Enhancing the thermoelectric properties of bismuth antimony tellurides containing excess Te with respect to sintering temperature

Bi–Te-based thermoelectric materials with excellent room-temperature properties are difficult to commercialise because of their low dimensionless figure of merit ( ZT). In this study, a powder was synthesised by adding an excess amount of Te to improve its thermoelectric performance at room temperature. The synthesised powder was sintered using spark plasma sintering at various temperatures to examine the effect of temperature-dependent behaviour of Te on the electrical resistivity and Seebeck coefficient. The excess Te-containing powder exhibited excellent electrical conductivity and Seebeck coefficient at high temperatures, and the thermal conductivity was significantly reduced. Bi0.4Sb1.6Te3+ x ( x = 2) showed a maximum room-temperature ZT of 1.57 at a sintering temperature of 450°C.