The Experts below are selected from a list of 8916 Experts worldwide ranked by ideXlab platform
Zhongtai Zhang - One of the best experts on this subject based on the ideXlab platform.
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preparation of long afterglow sr4al14o25 based Luminescent Material and its optical properties
Materials Letters, 2001Co-Authors: Zilong Tang, Zhongtai ZhangAbstract:Abstract Sr 4 Al 14 O 25 –Eu,Dy photoLuminescent Material with high brightness and long afterglow was prepared by sintering at high-temperature and weak-reducing atmosphere. The Luminescent properties of Sr 4 Al 14 O 25 -based Luminescent Materials have been studied systematically. The analytical results indicated that the emission spectra of Sr 4 Al 14 O 25 –Eu,Dy are similar to that of Sr 4 Al 14 O 25 –Eu. Both of them have two main peaks near 424 and 486 nm, respectively, which are ascribed to two types of Eu 2+ that existed in the Sr 4 Al 14 O 25 matrix crystal. However, the Sr 4 Al 14 O 25 –Eu phosphor does not have the long-afterglow phenomenon; the Sr 4 Al 14 O 25 –Eu,Dy showed the obvious long afterglow. As for the mechanism of the long afterglow of this phosphor, Dy 3+ acted as the trap level and captured the free holes in the system. It is the trapped–detrapped recombination process that resulted in the long-afterglow phenomenon of this phosphor.
Daxin Zhang - One of the best experts on this subject based on the ideXlab platform.
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new model for explaining the over response phenomenon in percentage of depth dose curve measured using inorganic scintillating Materials for optical fiber radiation sensors
Optics Express, 2019Co-Authors: Zhuang Qin, Xu Zhang, Tianci Xie, Xinyu Dai, Bin Zhang, Ihsan Ullah Khan, Yongji Yan, Wenhui Zhao, Ziyin Chen, Daxin ZhangAbstract:Inorganic scintillating Material used in optical fibre sensors (OFS) when used as dosimeters for measuring percentage depth dose (PDD) characteristics have exhibited significant differences when compared to those measured using an ionization chamber (IC), which is the clinical gold standard for quality assurance (QA) assessments. The percentage difference between the two measurements is as high as 16.5% for a 10 × 10 cm2 field at 10 cm depth below the surface. Two reasons have been suggested for this: the presence of an energy effect and Cerenkov radiation. These two factors are analysed in detail and evaluated quantitatively. It is established that the influence of the energy effect is only a maximum of 2.5% difference for a beam size 10 × 10 cm2 compared with the measured ionization chamber values. And the influence of the Cerenkov radiation is less than 0.14% in an inorganic scintillating Material in the case of OFS when using Gd2O2S:Tb as the Luminescent Material. Therefore, there must be other mechanisms leading to over-response. The luminescence mechanism of inorganic scintillating Material is theoretically analysed and a new model is proposed and validated that helps explain the over-response phenomenon.
Dirk Poelman - One of the best experts on this subject based on the ideXlab platform.
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Temperature dependent persistent luminescence: Evaluating the optimum working temperature
Scientific Reports, 2019Co-Authors: Olivier Q. De Clercq, Dirk PoelmanAbstract:Development of persistent Luminescent Materials has drawn continuous attention in recent years in view of their potential applications in the fields of security night-vision signage, in vivo bio-imaging and optical data storage. Currently, the normative evaluation of a new persistent Luminescent Material is focused on the light emission spectrum, the afterglow decay curve and the total duration time of the persistent luminescence. In this paper, we investigate the temperature dependent persistent luminescence in some well-known persistent phosphors and relate this to their thermoluminescence properties. The concept of the optimum working temperature is proposed as a new means for evaluating persistent phosphors. It is shown that there is a clear relation between the efficient temperature range of the afterglow output and the thermoluminescence glow curve. The experimental work is supported by simulations of thermoluminescence and afterglow characteristics. The concept of the optimum working temperature for persistent phosphors can be used as an evaluative criterion for applications in various working environments.
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temperature dependent persistent luminescence evaluating the optimum working temperature
Phosphor Safari 2018 (International Symposium for Phosphor Materials), 2018Co-Authors: Olivier De Clercq, Dirk PoelmanAbstract:Long persistent phosphors (LPPs) are a group of Luminescent Materials possessing an extraordinary energy storage ability which results in long-lasting emission after excitation has stopped. Development of such Materials has drawn continuous attention because of their applications in the fields of emergency signs, security displays, in vivo bio-imaging, and optical data storage [1-3]. Currently, the evaluation of a new persistent Luminescent Material is dominantly focused on the emission region, the afterglow decay curve and the duration time of the persistent luminescence. In this work, we study the temperature dependent persistent luminescence in some well-known persistent phosphors and relate this to their thermoluminescence properties. In addition, we propose the concept of the optimum working temperature as a new means for evaluating persistent phosphors. It is shown that there is a simple relation between the efficient temperature range of the afterglow output and the thermoluminescence glow curve in LPPs. REFERENCES [1] Pan, Z., Lu, Y.-Y. & Liu, F. Nat. Mater. 11, 58(2012). [2] Maldiney, T. et al. Nat. Mater. 13, 418(2014). [3] Zhuang, Y., Wang, L., Lv, Y., Zhou, T. L. & Xie, R. J. Adv. Funct.Mater. 28, 1705769 (2018).
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persistent luminescence in non eu2 doped compounds a review
Materials, 2010Co-Authors: Koen Van Den Eeckhout, Dirk Poelman, Philippe SmetAbstract:During the past few decades, the research on persistent Luminescent Materials has focused mainly on Eu2+-doped compounds. However, the yearly number of publications on non-Eu2+-based Materials has also increased steadily. By now, the number of known persistent phosphors has increased to over 200, of which over 80% are not based on Eu2+, but rather, on intrinsic host defects, transition metals (manganese, chromium, copper, etc.) or trivalent rare earths (cerium, terbium, dysprosium, etc.). In this review, we present an overview of these non-Eu2+-based persistent Luminescent Materials and their afterglow properties. We also take a closer look at some remaining challenges, such as the excitability with visible light and the possibility of energy transfer between multiple Luminescent centers. Finally, we summarize the necessary elements for a complete description of a persistent Luminescent Material, in order to allow a more objective comparison of these phosphors.
Peng Cheng - One of the best experts on this subject based on the ideXlab platform.
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experimental studies and mechanism analysis of high sensitivity Luminescent sensing of pollutional small molecules and ions in ln4o4 cluster based microporous metal organic frameworks
Journal of Physical Chemistry C, 2014Co-Authors: Jingmin Zhou, Huimin Li, Han Li, Peng ChengAbstract:Two new isostructural 3D lanthanide metal–organic frameworks (Ln-MOFs) {[Ln4(μ3-OH)4(BPDC)3(BPDCA)0.5(H2O)6]ClO4·5H2O}n (Ln = Tb (1) and Gd (2), BPDC2– = 3,3′-dicarboxylate-2,2′-dipyridine anion and BPDCA2– = biphenyl-4,4′-dicarboxylate anion) based on cubane-shaped [Ln4(μ3-OH)4]8+ clusters were successfully synthesized and fully characterized. There are two kinds of micropores with dimensions of 3.0 × 7.0 A2 along the b-axis and 4.5 × 5.5 A2 along the c-axis in the cationic framework. Ln-MOF 1 exhibits an intensive green luminescence triggered by the efficient antenna effect of ligands under UV light. Luminescent studies illustrate that Ln-MOF 1 could be an efficient multifunctional Luminescent Material for high-sensitivity sensing of small organic molecules, metal cations, and anions, especially for benzene and acetone, Cu2+, and CrO42–. The mechanism of the sensing properties was studied in detail as well. Additionally, this cationic framework also displays fast capture of pollutant CrO42– by anion exc...
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a novel 3d porous metal organic framework based on trinuclear cadmium clusters as a promising Luminescent Material exhibiting tunable emissions between uv and visible wavelengths
Chemical Communications, 2006Co-Authors: Yongquan Huang, Bin Ding, Haibin Song, Bin Zhao, Peng Ren, Peng Cheng, Honggen Wang, Daizheng Liao, Shiping YanAbstract:A novel 3D porous MOF built with trinuclear cadmium clusters exhibiting rhombohedral topology has been synthesized and characterized as a promising Luminescent Material that can give tunable emissions between UV and visible wavelengths by controlling the number of guest molecules.
Ruiqian Guo - One of the best experts on this subject based on the ideXlab platform.
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highly emissive carbon dots in solid state and their applications in light emitting devices and visible light communication
ACS Sustainable Chemistry & Engineering, 2019Co-Authors: Enshan Liu, Pengfei Tian, Ding Zhou, Xiaojie Zhou, Gufan Zhou, Han Xiao, Ruiqian GuoAbstract:As a new type of Luminescent Material, carbon dots (CDs) have attracted increased attention for their superior optical properties in recent years. However, CDs generally suffer from aggregation-ind...
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Highly Emissive Carbon Dots in Solid State and Their Applications in Light-Emitting Devices and Visible Light Communication
2019Co-Authors: Enshan Liu, Pengfei Tian, Ding Zhou, Xiaojie Zhou, Gufan Zhou, Han Xiao, Ruiqian GuoAbstract:As a new type of Luminescent Material, carbon dots (CDs) have attracted increased attention for their superior optical properties in recent years. However, CDs generally suffer from aggregation-induced luminescence quenching, which means they are highly emissive in solution or a dispersed state but dramatically quenched in a solid or aggregated state. This problem significantly limits the application of CDs, partially in the solid-state light-emitting devices. In this work, a new kind of solid-state emissive CDs have been synthesized via simple one-step hydrothermal strategy. Under 450 nm excitation, the CDs exhibit bright green luminescence in the solid state, with a quantum yield of 26%. The luminescence lifetime of the CDs is only 4 ns. Employing the CDs as a color converter, white light-emitting diodes were fabricated and a visible light communication system with high performance (modulation bandwidth of 55 MHz, data transmission rate of 181 Mbps) was realized
