Papers by Keyword: Nanophosphor

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Authors: Xiao Jun Wang, Xiao Chun Zhou
Abstract: A simple combustion process has been proposed to systematically synthesize Ca3((P, V)O4)2: Eu3+. All the Ca3((P, V)O4)2: Eu3+ products were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spect rophotometer. The results indicate that Ca3((P, V)O4)2: Eu3+ phosphor particles is special morphology with quadrate of length 2.5 μm and breadth 1 μm. From the photoluminescence spectra for Ca3((P, V)O4)2: Eu3+, the remarkable emission transition 5D0 – 7F0 are assigned to Eu3+ ions substituted for Ca2+, and the most intense emission transition 5D0 – 7F2 indicates at noncenter symmetrical environment for Eu3+ ions. It was observed that the spectral features possess sharp and bright emission for a red emitting nanophosphors potential applications.
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Authors: Je Hong Park, Sung Hoon Lee, Jong Su Kim, Tae Wan Kim, Hong Lee Park
Abstract: Manganese-doped ZnS nanophosphors were synthesized by two different methods: hydrothermal and low-temperature precipitation methods. The nanophosphors prepared by the hydrothermal precipitation and low-temperature methods had the size of 20 nm and 4 nm, respectively, and both were the cubic phase. The emission intensity of the nanophosphor prepared by the hydrothermal method was optimized at 10 mole % of Mn2+ concentration whereas that by low-temperature precipitation method was optimized at 3 mole % of Mn2+. The precipitationprepared nanophosphor, of size 4nm, showed a blueshift in the excitation spectrum and a redshift in the emission spectrum compared to the hydrothermal-prepared 20 nm nanophosphor. These phenomena can be explained in terms of the quantum confinement effect. The decay times especially were lengthened with decreasing particle size. This can be explained in terms of the variation in the transition probability induced from the quantum confinement effect.
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Authors: Kenji Toda, Masafumi Hosoume, Kenji Sato, Kazuyoshi Uematsu, Mineo Sato, Akira Watanabe, Takehisa Fukui
Abstract: We report synthesis of well-grown blue phosphor powder, CaMgSi2O6:Eu2+, from new vapor phase method (Flash creation method) derived nanopowder precursor. Single phase phosphor sample was obtained by post-annealing at 1100 oC. Luminescence properties were compared with that of the sample synthesized by a conventional solid state reaction. The post-annealed sample showed intense blue emission under UV excitation.
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Authors: M. Zachau, A. Konrad
Abstract: Luminescent and non-luminescent nano materials are used today in a variety of lighting applications. One example is the thin layer of densely packed nano alumina between glass and phosphor in fluorescent lamps that serves to increase the efficiency, to improve the maintenance and to reduce the mercury consumption of the lamps. Further, non-luminescent nano materials may be used to form a thin conformal coating around phosphor particles that protects the phosphor particles and improves the efficiency and maintenance of fluorescent lamps. Luminescent nano materials have been the subject of extensive research in the last 15 years. For particle sizes below 20 nm, the optical properties of nano phosphors change, e.g. the exciton energy increases and perhaps even more important, scattering decreases. We have synthesized nano Y2O3:Eu of particle sizes down to 10 nm, derived its optical properties, and investigated its use in Hg-free fluorescent lamps based on the Xe-excimer discharge. The possibility of using nano phosphors, e.g. semiconducting nano phosphors as CdSe or rare-earth doped phosphors as LaPO4:RE in LEDs, will be discussed.
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Authors: Sung Hoon Lee, Je Hong Park, Jong Su Kim, Tae Wan Kim, Hong Lee Park
Abstract: Spray pyrolysis was used to prepare ZnS:Mn2+ yellow nanophosphor. As an increase in firing temperature for spray pyrolysis, more nanoparticles of a hexagonal phase were formed together with these of the cubic structure. The optimized emission intensity was observed when the nanophosphor was fired at 900 oC after using a spraying solution of 3.5 pH. The particle size ranged from 60 nm to 400 nm. The ZnS:Mn2+ nanophosphor showed a redshift of about 10 nm in the emission spectrum compared to the microphosphor synthesized by solid-state reaction. The temperature-dependence photoluminescence showed different spectroscopic behaviour and displayed a longer decay time than the microphosphor.
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Authors: A. Martinez, J. Morales, P. Salas, C. Ángeles-Chávez, L.A. Diaz-Torres, E. De la Rosa Cruz
Abstract: This work is devoted to the structural and morphological study of co-doped Y2O3:Yb3+-Er3+ nanophosphors, with 1 mol% of Er2O3 and 2 mol% of Yb2O3, synthesized by hydrothermal precipitation method via cetyltrimethylammonium bromide (CTAB) surfactant complex for different ethanol/water solvent ratios ranging from 1:1 to 1:10. Structural characterization results showed the prevalence of cubic phase independent of the solvent ratio although particle size does depend on the solvent ratio. Concerning to morphology, microscopic characterization indicates that the content of water used in synthesis is determinant in the morphology of resulting samples: a high content of water favored the formation of nanorods/nanofibers while a low water content give rise to heterogeneous morphology with irregular particles. Also, solvent ratio determines the consistency of nanostructured materials; an intermediate solvent ratio leads to nanofibers while a high solvent ratio let to obtain nanorods with length/diameter ratio ~3-5. These results show that solvent concentration plays an important role in particle size and morphology of nanostructured materials while the annealing temperature determines the phase composition and crystallite size.
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Authors: R.S. Yadav, Y. Dwivedi, S.B. Rai
Abstract: Present article report synthesis and spectroscopic analysis of BiVO4 nanophosphor doped with trivalent Eu ions. It was observed that BiVO4 nanocrystals shows higher yield in comparison with the as-made nanocrystals on 266 nm laser excitation. On 266 nm excitation, emission composed of red dominated wide spectrum in the range of 400-950 nm was reported. Emission intensity enhanced five times on annealed sample than the counterpart. Time resolved analysis explores significant alteration in excited state relaxation process due to annealing. Detailed photo physics involved to improve optical emissions has also been explained.
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Authors: X.J. Wang, X.G. Fu
Abstract: Ca3(VO4)2:Eu3+,Bi3+ nanophosphate was prepared in the presence of stearic acid. The samples obtained were intensively characterized using XRD, SEM, photoluminescence (PL) spectra and FTIR. The results show that the red emission located at about 614 nm was ascribed to 5D0–7F2 transition of Eu3+, and the excitation and emission spectra indicate that this nanophosphor can be effectively excited by ultraviolet (UV) (395 nm), and exhibits a satisfactory red performance (614 nm), nicely fitting in with the widely applied UV LED chips.
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