Thermoelectric properties of Zn-In complex chalcogenides

Abstract

A ceramic compact of ZnIn/sub 2/S/sub 4/ with spinel structure and another polymorphism of ZnIn/sub 2/S/sub 4/ with a layer structure known as IIIa phase were synthesized by reaction-sintering of the mixed powder of ZnS and In/sub 2/S/sub 3/ at 450/spl deg/C and 800/spl deg/C under Ar (containing 1% H/sub 2/) atmosphere, respectively. Their thermoelectric properties were investigated in the temperature range from 200/spl deg/ to 600/spl deg/C. Power factor of IIIa type was much larger than that of the spinel type, although it was slightly lower than maximum power factor of the oxide homologous compounds ((ZnO)/sub m/In/sub 2/O/sub 3/). To increase the thermoelectric properties of ZnIn/sub 2/S/sub 4/ a c-plane oriented sintered body of IIIa phase was successfully fabricated by a usual ceramic process. The power factor in the direction perpendicular to c-axis was larger than that in the direction parallel to c-axis due to higher electrical conductivity in the former direction.