Thermoelectric Measurements on Bi0.5Sb1.5Te3 Under Hydrostatic Pressure

The thermoelectric power alpha and the electric resistivity rho of Bi_0.5Sb_1.5Te₃ were measured under hydrostatic pressure. Alumel-chromel thermocouples (used for the temperature detection and current leads) and Pt voltage leads were spot-welded on the both ends of the long and narrow sample and a film heater was fixed on the one end for generating the temperature gradient. The wired sample was set into a piston-cylinder type pressure cell together with pressure-transmitting medium and then compressed up to 2.5 GPa. The thermoelectric power slightly decreases with increasing pressure. Otherwise the electrical resistivity is reduced by about 50% at 2.5 GPa compared with 0.5 GPa. Consequently, the power factor alpha ²/rho increases by a factor of about 1.5 at 2.5 GPa relative to 0.5 GPa. The results indicate that the thermoelectric figure of merit is possibly improved by application of hydrostatic pressure