A Raman spectroscopic study of glasses in the system CaO-MgO-SiO 2

Abstract

The Raman spectra of a number of glasses in the system CaO-MgO-SiO2 have been prepared using solar furnace techniques. The spectra of glasses along the SiO2-CaO ' SiO2-MgO and SiOz-Cao sMgo sO joins are similar to those obtained in other studies, and are interpreted in terms of vibrations of tetrahedral silicate units with zero, one, two, three and four non-bridging oxygens, consistent with previous discussions. Some glasses were prepared with bulk compositions within the CaO-MgO-SiO2 two-liquid field, using both a "normal " and afast quench rate. The normal-quenched glasses were opaque and unmixed, the fast-quenched samples transparent and homogeneous. Both sets of samples had identical spectra, and the implications of this are discussed. Finally, a number of samples with varying CalMg ratio at constant high silica content were studied. Their Raman spectra are discussed along with results ofprevious studies on alkali and alkaline earth silicate glass systems to develop a molecular site model which describes the effect of changing metal cation on the distribution of silicate species.