Comparison of structure of alkali silicate glasses prepared by sol-gel and melt-quench methods

Abstract

Glasses of composition 15M 2 O-85SiO 2 , where M is Na or Li, were prepared by sol-gel and melt-quench methods. X-ray photoelectron spectroscopy and transmission electron microscopy were used to investigate their structure as the gels approach the glassy state. The fraction of non-bridging oxygens in gels approaches the value found in the melt-quench glass as the gel is heated to the glass transition temperature but does not always reach it. The chemical environment of the alkali species is more heterogeneous in the sol-gel glasses than in the melt-quench glasses. Thermodynamically favored phase separation is more easily achieved during the sol-gel process than in the melt-quench method of glass preparation.