In situ synthesis and thermoelectric properties of (Fe/Ni)xCo4−xSb12 compounds by SPS

The skutterudite (Fe/Ni)xCo4−xSb12 (x = 0–1.0) compounds were prepared by spark plasma sintering (SPS) technique at 800–1000 K using Co, Sb, Fe and Ni powder as raw materials. The thermoelectric properties of (Fe/Ni)xCo4−xSb12 (x = 0–1.0) compounds are investigated systematically. The results indicate that the thermal conductivity and lattice thermal conductivity of p-type FexCo4−xSb12 compounds decrease with the increasing Fe filling fraction. The thermal conductivity of n-type NixCo4−xSb12 compounds reach the minimum value when the Ni filling fraction is 0.2, and the lattice thermal conductivity reduce evidently with the increasing Ni content. The electrical conductivity and carrier concentration of (Fe/Ni)xCo4−xSb12 compounds increase with the increasing Fe, Ni content, and the Seebeck coefficient decreases with the increasing Fe, Ni content. In contrast with Fe substitution, Ni filling shows a more positive effect on the optimization of thermoelectric properties of CoSb3-based skutterudite compounds. In this study, the obtained maximum ZT value reaches 0.6 for n-type Ni0.2Co3.8Sb12 at 800 K.