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 Ag 2 S is particularly important for its heat collection applications. In this work, we reported, for the first time, that Cu-Se co-alloying in Ag 2 S can suppress phase transition and improve thermoelectric properties. Specifically, different elements and compounds alloying in Ag 2 S samples were prepared, and their influences on the phase change behavior and thermoelectric performance stability of Ag 2 S are systematically studied. It is found that the free enthalpy decreases and the heat absorption peak disappears for the Cu-Se co-alloyed Ag 2 S sample. In addition, the average lattice thermal conductivity is greatly reduced, and the κ L of Ag 1.8 Cu 0.2 S 0.5 Se 0.5 is around 0.27 W m −1 K −1 from 330 K to 450 K. Therefore, a high ZT is obtained for Cu-Se co-alloyed Ag 2 S.