Preparation of Single-Phase Pb-Filled Chevrel-Phase Sulfide and Its Thermoelectric Properties

Abstract

Pb-filled Chevrel-phase sulfides PbMo₆S_8−y were prepared from PbS, Mo, and MoS₂. The single phase was formed in the nominal composition PbMo₆S_7.8 (8−y=7.8). While the secondary PbS and Mo phases were formed in sulfur-poor compositions, the secondary MoS₂ phase was formed in sulfur-rich compositions. The sintered sample had a positive Seebeck coefficient. The Seebeck coefficient and electrical resistivity increased with temperature. Furthermore, the thermal conductivity was dominated by the electronic thermal conductivity, and the complex crystal structure yielded a low lattice thermal conductivity. The thermoelectric figure of merit ZT increased with temperature, reaching a value of 0.08 at 850 K.