Thermoelectric Properties of In_xFeCo₃Sb₁₂ 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 In_xCo₄Sb₁₂. Polycrystalline samples were prepared with the nominal compositions of In_xFeCo₃Sb₁₂ (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 In_xFeCo₃Sb₁₂, 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.