Thermoelectric Properties of Mechanically-Alloyed and Hot-Pressed Cu12-xCoxSb4S13 Tetrahedrites

Co-doped Cu12-xCoxSb4S13 (0 x 1) tetrahedrites were prepared by mechanical alloying and hot pressing. X-ray diffraction analyses revealed that all specimens consisted of single-phase tetrahedrite without secondary phases and that the lattice constant increased with increasing Co content. The electrical conductivity decreased and the Seebeck coefficient increased with increasing Co content because of the reduction in the carrier (hole) concentration resulting from the substitution of Co at Cu sites. In addition, the thermal conductivity decreased as the Co content increased owing to a decrease in the electronic thermal conductivity. A dimensionless figure of merit (ZT)of 0. 94 was obtained at 723 K for Cu11.8Co0.2Sb4S13.