Design of molecular species for synthesis of advanced ceramic materials

Abstract

In view of their solubility in organic solvents, case of purification due to their volatility and facile hydrolysability, alkoxides of metals have bee gaining increasing importance as precursors for the preparation of oxide ceramic materials by the sol-gel process. Synthesis and characterization of a number of soluble volatile bi- and poly-metallic alkoxides in the author's laboratories have added a new facet to the chemistry of metal alkoxides as these provide unique examples of coordination species stabilised by bridging alkoxy bonds between different metals. Molecular design of extraordinary homogeneous advanced ceramics has become a distinct possibility by employing a prefabricated volatile heterometal alkoxide, with a composition suited to that of the targeted material as a precursor in the sol-gel process. Care is required in some cases to introduce less hydrolysable auxiliary ligands like β-diketones at the metal centres at which hydrolysis rates tend to faster. The high over-all purity, with sometimes desired limits of impurities, is a dominant factor in attaining the predicted functionality of a product and it is possible to control this factor using the metal al oxide route.