Phase transformation of nanostructured titanium dioxide from anatase-to-rutile via combined ultrasound assisted sol–gel technique

An effort was made to synthesize nanostructured TiO2 via sol–gel technique to obtain a 100% rutile polymorph of nanostructured TiO2. The sol–gel synthesis technique was suitably modified by incorporating ultrasound to study the effect of cavitation on the phase transformation, crystallite size, crystallinity and morphological (scanning electron microscopy) properties of the obtained nano-TiO2. It was observed that using ultrasound, yield of the nano-TiO2 was improved from 86.35% to 95.078%. The phase transformation of anatase-to-rutile of TiO2 was studied for both (ultrasound assisted and conventional) the processes. Complete phase transformation of the TiO2 was observed as expected with and without the use of ultrasound but the marked reduction in the required calcination temperature for obtaining 100% phase transformation with ultrasound was the major achievement in the present study, leading to 70% energy savings during calcination.