Electron Poor Materials Research Group

EPMRG

Updates of Experiments in Augsburg

--- Crystallographic study of SiB3, ZnSb…

--- Synthetic attempts for 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 sinat much lower angle

• Enough data redundancy for good statistics

Multipole Refinement of ZnSb in Jana 2006

• Diffraction data were collected at 100K with 2 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

e 3 = 0 . 0 0 0

- 4 . 0- 2 . 00 . 02 . 04 . 0e 1- 4 . 0

- 2 . 0

0 . 0

2 . 0

4 . 0

e 2

Total Density

Total Laplaciane 3 = 0 . 0 0 0

- 3 . 0- 1 . 01 . 03 . 05 . 0e 1- 4 . 0

- 2 . 0

0 . 0

2 . 0

4 . 0

e 2

+/- 8, 4 , 2 * 10^n and n is +/- 3, 2, 1.

Dumbbell Rattling?

50 100 150 200 250 300

T (K)

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

C/T

3 (mJ/m

olK

4 )

ZnS b

50 100 150 200 250

T (K)

0.01

0.02

0.03

0.05

0.1

0.2

0.3

0.5

1

2

3

C/T

3 (mJ/m

olK

4 )

Zn4S b3

85% D = 250.8 K

+ 15% T E = 59.6 K 85% D = 257 K

+ 15% T E = 57.6 K

Heat Capacity of ZnSb

0 50 100 150 200 250 300 3500

100

200

300

400

500

Cp/

T (

mJ/

mol

K2)

T (K)

C/T_ZnSb Cal C/T_ZnSb

0 50 100 150 200 250 3000

10000

20000

30000

40000

50000

Cp

(m

J/m

olK

)

T (K)

ZnSb Cal_ZnSb

Synthesis of - SiB3 with high pressure

a

b

BSiGe

Si1-xGexB3

Si2: 90% Ge2: 10%

Si1: 84% Ge1: 16%Si1: 84% Ge1: 16%Si1: 84% Ge1: 16%

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 Sn-flux growth)

0 50 100 150 200 250 300 350

-200

-100

0

100

200

300

400

Th

erm

op

ow

er

(V

/K)

T (K)

Insb_Augsburg_heating_4p InSb_Agusburg_cooling_4p InSb_ASU_Sn Flux_2p InSb_ASU_Quenched_2p

InSb Seebeck

All Seebecks from Augsburg’s work

0 50 100 150 200 250 300

0

10

20

30

40

50

60

70

The

rmop

ower

(V

/K)

T (K)

x=0.9_Augsburg_4p x=0.85_Augsburg_2p x=0.8_Augsburg_2p

All TCs from Augsburg’s work

0 50 100 150 200 250 3000

1

2

3

4

Th

erm

al C

ondu

ctiv

ity (

W/m

K)

T (K)

x=0.85_Augsburg_2p x=0.8_Augsburg_2p x=0.9_Augsburg_4p

InSb_Sn Flux

All Resistivities

0 50 100 150 200 250 3000

5

10

15

20

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

Re

sist

ivity

(mc

m)

T(K)

Acknowledgement

Dr. Wolfgang Scherer Dr. Ernst-Wilhelm Scheidt

Dr. Georg Eickerling Dr. Francisco J. Garcia-Garcia

Christoph Hauf Andreas Fischer