Effects of Ce filling fraction and Fe content on the thermoelectric properties of Co-rich Ce_yFe_xCo_4−xSb₁₂

Single-phase filled skutterudite compounds, Ce_yFe_xCo_4−xSb₁₂ (x = 0 to 3.0, y = 0 to 0.74), were synthesized by a melting method. The effects of Fe content and Ce filling fraction on the thermoelectric properties of Ce_yFe_xCo_4−xSb₁₂ were investigated. The lattice thermal conductivity of Ce-saturated Ce_yFe_xCo_4−xSb₁₂, y being at the maximum corresponding to x, decreased with increasing Fe content (x) and reached its minimum at about x = 1.5. When x was 1.5, lattice thermal conductivity decreased with increasing Ce filling fraction till y = 0.3 and then began to increase after reaching the minimum at y = 0.3. Hole concentration and electrical conductivity of Ce_y Fe_1.5Co_2.5Sb₁₂ decreased with increasing Ce filling fraction. The Seebeck coefficient increased with increasing Ce filling fraction. The greatest dimensionless thermoelectric figure of merit T value of 1.1 was obtained at 750 K for the composition of Ce_0.28Fe_1.52Co_2.48Sb₁₂.