Evaluation of the f-electron rare-earth copper telluride GdCu1+xTe2 as a thermoelectric material

摘要

Abstract Chalcogenide compounds of composition ABX2 (with A, B, representing metal elements, X as the chalcogenide) have recently been attracting attention as thermoelectric materials. Possible magnetic enhancement of the thermoelectric properties has been proposed for electron-doped chalcopyrite CuFeS2 which exhibits large power factors at room temperature. Promising ZT values close to 1 have been reported for TmAgTe2 or YCuTe2 due to very low thermal conductivities ( 0.5Wm?1 K?1 at 800K) resulting from a disordered sublattice of Cu atoms. To further explore the possibilities of the ABX2 compounds, we study GdCu1+xTe2 which is a monoclinic layered compound that crystallizes in the C2/m space group, and has the f-electron Gd as a magnetic element, versus d-electron Fe in CuFeS2. Although the stoichiometric compound could not be stabilized, we report on the properties of this series of compounds sintered by spark plasma sintering (SPS). As for the other materials of ABX2 type, compositions with x 0.25 show very low thermal conductivities (0.64Wm?1 K?1 above 500K for x = 0.25), which, together wi