Heat treatment on TiO2 nanoparticles prepared by vapor-phase hydrolysis

TiO2 nanoparticles are prepared by vapor-phase hydrolysis of TiCl4 below 550°C and are characterized by TEM, XRD and XPS before and after heat treatment at various temperatures. It shows that anatase/amorphous particles start to transform to rutile at certain temperature. Such transformation temperature tends to decrease with the decrease of particle size. When the rutile phase starts to be formed, the particles grow rapidly, while they grow slowly before the appearance of rutile titania. The Ti2p3/2 binding energies tend to increase as particle sizes decrease, especially for particles below 50 nm in size.