Spectroscopy of nanocrystalline TiO2:Eu3+ phosphors

High-resolution spectroscopy was used to analyze narrow-dispersed nanocrystalline (1 − x/2)TiO2:(x/2)Eu2O3 phosphors. Nanoparticles have been synthesized by reverse micelles and solvothermal synthetic method in toluene solutions. Different concentrations of europium nitrate pentahydrate (0.2, 1.0, 2.0, 5.0, 10.0, 15.0, 20.0, and 25.0 mole%) were dissolved in water and nanocrystalline particles with average size of <10 nm were synthesized. The nanocomposites were composed nominally of TiO2 shell with locally concentrated Eu2O3 cores. The crystalline phase, microstructure, and luminescent spectra of the nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and luminescent spectrometer, respectively. The radiation was dominated by the red emission peak at 614 nm and the shape of emission spectra was independent of excitation wavelength, Eu concentration and temperature. The lifetime of the emission at 614 nm was the function of temperature and the photoluminescence and excitation spectra show similar behavior as a function of Eu concentration. It was proposed to describe the behavior of spectra that a kind of energy migration is occurred among Eu3+ ions and quenching centers located at the boundary between titanium oxide and locally concentrated Eu3+ ion cores.