Some Physical Properties and Boron Coordination Number of Glasses in the System CaO-Ga2O3-B2O3

Abstract

11B NMR spectra, density and refractive index were measured for the CaO-Ga2O3-B2O3 glasses and interpreted in term of the structure. Distribution of the fraction, NBO4, of boron atoms that are four-coordinated for the CaO-Ga2O3-B2O3 glasses showed roughly pattern as that for the CaO-Al2O3-B2O3 glasses. It was found that the CaO-Ga2O3-B2O3 glasses contain a considerable fraction of four-coordinated B3+ ions at the composition in which Ga2O3/CaO ratio is equal to unity, while the CaO-Al2O3-B2O3 glasses contain almost no four-coordinated B3+ ions at the same composition ratio, Al2O3/CaO=1. Ca3+ ions in this glass have a coordination number of four has been shown by NBO4 values and Raman study. Ga3+ ions takes the form of GaO4- groups with Ca2+ ion as a charge compensator and the form of GaO4 groups involving one tripod oxygen. © 1988, The Society of Materials Science, Japan. All rights reserved.