Phonon DOS of filled skutterudite, Ba/sub 0.1/CoSb/sub 3/

Phonon DOS of Ba-filled skutterudite, Ba/sub 0.1/CoSb/sub 3/, is observed at the energy resolution of 0.1meV(FWHM) by means of cold neutron incoherent scattering technique. 5meV shoulder and three new peaks appear at about 12, 15 and 18meV relative to the unfilled sample. Three peaks are interpreted as Einstein-type local excitation modes of Ba-atoms based on the all-electron first-principle band calculation. But the origin of the 5meV shoulder is not understood from present calculation. Structural relaxation of the filled skutterudite is performed during the calculation. The space symmetry of the relaxed lattice is consistent with the Pm-3-type and the cobalt and antimony positions appreciably shift by the barium introduction.