Thermoelectric properties, crystal and electronic structure of semiconducting RECuSe2 (RE=Pr, Sm, Gd, Dy and Er)

The ternary RECuSe2 phases have been prepared and structurally characterized. They adopt either a monoclinic structure (P21/c, z=4) for lighter rare earths (RE=Pr, Sm and Gd) or Cu-disordered trigonal structure for heavier rare-earths (P3¯m1, z=1, RE=Dy and Er). The resistivity and Seebeck coefficient measurements on GdCuSe2, DyCuSe2 and ErCuSe2 indicate that the studied phases are p-type semiconductors with relatively small activation energies (0.045–0.11eV). However, their electrical resistivities are too high (0.45–220Ωcm at room temperature) to make them competitive thermoelectric materials. Electronic structure calculations indicate presence of a band gap in the RECuSe2 phases.