ZnO-Nanoparticle-Dispersed Cu11.5Ni0.5Sb4S13−δ Tetrahedrite Composites with Enhanced Thermoelectric Performance

Cu 12 Sb 4 S 13 tetrahedrite is an abundant natural that is also environmentally friendly. There have been efforts made to reach a unity of ZT value through optimizing the interdependence of electrical and thermal performance. In this study, we reported on ZnO nanoparticles-dispersed Cu 11.5 Ni 0.5 Sb 4 S 13− δ composites that were synthesized by the mechanical alloying and spark plasma sintering method. The structural characterizations were conducted via scanning electron microscopy, electronic probe microscopic analysis and transmission electron microscopy. The ZnO-nanoparticles were uniformly distributed in the Cu 12 Sb 4 S 13 grains. ZnO was used as a heterogeneous nucleation site to reveal the effectiveness of reducing thermal conductivity, likely derived from the strong low/mid-frequency phonon scattering. The lowest lattice thermal conductivity, 0.33 W m −1  K −1 , was obtained at 673 K in 0.5 vol.% of ZnO sample. A small quantity of ZnO addition led to a high ZT  ∼ 1.0 at 723 K, which increased by ∼ 42% in the pure-phased Cu 12 Sb 4 S 13− δ sample.