Influence of Perchloric Acid on the Crystalline phase of Nanosized Tio 2 Formed in Reverse Micelles

Nanosized titania have been produced by the controlled hydrolysis of tetrabutyl titanate (TBT) in sodium bis(2-ethylhexyl)sulfosuccinate (SBS) reverse micelles. Nanoparticles could be produced at relatively high TBT concentrations. These nanoparticles aggregated into sols, with colloid sizes of 40–60 nm, eventually forming gelatinous precipitates. The effect of perchloric acid added during hydrolysis on the crystallinity of the titania nanopowders was investigated. The HClO₄ enhanced the phase transformations of the titania powders from amorphous to anatase as well as anatase to rutile. Different titania phases were produced, depending on the [HCIO₄]/[TBT] ratio. Thus [HclO₄]/[TBT]=0.15 yielded anatase at 80°C, while [HClO₄]/[TBT]=0.20 produced 100% rutile at 100°C.