Dual-frequency resonant phonon scattering in BaxRyCo4Sb12 (R=La, Ce, and Sr)

Low temperature transport properties of polycrystalline dual-element-filled skutterudites BaxRyCo4Sb12 (R=La, Ce, and Sr) are reported. Remarkably the combination of Ba and La or Ba and Ce is much more effective in reducing lattice thermal conductivity (kappa(L)) than Ba and Sr. The density-functional theory calculations and experimental data suggest that multiple-filled skutterudites using filler elements of different chemical natures, such as the rare earths, the alkaline earths, or the alkalines provide a broader range of resonant phonon scattering. The thermoelectric figure of merit of filled skutterudites can likely be improved by means of such multiple-element void filling. (C) 2007 American Institute of Physics.