A facile one-pot hydrothermal method to prepare europium-doped titania hollow phosphors and their sensitized luminescence properties

Abstract

Monodisperse europium-activated titania hollow phosphors had been synthesized by a facile one-pot hydrothermal method using carbon spheres as hard templates. Samples were characterized by X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive spectrometer and photoluminescence spectrum. The strongest emission intensity was observed with TiO 2:Eu 0.2 hollow spheres and TiO 2:Eu 0.2 hollow spheres calcining at 550 °C. Moreover, the strongest excitation of TiO 2:Eu 0.2 hollow spheres transferred from 400 to 500 °C and the effective nonradiative energy transfer from the TiO 2 hollow spheres host matrix to Eu 3+ ions crystal field states was realized due to changes of crystalline field in the environment around Eu 3+ ions occupying Ti 4+ sites. The proposed energy transfer mechanism was that UV light is absorbed in the band of TiO 2 hollow spheres crystal and then the energy is relaxed to the defect states of TiO 2 host. The energy can transfer to the crystal states of Eu 3+ ions ( 7F j , j = 0, 1, 2, 3 and 4), which results in efficient photoluminescence. The fluorescent intensity of TiO 2:Eu 0.2 hollow spheres was 2.2 times as strong as that of TiO 2:Eu 0.2 bulk material.