Effect of Aging Time on Crystalline Structure Evolution of TiO2 Nanoparticles

Abstract

It has been well realized that anatase TiO2 transforms to a more thermodynamically stable rutile phase by heat treatment at moderately high temperature, typically higher than 600 °C. However, by using suitable synthesis condition the anatast-to-rutitle phase transformation can occur at much lower temperature. In this present work, phase transformation during aging of TiO2 sol at room temperature was investigated. The sol was prepared based on hydrolysis and condensation of tetrabutyl orthotitanate precursor in the presence of small amount of water and hydrochloric acid. During aging time span of 50 days, the sol was sampled every 10 days for crystal structure and size analysis. It was found that aging time had a pronounced effect on anatase-to-rutile phase transformation accompanied by crystallite growth. Complete phase transformation was observed within 40 days of aging.