Raman-scattering spectra of Ge-filled and Sn-filled CoSb_(3) were studied as a function of polarization. Polarized Raman-scattering spectra of CoSb_(3) were used to help distinguish the symmetry of each vibrational mode observed in the filled skutterudite specimens. Seven out of the eight Raman-active Sb vibrational modes of CoSb_(3) and the Ge-filled skutterudites were identified for each specimen. We also compare our experimental assignments with theoretical calculations for CoSb_(3). The Sn atoms "rattle" inside the voids of the crystal structure and interact strongly with the lattice vibrations to shift and broaden the Sb-vibrational modes as compared to the spectra of CoSb_(3). The smaller and lighter Ge atoms however do not have such an effect on the lattice vibrations, indicating that the interaction of Ge with the lattice is relatively weak in comparison.
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