Sol-gel synthesis of monolithic silica gels and glasses from phase-separating tetraethoxysilane-water binary system

摘要

A facile synthetic route for monolithic silica gels and glasses from a phase-separating binary mixture of tetraalkoxysilane and water, free from alcohols, organic additives, or other third components, has been developed.rnBecause of their excellent transparency from the infrared to the deep-ultraviolet (DUV, <300 nm) spectral region and good radiation hardness, silica glasses are widely used as optical fibers for telecommunication, optical components for excimer laser photolithography, and DUV optical fibers. Compared with vapor phase methods, which are currently used to produce most silica glasses for optical applications, the sol-gel method has the major advantage that silica glasses can be prepared at relatively low temperatures, typically ～ 1000-1400 ℃, by consolidating silica gels without melting. The relatively low processing temperature is beneficial in suppressing devitrification and weight loss during sintering. However, cracking, which often occurs during drying and sintering of silica gels, has made it difficult to fabricate silica glass monoliths by the sol-gel method.