Structural evolution of a porous type-VI sol-gel silica glass

Abstract

The structural evolution of type-VI porous sol-gel-derived optical glasses is described. The average pore radius of the glasses studied is 30 ,A, with an exceptionally narrow pore size distribution. These glasses are particularly suited to laser surface densification. Their properties make them also attractive as matrices for impregnation of second phases and as a substrate material for the production of fully dense optical lens elements and micro-optical devices. The properties of the matrices are reported for the as-dried state to densities approaching 2.2 g/cm 3, with thermal treatments from room temperature to 1060°C. The parameters of sintering for the gel-glass transformation are measured, and the phenomena occurring for three temperature ranges are evaluated. An activation energy of 65 + 9 kcal/mol for sintering with a structure factor n = 1.0 + 0.3 was found for the initial stage sintering of the material.