Role of Li + ions on the surface morphology and thermoluminescence properties of Y 2 O 3 :Tm 3+ nanophosphor

• Published in: Luminescence (Chichester, England) England), 2020-08, Vol.35 (5), p.636-650
• Main Authors: Shivaramu, N J, Coetsee, E, Swart, H C
• Format: Article
• Language: English
• Subjects: Ions - chemistry; Lithium - chemistry; Nanoparticles - chemistry; Oxides - chemistry; Particle Size; Surface Properties; Thermoluminescent Dosimetry; Thulium - chemistry; Ultraviolet Rays; Ytterbium - chemistry
• ISSN: 1522-7235; 1522-7243
• DOI: 10.1002/bio.3768

Y O :Tm and Li co-doped Y O :Tm 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 that corresponded to the stretching and bending vibrations of Y-O, C=O and O-H. Thermoluminescence (TL) glow peaks for Y O :Tm 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.