Thermoelectric materials: ternary penta telluride and selenide compounds

摘要

Ternary tellurium compounds and ternary selenium compounds may be used in fabricating thermoelectric devices with a thermoelectric figure of merit (ZT) of 1.5 or greater. Examples of such compounds include Tl₂SnTe₅, Tl₂GeTe₅, K₂SnTe₅ and Rb₂SnTe₅. These compounds have similar types of crystal lattice structures which include a first substructure with a (Sn, Ge) Te₅ composition and a second substructure with chains of selected cation atoms. The second substructure includes selected cation atoms which interact with selected anion atoms to maintain a desired separation between the chains of the first substructure. The cation atoms which maintain the desired separation between the chains occupy relatively large electropositive sites in the resulting crystal lattice structure which results in a relatively low value for the lattice component of thermal conductivity (&kgr;_g). The first substructure of anion chains indicates significant anisotropy in the thermoelectric characteristics of the resulting semiconductor materials.