Formation of TiO/Al2O3/C composite in thermal co-decomposition of aluminium(III) acetylacetonate and titanium(IV) oxyacetylacetonate

Abstract

Thermal co-decomposition of Al(III) acetylacetonate-Ti(IV) oxyacetylacetonate mixture has been examined by using thermal gravimetry, differential scanning calorimetry and complementary analyses of evaporated products and solid residues by Fourier Transform Infrared, Raman and X-ray photoelectron spectroscopy, X-ray diffraction and scanning and transmission electron microscopy. The process is shown to differ from thermal decompositions of single acetylacetonates. Linear heating of the mixture allows predominant sublimation and minor degradation of Al(III) acetylacetonate along with extensive degradation of Ti(IV) oxyacetylacetonate to TiO2. Stepwise heating results in sublimation of one half of Al(III) acetylacetonate and co-decomposition of the residual chelates. The co-decomposition is judged to occur via an intermediary complex between both monomeric chelates. It primarily leads to an amorphous Ti, Al, C and O-containing phase which develops crystalline alumina and titanium monoxide upon annealing to high temperatures. The carbonaceous component of the amorphous phase assists in carbothermal formation and stabilization of titanium monoxide.