Thermoelectric properties of Bi_1-PbCu_1-SeO oxyselenides

In this work, Bi_1-PbCu_1- SeO (x = 0, 0.02, 0.06, and 0.08) compounds were synthesized by a solid state reaction followed by spark plasma sintering. The effect of simultaneous Bi to Pb substitution and Cu vacancy introduction on thermoelectric properties was investigated systematically. The power factor was significantly enhanced, contributing to the increase in the zT value. As a result, the zT_max of 0.75 at 773 K was obtained for the Bi_0.94Pb_0.06Cu_0.94SeO sample. To reveal the factors constraining the zT_max of Bi_1-PbCuSeO-based oxyselenides, a further careful analysis of literature data was performed. We highlighted that for Pb-doped oxyselenides, the power factor is almost independent of the synthesis technique, while the lattice thermal conductivity is the main property determining zT_max and is highly affected by the synthesis method.