Structure and transport properties of (Bi1-xSbx)2Te3 thermoelectric materials prepared by mechanical alloying and pulse discharge sintering

Mechanical alloying followed by pulse discharge sintering (MA-PDS) has been employed to develop the bulk (Bi1-xSbx)(2)Te-3 thermoelectric materials with various Sb alloying contents. Substitutional solid solutions of (Bi1-xSbx)(2)Te-3 are formed in the whole Sb content range by MA-PDS process. The sintered compacts are dense and have refined microstructures. Systematic investigations on the electrical, thermal and thermoelectric properties reveal that the transport properties of the obtained (Bi1-xSbx)(2)Te-3 samples arc quite sensitive to the Sb alloying content. At room temperature, the samples with x < 0.57 exhibit n-type semi-conduction. However, at x > 0.57, the samples become p-type. The pure constituents of Bi2Te3 and Sb2Te3 as well as the Sb-poor. n-type samples exhibit the room-temperature figure of merit of the order of 1.0 x 10(-3) K-1. High values of figure of merit have been obtained in the Sb-rich, p-type samples. The maximum value of 3.35 x 10(-3) K-1 is attained at x = 0.80, which corresponds to the carrier concentration and Hall mobility of 1.95 x 10(19) cm(-3) and 207 cm(2)/Vs, respectively.