INVESTIGATION OF NEW CHEVREL PHASE COMPOUNDS FOR IMPROVED EFFICIENCY OF THERMOELECTRIC POWER GENERATION DEVICES

Abstract

In the search for improved high-temperature thermoelectric materials, we investigate new Chevrel phase materials that combine substitution of Ru on some of the Mo sites and the intercalation of various metals into the Chevrel structure. We expect these materials to have low thermal conductivities, due to their rattling structure type. Nominal compositions are (generally) chosen to add 4 valence electrons to the basic Chevrel unit Mo6Se8, and make the structure semiconducting. Two series of compounds were synthesized, (CuyMo6S e8)1-x(Mo4Ru2Se8)x, with y = 2, 4 and x = 0, 0.2, 0.4, 0.6, 0.8, and MxMo5RuSey, with M = Zn, Cd, Sn and Pb, x < 1, and y < 8. These generally differ from loading stoichiometry, and only a few were found to be intrinsic semiconductors. For the first series we report the synthesis and transport property measurements, and for the latter we present the synthesis and characterization of each compound. Since nearly all previous studies of Chevrel phase compounds have exclusively involved either substitution or intercalation, this research is an important addition to the study of Chevrel phase compounds.