Effect of cr-doping on luminescence of nanocrystalline anatase tio2 powders

Abstract

We have studied the photoluminescence (PL) of titanium dioxide nanocrystalline powders (TiO2) synthesized by the thermal hydrolysis in the form of anatase (A), whose surface has been modified by the adsorption of chromium ions (Cr3+). The samples are characterized by X-ray diffraction, X-ray fluorescence, and Raman spectroscopy. PL spectra were excited by a nitrogen UV laser. The Cr3+ ion doping in А/TiO2 leads to short-wave and long-wave shifts of the PL peaks due to the Burstein–Moss effect and due to the contribution of radiation “tails” of the electron density of states, respectively. The PL intensity of Cr3+-doped A/TiO2 at low concentration of Cr3+ (up to 0.5 at.%) increases in comparison with the undoped A/TiO2 due to the formation of additional centers of radiative recombination of carriers. With increasing the concentration of Cr3+ (∼1.0 at.%), the A/TiO2 PL intensity decreases due to the concentration quenching.