Grain size and compositional gradient dependence of thermoelectric performance for Cu3−xNixSbSe4 materials

The ternary Cu 3 SbSe 4 thermoelectric material with diamond-like structure exhibit good thermoelectric performance in the middle temperature region. In this study, the Cu 3− x Ni x SbSe 4 ( x  = 0–0.03) materials were fabricated by melting-ball milling-hot pressing process. The influences of grain size and compositional gradient on the microstructure and thermoelectric properties of Cu 3− x Ni x SbSe 4 were evaluated. It is found that the electrical conductivity of Cu 2.97 Ni 0.03 SbSe 4 was about 33% higher than that of Cu 3 SbSe 4 sample, and the lattice thermal conductivity was reduced from 3.3 Wm −1 K −1 to 2.4 Wm −1 K −1 at room temperature due to the grain refinement and more V Se defects. The maximum zT value for the Cu 2.97 Ni 0.03 SbSe 4 sample was 0.62 at 650 K.