Phase stability and thermoelectric properties of Cu10.5Zn1.5Sb4S13 tetrahedrite

Cu10.5Zn1.5Sb4S13 tetrahedrite compound was prepared by mechanical milling of Cu2S, ZnS and Sb2S3 powders and spark plasma sintered (SPS) to dense samples. The phase formation, chemical homogeneity, thermal stability of the compound and the thermoelectric properties of the sintered samples were evaluated. Single phase tetrahedrite with the crystallite size of 40 nm was obtained after 30 h of milling followed by annealing at 573 K for 6 h in an argon atmosphere. In-situ high-temperature X-ray diffraction studies revealed that the phase is stable up to 773 K. The Seebeck coefficient of the sintered samples of density >98% shows p-type behavior with maximum thermopower of 170 mu V/K at 573 K. The electrical resistivity (rho) decreases with temperature up to 475 K and then increases. A low thermal conductivity of 0.5 W/(m.K), in combination with moderate power factor gave a maximum ZT of similar to 0.038 at 573 K in Cu10.5Zn1.5Sb4S13 sample having a grain size of similar to 200 nm. (C) 2016 Elsevier B.V. All rights reserved.