Influence of particle size on the phonon confinement of TiO2 nanoparticles

Titanium dioxide nanocrystals are prepared by a hydrolysis process of Titanium tetraisopropoxide. Nano crystals of various sizes are obtained after annealing from 300 to 450 degrees C. Raman scattering was employed to investigate the evolution of the anatase phase in the nano crystals during annealing. X-ray diffraction, transmission electron microscopy and dynamic light scattering studies were done to supplement the Raman scattering results on particle size. Phonon confinement and non-stoichiometry effects are responsible for the blue shift and broadening of the lowest-frequency E-g Raman mode.