Thermoelectric Properties of Mineral Tetrahedrites Cu10Tr2Sb4S13 with Low Thermal Conductivity

We have investigated thermoelectric properties of synthesized mineral Cu10Tr2Sb4S13 (Tr = Mn, Fe, Co, Ni, Cu, and Zn) tetrahedrites, which have a cubic and complex crystal structure. The mother phase Tr = Cu shows metal-semiconductor transition and anomalous hysteresis. Through various Tr substitutions, the thermopower was increased and thermal conductivity was decreased. Results show that Tr = Ni had the largest dimensionless figure of merit ZT of 0.15 at 340 K. The main advantage for the large ZT is the quite low lattice thermal conductivity. Because of the large ZT and the environmentally friendly components, tetrahedrites are anticipated as a good thermoelectric material. (c) 2012 The Japan Society of Applied Physics