HETEROMETALLIC ALKOXIDES AND OXOALKOXIDES AS INTERMEDIATES IN CHEMICAL ROUTES TO MIXED-METAL OXIDES

Metal alkoxides are often associated with more accessible precursors such as carboxylates, nitrates, beta-diketonates in chemical routes to complex metal oxides. The molecular constitution of such solutions has been examined for systems related to ferroelectrics and based on niobium, titanium or zirconium alkoxides. A variety of oxo or non-oxo mixed-metal acetatoalkoxides have been characterized in the solid (X-ray on single crystals) as well as in solution (FT-IR, multinuclear NMR). Conversion from these molecules to the final material through hydrolysis-polycondensation has been estimated. The amorphous and crystalline powders have been characterized by thermogravimetric analysis and X-ray diffraction, respectively. Strategies for a control of the stoichiometry between the metals in the precursors are discussed. Homoleptic alkoxides Pb6Nb4O4(OEt)24 and BaTi4(OEt)18 were used as models for getting insight into chemical transformations.