Thermoelectric performance of quaternary Cu–Bi–Sb–Te alloys prepared by cold pressing

Quaternary Cu–Bi–Sb–Te alloys with general formula of CuxBi0.5Sb1.5−xTe3 (x = 0–0.4) were prepared by cold pressing and their thermoelectric performance was evaluated. It was found that both the electrical and thermal properties were closely related with the mole fraction x, i.e. Cu concentration. Superior electrical properties were obtained when mole fraction x was controlled to be 0.05 and 0.1. Not only can higher Cu content deteriorate the Seebeck coefficients (when x = 0.4), but also the electrical conductivities (x ≥ 0.13), even though low thermal conductivities were obtained (x = 0.4). A measurement showed that the maximum figure of merit ZT, corresponding to the alloys (x = 0.05–0.1), is about 0.74, approximate 2.7 times that of state-of-the-art material Bi0.5Sb1.5Te3 at 442 K.