Effect of annealing on photoluminescent properties of titanium dioxide nanoparticles

The luminescent properties of titanium dioxide nanoparticles obtained by laser ablation have been determined. The position of the luminescence peaks is shown to depend on the excitation wavelength. The luminescence peaks are assigned to certain types of defects in the nanoparticles. The effect of annealing in the range 400°C–1000°C on the photoluminescent properties of TiO2 nanoparticles is studied. It is shown that annealing at 400°C leads to a decrease in only the oxygen vacancy defects, while annealing above 600°C also leads to recombination of titanium vacancy and interstitial titanium defects. It has been established that the trapping centers coincide for luminescence peaks 445, 511, and 698 nm, while the trapping center for the 1100 nm peak lies 70 meV lower.