Electron Paramagnetic Resonance in R₂O‐Al₂O₃−SiO₂ Glass Systems

Abstract

Systematic detection of an EPR signal was conducted for three alkali oxide‐Al2O3−SiO2 glass systems. Observed EPR spectra, having a main line with g=2.03 and a broad and anisotropic shape, are attributed to the unsaturated bridging oxygen bond resulting from the breakup of the SiO2 random network. This signal appears in the area AValkali atom ratio >1 for the Na20 and K2O systems, indicating that the collapse of the Al 4‐coordinated structure begins at an equimolar ratio when alumina is substituted for the alkali oxide, whereas somewhat different behavior was observed for the Li2O system.