Raman scattering by glassy lithium tetrabotate activated with Tb$_{2}$O$_{3}$

Raman spectra of glassy lithium tetraborate activated with terbium oxide of various concentrations were investigated. Most of the observed structure in the Raman spectra of the Li$_{2}$В$_{4}$О$_{7}$: Tb$_{2}$О$_{3}$ glass is due to mixed vibrations of complex boron- and terbium-oxygen complexes which are typical to a superposition of tetragonal Li$_{2}$В$_{4}$О$_{7}$ and cubic Tb$_{2}$O$_{3}$ structures.