Thermoelectric properties of InxFeCo3Sb12 consisting mainly of in-filled p-type skutterudites

Abstract

Indium (In)-filled CoSb3 skutterudite is known as a good n-type thermoelectric (TE) material. Its p-type samples have not been intensively studied. In this study, we tried to reduce the electron concentration of (In)-filled CoSb3 by substitute Fe atoms for 1/4 of Co atoms in InxCo4Sb12. Polycrystalline samples were prepared with the nominal compositions of InxFeCo3Sb12 (x = 0.3, 0.5, 0.7, and 0.9) and their constituent phases, microstructure, high-temperature TE properties were carefully investigated. All the samples showed positive sign of Seebeck coefficient as we expected from the nominal compositions. The filling fraction of In in InxFeCo3Sb12, was revealed to extend to the value of x = 0.43. The largest dimensionless figure of merit zT = 0.39 was observed at 705 K for the sample prepared at x = 0.5.