Study the effect of alloying on the phase transition behavior and thermoelectric properties of Ag2S

Phase transition will lead to abrupt change of thermoelectric material's properties, which will have a negative influence on the application of thermoelectric device. Therefore, avoiding the phase transition of Ag2S is particularly important for its heat collection applications. In this work, we reported, for the first time, that Cu-Se co-alloying in Ag2S can suppress phase transition and improve thermoelectric properties. Specifically, different elements and compounds alloying in Ag2S samples were prepared, and their influences on the phase change behavior and thermoelectric performance stability of Ag2S are systematically studied. It is found that the free enthalpy decreases and the heat absorption peak disappears for the Cu-Se co-alloyed Ag2S sample. In addition, the average lattice thermal conductivity is greatly reduced, and the κL of Ag1.8Cu0.2S0.5Se0.5 is around 0.27 Wm−1K−1 from 330 K to 450 K. Therefore, a high ZT is obtained for Cu-Se co-alloyed Ag2S. © 2021 Elsevier B.V.