Enhancement of thermoelectric properties of p-type single-filled skutterudites CexFeyCo4-ySb12 by tuning the Ce and Fe content

Abstract

CoSb3-based filled skutterudites are known as good n-type thermoelectric (TE) materials. However, the p-type ones have not been intensively investigated. In this study, we focus on Ce-filled Fe-substituted CoSb3 as p-type skutterudites, where Fe will act as a hole dopant. Polycrystalline samples with nominal compositions of CexFeyCo4-ySb12 (x = 0.8, 0.9, 1.0 and y = 3.0, 3.5) are synthesized and the high temperature TE properties are investigated. All the samples show the p-type conduction as we expected. It is found that the samples with y = 3.5 exhibit clearly lower κlat values than those of the samples with y = 3.0, meaning that the Fe/Co substitution is more predominant than the Ce filling for the κlat reduction. The maximum zT value observed in this study is 0.78 at 704 K for the sample with x = 1.0, y = 3.5, which is close to the best value reported so far for Ce-filled Fe-substituted CoSb3-based p-type skutterudites.