Highly enhanced luminescence of nanocrystalline TiO2:Eu3+ phosphors

Narrow-dispersed nanocrystalline TiO2:Eu3+ phosphors have been synthesized by reverse micelles and solvothermal synthetic method in toluene solutions. Different concentrations of europium nitrate pentahydrate (5.0, 10.0, 20.0 and 25.0 mol%) were dissolved in water. After the solution was thermally treated at 250 °C for 20 h in an autoclave, low-dispersed TiO2:Eu3+ nanocrystalline particles with average size of <5 nm were synthesized. The nanocomposites were composed nominally of TiO2 shell with Eu2O3 core. The crystalline phase and microstructure of the nanoparticles were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. Also, luminescent spectra and composition ratio were measured using luminescent spectrometer and energy dispersive X-ray spectrometer. The radiation was dominated by the red emission peak at 616 nm and the highest emission intensity was observed with TiO2:Eu0.2, whose brightness was increased by a factor of 1.9 in comparison with that of TiO2:Eu0.05. The photoluminescence and excitation spectra show similar behavior as a function of Eu concentration.