Sol‐Gel Synthesis of Magnesium Oxide‐Silicon Dioxide Glass Compositions

Abstract

MgO‐SiO2 glasses containing up to 15 mol% MgO, which could not have been prepared by the conventional glass‐melting method because of the presence of stable liquid‐liquid immiscibility, have been synthesized by the sol‐gel technique. The gelling time decreased with increase in magnesium content, water: TEOS ratio, and reaction temperature. The gels were subjected to various thermal treatments and characterized using DTA, TGA, IR spectroscopy, XRD, and surfacearea‐ and port‐size‐distribution measurements. No organic groups could be detected in the glasses after heat treatments to ∼800°C, but trace amounts of hydroxyl groups were still present. The overall activation energy for gel formation in the 10MgO·90SiO2 (mol%) system for the water: TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.