In-doped Pb_0.5Sn_0.5Te p-type samples prepared by powder metallurgical processing for thermoelectric applications

Lead tin telluride-based alloys are appropriate p-type materials for thermoelectric applications in the 50-600 °C temperature range. Optimization of the thermoelectric performance in different temperature ranges can be achieved by varying the composition (x values) in Pb_1-xSn_xTe alloys. An alternative approach for controlling the carrier concentration can be attained by indium doping the Pb_1-xSn_xTe alloys at a fixed composition. This second approach allows attaining a controlled energy gap and a specific lattice thermal conductivity. The present communication focuses on the development of Pb_0.5Sn_0.5Te alloys doped to different levels of indium concentration. The preparation techniques included preparation of master alloys with the desired composition, comminuting to appropriate powder particle size, cold compaction, sintering and annealing. The samples were examined by transport properties measurements. Thermoelectric figures of merit, Z, of ∼0.6-0.7×10^-3 K^-1 were obtained for Pb_0.5Sn_0.5Te samples doped to levels of 0.5, 0.1 and 0.03 at% indium for the ∼100-300, 300-400 and 400-500 °C temperature ranges, respectively.