Synthesis and Thermoelectric Characterization of Sb-Doped Cu2Se by Mechanical Alloying and Solid-State Reaction

In this study, Sb-doped Cu2Se1−xSbx (x = 0, 0.005, 0.01, 0.015, 0.02, and 0.025) compounds were synthesized using mechanical alloying combined with a solid-state reaction technique. The crystal structure of the Sb-doped samples was a mixture phase between α-Cu2−δSe and β-Cu2−δSe, and a minor phase of Cu3Se2, Cu2O, and excess Sb in high-doping-level samples. The electrical properties of Sb-doped samples were improved when compared to the undoped sample by the enhancement of carrier concentration via the creation of an acceptor level after Sb doping. The thermal conductivity decreased with increasing x and reached the lowest value in the Cu2Se0.98Sb0.02 sample. As a result, the sample with an Sb-doped level of 0.02 showed the highest ZT value of 1.22 at 823 K.