Cu 3 SbSe 3 , a compound with an ultralow thermal conductivity, has been predicted as a promising thermoelectric material, but relevant experimental results are inadequate. In this work we studied the high-temperature thermoelectric properties of this ternary chalcogenide. An extremely low thermal conductivity was observed and a glass-like behavior was seen above an order-disorder transition.Possible mechanisms causing such an ultralow thermal conductivity were discussed concerning the disorder of Cu atoms. With a large band gap of $0.95 eV obtained by an optical absorption edge measurement, Cu 3 SbSe 3 was found to be a nondegenerate p-type semiconductor, different from previous reports. A maximum zT of $0.25 was obtained at 650 K for Cu 3 SbSe 3 , which is much higher than the previously reported values, but this compound was considered inferior to Cu 3 SbSe 4 in its thermoelectric performance by comparing some key physical parameters.
ExperimentalStoichiometric Cu, Sb and Se raw powders were mixed and sealed into quartz tubes that were evacuated and slowly heated up to 1273 K, soaked for 12 h and then quenched in water,