Luminescence Properties of CaF 2

Nanostructures of calcium fluoride (CaF2) doped with Eu, Tb, Dy, Cu, and Ag were synthesized by the coprecipitation method and studied for their thermoluminescence (TL) and photoluminescence (PL) properties. The PL emission spectrum of pure CaF2 nanostructure has a broad band in the 370–550 nm range. Similar spectra were observed in case of doped samples, beside extra bands related to these impurities. The maximum PL intensity was observed in Eu doped sample. The TL results of Eu, Cu, Ag, and Tb doped samples show weak glow peaks below 125°C, whereas Dy doped one is found to be highly sensitive with a prominent peak at 165°C. This sample was further exposed to a wide range of gamma rays exposures from 137Cs source. The response curve is linear in the 100 Gy-10 kGy range. It is also observed that the particle size of CaF2 nanostructure was significantly reduced by increasing Dy concentration. These results showed that Dy is a proper activator in the host of CaF2 nanostructure, providing a highly sensitive dosimeter in a wide range of exposures and also plays a role as a controlling agent for particle size growth

Thermoluminescence Characteristics of CaS: Ce Nanophosphors

The thermoluminescence characteristics of cerium doped calcium sulphide nanoparticles under UV radiations have been studied. The average grain size of the nanoparticles is found to be 53nm which is confirmed by TEM micrograph. The TL glow curve shows a single peak at 376K. TL intensity increases linearly unto 2hr UV exposure. Further increase in the dose results into a decrease of TL intensity. Variation in TL intensity as a function of cerium concentration is studied and 0.4mol% is found to be the optimum concentration for TL. The trap parameters namely, activation energy (E), order of kinetics (b) and frequency factor (s) of CaS: Ce (0.4 mole %) sample have been determined using Chen's method. The order of Kinetics is found to be 2 indicating retrapping of charge carriers in CaS: Ce nanoparticles. The effect of different heating rates has also been studied. The PL emission spectrum shows two peaks at 506nm and 565nm when excited at 450nm

THERMOLUMINESCENCE CHARACTERISTICS OF CaS: Ce NANOPHOSPHORS

The thermoluminescence characteristics of cerium doped calcium sulphide nanoparticles under UV radiations have been studied. The average grain size of the nanoparticles is found to be 53nm which is confirmed by TEM micrograph. The TL glow curve shows a single peak at 376K. TL intensity increases linearly unto 2hr UV exposure. Further increase in the dose results into a decrease of TL intensity. Variation in TL intensity as a function of cerium concentration is studied and 0.4mol% is found to be the optimum concentration for TL. The trap parameters namely, activation energy (E), order of kinetics (b) and frequency factor (s) of CaS: Ce (0.4 mole %) sample have been determined using Chen's method. The order of Kinetics is found to be 2 indicating retrapping of charge carriers in CaS: Ce nanoparticles. The effect of different heating rates has also been studied. The PL emission spectrum shows two peaks at 506nm and 565nm when excited at 450nm

Thermoluminescent response of nanocrystalline Ba_0.97Ca_0.03SO₄: Eu for proton beam

500-504Nanocrystalline Ba0.97Ca0.03SO4 doped with Eu, was prepared by the chemical co-precipitation method. The formation of the compounds was confirmed by XRD. The particle size was calculated by the broadening of the XRD peaks using Scherrer’s formula. The particle size was found to be around 45 nm. Samples in the form of pellets were irradiated by 150 MeV proton beam. Thermoluminescence (TL) glow curves of the irradiated samples were recorded and studied. It has been found that there is a prominent TL glow peak at 498 K with a small shoulder at around 465 K. The TL response is linear in the range 0.1-150 Gy and then saturates for higher doses. The wider linear TL response of nanocrystalline Ba0.97Ca0.03SO4: Eu and low fading makes it a good candidate as a dosimeter to be used for detecting the doses of protons which are commonly being used in proton therapy for the treatment of cancer