Vibrational spectra of simple silicate glasses

Abstract

An attempt has been made to describe the vibrational spectrum of a vitreous material in terms of a simple model based on the unit cell of the crystal. The model has been adapted to include broad distributions of intertetrahedral angles and configurations which are salient features of the structures of silicate glasses. Normal coordinate calculations of the spectra of models representing vitreous chain silicates and vitreous silica have been performed. The results show that some detailed structural information is accessible using this approach and it has been possible to provide explanations for the shape of the infra-red spectrum of vitreous silica and sodium metasilicate at high frequencies and to offer a reason for the low-frequency Raman continuum and excess infra-red absorption which are features of the spectra of all silicate glasses.