Laser Raman Spectroscopy of Crystals with the Structure of Sillenite

The experimental data of the past 10–15 years for the vibrational spectra of crystals with the structure of sillenite Bi12MxO20±δ obtained by the methods of laser Raman scattering and infrared (IR) absorption are generalized. Correlations between the chemical composition and crystal structure of the compounds (variations of the cation M) and their vibrational spectra are established. It is shown that the main contribution to formation of the high‐frequency part of the spectrum of two‐, three‐, and four‐phonon absorption is given by phonons related to vibrations of the [MO4]n- complexes. On the basis of the analysis of Raman spectra, the effective use of crystals with the structure of sillenite in acousto‐optics is justified.