproportionation of SnO at ambient pressure
t = 180 s t = 615 s t = 825 s t =1020 s t =1220 s t =1425 s t =1620 s
- at beamline F3 it is possible to do angle dispersive XRD (ADXRD) - the CCD camera is from GeoForschungsZentrum Potsdam with a time resolution of 150 s per frame- one test measurement was carried out at ambient pressure in the HP cell
H. Giefers, Universität Paderborn
0 500 1000 1500 20000.0
0.2
0.4
0.6
0.8
1.0
SnO fromAldrich
time (s)
yie
ld fr
act
ion
0.0
0.2
0.4
0.6
0.8
1.0
kinetik.opj
SnO fromChemPur
yie
ld fr
actio
n
SnO SnO
2
2. Disproportionation of SnO at ambient pressure
ADXRD kinetic study on the disproportionation of SnOwith 2 different SnO samples in the HP cell at 434 °C
H. Giefers, Universität Paderborn
3. Disproportionation of SnO at high pressure
Reaction kinetics under pressure
- high pressure cell made of a Ti-alloy- temperatures up to 500 °C can be reached- temperature at sample position was calibrated by the melting points of Pb, Sn, Zn- diamond flats of 1 mm and 0.5 mm were used- pressures of 20 GPa were reached- NaCl or MgO for pressure determination (Au was alloyed with Sn) - lN2 as pressure transmitting medium
H. Giefers, Universität Paderborn
0 2000 40000.0
0.2
0.4
0.6
0.8
1.0
1.2p = 3.3 GPa T = 296 °C
Time (s)
Yie
ld f
ract
ion
SnO SnO
2
0 2000 4000
p = 5.8 GPa T = 296 °C
Time (s)
under pressure:- no nanocrystalline SnO2 and Sn at low T- no radiation induced disproportionation- no production of Sn2O3 under pressure due to the low crystallographic density
3. Disproportionation of SnO at high pressure
some examplesunder pressure
H. Giefers, Universität Paderborn
3. Disproportionation of SnO at high pressure
Sharp-Hancock plot of
tmkm
emtk
lnln1lnln
1
m: reaction exponentk: reaction rate: reaction progress
5 6 7 8 9 10 11-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0SnO
2
p(GPa) / T(°C) 2.4/232 3.1/241 4.8/241 5.4/241 5.8/241 8.0/241 8.0/241 4.9/269 2.3/296 3.3/296 3.3/296 4.9/296 5.8/296 5.8/296 6.4/296 11.0/296 14.8/296 3.0/324 3.6/324 2.2/370
ln(-
ln(1
-))
ln(t (s))
H. Giefers, Universität Paderborn
3. Disproportionation of SnO at high pressure
- the reaction kinetic changes strongly under pressure
- the reaction exponent m is very low at 3 GPa
- in the measured p,T range the reaction exponent m is T independent
reaction exponent m:diffusion m ≈ 0.5phase-boundary ≈ 1nucleation and growth ≈ 2
rad
iatio
nin
duc
ed
0 2 4 6 8 10 12 14 160 .0
0 .2
0 .4
0 .6
0 .8
1 .0
1 .2
1 .4
1 .6
1 .8 = 1 - exp (-( k·t ) m ) = 0 .2 .. 0 .63
425 °C 370 °C 324 °C 296 °C 269 °C 241 °C 232 °C
m
p (G P a)
H. Giefers, Universität Paderborn
The reaction rate k of the disproportionation of SnO depends onthe phase of metallic Sn (liquid, Sn-I, Sn-II).
3. Disproportionation of SnO at high pressure
0 2 4 6 8 10 12 14 16
-13
-12
-11
-10
-9
-8
-7
-6
-5 liqu id -S n
S n-II
S n -I
p (G P a)
ln(k
(s-1
))
425 °C 400 °C 370 °C 350 °C 324 °C 296 °C 269 °C 241 °C 232 °C open: ex s itu
1E -5
1E -4
1E -3
k(s
-1)
H. Giefers, Universität Paderborn
4. Summary
- EDXRD provides a tool to study reaction kinetics in situ even at high pressure
- results are: reaction rates k and reaction mechanism m (nucleation, growth…)
the existence of intermediate products or not (Sn2O3)
the formation of high pressure phases at lower pressure (here SnO2-fcc)
H. Giefers, Universität Paderborn
- Felix Porsch: EDXRD Messungen
- H.-D. Niggemeier: ex situ Proben
-Ulrich Ponkratz: ADXRD Messungen
5. Acknowledgement