Sol-gel process of making gradient-index glass

Abstract

The present invention relates to a process for making glass by a sol-gel process. The process is initiated by forming a mixture of silicon alkoxide and an alcohol in a solution sufficiently acidic to partially hydrolyze the silicon alkoxide. An index modifying metal alkoxide selected from the group consisting of alkoxides of titanium and zirconium is then added to the mixture. Water is next added to convert the metal alkoxides to a network of corresponding metal oxides suitable for gelation. The mixture containing the network of metal oxides is then contained for sufficient time to form a gel. The gel is acid leached for enough time to remove some of the index modifying metal oxide. To prevent further removal of index modifying metal oxide from the gel, the gel is fixed. The fixed gel is then rinsed with a solvent to remove precipitates from the gel, dried, and sintered into a transparent gradient-index glass. In another aspect of the present invention, the fixing agent can be acetone or a mixture of water and acetone.