Skinnerite Cu3SbS3: Solid-State Synthesis and Thermoelectric Properties

Abstract

Skinnerite Cu3SbS3, which consists of non-toxic and low-cost elements, is a potential thermoelectric material, however, studies on its thermoelectric properties are limited. In this study, the optimal conditions of mechanical alloying (MA) and hot pressing (HP) for the synthesis of the Cu3SbS3 phase were investigated, and its thermoelectric properties were evaluated. The MA powder had a theoretically predicted cubic skinnerite phase, which remained even after HP. Thermal analyses revealed that the MA powders and HP specimens exhibited large endothermic peaks at approximately 880 K, corresponding to the melting point of Cu3SbS3. Compacts with high relative densities above 99% without cracks and pores were obtained at an HP temperature of 623 K and above. The lattice constants of the MA powder and HP specimens were in the range of 1.0343–1.0394 nm. As the HP temperature increased, the electrical conductivities of the specimens decreased because of changes in their carrier concentrations; however, their Seebeck coefficients increased. As a result, the power factor values of all the specimens were in the range of 0.58–0.61 mW m−1 K−2 at 623 K. The thermal conductivities were lower than 0.78 Wm−1K−1. The maximum dimensionless figure of merit, <i>ZTmax</i> of 0.57 was obtained at 623 K when the skinnerite was prepared under the optimal solid-state synthesis conditions (HP at 673 K for 2 h using MA powder at 350 rpm for 18 h).