Photoluminescence studies on Eu doped TiO2 nanoparticles

Eu3+ doped TiO2 nanoparticles were prepared by urea hydrolysis in ethylene glycol medium at low temperature of 150 degrees C. X-ray diffraction study showed that anatase phase of tetragonal structure was formed below 500 degrees C; and above this temperature, additional peaks due to rutile phase were also observed. From luminescence study, it was found that as prepared nanoparticles showed the enhanced luminescence intensity due to energy transfer from host to europium ions. However, photoluminescence from these nanoparticles was found to disappear when the samples were heated above 900 degrees C. We established the origin of the reduction in the luminescence intensity from Eu3+ when doped in TiO2 and heated at 900 degrees C. Based on detailed studies at different heat-treatment temperatures using techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, electron paramagnetic resonance, Raman spectroscopy, and Mossbauer spectroscopy, it has been established that formation of Eu2Ti2O7 phase, wherein Eu3+ ions occupy high symmetric environment (D-3d) and also reduced distance between Eu3+ and Eu3+ ions is responsible for the decrease/loss in the luminescence intensity. (C) 2009 Elsevier B.V. All rights reserved.