Effect of particle size and dopant concentration on the Raman and the photoluminescence spectra of TiO2:Eu3+ nanophosphor thin films

Eu doped TiO2 nanocrystalline films have been deposited by sol-gel spin coating technique on the glass substrate using titanium (IV) propoxide as a precursor. The obtained films were characterized by X-ray diffractometer (XRD), TEM, EDX, UV-Vis spectrophotometer, Raman spectrometer, and fluorescence spectrometer. As revealed by XRD, and TEM, all the TiO2 films were a single anatase phase with nanocrystallite structures and hinder the crystal growth with the Eu-doping concentration in deposited films. The images of TEM showed that all the particles have spherical in shape with an average diameter ranging from 6 to 12 nm. The TiO2: Eu3+ coatings have higher values of energy gap compared to pure Titania. The Raman spectra shows the characteristic modes of anatase TiO2 and intensity of modes reduced with an increase of Eu doping concentration. An occurrence of Raman blue shifts was due to reduction of particle size. At 393 nm excitation, the Eu doped TiO2 nanophosphor thin films showed typical PL emission D-5(0)-> F-7(J) (J = 0, 1, 2, 3, 4, 5) transitions of Eu3+ ions in the visible spectra. The more effective photoluminescence emission was observed for the 7 at. % Eu-doped TiO2 nanoparticles. The experimental decay times of the D-5(0) level through D-5(0)-> F-7(2) transition obtained by exciting at 393 nm. The electron-phonon coupling strength (g) of the PSB was estimated from the excitation spectra. Judd-Ofelt (JO) intensity parameters, radiative possessions were estimated from the emission spectra. The photocatalytic activity (PCA) of Eu-doped TiO2 nanoparticles showed that the strong photocatalytic activity response, decrease the efficiency of degradation of methyl blue (MB) under visible light irradiation with an increase in the amount of Eu-doping. In addition, the photocatalytic performances of all Eu doped TiO2 nanocrystalline films were found to be better than that of pure TiO2 thin film.