Effect of pH on Lyoluminescence of Mixed Alkali Sulphate Phosphor K 3 Na(SO 4 ) 2 :Eu 3+ for its Application in Dosimetry (original) (raw)
Lyoluminescence (LL) of microcrystalline K 3 Na(SO 4) 2 doped with Eu (0.1 mol%) as an impurity was studied for different doses and for different pH values of solvents. The material was prepared by simple melt method and then crushed and sieved to get particle size between 75-125 µm. K 3 Na(SO 4) 2 :Eu 3+ (0.1%) phosphor thus obtained was given proper heat treatment (annealed at 400 0 C for 1 h). It was then irradiated with γ rays from 60 Co radioactive source to study its LL characteristics and the effect of pH of the solvent on LL intensity. This has great importance for its application in dosimetry of high-energy radiation using LL. The decay curves, dose response and variation of the LL intensity with pH were studied for different doses (10 Gy-25 kGy). pH of the solutions used for studying LL was varied in the range of 0.55-13 using diluted H 2 SO 4 (acidic) and NaOH (basic) solutions. The material shows linear dose response for a broad range of doses (1.0 Gy-15 kGy). The LL intensity was found to be the maximum for a solution having pH value of 3.0. Initially the LL intensity increased with the pH of the solvent but later the intensity decreased gradually with increasing the pH till 7.0 (pH of distilled water). Another peak of the LL intensity could also be observed at around the pH of the solvent between 8.0-13.0. It was also observed that the fading of the LL intensity is more if the material is exposed to room light than its storage in dark.
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Lyoluminescence (LL) of microcrystalline K 3 Na(SO 4) 2 :Eu 3 þ was studied for different doses and for different pH values of solvents. The material was prepared by a simple melt method and was then crushed and sieved to get particle sizes in different ranges between 50-250 mm. K 3 Na(SO 4) 2 :Eu 3 þ (0.1%) phosphor thus obtained was given proper heat treatment (annealed at 800°C for 1 h). It was then irradiated with γ rays from 60 Co radioactive source to study its LL characteristics and the effect of pH of the solvent on LL intensity. The glow (decay) curves, dose response and variation of the LL intensity with pH were studied for different doses (10 Gy-25 kGy). pH of the solutions used for studying LL was varied in the range of 0.55-13.0 using different diluted acids (i.e., H 2 SO 4 , HCl and HNO 3) and alkalies (i.e., LiOH, NaOH and KOH) solutions. The LL intensity was not only found to vary with the net pH of the solution used for taking LL but also with the different acids/alkalies used for varying the pH. This has a great importance in radiation dosimetry using LL as the user needs to know which solution is best suited. The material shows linear dose response for a broad range of doses (10 Gy-10 kGy). It was also observed that the fading of the LL intensity is more if the material is exposed to room light than its storage in dark. Very wide dose range, high-sensitivity and low fading make the material suitable for dosimetry of high-energy radiations using LL technique.
Journal of Luminescence
Lyoluminescence (LL) of microcrystalline K 3 Na(SO 4) 2 :Eu 3 þ was studied for different doses and for different pH values of solvents. The material was prepared by a simple melt method and was then crushed and sieved to get particle sizes in different ranges between 50-250 mm. K 3 Na(SO 4) 2 :Eu 3 þ (0.1%) phosphor thus obtained was given proper heat treatment (annealed at 800°C for 1 h). It was then irradiated with γ rays from 60 Co radioactive source to study its LL characteristics and the effect of pH of the solvent on LL intensity. The glow (decay) curves, dose response and variation of the LL intensity with pH were studied for different doses (10 Gy-25 kGy). pH of the solutions used for studying LL was varied in the range of 0.55-13.0 using different diluted acids (i.e., H 2 SO 4 , HCl and HNO 3) and alkalies (i.e., LiOH, NaOH and KOH) solutions. The LL intensity was not only found to vary with the net pH of the solution used for taking LL but also with the different acids/alkalies used for varying the pH. This has a great importance in radiation dosimetry using LL as the user needs to know which solution is best suited. The material shows linear dose response for a broad range of doses (10 Gy-10 kGy). It was also observed that the fading of the LL intensity is more if the material is exposed to room light than its storage in dark. Very wide dose range, high-sensitivity and low fading make the material suitable for dosimetry of high-energy radiations using LL technique.
Radiation Effects and Defects in Solids, 2012
The lyoluminescence (LL), thermoluminescence and mechanoluminescence (ML) of a γ-ray-irradiated powder of NaCl:Dy (0.05-0.5 mol%) phosphor are reported in this paper. The nature of intensity variation of the respective luminescence spectra with different γ-ray doses and with different concentrations of Dy 3+ doped in NaCl are found to be similar. The LL and ML intensities differed from each other, but their nature is found to be similar in a sublinear form up to a high dose (5.0 kGy) of γ-rays. Thus, the prepared phosphor may be useful for accidental radiation dosimetry up to a high dose (5.0 kGy) of γ-rays using the LL and ML techniques.
ESR-aided evaluation of lyoluminescence processes in ‘Tris’
International Journal of Radiation Applications and Instrumentation. Part A. Applied Radiation and Isotopes, 1992
ESR spectral analysis of y-ray irradiated lyoluminescence (LL) phosphor powder, Tris (hydroxymethyl) aminomethane-referred to as 'Tris' showed the presence of two free radical species. It was observed that at higher exposure levels radical II with a singleispectrum shows a higher growth compared to radical I with a three comnonent snectrum. Radical I had been identified as RCHOH. The ESR-LL correlation studies indicate that the RCHOH radical formed in a low dose range is responsible for LL emission and the radical II either inhibits or does not have any role in the LL process. The LL yield of Tris measured under deoxygenated conditions showed a 40% reduction in the yield in luminol solution and 87% in distilled water. The range of linearity of the y-ray response extends further from 200 to 2000 Gy when the LL is measured under oxygen equilibrated condition.
A detailed investigation of the thermoluminescence (TL) properties of γ-ray and C5+ ion beam irradiated K2CaMg(SO4)3:Dy (KCM) phosphor was carried out. KCM was irradiated by 50 and 75 MeV energy C5+ ion beams with a fluence range of 15 × 1010 ions cm−2 to 30 × 1012 ions cm−2. The TL glow curves along with the response curves of these phosphor samples were analyzed and compared with commercial CaSO4:Dy phosphor. The TL glow curves of the phosphor exposed to γ-rays from 60Co and 137Cs sources were also examined in this study for comparative analysis. Theoretical analysis of the glow curves of the C5+ ion beam and γ-ray irradiated samples was performed using the glow curve deconvolution method. SRIM/ TRIM simulations were performed in order to identify the ion beam profile, range, distribution, etc. The enhancement in the intensity of the low temperature glow peak is explained with the help of an energy level model and the decrease in TL intensity with increasing ion fluence is also explored in detail. The radicals produced after irradiation were verified using the electron paramagnetic resonance (EPR) technique. The effects of temperature and microwave power on the EPR signal are also studied.
Luminescence in the Concentrated Phosphor
Radiation Measurements, 2007
Powder samples of EuAl 2 O 4 and (Eu, Sr)Al 2 O 4 with a quantum efficiency (QE) of the Eu 2+ emission more than 0.30 were synthesized. A modified method of QE determination is described and results of the QE measurements for EuAl 2 O 4 , (Eu 0.8 Sr 0.2 )Al 2 O 4 , (Eu 0.65 Sr 0.35 )Al 2 O 4 , and a diluted sample (Sr 0.98 Eu 0.02 )Al 2 O 4 are presented. Excitation and emission spectra as well as decay behaviour of the Eu 2+ luminescence in (Eu 1−x Sr x )Al 2 O 4 in the temperature region of 20-300 K are studied. It is concluded that the main reason for the high QE is a pronounced relaxation of the crystal lattice after excitation of the Eu 2+ ions resulting in an emission with a large Stokes shift and, therefore, in a restriction of energy migration. Eu ions occupying the crystallographic sites with the higher coordination number (Eu II ) are supposed to be the luminescence centres in (EuSr)Al 2 O 4 lattice.
Journal of Luminescence, 2019
Potassium calcium borate doped with dysprosium was synthesized by solid state diffusion method. Phase determination and compound confirmation were done by x-ray diffraction (XRD). Crystallite size calculated using Scherrer's formula was found to be around 117 nm. Other characteristics were studied using techniques like field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). Band gap of the material was determined using ultraviolet-visible diffuse reflectance spectroscopy (UV-VIS DRS). The phosphor KCaBO 3 :Dy was irradiated by photon beams (of 1.25 MeV gamma and 4.88 eV UV rays) and ion beams (of 65 MeV and 85 MeV of O 6+ and 75 MeV of C 6+) with different doses in order to study its thermoluminescence (TL) properties. The phosphor showed good TL sensitivity towards these ionizing radiations. A good linear dose response was also shown by the phosphor for photon beam exposure. However, in case of ion beams exposure, dose response of the phosphor was good only for low energy oxygen ion beam. Also the phosphor showed good photoluminescence (PL) property with sharp peaks present in the PL emission and excitation spectra corresponding to the characteristic peaks of the dopant Dy. The Commission International de l'E clairage (CIE) was also used to calculate chromaticity coordinates and color temperature in order to investigate the phosphor's application in white LEDs. All these good characteristics make this phosphor a suitable candidate for radiation dosimetry and solid state lighting.
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