THE SYNTHESIS OF TiO_2 NANOPARTICLES BY WET-CHEMICAL METHOD AND THEIR PHOTOLUMINESCENCE, THERMAL AND VIBRATIONAL CHARACTERIZATIONS: EFFECT OF GROWTH CONDITION

摘要

Low temperature calcination methods have been developed to obtain anatase TiO_2 nanocrystals using three different synthesis routes. The DSC thermograms have been used to set the annealing temperature. Various size of TiO_2 nanocrystals ranging from 8 nm to 16.5 nm have been used to synthesize by setting up the annealing temperature and time. The X-ray diffraction (XRD) and Raman spectrum have been used to identify and confirm the anatase crystal structure having long range ordering. The photoluminescence (PL) spectra have been recorded as a function of particle size and excitation power, which is attributed to the defects inside the grain that can migrate into the grain surface region during annealing. In a typical TiO_2 nanocrystals (sample TN12), luminescence efficiency increases with the decrease in size due to e~-/h~+ recombination process.