Preparation of Glasses and Ceramics by the Sol-Gel Method

Abstract

In the sol-gel method, a homogeneous solution containing metal alkoxi des, other organic metal compounds or inorganic metal compounds is prepared. The solution is gelled by the hydrolysis and polycondensation of the compounds in the solution and the gel is converted to the aimed oxide glass or ceramics by heating it up to certain high temperatures. This method produces glasses and ceramics at much lower temperatures than the conventional method does, especially when the metal alkoxides are used as starting materials. In this review paper, the outline of the sol-gel method is presented at first. Then, the direct preparation of bulk bodies and fibers of silica will be described in detail, in which the shapes are formed as gel and then are converted to glass or ceramics without the change of shape.