Synthesis of Rare Earth Filled Skutterudite Composite with Dispersed Oxide Particles by Mechanical Milling and SPS Techniques and Investigation of its Thermoelectric Properties

Abstract

We have tried to improve the performance of the thermoelectric properties of the skutterudite CoSb₃ by controlling the microscopic structure. The thermal conductivity of CoSb₃ is much reduced by the insertion of Ce into voids and the substitution for Co by Fe. We have also investigated the effect of mechanical milling on the thermoelectric properties of CeFe₃CoSb₁₂, The Seebeck coefficient of the milled CeFe₃CoSb₁₂ decreases, while the thermal conductivity of them increases, which is perhaps due to the precipitated impurity phases during mechanical milling. As a result, the dimensionless figure of merit, ZT, was reduced by mechanical milling. Next, we have prepared CeFe₃CoSb₁₂-MoO₂ or -WO₂ composites where MoO₂ or WO₂ particles are dispersed in the CeFe₃CoSb₁₂ matrix by mechanical milling. The electrical resistivity and thermal conductivity of the CeFe₃CoSb₁₂-MoO₂ composite whose mechanical milling time is 5h become smaller than those of CeFe₃CoSb₁₂. The composite whose molar ratio of CeFe₃CoSb₁₂ to MoO₂ is 0.95:0.05 shows a maximum ZT of 1.22 at 773K, which is larger than ZT of CeFe₃CoSb₁₂.