TABLE OF CONTENTS Apart from the colloidal chemistry routes discussed in Chapters 1 to 3, the sol gel technique has been extensively used for the manufacturing of nanophased materials for the last three decades (Pathak, et al., 1997, Lessing, 1989 Anderton, et al., 1979). Among the physical and chemical methods devised for preparation of nanoscaled materials, synthesis from atomic or molecular precursors such as the sol-gel route can give better control of particle size and homogeneity in particle distribution.
The sol-gel processing, which is based on inorganic polymerization reactions, can loosely be defined as the preparation of inorganic oxides such as glasses and ceramics by wet chemical methods (Brinker, et al., 1988: Hench, et al., 1990). The goals of sol-gel processing in general are to control the composition homogeneity and the nanostructure during the earliest stages of productions. By controlling the chemical additives and processing, the products with nanostructured grains can be attained without vacuum conditions
This technique exhibits a number of advantages, such as the potentially higher purity and homogeneity and the lower processing temperatures, over both conventional ceramic processing and traditional glass melting, especially in preparing multicomponent systems. Many unique processing characteristics of the sol-gel route provide unique opportunities to make pure and well-controlled composition inorganic composited oxides (Armelao, et al., 1995b; Zhang, et al., 1990; Kuhn, et al., 1995; Kawamuura, et al., 1996; S nchez, et al., 1996; Choy, et al., 1995; Ding, et al., 1996; Ishikawa, et al., 1996; De, et al.,...
