Roughness and fractality of nanostructured TiO2 films prepared via sol-gel technique

Titanium dioxide nanocrystalline thin films were prepared by applying the sol-gel dipping technique using two different titanium (IV) alkoxides: titanium isopropoxide and titanium butoxide. Morphological, structural characterization and examination of the fractal properties were performed by atomic force microscopy (AFM). The effect of the nature of the precursor on the hydrolysis rate and the resulting particle size distribution, roughness, and surface complexity of the TiO₂ films was investigated. Titanium isopropoxide presents higher hydrolysis rates leading to more rough and complex characteristics whereas titanium butoxide films show a relatively smoother surface. Higher fractal dimension values and lower roughness were observed for titania films derived from titanium butoxide. In both cases the obtained films present a complex granular surface network of interconnected particles, suitable for practical applications.