Brillouin Scattering in B2O3–Li2O–LiCl Glass

Abstract

Brillouin scattering measurement has been carried out in B2O3–Li2O–LiCl glass. The observed Brillouin frequency shift increases with the addition of a modifier element (both Li2O and LiCl). However, if the ratio of B2O3 to the modifier is a constant, Brillouin frequency shift decreases with increasing LiCl concentration. In order to obtain additional information on the local structure, Raman scattering and density measurements have been performed. Raman spectra have been observed as a distinct peak near 780 cm-1 which shows the formation of tetrahedrally coordinated boron. By increasing LiCl concentration, the Raman band near 780 cm-1 decreases, but the band near 806 cm-1 increases. This illustrates the breathing motion of oxygen in a boroxol ring. This result indicates that LiCl mainly modifies the B2O3 network without forming tetrahedrally coordinated boron. By comparing the glass transition temperature (Tg) obtained from the temperature dependence of the Brillouin frequency shift with that from the results of differential scanning calorimetry (DSC) measurement, it is observed that both the values of Tg almost agree. The concentration dependence of Tg is discussed in terms of viscosity.