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21.
Xue YuXuhui Xu Penghui YangQing Jiao Zhengwen YangZhiguo Song Jianbei Qiu 《Optical Materials》2012,34(5):931-934
The optical properties of Eu-activated CaAl2Si2O8 appear to be totally dependent on the atmosphere during the synthesis processing. Compared with oxidizing/reducing-sintered samples, a significant enhancement in both the photoluminescence and afterglow for the vacuum-sintered sample is observed. The deficiency of energy transfer among the different emission centers is the prevailing contribution to the highest photoluminescence intensity of the vacuum-sintered sample. A distinction in afterglow characteristics of CaAl2Si2O8:Eu prepared in different atmosphere is suggested to be mainly due to the distribution of different trap depths at three types of emission centers. 相似文献
22.
D.G. Zverev 《Optical Materials》2011,33(6):865-871
Rare-earth related centres have been investigated in K2YF5:Tb3+ crystals, exhibiting thermoluminescence (TL) below and above room temperature (RT), using electron paramagnetic resonance (EPR) spectroscopy at Q (34 GHz) and W-band (94 GHz). The spectra have been studied prior to irradiation, after exposure in the kGy range to X-rays at 77 K and subsequent pulse annealing up to 570 K. In addition to Gd3+, previously studied in detail, we identified Er3+ and Yb3+ centres as accidental impurities in as-grown crystals and determined their effective g tensors. The EPR spectra of irradiated and annealed crystals provide evidence for the production of at least three distinct Tb-related trapped hole centres, two of which could definitely be identified as Tb4+. Hence, we prove that the Tb3+ activator ions also act as hole traps in K2YF5. Pulse annealing experiments indicate that the TL above RT results from thermal release of electrons, recombining at these Tb4+ ions. 相似文献
23.
Suchinder K. Sharma Shreyas S. Pitale M. Manzar Malik M.S. Qureshi R.N. Dubey 《Journal of Alloys and Compounds》2009,482(1-2):468-475
We report, for the first time Sm3+ doped nanocrystalline Sr3Al2O6 phosphor. Effect of Eu3+ doping in the present host is also studied. XRD results match with standard data from JCPDS file confirming cubic structure with Pa3 space group. PL Maximum for Eu/Sm is obtained at 590 nm and 573 nm respectively, and corresponds to orange-red region of electromagnetic spectrum. Morphology of combustion synthesized powder is platelet, while for calcined powders, cubic shaped crystallites are obtained. Information on various trapping parameters is obtained from thermally stimulated Luminescence (TSL) studies. Non-shifting Tm property is applied to define the order of kinetics and is thereafter assumed as 1. Tm − Tstop procedure and repeated initial rise method are applied to estimate apparent activation energies and peak positions. Further, chi-square minimization procedures via computerized glow curve deconvolution (CGCD) technique provide best-fit results. The figure of merit for deconvoluted Eu and Sm doped samples are 0.48% and 0.67% respectively. The apparent activation energies for Eu doped samples are 0.89 eV, 1.05 eV, 1.30 eV, while, for Sm doped samples, the activation energies are 0.84 eV and 1.06 eV. Persistence behavior of the present phosphor is attributed to contribution due to shorter and longer components as are obtained during phosphorescence decay studies. In both the cases; probability of recombination is more in comparison to the retrapping within a quasi continuous framework of trapping sites. 相似文献
24.
Rare-earth doped sol-gel derived oxyfluoride glass-ceramics: Structural and optical characterization
Glass-ceramics containing RE3+-doped BaF2 nanocrystals (RE = Eu, Sm, Dy, Ho and Pr) with the size below 10 nm size have been made by using the controlled crystallization at higher temperatures of the RE3+-doped SiO2-BaF2 xerogels. Photoluminescence measurements have indicated the incorporation of the RE3+ ions in both silica network and in the BaF2 nanocrystals. Thermoluminescence measurements have shown a peak whose position depends on the nature of RE3+-dopant as it follows: 140 °C (for Ho3+, Dy3+), 340 °C (for Sm3+) and 370 °C (for Eu3+); in Eu3+-doped SiO2 glass the TL peak is shifted to 383 °C. The peaks in glass-ceramics were assigned to the recombination of the electrons thermal released from the RE3+-electron traps located in both glass-matrix and BaF2 nanocrystals. Within the series the trivalent lanthanide ions act as increasingly deeper electron trapping centres. 相似文献
25.
在 Bridgman 生长的 BGO 闪烁单晶中,含量为 10~(-4)~10~(-6)wt%的 Fe、Pb、Cr、Mn、Co、Ni、Cu、Al 等微量杂质主要来源于原料和工艺过程中的局外污染。铂从坩埚上被侵蚀进入 BGO 熔体,其含量<2×10~(-5)wt%。用 AAS 和 ICP 分析测定了 Bridgman 生长中微量杂质的有效分凝系数。过渡金属杂质,特别是 Fe,使 BGO 染色并引起辐照损伤,形成300~700nm 范围的强吸收谱,致使 BGO 单晶的能量分辨率、相对荧光输出下降约10—20%。在辐照损伤下形成的 Fe、Pb 杂质色心,受热时形成晶体的热发光。 相似文献
26.
热释光法用于中国古陶辨伪鉴定(英文) 总被引:1,自引:0,他引:1
本文叙述的方法是对一般的碎陶片进行断代的方法的改进,对陶器损害小,但结果仍相当精确。在过去几年中成功地分析了31个样品,大部分样品的年龄估计为1100—4500年,其中已有19个样品被证明与实际年龄相符。叙述了分析的一般程序和所遇到的问题。 相似文献
27.
J. Marcazzó M. Santiago C. D’Angelo C. Furetta 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(2):183-186
The photoluminescence (PL), radioluminescence (RL) and thermoluminescence (TL) of KMgF3 doped at several Sm concentrations have been investigated. The maximum TL and RL yield under beta irradiation has been observed in KMgF3:Sm 0.02 mol%. The glow curve of this doped perovskite is made up of at least five peaks located at 95, 120, 160, 270, and 330 °C. The third peak appears to be the most convenient for personal or environmental dosimetry, since it shows no fading and good linearity within the investigated dose range (0.020-200 Gy). From the RL and PL spectra it has been found that most of KMgF3:Sm emission is located at wavelengths higher than 650 nm. This emission, which is characteristic of Sm2+, makes this doped compound attractive for fiber-optic dosimetry. 相似文献
28.
29.
Winicjusz Drozdowski Andrzej J. Wojtowicz Dariusz Wi
niewski Piotr Szupryczy
ski Sebastian Janus Jean-Luc Lefaucheur Zhenhui Gou 《Journal of Alloys and Compounds》2004,380(1-2):146-150
Radioluminescence and UV-excited photoluminescence spectra, photoluminescence time profiles, thermoluminescence glow curves and gamma-excited energy spectra (determining scintillation light yields) of several Lu2SiO5:Ce and Y2SiO5:Ce samples were recorded. The results are analyzed with attention focused on possible correlations between trap distributions, VUV responses, and light yields. The aspect of two distinct sites occupied by Ce3+ ions is also discussed. 相似文献
30.
《Advanced Powder Technology》2020,31(7):2597-2604
A series of Dy3+ activated RbCaF3 phosphors was synthesized by the conventional high temperature solid state reaction technique under ambient atmosphere. The structural properties and morphology of synthesized compounds were analyzed by PXRD and FE-SEM, respectively. The chemical composition of synthesized phosphors was obtained by EDAX. The phosphor was excited at 386 nm and monitored at 484 and 574 nm, and the strongest peak was located at 484 nm (blue region). In addition, the point of RbCaF3:Dy3+ with calculated chromaticity coordinates in the CIE diagram was located in the yellow region. TL characteristics of the RbCaF3:Dy3+ phosphor was analyzed and the glow curve peak was emitted at 355 K. The symmetry factor, Balarin parameter, activation energy and frequency factor were calculated by Chen method from the TL glow curve, and the TL signal degradation was also analyzed. 相似文献