Spectroscopic study of group IV alkoxides as molecular precursors of metal oxides

Abstract

Numerous metal-organic compounds are used in soft chemistry [sol-gel, metal organic deposition (MOD), metal organic chemical vapour deposition (MOCVD)] in order to make inorganic oxide materials at low temperature and with a high level of purity suitable for high-tech devices. The main families are alkoxides and carboxylates. We focused our study on the synthesis and the analytical characterisation of new molecular precursors of titanium oxide for the sol-gel process. Among those compounds, halogenoalkoxides are very promising. They have a lower sensitivity towards hydrolysis than common alkoxides and so are easier to handle. Moreover, they exhibit very interesting properties during the final thermal treatment in which the organic compounds are eliminated and allow pure mineral phases to be obtained at low temperature. Hydrolysed titanium halogenoalkoxides (in which we changed the halide element) were studied using thermogravimetric analysis coupled to Fourier transform infrared spectroscopy allowing to perfectly determine the nature of the eliminated compounds. The quality of the mineral phases was characterised by Raman spectroscopy and energy-dispersive X-ray microanalysis showing that by using titanium halogenoalkoxides it is possible to obtain almost pure TiO2 in anatase form.