Grain Size Dependence of the Thermoelectric Performance in Cu_2.98Co_0.02SbSe₄

Ternary Cu₃SbSe₄ thermoelectric material with a diamond-like structure exhibits good thermoelectric performance in the middle-temperature region. In this study, Cu_2.98Co_0.02SbSe₄ material with intrinsically low thermal conductivity was prepared by a melting–ball milling–hot pressing process. The maximum zT value for the Cu_2.98Co_0.02SbSe₄ sample was 0.7 at 650 K, which was about 190% higher than that of the pristine sample. The improvement in thermoelectric performance was ascribed to the realization of multi-scale features induced by ball milling. It was found that multiple scattering centers of phonons were formed via interfacial engineering, including dislocations, nano-holes and grain boundaries, which offers an applicable pathway for the reduction of lattice thermal conductivity. Graphical Abstract: [Figure not available: see fulltext.]