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

Abstract

Pb-filled Chevrel-phase sulfides PbMo 6 S 8Ày were prepared from PbS, Mo, and MoS 2 . The single phase was formed in the nominal composition PbMo 6 S 7:8 (8 À y ¼ 7:8). While the secondary PbS and Mo phases were formed in sulfur-poor compositions, the secondary MoS 2 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.

Towards the prediction of the transport properties of cluster-based molybdenum chalcogenides

“…Since the end of the 90s, the Chevrel phases of general formula MxMo6Q8 (M = transition metal or rare-earth metal, x = 0-4, and Q = S, Se, or Te) have been investigated for their thermoelectric properties. [1][2][3][4][5][6][7] These compounds based on face-capped octahedral Mo6Q8 units were considered as promising candidates for electrical power generation because of their ability to accommodate metal cations that can cause effective phonon scattering, thus reducing significantly their lattice thermal conductivity. 8 Indeed, the amount x of metal cations modifies the electron count that governs the electrical properties of these materials.…”