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

Abstract

We explored effects of the degree of supersaturation, which depends on solution concentration, pH, and temperature, on the development of microstructures of the TiO2 thin films deposited from the controlled hydrolysis of TiCl4 aqueous solutions. It was shown that, with precursor (TiCl4) 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 TiO2 crystals from the already‐deposited films, whereas the latter to the bulk precipitated TiO2 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 TiO2 microstructures using the low‐temperature aqueous solution processing.