FT RAMAN SPECTROSCOPY OF SOME METAL HEXABORIDES

摘要

Fourier-transform Raman (FT) spectra of single-crystal LaB6 and SmB6 and of sintered EuB6-XCX (X approximate to 0.1) were measured at room temperature, For excitation a Nd:YAG laser with about 2 W irradiation power was used. The spectra exhibited many more details of the phonon densities of states than those obtained with conventional Raman spectroscopy by other authors. In particular two low-energy peaks were found at 104 and 204 cm(-1), which can he easily attributed to the acoustical and the lowest optical branches. The FT Raman spectra of LaB6 agree well with the phonon densities of states determined by other experimental methods and theoretical calculation, while for SmB6 a considerable softening of the optical modes is observed, which is probably due to nonlinear effects in consequence of the high excitation power used in the FT Raman spectrometer. (C) 1997 Academic Press. [References: 15]