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1.
In this paper, thermoluminescence (TL) studies of BaCa(SO4)2:Eu,Dy phosphor are reported. A microcrystalline sample of BaCa(SO4)2:Eu,Dy was prepared by a solid state diffusion method and the formation of the compound was confirmed by the X-ray diffraction study. Morphology of the phosphor was analyzed by scanning electron microscopy (SEM). The sample is found to have an average particle size of 5?µm. TL glow curves of the γ-irradiated samples with different concentrations of Eu and Dy were studied and compared with BaCa(SO4)2:Eu and BaCa(SO4)2:Dy. It has been found that a single peak was located at around 230°C with the highest TL intensity in BaCa(SO4)2:Eu,Dy which is eight times and two times more than singly Dy- and Eu-doped BaCa(SO4)2 phosphor, respectively. For TL analysis, BaCa(SO4)2:Eu,Dy (0.2?mol%, 1?mol%) is annealed at different temperatures ranging from 900°C to 1100°C. Analysis of the TL glow curve was carried out by a glow curve deconvoluted method. Trapping parameters (activation energy and frequency factor) of all TL glow curves were evaluated by Chen's peak shape method. A comparison of trapping parameters between BaCa(SO4)2:Eu,Dy; BaCa(SO4)2:Eu and BaCa(SO4)2:Dy phosphors at 900°C, 1000°C and 1100°C is also reported in this paper. 相似文献
2.
Abstract Measurements of the electrical properties of unirradiated as well as γ-irradiated La2CuO4 crystals were carried out at different temperatures in the frequency range of 0.1-100 kHz. Thermoluminescence (TL) studies were also performed on such crystals in the temperature range of 300-600K. The conductivity of the unirradiated La2CuO4 crystals were found to obey the power law frequency dependence at each measured temperature below the transition temperature (Tc = 450K). The activation energies for conduction and dielectric relaxation time have been calculated. The TL response and the dc resistance were found to increase with γ-irradiation dose up to 9-10 kGy. The results showed that the ferroelastic domain walls of La2CuO4 crystal as well as its TL traps are sensitive to γ-raditaion. This material can be used in radiation measurements in the range 225 Gy-10 kGy. 相似文献
3.
Archana Deshpande N. S. Dhoble S. J. Dhoble V. G. Rane R. M. Kadam 《辐射效应与固体损伤》2013,168(9-10):790-808
ABSTRACTThe present phosphor K2Ca(SO4)2, doped by dysprosium and europium, is synthesized by the solid-state diffusion method. The doping concentration varied from 0.1 to 0.5?mol% by weight. A phosphor is studied for X-ray powder diffraction, surface morphology analytical scanning electron microscopy and analyzed by energy-dispersive X-ray spectroscopy. The prepared phosphor K2Ca(SO4)2, doped by Dy and Eu, has been characterized for thermoluminescence (TL) glow curve, showing maximum peak temperatures at 176°C and at 200°C, respectively. TL peak intensity of K2Ca(SO4)2: Dy and Eu was compared with the standard TLD CaSO4:Dy phosphor. Both phosphors show the dose linearity ranging from 20 to 240?Gy doses of γ-rays of 60Co source at room temperature. Negligible fading has been observed when irradiated with γ-rays and stored for 60 days without taking any care from sunlight. The TL materials were used in powder forms. The linearity of ESR response with dose for powder forms of K2Ca(SO4)2: Dy was also studied using the signals at g?=?2:0039 (SO3?) and at g?=?2:02282 (SO4?). It was observed that the range of linearity of dose response extended between 20 and 240?Gy. Kinetic parameters have been calculated using three different methods: Chen's peak shape method, various heating rate method and initial rise method. To study the heating rate method, the glow curve was recorded for the heating rate as 1°C, 3°C, 5°C, 7°C, 9°C each time. Electron spin resonance (ESR) shows the ionic radical formation during γ-irradiation, which is responsible for TL. The effect of temperature and microwave power on the ESR signal was also studied. 相似文献
4.
The mechanoluminescence (ML) of γ-irradiated coloured powder of (KNa)Br:Ce(0.1–10 mol%) phosphor is reported in this paper. The samples are prepared by wet chemical method. The ML intensities are found to be dependent on concentrations of Ce3+ ion and γ-rays radiation dose. The variation of peak ML intensity of (KNa)Br:Ce(0.5 mol%) with different γ-rays dose is found as linear up to 2.5 kGy high dose from 0.08 kGy, whereas for the KBr:Ce(0.5 mol%) and NaBr:Ce(0.5 mol%) samples the ML intensities increases sublinearly. The prepared sample shows minimum fading in ML intensity. The ML characterisation shows the good linearity, less fading and simple ML glow curve structure, thus the prepared material may be useful for radiation dosimetry. 相似文献
5.
Y. Zorenko T. Zorenko V. Gorbenko B. Pavlyk V. Laguta M. Nikl V. Kolobanov D. Spassky 《Radiation measurements》2010,45(3-6):419-421
The influence of γ-irradiation with a dose of ~104 Gy on the characteristics of LuAG:Ce single crystalline films (SCF) was investigated using ESR and time-resolved luminescence spectroscopy under excitation by synchrotron radiation with the energies ranging from 3.7 to 12 eV. The origin of γ-ray induced radiation defects in LuAG:Ce SCF is discussed. 相似文献
6.
Hexagonal YPO4 phosphors doped with Eu3+/Dy3+ and co-doped with Ce3+ were synthesized by a hydrothermal route assisted using lauric acid as a capping agent. The prepared phosphors were characterized by transmission electron microscopy, infrared spectroscopy, powder X-ray diffraction and photoluminescence spectra. YPO4: Eu3+ gives two red emission peaks at 587 and 610?nm corresponding to 5D0→7F1 and 5D0→7F2 transitions, respectively. YPO4: Dy3+ exhibits two emission peaks at 485?nm (blue) and 575?nm (yellow) corresponding to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions, respectively. Ce3+ ions enhanced the emission intensity as a co-dopant in both phosphors. Moreover, the effect of γ-radiation in the dose range 5–300?kGy on the photoluminescence behaviour of YPO4:Eu3+,Ce3+ and YPO4:Dy3+,Ce3+ was also investigated. Quenching of emission intensity, after irradiation at 5 and 300?kGy, was observed in both the phosphors due to loss of excess energy through a non-radiative relaxation process. 相似文献
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8.
This paper reports that polycrystalline α-Al2O3:C ceramics are fabricated by conventional ceramics process. The excitation, emission spectra, thermoluminescence (TL) and optical stimulated luminescence (OSL) of α-Al2O3:C polycrystalline ceramics are investigated. There exists 410nm maximum emission peak which is caused by recombination of an electron with F+ centre to produce an excited F centre. The samples show three clear TL glow peaks at 405, 493 and 610K. The attenuation constant of exponentially decaying fast component (τ1) and slow component(τ2) of OSL curve are 8.43s and 41.73s, respectively. Those fluorescence and thermoluminescence characteristics are similar with α-Al2O3:C crystal. 相似文献
9.
《Journal of Magnetic Resonance (1969)》1976,21(2):197-210
Gamma-irradiated monoclinic single crystals and powders of LiH3(SeO3)2 and LiD3(SeO3)2 have been investigated at room temperature by ESR in both the X and the Q band. Twelve species consisting of six pairs of inequivalent radicals have all been identified as SeO2−-type radicals pairwise located in two different sites. The origin of the difference in the principal values of the g-tensors for the radicals is attributed to a difference between the SeO bond lengths, which in fact gives a lower symmetry of the radicals. The generation of the radicals has been explained as a rupture of a SeO bond, which can occur in six different ways due to the crystal structure. The orientations of the radicals in the crystal are different compared to corresponding SeO2 groups in the host crystal, and this phenomenon presumably depends either on a reorientation of the radicals or on a radical reaction. One extra splitting of peaks originating from two of the radicals in LiH3(SeO3)2 is absent in LiD3(SeO3)2, thus indicating hydrogen bonding to the radicals. 相似文献
10.
A.K. Bedyal V.K. Singh S.P. Lochab Fouran Singh O.M. Ntwaeaborwa 《辐射效应与固体损伤》2013,168(11-12):1022-1029
In this paper, we present a detailed investigation of the thermo-luminescence (TL) kinetics of the long afterglow phosphor, Sr4Al14O25:Eu2+,Dy3+, synthesized by the combustion method. Kinetic parameters such as the activation energy (Eα), the frequency factor (s) and the order of kinetics (b) were calculated using Chen's formulism. The crystalline structure of the phosphor was examined using X-ray powder diffraction and transmission electron microscopy. The average particle size was found to be in the range of 45–52 nm. The optimum dopant concentrations were Eu (1 mol%) and that of Dy (2 mol%). The TL response of the phosphor was monitored after the samples were irradiated with a γ-dose using a 60Co source in the 20-800 Gy range. A broad TL peak, (stretching from 328 to 410 K) with a maximum at 368 K was observed. With increasing irradiation dose, the main peak shifts toward higher temperatures. Symmetry factor calculations show that the main TL glow peak obeys second-order kinetics, which could be attributed to the creation of deep level traps. This means that γ-ray irradiation greatly affects the distribution of traps in the Sr4Al14O25:Eu2+,Dy3+ phosphor. The phosphor showed a linear response with γ-dose. 相似文献
11.
J.R. Rowlands 《Molecular physics》2013,111(6):565-571
The electron spin resonance spectrum of the radical NH(SO3 - trapped in a single crystal of potassium sulphamate is interpreted. The hyperfine couplings for the hydrogen and nitrogen nuclei are given. The radical is planar, the unpaired electron occupying an orbital of π symmetry being predominantly a nitrogen 2p orbital. 相似文献
12.
This paper reports that KI doped with Ce3+ or double doped with Tb3+ and Ce3+ were prepared by the Bridgman-Stockbarger method and characterized by optical absorption photoluminescence (PL), thermoluminescence (TL), photostimulated emission (PSL) and TL emission. The optical absorption measurement indicates that F and V1, V2 centers are formed in the crystals during the γ irradiation process. It was attempted to incorporate a broad band of Ce3+ activator into the narrow band emission of Tb3+ in the KI host without the reduction of emission intensity. Ce3+-co-doped KI and Tb crystals showed a broad band emission due to the d-f transition of Ce3+ and a reduction in the intensity of emission peaks due to the 5D3-7Fj (j=3,4,5,6) transition of Tb3+, when they were excited at 240 nm.These results supported that an effective energy transfer occurs from Tb3+ to Ce3+ in the KI host. Co-doping Ce3+ ions greatly intensified the excitation peak at 260 nm for the emission at 393 nm of Tb3+, which means that more lattice defects, involved in the energy absorption and transfer to Tb3+, are formed by the Ce3+ co-doping. The integrated light intensity is an order of magnitude higher as compared to the undoped samples for similar doses of irradiation and heating rates. The defects generated by irradiation were monitored by optical absorption and TSL Trap parameters for the TL process are calculated and presented. 相似文献
13.
Ca8Mg(SiO4)4Cl2中Ce3+和Eu2+的光谱性质和能量传递 总被引:1,自引:1,他引:0
首次合成了Ce^3+和Eu^2+共激活氯硅酸镁钙Ca8Mg(SiO4)4Cl2:Ce^3+,Eu^2+高效绿色荧光粉,报道了它们的漫反射光谱、激发和发射光,观察到氯硅酸镁钙中Ce^3+ Eu^2+ 相似文献
14.
Ca5(PO4)3F:Ce,Mn荧光粉的老化性能研究 总被引:1,自引:0,他引:1
通过对一系列Ca5(PO4)3F:Ce和Ca5(PO4)3F:Ce,Mn(以下简称FAP:Ce和FAP:Ce,Mn)样品在荧光灯中和在强紫外光(185nm+254nm)辐照下,发光效率衰减规律及样品漫反射光谱的变化的研究,并与普通卤粉((F,Cl)AP:Sb,Mn)进行对比,发现了该材料的老化速率与样品组分的关系,即随着材料中Ce浓度的增大和氧空位的增多,老化速率变快。并根据Ryan老化理论,对材料老化的物理机制进行了初步的推测。 相似文献
15.
Na2Ca6La2(PO4)6F2:Eu3+的荧光和结构的局部对称性 总被引:1,自引:0,他引:1
稀土Eu3+离子的荧光谱线的数目、位置和强度与其所处的周围环境对称性有明确的联系。为了测定La3+离子在Na2Ca6La2(PO4)6F2相中所处格位的对称性,合成样品时,适量掺杂Eu3+离子,得到Na2Ca6La2-x(PO4)6F2:Eux红色荧光体。研究此种发光体的荧光光谱性质,能够证实La3+在Na2Ca6La2(PO4)6F2中处于两种不同的对称格位(D3h和C6)。 相似文献
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17.
Europium doped calcium pyrovanadate nanoparticles Ca2V2O7:Eu3+, having a size of 57–63 nm, were synthesized using combustion process. Structure, morphological and optical properties of nanophosphors have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), fluorescence spectrometry (PL) and Fourier transform infra-red (FT-IR) spectroscopy. X-ray studies shows that a pure triclinic Ca2V2O7 phase was obtained at 900 °C temperature. The red emission observed at 620 nm upon excitation at 305 nm is due to hypersensitive transition 5D0 → 7F2 of luminescent activator Eu3+ location at a site with no inversion symmetry in Ca2V2O7 crystal lattice. High luminescent intensity and easy synthesis technique make this red phosphor a promising candidate for application as luminescent materials. 相似文献
18.
L. S. Smirnov A. I. Baranov L. A. Shuvalov L. Bobrowicz-Sarga I. Natkaniec S. Waplak 《Physics of the Solid State》2001,43(1):117-126
The (NH4)3H(SO4)2 and [(NH4)0.82Rb0.18]3H(SO4)2 crystals are investigated by dielectric spectroscopy, inelastic incoherent neutron scattering (IINS), and neutron powder diffraction. A comparative analysis of the data obtained is given. It is shown that the phase transitions II ? III, III ? IV, IV ? V, and V ? VII in the (NH4)3H(SO4)2 crystal are accompanied by changes in the orientation ordering of the NH 4 + ions. In the [(NH4)0.82Rb0.18]3H(SO4)2 crystal, these phase transitions are completely suppressed and the long-range order inherent in the II phase is retained over the entire temperature range covered (6–300 K). It is revealed that this crystal at the temperature T g≈70 K undergoes a transition to the dipole glass phase, which is attended by “freezing” the orientation disordering of the ammonium ions. 相似文献
19.
M.V. Krishnamurthy 《Molecular physics》2013,111(6):1353-1359
The electron paramagnetic resonance of γ-irradiated single crystals of K2C2O4.H2O and (NH4)2C2O4.H2O has been studied. The spectra show interesting microwave power saturation effects. The singlet spectrum is attributed to the C2O4 - radical derived from the C2O4 -- ion. The principal g-values are determined to be 1·998, 2·0028 and 2·0004. Certain weak lines are observed with different power saturation and interpreted as due to OH radicals derived from water molecules in the crystal lattice. 相似文献