Satinder Kumar; S. P. Lochab;Ravi Kumar; Arvind K. Gathania; Ankush Vij; A. K. Sharma; R. Dogra
Abstract
We synthesized single phase pure and Eu doped LiF having micro-cubical morphology by modified co-precipitation method. The complete solid solubility of Eu in LiF has been observed up to 0.04 mol% and afterwards phase segregation started. The absorption spectra of pure and Eu doped LiF revealed the formation ...
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We synthesized single phase pure and Eu doped LiF having micro-cubical morphology by modified co-precipitation method. The complete solid solubility of Eu in LiF has been observed up to 0.04 mol% and afterwards phase segregation started. The absorption spectra of pure and Eu doped LiF revealed the formation of γ-irradiation induced and dose dependent F, M and F3 color centers at room temperature. The concentrations of both F and M color centers calculated by using Smakula’s formula, increased almost ten times for γ- irradiated Eu doped LiF in comparison to γ-irradiated pure LiF. Non irradiated LiF doesn’t show any photoluminescence (PL) signal. However, γ-irradiated LiF showed broad emission peak around 681 nm, which is due to the excitation of F2 color centers. The Eu doped LiF samples exhibit PL emission peaks at 577, 591, 612, 648 and 690-698 nm correspond to Eu 3+ ion transitions from 5D0 to 7 FJ (J=0,1,2,3,4). The γ-irradiated Eu doped LiF show simultaneous PL emission spectrum of Eu 3+ ions and radiation induced F2 color centers. Thermoluminescence (TL) glow curves of γ- irradiated LiF and LiF: Eu (0.03 mol %) samples were also investigated and various trapping parameters for were evaluated by using Chen’s peak shape method
Vinay Kumar; Jitendra Sharma; O.M. Ntwaeaborwa; H.C. Swart
Abstract
In this letter, the thermoluminescence response and surface properties of Sr3B2O6:Dy 3+ nanophosphor prepared by combustion method exposed to γ–rays are reported. The crystalline structure of nanophosphors was confirmed by X-ray powder diffraction. The result indicates rhombohedral nanocrystalline ...
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In this letter, the thermoluminescence response and surface properties of Sr3B2O6:Dy 3+ nanophosphor prepared by combustion method exposed to γ–rays are reported. The crystalline structure of nanophosphors was confirmed by X-ray powder diffraction. The result indicates rhombohedral nanocrystalline structure with an average grain size of 41 nm. The microstructure and morphology were studied by transmission electron microscopy, which show nanowire like structure with an average diameter of 42 nm. The samples were irradiated with a γ-dose using 60Co source in the range of 100 Gy - 5000 Gy. The kinetic parameter such as activation energy (E), order of kinetics (b), and frequency factor (s) of the main glow peaks of the Sr3B2O6:Dy 3+ sample at 5000 Gy and different heating rates were determined using both the TLAnal program and Chen’s method. The effect of different heating rate at a fixed dose is discussed. X-ray photoelectron spectroscopy was used to study the surface chemical composition and the electronic states.
N.J. Shivaramu; B.N. Lakshminarasappa; K.R. Nagabhushana; Fouran Singh
Abstract
Nanocrystalline erbium doped yttrium oxide (Y2O3:Er 3+ ) was synthesized by the sol-gel technique using citric acid as complexing agent. The synthesized samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM) techniques for phase-purity and microstructure. ...
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Nanocrystalline erbium doped yttrium oxide (Y2O3:Er 3+ ) was synthesized by the sol-gel technique using citric acid as complexing agent. The synthesized samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM) techniques for phase-purity and microstructure. Er 3+ doped Y2O3 crystallizes in cubic phase with an average crystallite size of 24.3 nm. The pellets of Y2O3:Er 3+ were irradiated with 100 MeV swift Si 8+ ions with fluence in the range of 3×10 11 - 3×10 13 ions cm -2 . Three well resolved thermoluminescence (TL) glows with peaks at ~422, 525 and 620 K were observed in Er 3+ doped Y2O3 samples. It was observed that the TL intensity was found to increases with increasing Er 3+ concentration up to 0.4 mol% in Y2O3 and thereafter it decreases with further increase of Er 3+ concentration. Also, the intensity of low temperature TL glow peak (~422 K) increases with increasing ion fluence up to 1×10 12 ions cm -2 and decreases with further increase of ion fluences. The TL trap parameters were calculated by glow curve shape method and the deconvoluted glows were exhibit of second order kinetics.
Anil Kumar Choubey; Nameeta Brahme; S.J. Dhoble; D. P. Bisen; K.B. Ghormare
Abstract
Dy doped strontium aluminate phosphor (SrAl4O7:Dy(15% molar concentration)) was synthesized by combustion method using urea as a reducer at initiating temperature of 600oC. The absorption spectra shows the absorption edges at l = 242 nm, thus the band gap of 5.11 eV. The Thermoluminescence (TL) property ...
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Dy doped strontium aluminate phosphor (SrAl4O7:Dy(15% molar concentration)) was synthesized by combustion method using urea as a reducer at initiating temperature of 600oC. The absorption spectra shows the absorption edges at l = 242 nm, thus the band gap of 5.11 eV. The Thermoluminescence (TL) property of Dy(15%) doped SrAl4O7 nanophosphor has been investigated for l-irradiation. The TL glow curve of SrAl4O7:Dy (15%) phosphor with different ?-ray doses show the dose increases the TL- intensity while the temperature corresponding to maximum intensity remains nearly same. The maximum TL-intensity observes around 172.84 oC for the different doses. It was found that TL intensity strongly depends upon the -dose. It shows linear response upto 2.36 kGy. Hence Dy(15%) doped SrAl4O7 could be used for TL Dosimetry upto 2.36 kGy.
J. A. Wani; N. S. Dhoble; S. J. Dhoble
Abstract
Very little data on copper co-doped CaSO4: Dy and CaSO4: Dy, P phosphors seems to have been reported so far. In the present study the influence of copper and rare earths co-doping on thermoluminescence intensity of CaSO4: Dy, P phosphor has been investigated. Acid evaporation re-crystallization method ...
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Very little data on copper co-doped CaSO4: Dy and CaSO4: Dy, P phosphors seems to have been reported so far. In the present study the influence of copper and rare earths co-doping on thermoluminescence intensity of CaSO4: Dy, P phosphor has been investigated. Acid evaporation re-crystallization method was adopted for the synthesis purpose. Phosphors were characterized by scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) techniques. Results obtained through this study are of mixed nature. In some cases, TL intensity is either greater or nearly equal to standard CaSO4: Dy while in other cases it is half or rather weak in comparison to standard CaSO4: Dy phosphor. Copper was found to suppress temperature peak structure above 300 o C. SEM micrographs of CaSO4: P, Dy, Cu, RE phosphors show that the particle size is in the micrometer range, 1 to 5 µm approximately. The systematic study carried out in this work is solely novel as no such report existed before. From this study it is clear now that by co-doping multi-impurities simultaneously to enhance TL characteristics of CaSO4: Dy phosphor is no longer useful because it proved otherwise.
K. V. Dabre;S. J. Dhoble
Abstract
In this work we report the synthesis of CaWO4 pure and doped by various concentration of Eu 3+ by solid state method. Crystallinity and formation of as-synthesized phosphors were confirmed by XRD technique. PL emission of the Eu 3+ activated as-synthesized phosphors shows the strong red emission at 619 ...
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In this work we report the synthesis of CaWO4 pure and doped by various concentration of Eu 3+ by solid state method. Crystallinity and formation of as-synthesized phosphors were confirmed by XRD technique. PL emission of the Eu 3+ activated as-synthesized phosphors shows the strong red emission at 619 nm which corresponds to the characteristic transition 5 D0 → 7 F2 of Eu 3+ ion at excitation wavelength 273 nm. TL glow curve of Eu 3+ activated CaWO 4 shows the two glow peaks was observed at 400K and 500K whereas undoped CaWO4 shows only single peak observed at low temperature (354K). Doping effect on TL glow curve was discussed. Glow curve of Eu 3+ activated were fitted to five peaks which were analyzed and trap parameter were calculated by using Chens’ method, and the dose response curve shows the phosphor is fairly sensitivity to lower dose also. Thus reported phosphor can be applicable in LED and environmental dosimetry.
