Thermoelelctric properties of nanostructured skutterudite-related compounds

Nanostructuring is one of the effective approaches to lower the thermal conductivity of materials. Nanostructured skutterudite-related compounds CoSb₃, Fe_0.5Ni_0.5Sb₃, Fe_0.25Ni_0.25Co_0.5Sb₃ and Te-doped CoSb₃ were synthesized by a solvothermal route. The bulk materials were prepared by hot pressing or spark plasma sintering from the solvothermally synthesized nanopowders. The thermal conductivity values of the materials are decreased, which is mainly contributed to the small grain sizes and the high porosity. A thermoelectric figure of merit of 0.61 has been obtained for CoSb₃, which is notably high for the unfilled skutterudites. Filled skutterudites La_0.3Co₄Sb₁₂ and La_0.3FeCo₃Sb₁₂ were also synthesized by solvothermally process followed by annealing under hydrogen atmosphere. The thermoelectric properties are presented and discussed.