Precursors for the combustion synthesis of metal oxides from the sol-gel processing of metal complexes

Sol-gel processing of methanol solutions of Cu(II) acetylacetonates was used for obtaining controlled polymerization of the complex molecules. The resulting sols were evaporated and the resulting precipitate was heated until a self-sustaining combustion reaction took place. The simultaneous presence of nitrate ions and the acetylacetonato ligands resulted in a sharp combustion process, characterized by low activation temperature and intense exothermic feature. The same processing was applied to other metals and other ligands, showing that the sol-gel processing of transition metal complexes can be a simple, convenient, flexible generalization of the citrate-nitrate method for preparing precursors for the combustion synthesis of oxide powders. Moreover, the controlled sol-gel processing of the metal complex can be used as a tool for controlling the precursor structure and. hence, the morphology of the final product. (c) 2006 Elsevier Ltd. All rights reserved.