Investigation of the Effect of Double-Filler Atoms on the Thermoelectric Properties of Ce-YbCo₄Sb₁₂

Skutterudite compounds have been studied as potential thermoelectric materials due to their high thermoelectric efficiency, which makes them attractive candidates for applications in thermoelectric power generation. In this study, the effects of double-filling on the thermoelectric properties of the Ce_xYb_0.2−xCo₄Sb₁₂ skutterudite material system were investigated through the process of melt spinning and spark plasma sintering (SPS). By replacing Yb with Ce, the carrier concentration was compensated for by the extra electron from Ce donors, leading to optimized electrical conductivity, Seebeck coefficient, and power factor of the Ce_xYb_0.2−xCo₄Sb₁₂ system. However, at high temperatures, the power factor showed a downturn due to bipolar conduction in the intrinsic conduction regime. The lattice thermal conductivity of the Ce_xYb_0.2−xCo₄Sb₁₂ skutterudite system was clearly suppressed in the range between 0.025 and 0.1 for Ce content, due to the introduction of the dual phonon scattering center from Ce and Yb fillers. The highest ZT value of 1.15 at 750 K was achieved for the Ce_0.05Yb_0.15Co₄Sb₁₂ sample. The thermoelectric properties could be further improved by controlling the secondary phase formation of CoSb₂ in this double-filled skutterudite system.