Raman scattering of RB 6 (R=Ca, Ce, Pr, Gd, Dy and Yb)

Abstract

In Raman scattering spectra of RB 6, anomalous peaks have been found below 200 cm −1 for the R +3B 6, except for phonons and CEF excitations. Their peak intensities decrease with decreasing temperature, and this temperature dependence correlates with that of the mean square displacement of R. Furthermore, their energies decrease with the increase of the cage size of B. This new excitation can be attributed to a local vibration of the R ion, which can be regarded as “rattler” in the cage of B.