Thermoelectric properties of Ce_yFe_xCo_4-xSb₁₂ prepared by a solid state reaction

The filled skutterudite compounds, Ce_yFe_xCo_4-xSb₁₂(x = 0-1.0, y = 0-0.15), were prepared from powders of Co, Fe, Sb and CeCl₃·6H₂O by solid state reaction, and their thermoelectric properties were investigated. Ce_yFe_xCo_4-xSb₁₂(x = 0-1.0, y = 0-0.15) compounds showed p-type conductivity. Carrier concentration (p) increased with increasing substitution Fe for Co site, and decreased with increasing Ce content. Electrical conductivity (σ) increased with increasing Fe content. The seebeck coefficient (α) increased with increasing Fe content for CeFe_xCo_4-xSb₁₂, but decreased with increasing Fe content for Fe_xCo_4-xSb₁₂. Thermal conductivity (κ) decreased significantly with the substitution of Fe for Co and filling of Ce into Sb dodecahedron voids. The thermoelectric figure of merit was improved by the combination of Fe substitution and Ce filling. The maximum ZT value of 0.8 was obtained for Ce_0.12Fe_0.71Co_3.29Sb₁₂ at 750 K.