TiS₂-based Misfit Layer Sulfides as Novel Thermoelectric Materials

Abstract

We are now trying to improve the thermoelectric performance of TiS₂-based misfit layered sulfides, (BiS)_1.2(TiS₂)₂ by forming (Bi_1-xAE_xS)_1.2 (TiS₂)₂ and (BiS)_1.2 (AE_xTi_1-xS₂)₂, (AE=alkaline earth) in order to decrease the carrier concentration. The substitution did reduce the carrier concentration, so that the electrical conductivity also decreased. However, Seebeck coefficient decreased slightly due to the decrease in effective mass of carrier electrons. Moreover, the total thermal conductivity increased due to the formation of an ordered and a commensurate structure. However, it seems that the substitution in the phonon barrier layers (BiS) would be more effective than in the host layers (TiS₂).