メカニカルミリングおよびＳＰＳによる酸化物微細分散希土類充填スクッテルダイト複合焼結体の作製とその熱電特性

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.