On the study of the C6+ ion beam and γ-ray induced effect on structural and luminescence properties of Eu doped LiNaSO4: explanation of TSL mechanism using PL, TL and EPR study.

The present paper reports on the γ-ray and C6+ ion beam induced effect on the structural and luminescence properties of Eu doped LiNaSO4 phosphors synthesized via wet the chemical method. The material was irradiated by 60Co and 137Cs γ-rays and 75 MeV C6+ ions in a fluence range varying from 2 × 1010 to 1 × 1012 ion per cm2. The ion induced modified properties were investigated using X-ray diffraction (XRD), micro-Raman spectroscopy, photoluminescence (PL), thermoluminescence (TL) and electron paramagnetic resonance (EPR) studies. The XRD and micro-Raman results confirm the loss of crystallinity and elongation of the lattice parameters after ion beam irradiation. The presence of both divalent as well as trivalent states of Eu ions at multiple sites of LiNaSO4 is observed by PL study. Irradiation of the LiNaSO4:Eu phosphor with a C6+ ion beam modifies the population of the valence state of the doped rare earth Eu ion and enhances the TL sensitivity of this phosphor. The nature of the prominent TL glow curve is identical for both γ-ray and C6+ ion beam irradiated materials while additional deep trap levels appear in the latter due to the formation of several types of cation and anion vacancy. The electron paramagnetic resonance (EPR) technique also supports the presence of the Eu ion at multiple sites and provides information regarding several types of radical produced after γ-ray and C6+ ion irradiation. Finally, a mechanism is presented for the thermally stimulated luminescence phenomenon on the basis of our observed results from the PL, TL and EPR studies. The reason behind ion beam irradiation induced modification of the TL properties and enhancement of luminescence intensity is also explained in this report.

Comparison of thermoluminescence characteristics in γ-ray and C(5+) ion beam-irradiated LiCaAlF6 :Ce phosphor.

We compare the thermoluminescence (TL) behavior of Ce(3+) ion-activated LiCaAlF6 exposed to γ-rays and a carbon ion beam. The reported phosphor is synthesized using an in-house precipitation method with varying concentrations of activator ion and is characterized by X-ray diffraction (XRD) and TL. Rietveld refinement is performed to study the structural statistics. The TL glow curve consists of a prominent glow peak at 232°C with three shoulders at 115, 159 and 333°C when exposed to γ-rays from a (60) Co source. When exposed to a C(5+) ion beam, the TL glow curve consists of five peaks with peak temperatures near 156, 221, 250, 287 and 330°C, and is found to vary slightly with changing fluence. Glow curve convolution deconvolution (GCCD) functions are applied to the TL curves for complete analysis of the glow curve structure and TL traps. The order of kinetics (b), activation energy (E) and frequency factor are determined using Chen's peak shape method and theoretical curves are drawn using GCCD functions. A track interaction model (TIM) is used to explain the sublinearity/saturation at higher fluences. Ion beam parameters are analyzed using Monte-Carlo simulation-based SRIM-2013 code. Copyright © 2016 John Wiley & Sons, Ltd.

Luminescence study of Dy or Ce activated LiCaBO3 phosphor for γ-ray and C5+ ion beam irradiation.

The photoluminescence and thermoluminescence characteristics of rare earths (Dy or Ce) activated LiCaBO3 phosphors have been studied. Phosphors were synthesized by modified solid state synthesis. The phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) for structural, morphological and luminescence studies. Dy(3+) activated LiCaBO3 shows emission at 486 and 577 nm due to (4) F9/2 →(6) H15/2 and (4) F9/2 → (6) H13/2 transition, respectively, whereas the PL emission spectra of Ce(3+) activated LiCaBO3 phosphor shows a broad band peaking at 432 nm, which is due to the transition from 5d level to the ground state of the Ce(3+) ion. The thermoluminescence study was also carried out for both these phosphors for γ-ray irradiation and carbon beam irradiation. Linearity was studied for a 0.4-3.1 Rad dose γ-rays. Linear behaviour over this dose range was observed. Gamma ray-irradiated phosphors were shown to be negligible fading upon storage. All the samples were also studied for 75 MeV C(5+) ion beam exposure in the range of 3.75 × 10(12) - 7.5 × 10(13) ion cm(-2) fluence. In addition to this, trapping parameters of all the samples were also calculated using Chen's peak shape method.

Swift heavy ion induced structural and luminescence characterization of Y2O3:Eu³âº phosphor: a comparative study.

We report a comparative study on structural and thermoluminescence modifications of Y2O3:Eu(3+) phosphor induced by 150 MeV Ni(7+), 120 MeV Ag(9+) and 110 MeV Au(8+) swift heavy ions (SHI) in the fluence range 1 × 10(11) to 1 × 10(13) ions/cm(2). X-Ray diffraction and transition electron microscopy studies confirm the loss of crystallinity of the phosphors after ion irradiation, which is greater in the case of Au ion irradiation. Structural refinement using the Rietveld method yields the various structural parameters of ion-irradiated phosphors. Thermoluminescence glow curves of ion-irradiated phosphors show a small shift in the position of the peaks, along with an increase in intensity with ion fluence. Stopping range of ions in Matter (SRIM) calculations were performed to correlate the change in thermoluminescence properties of various ion-irradiated phosphors. It shows that the defects created by 110 MeV Au(8+) ions are greater in number. Trapping parameters of ion-irradiated phosphors were calculated from thermoluminescence data using various glow curve analysis methods.