A low thermal conductivity compound for thermoelectric applications: β-Zn/sub 4/Sb/sub 3/

Abstract

The potential of the semiconducting compound /spl beta/-Zn/sub 4/Sb/sub 3/ for thermoelectric energy conversion was investigated. The thermoelectric properties were measured on hot-pressed samples characterized by X-ray and microprobe analysis. All samples had p-type conductivity and the thermoelectric properties of the samples were measured between room temperature and 400/spl deg/C. Exceptionally low thermal conductivity values were measured and the room temperature lattice thermal conductivity was estimated at 7 mW cm/sup -1/ K/sup -1/. High figures of merit were obtained between 200 and 400/spl deg/C and a maximum dimensionless thermoelectric figure of merit ZT of about 1.3 was obtained at a temperature of 400/spl deg/C. The stability of the compound was investigated by thermogravimetric studies and showed that the samples were stable under Ar atmosphere up to about 400/spl deg/C and up to 250/spl deg/C in dynamic vacuum. The high thermoelectric performance of /spl beta/-Zn/sub 4/Sb/sub 3/ in the 200 to 400/spl deg/C temperature range fills the gap established in the ZT spectrum of p-type state-of-the-art thermoelectric materials between Bi/sub 2/Te/sub 3/-based alloys and PbTe-based alloys. This material, relatively inexpensive, could be used in more efficient thermoelectric generators for waste heat recovery and automobile industry applications, for example.