Multi-filling approach for the improvement of thermoelectric properties of skutterudites

Several skutterudite antimonides filled with atoms of different kinds, (Ba, M)/sub y/Co/sub 4/Sb/sub 12/ (M=Ce, La, Sr), have been synthesized by the combination of solid state reaction and melting methods. Thermal conductivity of (Ba,Sr)/sub y/Co/sub 4/Sb/sub 12/ samples shows a behavior similar to that of Ba/sub y/Co/sub 4/Sb/sub 12/. Adding a small amount of Ce or La to the Ba/sub y/Co/sub 4/Sb/sub 12/ system is effective in further reducing the lattice thermal conductivity. The difference in the ionic radii of the two co-filler atoms is the most sensitive factor for scattering of phonons. The multi-filled (Ba, M)/sub y/Co/sub 4/Sb/sub 12/ (M=Sr, Ce, La) show lower Seebeck coefficients as compared to the single-filled Ba/sub y/Co/sub 4/Sb/sub 12/ having the same total filling fraction. It is expected that higher thermoelectric performance could be realized by further optimization of the composition of filler species.