RAMAN SPECTRAL STUDIES OF BORATE GLASSES

Raman spectroscopic measurements in borate glasses have been reviewed. The review shows that the technique is useful in identifying the structural groups present in the borate glasses on the basis of the Krogh-Moe hypothesis. Vitreous B2O3 and alkali borates are extensively studied and a satisfactory assignment of bands is possible by a careful consideration of the literature. A cation effect on the borate network is observed. Available measurements on binary borates other than alkali borates and on ternary borates are limited and more work is required to identify the structural modifications that take place with composition. Mixed alkali effect is reported only in lithium-caesium borate and shows the formation of non-bridging oxygens, destroying the six-membered rings when Li2O is replaced by Cs2O. Fast ionic glasses (alkali borates containing alkali halides) yield the same Raman spectra as the alkali borates, except when the alkali halide is a fluoride.