Raman spectra of double-filled skutterudites InxYbyCo4Sb12

The lattice dynamics of double-filled skutterudites InxYbyCo4Sb12 have been studied by means of Raman spectra as a function of the In and Yb filling ratios. We have studied the impact of void-filling process on the peak position and peak linewith. In particular, the relative height of the higher-energy Ag mode decreases gradually upon void-filling, which has been attributed to the “rattling” effects of the filling atoms in Sb icosahedrons. It is found that the double-filling process has produced more pronounced “rattling” effects than the single-filling process, accounting for more effective scattering of phonons and lower lattice thermal conductivity.