Oxime-modified aluminium(III) alkoxides: Potential precursors for γ-alumina nano-powders and optically transparent alumina film

Abstract Reactions of aluminium(III) iso-propoxide with acetoxime in anhydrous benzene yielded complexes of the type [Al(OiPr)3-n{ONC(CH3)2}n], where n = 1, 2 or 3. These complexes were characterized by elemental analysis, FTIR and NMR (1H, 13C, 27Al) spectral studies. Spectral studies of these complexes suggest the presence of bi-dentate mode of the oximato moieties in the solution state. Soft transformations of aluminium(III) iso-propoxide and their oxime derivatives to pure alumina were carried out by the sol-gel technique. The powder XRD patterns of all the formed alumina suggest formation of cubic phase (γ-alumina) with average crystallites size of 7–30 nm. Optically transparent crack free alumina film was deposited on glass substrate using alumina sol, prepared by complex [Al(OiPr){ONC(CH3)2}], through dip coating method. The film sintered at 500 °C is amorphous in nature as indicated by XRD study. The alumina film is found to be ∼95% optically transparent in the visible region. The observed particle size distribution of alumina thin film in AFM images is found to be 13 ± 2 nm.