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Luminescence characteristics of K2Ca2(SO4)3:Eu,Tb micro- and nanocrystalline phosphor
Authors:Numan Salah  P. D. Sahare  Shah Nawaz  S. P. Lochab †
Affiliation:1. Department of Physics and Astrophysics , University of Delhi , Delhi, 110007, India nsalah@physics.du.ac.in;3. Department of Physics and Astrophysics , University of Delhi , Delhi, 110007, India;4. Nuclear Science Center , Aruna Asaf Ali Marg , New Delhi, 110 067, India
Abstract:K2Ca2(SO4)3 microcrystalline pure, doped with Eu, Tb and co-doped with Eu, Tb was prepared by solid-state diffusion method. Nanoparticles of these phosphors were also prepared by the chemical co-precipitation method. The formation of the compounds was confirmed by XRD. The particle size was calculated by broadening of the XRD peaks using Scherrer's formula. The particle size of nanocrystalline powder material was approximately found to be around 20 nm. Thermoluminescence and photoluminescence were studied to see the effect of co-doping and particle size. Tb3+ co-doping decreases the intensity in the Eu2+ doped phosphor due to the energy transfer and multiple de-excitations through various radiative and non-radiative processes. The sensitivity of K2Ca2(SO4)3:Eu,Tb microcrystalline phosphor was around 15 times more than LiF-TLD 100 and 7 times more than CaSO4:Dy. A high temperature peak (615 K) was observed in case of the nanoparticles, which was attributed to a particle size induced phase transition. This was confirmed by differential scanning calormetry measurements. The decrease in the sensitivity in case of nanoparticles is attributed to the particle size effect i.e. volume to surface ratio. Theoretical analysis of the glow curves was done by glow curve convolution deconvolution method to calculate trapping parameters of various peaks.
Keywords:TLD phosphor  K2Ca2(SO4)3:Eu,Tb  Nanoparticles  Co-doping  Energy transfer
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