Luminescence study of LiMgBO₃:Dy for γ‐ray and carbon ion beam exposure

Abstract

LiMgBO 3 :Dy 3+ , a low Z eff material was prepared using the solution combustion method and its luminescence properties were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermoluminescence (TL), photoluminescence (PL), Fourier transform infrared spectroscopy, and electron paramagnetic resonance (EPR) techniques. Reitvield refinement was also performed for the structural studies.The PL emission spectra for LiMgBO 3 :Dy 3+ consisted of two peaks at 478 due to the 4 F 9/2 → 6 H 15/2 magnetic dipole transition and at 572 nm due to the hypersensitive 4 F 9/2 → 6 H 13/2 electric dipole transition of Dy 3+ , respectively. A TL study was carried out for both the γ-ray-irradiated sample and the C 5+ irradiated samples and was found to show high sensitivity for both. Moreover the γ-ray-irradiated LiMgBO 3 :Dy 3+ sample showed linearity in the dose range 10 Gy to 1 kGy and C 5+ -irradiated samples show linearity in the fluence range 2 × 10 10 to 1 × 10 11 ions/cm 2 . In the present study, the initial rise method, various heating rate method, the whole glow curve method, glow curve convolution deconvolution function, and Chen's peak shape method were used to calculate kinetic parameters to understand the TL glow curve mechanism in detail. Finally, an EPR study was performed to examine the radicals responsible for the TL process. KEYWORDS ESR, LiMgBO 3 , tissue equivalent material, trapping parameters | INTRODUCTIONBoron-based materials show interesting thermoluminescence (TL) properties when exposed to ionizing radiation [1,2] . The luminescence properties of lithium borate and magnesium borate in both microcrystalline and nanocrystalline forms have been studied previously [1][2][3][4] . Recently, researchers who studied lithium magnesium borate phosphor found that it was useful for applications in dosimetry [5,6] .To date, only a few studies on LiMgBO 3 have been reported [5] .Recently, the TL properties of rare earth ion (RE = Tb, Gd, Dy, Pr, Mn, Ce, Eu)-doped lithium magnesium borate (LMB), prepared using the solid state diffusion method, have been documented [6] . LMB:Tb 3+ showed the best results with a stable TL peak at 240°C. LMB:Tb 3+ was about four times more sensitive than TLD-100. Optical properties of LMB glasses doped with Dy 3+ ,Sm 3+ ions have been studied [7] .Photoluminescence properties of LMB:Eu and LMB:Eu,Bi have also been studied in detail [8] . LiMgBO 3 :Dy 3+ in its polycrystalline form has been prepared using a novel solution combustion method and its TL sensitivity was found to be half compared with commercial TLD-100 and showed a high degree of fading of 30% after 20 days [9] . Furthermore, LiMgBO 3 :Dy 3+ in its nanocrystalline form has been prepared using the combustion method and its structural and optical properties have been studied [10] .

Development of LiMgBO3:Tb3+ as a new generation material for thermoluminescence based personnel neutron dosimetry

“…[28][29][30][31][32] However, although there are reports on the TL based dosimetry studies on LiMgBO 3 for beta-and gammaradiation, its applications for neutron dosimetry have not been studied so far. 33,34 Recently TL based personnel neutron dosimetry study was reported for LiMgBO 3 :Dy 3+ but the low neutron sensitivity and high fading of this phosphor have limited its practical use. 35 Therefore, aiming at better neutron dosimetry properties, and based on previous research experiences, the present paper investigated the novel LiMgBO 3 :Tb 3+ phosphor (using the Tb 3+ dopant instead of Dy 3+ ) which not only overcomes the above-mentioned shortcomings but also provides very promising results which might become a potential alternative to the existing LiF:Mg,Ti dosimeter.…”