Titanium Oxide Nanoparticles Precipitated from Low‐Temperature Aqueous Solutions: II. Thin‐Film Formation and Microstructure Developments

We explored effects of the degree of supersaturation, which depends on solution concentration, pH, and temperature, on the development of microstructures of the TiO 2 thin films deposited from the controlled hydrolysis of TiCl 4 aqueous solutions. It was shown that, with precursor (TiCl 4 ) solution of low degree of supersaturation, a porous flower‐like dendritic structure was synthesized, while a densely packed particulate nanostructure was obtained with that of high degree of supersaturation. The former morphology was attributed to the directional growth of TiO 2 crystals from the already‐deposited films, whereas the latter to the bulk precipitated TiO 2 nanoparticles nucleated in the solution, followed by their attachment and self organization. By establishing the processing–microstructure relations, this study provided a means of generating a wide spectrum of reproducible TiO 2 microstructures using the low‐temperature aqueous solution processing.