Synthesis and thermoelectric properties of filled skutterudite compounds Ce_yFe_xCo_4-xSb₁₂ by solid state reaction

Filled skutterudite compounds, Ce_yFe_xCo_4-xSb₁₂(x = 0-1.0, y = 0-0.15), were synthesized by solid state reaction using Co, Fe, Sb and CeCl₃ · nH₂O powders as source materials. The lattice constants of Ce_yFe_xCo_4-xSb₁₂ increased with increasing substitution of Fe at Co sites and with increasing Ce filling fraction in the Sb-icosahedron voids. All specimens showed p-type conduction. Carrier concentration (p) and electrical conductivity (σ) increased with increasing substitution of Fe at Co sites and decreased with increasing Ce filling fraction. The Seebeck coefficient (α) decreased with increasing Fe content and increased with increasing Ce filling fraction. Thermal conductivity (κ) decreased with increasing substitution of Fe at Co sites and with increasing Ce filling fraction. A maximum ZT value of 0.8 was obtained for Ce_0.12Fe_0.71Co_3.29Sb₁₂ at 750 K.