Effect of processing parameters on thermoelectric properties of p-type (Bi2Te3)0.25(Sb2Te3)0.75 prepared via BMA–HP method

Starting from elemental granules of Bi, Sb, and Te, p-type (Bi2Te3)0.25(Sb2Te3)0.75 thermoelectric materials was prepared via bulk mechanical alloying (BMA) plus subsequent hot pressing (HP) method in this paper. (Bi2Te3)0.25(Sb2Te3)0.75 solid solution phase appeared after 200 cycles’ BMA, and alloying proceeded with increasing BMA cycles. The figures of merit (Z) of the as hot pressed samples increased with BMA cycles’ increasing and leveled off after 800 cycles. Increasing the hot pressing temperature from 260 to 420°C, electrical and thermal conductivity increased; relative densities, figures of merit of the as HPed samples also increased. The maximum figure of merit is obtained as 2.99×10−3 K−1 with the processing parameter of 800 cycle BMA and hot pressing at 420°C, 1.2 GPa for 1 h. Further prolonging BMA cycles and increasing hot pressing temperature, no evident improvement to thermoelectric properties was resulted in.