Zn-Sb alloys for thermoelectric power generation

Abstract

/spl beta/-Zn/sub 4/Sb/sub 3/ was identified as a new high performance p-type thermoelectric material (Caillat et al., 1996). A maximum dimensionless thermoelectric figure of merit ZT of about 1.3 was obtained on p-type /spl beta/-Zn/sub 4/Sb/sub 3/ samples at a temperature of about 400/spl deg/C. This is the highest figure of merit ever obtained at this temperature for a p-type thermoelectric material. The possibility of improving ZT values by forming Zn/sub 4-x/Cd/sub x/Sb/sub 3/ solid solutions was studied. Preliminary results obtained on alloys between Zn/sub 4/Sb/sub 3/ and Cd/sub 4/Sb/sub 3/ are presented and show that the lattice thermal conductivity can be reduced. As a result, a maximum ZT value of 1.4 at a temperature of about 250/spl deg/C was obtained for a sample with a composition Zn/sub 3.2/Cd/sub 0.8/Sb/sub 3/. Initial bonding and stability studies are presented and show that the integration of these materials into devices is possible. The efficiency of a thermoelectric generator using these new materials was calculated and the results show that significant improvements are possible compared to state-of-the-art thermoelectric materials. Some potential applications for these new thermoelectric materials are described.