Microstructural evolution of titania nanocrystallites by a hydrothermal treatment: A HRTEM study

Nanocrystalline anatase titanium dioxide films were formed by a hydrothermal treatment at temperatures below 100°C. The microstructural evolution of the crystallites was monitored by high-resolution transmission electron microscopy (HRTEM). HRTEM analysis of the as-grown film revealed the presence of nanocrystalline brookite TiO 2 within an amorphous matrix. After 90 min of the hydrothermal treatment, the TiO 2 nanoparticles remained of brookite form and a small increase in grain size was observed. Intergranular amorphous TiO 2 between the nanoparticles was observed in both as-grown and 90-min-treated films. However, after further 90 min of the treatment, TiO 2 nanoparticles were transformed into anatase phase with a rapid growth in grain size.