Calotropis procera mediated combustion synthesis of ZnAl2O4:Cr3+ nanophosphors: Structural and luminescence studies

ZnAl2O4:Cr3+ nanophosphors were synthesized for the first time by a simple and environment friendly route using Calotropis procera milk latex as fuel. The structural and surface morphological studies were carried out using powder X-ray diffraction (PXRD), scanning electron microscopy and transmission electron microscopy techniques. The photoluminescence (PL) properties of ZnAl2O4:Cr3+ as a function of dopant concentration and calcination temperature was studied in detail. The PXRD patterns and Rietveld confinement confirmed the cubic crystal system with space group Fd-3m. The crystallite size estimated from Scherrer's and W-H plots was found to be in the range of 16-26 nm. The PL spectrum shows an intense peak at similar to 688 and similar to 699 nm assigned to spin - forbidden E-2(g) -> (4)A(2g) transition of Cr3+ ions. The PL measurements for two excitations (similar to 410 and 527 nm) and with respect to calcination temperature indicated no significant change in the shape and position of emission peak except PL intensity. The CIE chromaticity coordinates lies well within the white region. Thermoluminescence (TL) studies revealed well resolved glow peak at similar to 212 degrees C with a small shoulder at 188 and 233 degrees C. The glow peak intensity at similar to 212 degrees C increases linearly with gamma-dose which suggest ZnAl2O4:Cr3+ is suitable candidate for radiation dosimetric applications. The activation energy (E in eV), order of kinetics (b) and Frequency factor (s) were estimated using glow peak shape method. (C) 2014 Elsevier B.V. All rights reserved.