Role of Li+ ions on the surface morphology and thermoluminescence properties of Y2O3:Tm3+ nanophosphor

Y2O3:Tm3+ and Li+ co-doped Y2O3:Tm3+ nanopowders were synthesized using the solution combustion method for possible application in ultraviolet (UV) light dosimetry. X-ray diffraction revealed the crystallite sizes to be in the range 21-44 nm and 30-121 nm using the Scherrer equation and the W-H plot relationship, respectively. Field emission scanning electron microscopy confirmed that, after co-doping with 4 mol% concentration of Li+, the particles were spherical in nature with an average size of 30 nm. Fourier transformed infrared spectroscopy results showed bands at wavenumbers of 556, 1499, 1704, 2342, 2358, 2973, 3433, and 3610 cm(-1) that corresponded to the stretching and bending vibrations of Y-O, C=O and O-H. Thermoluminescence (TL) glow peaks for Y2O3:Tm3+ nanophosphors observed at 399 and 590 K were attributed to oxygen defects caused using UV irradiation. These oxygen defects firstly resulted in an increased prominent peak TL intensity for up to 270 min of irradiation and then a decrease. This was attributed to the presence of oxygen defect clusters that caused a reduction in recombination centres. The Li+ co-doped sample showed peaks at 356, 430, and 583 K and its intensity sublinearly increased up to 90 min and then thereafter decreased. The TL trapping parameters were calculated using computerized glow curve deconvolution methods. The Li+ co-doped sample exhibited less fading and high trap density under the UV radiation.