Electron Poor Materials Research Group

EPMRG

Updates of Experiments

--- Synthesis of B, SiB3, ZnSb…

--- Property measurements of

(ZnSnSb2)1-x(InSb)2x

Complex-Structured Materials and their Electron Densities

Group IV C, Si, Ge…

Group III + Group VBN, GaN, GaAs, InSb…

…

Less # of electrons per atom

Less

Pola

rity

NaTl, BaSi2, NaSi

Group III + Group IVSiB3…Group III

B…Group II + Group VZn-Sb…More Complex Group II + Group VI

ZnS, ZnTe, CdSe, CdTe…

NaCl, CaO, KBr

Experimental Preparation

• Boron (, boron)

• - SiB3

• ZnSb

• ZnSnSb2 + InSb (Solid Solution for TE study)4e-

3e-

Crystallization of BoronIn History… & Now…

Horn, F. H., et at, J. Electrochemical Soc., 106, 905 (1959)

Making Boron Crystals

• HP series samplePressurize the Pt-B mixture (45-

55) at 2GPa melted at 1500C then cooled to

1000C

• CSSS series sampleLoad the Pt-B mixture in the a

BN capsule w/t screw-on cap (right)

melted at 1500C then cooled to 1000C for compositions of 45:55 and 50:50

Boron Crystals

*Slack, G. A.; Hejna, C. I.; Garbauskas, M. F.; et al. Journal of Solid State Chemistry 1988, 76, 52-63.  

Amorphous Boron?

- SiB3, 3.25e/atom

Salvador, J. R.; Bilc, D.; Mahanti, S. D.; et al. Angewandte Chemie International Edition 2003, 42, 1929-1932.

Synthesis of - SiB3 with high pressure

- SiB3 with high pressure

Starting mixure: 72 mg of B-Si-Ge at 2:1:1

Pressure: 8GPa

Heating Program: Held at 1000C for 1h, cooled to 950C at 5C/h, held at 950C for 2h then quench.

Thermoelectric Chalcopyrite

(ZnSnSb2)1-x(InSb)2x + 4Sn

x = 0.9, x = 0.85, x=0.8 and InSb

Thermoelectric Chalcopyrite

0 50 100 150 200 250 300 350 400

-60

-50

-40

-30

-20

-10

0

10

20

30

40

50

60 x=0.8 x=0.85 x=0.9 InSb

Th

erm

al P

ow

er(V

/K)

T (K)

Thermoelectric Chalcopyrite

0 50 100 150 200 250 300 3500.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Th

erm

al C

on

du

ctiv

ity (

W/m

K)

T (K)

x=0.8 x=0.85 x=0.9 InSb

Thermoelectric ChalcopyriteResistivity of InSb

0.00 0.02 0.04 0.06 0.08 0.10-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Y A

xis

Titl

e

X Axis Title

0 50 100 150 200 250 300 350 400

0

2

4

6

8

10

12

14

Re

sist

ivity

(c

m)

T(K)

0 50 100 150 200 250 300 350

5

10

15

Re

sist

ivity

(mc

m)

T (K)

x=0.9 4 probe vdp x=0.9 4 probe in-line x=0.8 4 probe vdp x=0.8 4 probe in-line

Thermoelectric Chalcopyrite

Resistivity of (ZnSnSb2)1-x(InSb)2x