Electron Poor Materials Research Group
RG
EPM
Updates of Experiments in
Augsburg
--- Crystallographic study of SiB3,
ZnSb…
--- Synthetic attempts for a-B
--- Property measurements of
(ZnSnSb2)1-x(InSb)2x
Charge Density Study by the Analysis of High
Resolution Diffraction Data
• Bruker AXS diffractometer with Imus
micro-focus X-Ray Source
• Ag-radiation, the same sinq/l at much
lower angle
• Enough data redundancy for good statistics
Multipole Refinement of ZnSb in Jana 2006
• Diffraction data were collected at 100K with 2q up
to 120o
• Extinction and anharmonicity were refined before
starting the multipole refinement
• d electrons of Zn were considered as valence
electrons
• Multipole refinment was stopped at 2nd order
(quadruple)
• R=1.38% and highest peak of 0.34 e/Å3
Total Density
Total Laplacian
+/- 8, 4 , 2 * 10^n and n
is +/- 3, 2, 1.
Dumbbell Rattling?
3
ZnSb
0.5
Zn4Sb3
2
1
0.5
4
C/T (mJ/molK )
0.1
0.05
3
4
C/T (mJ/molK )
0.2
3
0.02
0.2
0.1
0.05
0.01
85%
0.005
0.3
D
= 250.8 K
0.03
+ 15% T E = 59.6 K
0.02
85%
D
= 257 K
+ 15% T E = 57.6 K
0.01
0.002
50
100
150
T (K)
200
250
300
50
100
150
T (K)
200
250
Heat Capacity of ZnSb
ZnSb
Cal_ZnSb
50000
C/T_ZnSb
Cal C/T_ZnSb
500
400
2
Cp/T (mJ/molK )
Cp (mJ/molK)
40000
30000
20000
300
200
100
10000
0
0
0
50
100
150
T (K)
200
250
300
0
50
100
150
200
T (K)
250
300
350
Synthesis of b- SiB3 with high pressure
Si1-xGexB3
b
a
Si1: 84% Ge1: 16%
Si2: 90% Ge2: 10%
B
SiGe
Thermoelectric Chalcopyrite
(ZnSnSb2)1-x(InSb)2x + 4Sn
x = 0.9, x = 0.85, x=0.8 and InSb
(quenched from 1:1 melt and Snflux growth)
InSb Seebeck
400
Insb_Augsburg_heating_4p
InSb_Agusburg_cooling_4p
InSb_ASU_Sn Flux_2p
InSb_ASU_Quenched_2p
Thermopower (V/K)
300
200
100
0
-100
-200
0
50
100
150
200
T (K)
250
300
350
All Seebecks from Augsburg’s work
70
x=0.9_Augsburg_4p
x=0.85_Augsburg_2p
x=0.8_Augsburg_2p
60
Thermopower (V/K)
50
40
30
20
10
0
0
50
100
150
T (K)
200
250
300
All TCs from Augsburg’s work
Thermal Conductivity (W/mK)
4
3
2
x=0.85_Augsburg_2p
x=0.8_Augsburg_2p
x=0.9_Augsburg_4p
InSb_Sn Flux
1
0
0
50
100
150
T (K)
200
250
300
All Resistivities
x=0.9_Augsburg_2p
x=0,9_ASU_4p
x=0.85_Augsburg_2p
x=0.8_ASU_4p
x=0.8_Augsburg_2p
20
Resistivity (mcm)
15
10
5
0
0
50
100
150
T(K)
200
250
300
Acknowledgement
Dr. Wolfgang Scherer
Dr. Ernst-Wilhelm Scheidt
Dr. Georg Eickerling
Dr. Francisco J. Garcia-Garcia
Christoph Hauf
Andreas Fischer