Near white light emitting ZnAl2O4:Dy3+ nanocrystals: Sol-gel synthesis and luminescence studies

ZnAl2O4:Dy3+ nanoparticles were synthesized using citrate sol-gel method and characterized systematically using X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy. Emission spectrum of pure ZnAl2O4 shows intense violet blue emission under ultra violet irradiation. Based on electron paramagnetic resonance (EPR) results; it was attributed to presence of singly ionized oxygen vacancy centres in ZnAl2O4. On doping Dy3+ in ZnAl2O4, complete host-dopant energy transfer does not take place. Local structural investigation and lifetime measurements reveal that dysprosium ion is distributed between both Zn2+ and Al3+ sites. Near white light from ZnAl2O4:Dy3+ is attributed to combined host and dopant luminescence. The trap parameters such as activation energy (E) and frequency factor (s) for TSL glow peak 165 degrees C were determined using different heating rate method. Thermally stimulated emission showed the presence of oxygen related defect centre. (C) 2015 Elsevier Ltd. All rights reserved.