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Sample records for doped thermographic phosphor

  1. Functional doped metal oxide films. Zinc oxide (ZnO) as transparent conducting oxide (TCO) titanium dioxide (TiO{sub 2}) as thermographic phosphor and protective coating

    Energy Technology Data Exchange (ETDEWEB)

    Nebatti Ech-Chergui, Abdelkader

    2011-07-29

    Metalorganic chemical vapor deposition (MOCVD) was used in the present work. Un-doped and Al-doped ZnO films were developed using two reactors: Halogen Lamp Reactor (HLR) (a type of Cold Wall Reactor) and Hot Wall Reactor (HWR), and a comparison was made between them in terms of the film properties. Zinc acetylacetonate was used as precursor for ZnO films while aluminum acetylacetonate was used for doping. The amount of Al doping can be controlled by varying the gas flow rate. Well ordered films with aluminum content between 0 and 8 % were grown on borosilicate glass and silicon. The films obtained are 0.3 to 0.5 {mu}m thick, highly transparent and reproducible. The growth rate of ZnO films deposited using HLR is less than HWR. In HLR, the ZnO films are well oriented along c-axis ((002) plane). ZnO films are commonly oriented along the c-axis due to its low surface free energy. On the other hand, the HWR films are polycrystalline and with Al doping these films aligned along the a-axis ((100) plane) which is less commonly observed. The best films were obtained with the HLR method showing a minimum electrical resistivity of 2.4 m{omega}cm and transmittance of about 80 % in the visible range. The results obtained for Al-doped films using HLR are promising to be used as TCOs. The second material investigated in this work was un-doped and doped titanium dioxide (TiO{sub 2}) films- its preparation and characterization. It is well known that thermographic phosphors can be used as an optical method for the surface temperature measurement. For this application, the temperature-dependent luminescence properties of europium (III)-doped TiO{sub 2} thin films were studied. It was observed that only europium doped anatase films show the phosphorescence. Rutile phase do not show phosphorescence. The films were prepared by the sol-gel method using the dip coating technique. The structures of the films were determined by X-ray diffraction (XRD). The excitation and the emission

  2. Effect of frost on phosphorescence for thermographic phosphor thermometry

    Science.gov (United States)

    Kim, Dong; Kim, Mirae; Kim, Kyung Chun

    2017-12-01

    In this study, we analyzed phosphorescence lifetime and its accuracy by growing frost for thermographic phosphor thermometry in a low-temperature environment. Mg4FGeO6:Mn particles were coated on an aluminum plate and excited with a UV-LED to obtain phosphorescence signals. The surface temperature was maintained at  -20, -15, -10 °C, and the phosphorescence signal was acquired as the frost grew for 3700 s. The lifetime was calculated and compared with the calibration curve under no-frost conditions. The error of the measured lifetime was within 0.7% of that in the no-frost conditions. A 2D surface temperature profile of the target plate was successfully obtained with the frost formation.

  3. Implementation of an Ultra-Bright Thermographic Phosphor for Gas Turbine Engine Temperature Measurements

    Science.gov (United States)

    Eldridge, Jeffrey I.; Bencic, Timothy J.; Zhu, Dongming; Cuy, Michael D.; Wolfe, Douglas E.; Allison, Stephen W.; Beshears, David L.; Jenkins, Thomas P.; Heeg, Bauke; Howard, Robert P.; hide

    2014-01-01

    The overall goal of the Aeronautics Research Mission Directorate (ARMD) Seedling Phase II effort was to build on the promising temperature-sensing characteristics of the ultrabright thermographic phosphor Cr-doped gadolinium aluminum perovskite (Cr:GAP) demonstrated in Phase I by transitioning towards an engine environment implementation. The strategy adopted was to take advantage of the unprecedented retention of ultra-bright luminescence from Cr:GAP at temperatures over 1000 C to enable fast 2D temperature mapping of actual component surfaces as well as to utilize inexpensive low-power laser-diode excitation suitable for on-wing diagnostics. A special emphasis was placed on establishing Cr:GAP luminescence-based surface temperature mapping as a new tool for evaluating engine component surface cooling effectiveness.

  4. Investigation of the effect of engine lubricant oil on remote temperature sensing using thermographic phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Abou Nada, Fahed, E-mail: Fahed.Abou_Nada@forbrf.lth.se; Aldén, Marcus; Richter, Mattias

    2016-11-15

    Phosphor thermometry, a remote temperature sensing technique, is widely implemented to measure the temperature of different combustion engines components. The presence of engine lubricant can influence the behavior of the applied sensor materials, known as thermographic phosphors, and thus leading to erroneous temperature measurements. The effect of two engine lubricants on decay times originating from six different thermographic phosphors was investigated. The decay time of each thermographic phosphor was investigated as a function of lubricant/phosphor mass ratio. Tests were conducted at temperatures around 293 K and 376 K for both lubricants. The investigations revealed that ZnO:Zn and ZnS:Ag are the only ones that exhibit a change of the decay time as function of the lubricant/phosphor mass ratio. While the remaining thermographic phosphors, namely BaMg{sub 2}Al{sub 16}O{sub 27}:Eu (BAM), Al{sub 2}O{sub 3}-coated BaMg{sub 2}Al{sub 16}O{sub 27}:Eu, La{sub 2}O{sub 2}S:Eu, Mg{sub 3}F{sub 2}GeO{sub 4}:Mn, displayed no sensitivity of their characteristic decay time on to the presence of lubricant on the porous coating. Biases in the calculated temperature are to be expected if the utilized thermographic phosphor displays decay time sensitivity to the existence of the engine lubricant within the sensor. Such distortions are concealed and can occur undetected leading to false temperature readings for the probed engine component.

  5. Thermographs

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Thermograph data collection consists primary of weekly circular charts recording continuous temperature at a given station. The collection also includes...

  6. Determination of surface temperatures in combustion environments using thermographic phosphors; Wandtemperaturmessungen in Verbrennungsumgebungen mithilfe thermographischer Phosphore

    Energy Technology Data Exchange (ETDEWEB)

    Bruebach, J.; Kissel, T. [TU Darmstadt (Germany). FG Energie- und Kraftwerkstechnik; Dreizler, A. [TU Darmstadt (Germany). FG Reaktive Stroemungen und Messtechnik

    2009-07-01

    A phosphor thermometry system was characterised with regard to all sources of systematic errors. Exemplary, the point measurement of a surface temperature and the determination of wall-normal temperature gradients within an optically accessible combustion chamber are outlined. Furthermore, the temporal temperature characteristic at the quartz ring of an optically accessible engine is presented. (orig.)

  7. Noncontact thermometry via laser pumped, thermographic phosphors: Characterization of systematic errors and industrial applications

    International Nuclear Information System (INIS)

    Gillies, G.T.; Dowell, L.J.; Lutz, W.N.; Allison, S.W.; Cates, M.R.; Noel, B.W.; Franks, L.A.; Borella, H.M.

    1987-10-01

    There are a growing number of industrial measurement situations that call for a high precision, noncontact method of thermometry. Our collaboration has been successful in developing one such method based on the laser-induced fluorescence of rare-earth-doped ceramic phosphors like Y 2 O 3 :Eu. In this paper, we summarize the results of characterization studies aimed at identifying the sources of systematic error in a laboratory-grade version of the method. We then go on to present data from measurements made in the afterburner plume of a jet turbine and inside an operating permanent magnet motor. 12 refs., 6 figs

  8. Color stable manganese-doped phosphors

    Science.gov (United States)

    Lyons, Robert Joseph [Burnt Hills, NY; Setlur, Anant Achyut [Niskayuna, NY; Deshpande, Anirudha Rajendra [Twinsburg, OH; Grigorov, Ljudmil Slavchev [Sofia, BG

    2012-08-28

    A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

  9. Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame Using a YAG:Tm Thermographic Phosphor

    Science.gov (United States)

    Eldridge, J. I.; Walker, D. G.; Gollub, S. L.; Jenkins, T. P.; Allison, S. W.

    2015-01-01

    Luminescence-based surface temperature measurements were obtained from a YAG:Tm-coated stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing was to demonstrate that reliable surface temperatures based on luminescence decay of a thermographic phosphor producing short-wavelength emission could be obtained from the surface of an actual engine component in a high gas velocity, highly radiative afterburner flame environment. YAG:Tm was selected as the thermographic phosphor for its blue emission at 456 nm (1D23F4 transition) and UV emission at 365 nm (1D23H6 transition) because background thermal radiation is lower at these wavelengths, which are shorter than those of many previously used thermographic phosphors. Luminescence decay measurements were acquired using a probe designed to operate in the afterburner flame environment. The probe was mounted on the sidewall of a high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick YAG:Tm thermographic phosphor layer was deposited by solution precursor plasma spray (SPPS). Spot temperature measurements were obtained by measuring luminescence decay times at different afterburner power settings and then converting decay time to temperature via calibration curves. Temperature measurements using the decays of the 456 and 365 nm emissions are compared. While successful afterburner environment measurements were obtained to about 1300C with the 456 nm emission, successful temperature measurements using the 365 nm emission were limited to about 1100C due to interference by autofluorescence of probe optics at short decay times.

  10. Thermographic Phosphors for High Temperature Measurements: Principles, Current State of the Art and Recent Applications

    Directory of Open Access Journals (Sweden)

    Konstantinos Kontis

    2008-09-01

    Full Text Available This paper reviews the state of phosphor thermometry, focusing on developments in the past 15 years. The fundamental principles and theory are presented, and the various spectral and temporal modes, including the lifetime decay, rise time and intensity ratio, are discussed. The entire phosphor measurement system, including relative advantages to conventional methods, choice of phosphors, bonding techniques, excitation sources and emission detection, is reviewed. Special attention is given to issues that may arise at high temperatures. A number of recent developments and applications are surveyed, with examples including: measurements in engines, hypersonic wind tunnel experiments, pyrolysis studies and droplet/spray/gas temperature determination. They show the technique is flexible and successful in measuring temperatures where conventional methods may prove to be unsuitable.

  11. Application of structured illumination to gas phase thermometry using thermographic phosphor particles: a study for averaged imaging

    Science.gov (United States)

    Zentgraf, Florian; Stephan, Michael; Berrocal, Edouard; Albert, Barbara; Böhm, Benjamin; Dreizler, Andreas

    2017-07-01

    Structured laser illumination planar imaging (SLIPI) is combined with gas phase thermometry measurements using thermographic phosphor (TGP) particles. The technique is applied to a heated jet surrounded by a coflow which is operated at ambient temperature. The respective air flows are seeded with a powder of BaMgAl10O17:Eu2+ (BAM) which is used as temperature-sensitive gas phase tracer. Upon pulsed excitation in the ultraviolet spectral range, the temperature is extracted based on the two-color ratio method combined with SLIPI. The main advantage of applying the SLIPI approach to phosphor thermometry is the reduction of particle-to-particle multiple light scattering and diffuse wall reflections, yielding a more robust calibration procedure as well as improving the measurement accuracy, precision, and sensitivity. For demonstration, this paper focuses on sample-averaged measurements of temperature fields in a jet-in-coflow configuration. Using the conventional approach, which in contrast to SLIPI is based on imaging with an unmodulated laser light sheet, we show that for the present setup typically 40% of the recorded signal is affected by the contribution of multiply scattered photons. At locations close to walls even up to 75% of the apparent signal is due to diffuse reflection and wall luminescence of BAM sticking at the surface. Those contributions lead to erroneous temperature fields. Using SLIPI, an unbiased two-color ratio field is recovered allowing for two-dimensional mean temperature reconstructions which exhibit a more realistic physical behavior. This is in contrast to results deduced by the conventional approach. Furthermore, using the SLIPI approach it is shown that the temperature sensitivity is enhanced by a factor of up to 2 at 270 °C. Finally, an outlook towards instantaneous SLIPI phosphorescence thermometry is provided.

  12. An imaging system for quantitive surface temperature mapping using two-color thermographic phosphors

    Science.gov (United States)

    Buck, Gregory M.

    1988-01-01

    A technique for obtaining detailed quantitative temperature distributions on test models in hypersonic wind tunnels is presented. This technique is based on the ratio of blue to green (450, 520 nm) emission from an UV (365 nm) excited phosphor coating. Separately filtered images are recorded from a three-tube color camera, utilizing off-the-shelf front-end video optics to discriminate wavelengths. Two demonstration studies in a 31-inch Mach 10 tunnel are discussed. One study presents the windward surface temperature-time history for a transatmospheric vehicle, and the other illustrates nosetip heating on a spherically blunted slender cone.

  13. New optical method for heat flux measurements in stagnation point laminar methane/air flames and hydrogen/methane/air flames using thermographic phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Elmnefi, Mohamed Salem

    2010-11-24

    In the present study, a new optical method was implemented to study the heat transfer from flat stagnation point flames which can be regarded as one-dimensional in the central part. Premixed methane-air flames and hydrogen-methane-air flames were investigated. The effects of burner-to-plate distance and the fresh gas mixture velocity on heat transfer were examined. Experiments were performed using light induced phosphorescence from thermographic phosphors to study the wall temperatures and heat fluxes of nearly one-dimensional flat premixed flames impinging upward normally on a horizontal water cooled circular flat plate. The investigated flames were stoichiometric, lean and rich laminar methane/air flames with different equivalence ratios of {phi} =1, {phi} = 0.75 and {phi} = 1.25 and stoichiometric laminar hydrogen/methane/air flames. Mixtures of air with 10, 25, 50 and 75 % hydrogen in methane (CH{sub 4}) as well as a pure hydrogen flames at ambient pressure were investigated. The central part of this plate was an alumina ceramic plate coated from both sides with chromium doped alumina (ruby) and excited with a Nd:YAG laser or a green light emitting diode (LED) array to measure the wall temperature from both sides and thus the heat flux rate from the flame. The outlet velocity of the gases was varied from 0.1 m/s to 1.2 m/s. The burner to plate distance ranged from 0.5 to 2 times the burner exit diameter (d = 30 mm).The accuracy of the method was evaluated. The measured heat flux indicate the change of the flame stabilization mechanism from a burner stabilized to a stagnation plate stabilized flame. The results were compared to modeling results of a one dimensional stagnation point flow, with a detailed reaction mechanism. In order to prove the model, also measured gas phase temperatures by OH LIF for a stoichiometric stagnation point flame were discussed. It turns out that the flame stabilization mechanism and with it the heat fluxes change from low to high

  14. Lanthanide-doped upconverting phosphors for bioassay and therapy

    Science.gov (United States)

    Guo, Huichen; Sun, Shiqi

    2012-10-01

    Lanthanide-doped fluorescent materials have gained increasing attention in recent years due to their unique luminescence properties which have led to their use in wide-ranging fields including those of biological applications. Aside from being used as agents for in vivo imaging, lanthanide-doped fluorescent materials also present many advantages for use in bioassays and therapy. In this review, we summarize the applications of lanthanide-doped up-converting phosphors (UCPs) in protein and gene detection, as well as in photodynamic and gene therapy in recent years, and outline their future potential in biological applications. The current report could serve as a reference for researchers in relevant fields.

  15. doped LiMgPO4 phosphor

    Indian Academy of Sciences (India)

    attention because of their remarkable luminescence proper- ties and .... Figure 1. (a) X-ray diffraction patterns of LiMgPO4:Tb3+ phosphor and (b) standard data. ICDD file. .... ground signal which affects the signal to noise ratio [17]. MDD was ...

  16. Rare Earth Doped Lanthanum Calcium Borate Polycrystalline Red Phosphors

    Directory of Open Access Journals (Sweden)

    H. H. Xiong

    2014-01-01

    Full Text Available Single-phased Sm3+ doped lanthanum calcium borate (SmxLa2−xCaB10O19, SLCB, x=0.06 polycrystalline red phosphor was prepared by solid-state reaction method. The phosphor has two main excitation peaks located at 398.5 nm and 469.0 nm, which are nicely in accordance with the emitting wavelengths of commercial near-UV and blue light emitting diode chips. Under the excitation of 398.0 nm, the dominant red emission of Sm3+ in SLCB phosphor is centered at 598.0 nm corresponding to the transition of 4G5/2 → 6H7/2. The Eu3+ fluorescence in the red spectral region is applied as a spectroscopic probe to reveal the local site symmetry in the host lattice and, hence, Judd-Ofelt parameters Ωt  (t=2, 4 of Eu3+ in the phosphor matrix are derived to be 3.62×10-20 and 1.97×10-20 cm2, indicating a high asymmetrical and strong covalent environment around rare earth luminescence centers. Herein, the red phosphors are promising good candidates employed in white light emitting diodes (LEDs illumination.

  17. Phosphorous Doping of Nanostructured Crystalline Silicon

    DEFF Research Database (Denmark)

    Plakhotnyuk, Maksym; Davidsen, Rasmus Schmidt; Steckel, André

    Nano-textured silicon, known as black silicon (bSi), is attractive with excellent photon trapping properties. bSi can be produced using simple one-step fabrication reactive ion etching (RIE) technique. However, in order to use bSi in photovoltaics doping process should be developed. Due to high s...

  18. Concentration and wavelength dependent frequency downshifting photoluminescence from a Tb3+ doped yttria nano-phosphor: A photochromic phosphor

    Science.gov (United States)

    Yadav, Ram Sagar; Rai, Shyam Bahadur

    2018-03-01

    In this article, the Tb3+ doped Y2O3 nano-phosphor has been synthesized through solution combustion method. The structural measurements of the nano-phosphor have been carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques, which reveal nano-crystalline nature. The Fourier transform infrared (FTIR) measurements reveal the presence of different molecular species in the nano-phosphor. The UV-Vis-NIR absorption spectrum of the nano-phosphor shows large number of bands due to charge transfer band (CTB) and 4f-4f electronic transitions of Tb3+ ion. The Tb3+ doped Y2O3 nano-phosphor emits intense green downshifting photoluminescence centered at 543 nm due to 5D4 → 7F5 transition on excitation with 350 nm. The emission intensity of the nano-phosphor is optimized at 1.0 mol% concentration of Tb3+ ion. When the as-synthesized nano-phosphor is annealed at higher temperature the emission intensity of the nano-phosphor enhances upto 5 times. The enhancement in the emission intensity is due to an increase in crystallinity of the nano-phosphor, reduction in surface defects and optical quenching centers. The CIE diagram reveals that the Tb3+ doped nano-phosphor samples show the photochromic nature (color tunability) with a change in the concentration of Tb3+ ion and excitation wavelength. The lifetime measurement indicates an increase in the lifetime for the annealed sample. Thus, the Tb3+ doped Y2O3 nano-phosphor may be used in photochromic displays and photonic devices.

  19. Temperature Mapping of Air Film-Cooled Thermal Barrier Coated Surfaces Using Cr-Doped GdAlO3 Phosphor Thermography

    Science.gov (United States)

    Eldridge, Jeffrey I.; Shyam, Vikram; Wroblewski, Adam C.; Zhu, Dongming; Cuy, Michael D.; Wolfe, Douglas E.

    2016-01-01

    It has been recently shown that the high luminescence intensity from a Cr-doped GdAlO3 (Cr:GdAlO3) thermographic phosphor enables non-rastered full-field temperature mapping of thermal barrier coating (TBC) surfaces to temperatures above 1000C. In this presentation, temperature mapping by Cr:GdAlO3 based phosphor thermometry of air film-cooled TBC-coated surfaces is demonstrated for both scaled-up cooling hole geometries as well as for actual components in a burner rig test environment. The effects of thermal background radiation and flame chemiluminescence on the measurements are investigated, and advantages of this method over infrared thermography as well as the limitations of this method for studying air film cooling are discussed.

  20. Photoluminescence studies on holmium (III) and praseodymium (III) doped calcium borophosphate (CBP) phosphors

    Science.gov (United States)

    Reddy Prasad, V.; Damodaraiah, S.; Devara, S. N.; Ratnakaram, Y. C.

    2018-05-01

    Using solid state reaction method, Ho3+ and Pr3+ doped calcium borophosphate (CBP) phosphors were prepared. These phosphors were characterized using XRD, SEM, FT-IR, 31P solid state NMR, photoluminescence (PL) and decay profiles. Structural details were discussed from XRD and FT-IR spectra. From 31P NMR spectra of these phosphors, mono-phosphate complexes Q0-(PO43-) were observed. Photoluminescence spectra were measured for both Ho3+ and Pr3+ doped calcium borophosphate phosphors and the spectra were studied for different concentrations. Decay curves were obtained for the excited level, 5F4+5S2 of Ho3+ and 1D2 level of Pr3+ in these calcium borophosphate phosphors and lifetimes were measured. CIE color chromaticity diagrams are drawn for these two rare earth ions in calcium borophosphate phosphors. Results show that Ho3+ and Pr3+ doped CBP phosphors might be served as green and red luminescence materials.

  1. Synthesis and luminescence properties of Eu"2"+ doped CaSO_4 phosphor

    International Nuclear Information System (INIS)

    Aghalte, G.A.; Dhoble, S.J.; Pawar, N.R.

    2016-01-01

    Eu"2"+ doped CaSO_4 Phosphor were synthesized by precipitation method. PL analysis of Eu"2"+ activated CaSO_4 phosphor exhibited characteristic emission properties; CaSO_4:Eu Phosphor has received considerable attention because of its high sensitivity to X-ray and λ ray irradiation. CaSO_4:Eu phosphor powder was successfully synthesized by the wet chemical co-precipitation method. The structure morphology and luminescent properties of the phosphor were characterized by X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy

  2. Neutron scintillator using Ga-doped ZnO phosphor with high detection efficiency

    International Nuclear Information System (INIS)

    Koyama, Shin; Kinoshita, Atsushi; Fujiwara, Akihiko; Kobayashi, Haruki; Takei, Yoshinori; Nanto, Hidehito; Katagiri, Masaki

    2009-01-01

    Zinc Oxide (ZnO) family phosphors as phosphor for neutron detector have prepared using Spark Plasma Sintering (SPS) method. The optical properties of ZnO phosphor prepared are investigated. The following results were obtained. Two dominant photoluminescence (PL) emission peaks at 395 nm and 495 nm were observed. The lifetime of the PL emission peak at 395 nm (UV emission band) is about 20 ns, which is suitable for neutron detection. The Ga (30 mol%)-doped ZnO phosphor exhibited an intense UV emission band without the visible emission band. The Ga-doped ZnO phosphor can be prepared at the atmospheric pressure of about 8 Pa using SPS method. It was found that the PL intensity of UV emission band is increased with improving the crystallinity of the ZnO phosphor. (author)

  3. Phosphors doped with Dy3+ and Gd3+ for lighting

    International Nuclear Information System (INIS)

    Su, Q; Pei, Z.; Zeng, Q.; Chi, L.

    1998-01-01

    Full text: Some heavy lanthanide ions with even atomic number such as Dy 3+ and Gd 3+ are abundant in the ion adsorption type deposit of China. Their price is cheap and they have specific spectroscopic properties which can be used as phosphors. Dy 3i on has two dominant bands in the emission spectrum. The yellow band (575 nm) corresponds to the hypersensitive transition 4 F 9/2 → 6 H 13/2 (ΔL=2, ΔJ=2), and the blue band (485 nm) corresponds to the 4 F 9/2 → 6 H 15/2 transition. Factors which influence on the yellow- to-blue intensity ratio (Y/B) were investigated. Adjusting to a suitable Y/B, Dy 3+ will emit white light with high colour temperature and can be used for lighting. But Dy 3+ ion has only narrow excitation bands of f-f transitions ranging from 300-500 nm, no broad excitation band such as charge transfer band or f-d transition band exists in the UV region 200-300 nm. Hence its luminescent efficiency is low when it is excited by UV radiation emitted from the mercury plasma. This is one of the drawbacks to its use as lamp phosphor. However, this can be overcome by sensitisation with Gd 3+ , Pb 2+ or other sensitisers such as vanadate shown in this report. Gd 3+ is not only a good matrix, but also a good sensitiser. Using its 8 S 7/2 → 6 D, 6 I and 6 P transitions, the UV excitation energy can be absorbed and transferred to the activator such as Dy 3+ . Therefore, in some cases Gd 3+ is better than Y 3+ which is optical inert as a matrix. For the phosphor Ca 1.96 Pb 0.04 RE 7.9 Dy 0.1 (SiO 4 ) 6 O 2 prepared by sol-gel method, the intensity of Dy 3+ in the Gd 3+ compound (RE=Gd 3+ ) is six times that in the Y 3+ compound. Some new phosphors doped with Dy 3+ and Gd 3+ prepared in our laboratory are reported

  4. Co-doping with antimony to control phosphorous diffusion in germanium

    KAUST Repository

    Tahini, H. A.; Chroneos, Alexander; Grimes, R. W.; Schwingenschlö gl, Udo

    2013-01-01

    donor co-doping on the migration activation energies of vacancy-mediated diffusion processes. The migration energy barriers for phosphorous and antimony were found to be increased significantly when larger clusters involving two donor atoms and a vacancy

  5. Thermoluminescence studies of natural and doped calcium fluoride phosphors

    International Nuclear Information System (INIS)

    El Kolaly, M.A.

    1977-01-01

    The various aspects of thermoluminescence (TL) of calcium fluoride phosphors obtained both from natural and laboratory-grown CaF 2 crystals have been investigated in the temperature range from room temperature to 750 deg C. Dopants used in these studies were Mn, Y and lanthanide series rare earths. The aspects which have been investigated are : (1) effect of single and double doping on TL glow curves and TL emission spectra after gamma irradiation, (2) TL traps : their kinetics including evaluation of the activation energy using different techniques, their decay kinetics and their behaviour under partially filled conditions, and (3) effect of temperature on emission of intensity of X-ray induced luminescence and TL. During the course of these investigations, a new glow peak was observed at 650 deg C in natural CaF 2 . It was found that this peak could also be produced in synthetic CaF 2 doped with (Y + Sm). A new model for the TL trap has also been proposed. (M.G.B.)

  6. UV, blue and red upconversion emission in Tm3+ doped Y2O3 phosphor

    International Nuclear Information System (INIS)

    Pandey, Anurag; Kaushal Kumar; Rai, Vineet Kumar

    2012-01-01

    Optimized solution combustion route has been adopted to prepare Tm 3+ doped Y 2 O 3 phosphor. The X-ray diffraction analysis of the doped phosphor for getting the structural information has been performed. Intense UV, blue and red emissions exhibiting narrow band have been monitored using 980 nm diode laser excitation. The origin of UV, blue and red upconversion emissions has been explained based on the available data. (author)

  7. Phosphor-Doped Thermal Barrier Coatings Deposited by Air Plasma Spray for In-Depth Temperature Sensing

    Directory of Open Access Journals (Sweden)

    Di Peng

    2016-09-01

    Full Text Available Yttria-stabilized zirconia (YSZ-based thermal barrier coating (TBC has been integrated with thermographic phosphors through air plasma spray (APS for in-depth; non-contact temperature sensing. This coating consisted of a thin layer of Dy-doped YSZ (about 40 µm on the bottom and a regular YSZ layer with a thickness up to 300 µm on top. A measurement system has been established; which included a portable; low-cost diode laser (405 nm; a photo-multiplier tube (PMT and the related optics. Coating samples with different topcoat thickness were calibrated in a high-temperature furnace from room temperature to around 900 °C. The results convincingly showed that the current sensor and the measurement system was capable of in-depth temperature sensing over 800 °C with a YSZ top layer up to 300 µm. The topcoat thickness was found to have a strong effect on the luminescent signal level. Therefore; the measurement accuracy at high temperatures was reduced for samples with thick topcoats due to strong light attenuation. However; it seemed that the light transmissivity of YSZ topcoat increased with temperature; which would improve the sensor’s performance at high temperatures. The current sensor and the measurement technology have shown great potential in on-line monitoring of TBC interface temperature.

  8. Thermoluminescence dosimetric characteristics of thulium doped ZnB2O4 phosphor

    International Nuclear Information System (INIS)

    Annalakshmi, O.; Jose, M.T.; Madhusoodanan, U.; Subramanian, J.; Venkatraman, B.; Amarendra, G.; Mandal, A.B.

    2014-01-01

    Polycrystalline powder samples of rare earth doped Zinc borates were synthesized by high temperature solid state diffusion technique. Dosimetric characteristics of the phosphor like thermoluminescence glow curve, TL emission spectra, dose–response, fading studies, reproducibility and reusability studies were carried out on the synthesized phosphors. Among the different rare earth doped phosphors, thulium doped zinc borate was found to have a higher sensitivity. Hence detailed dosimetric characteristics of this phosphor were carried out. It is observed that the dose–response is linear from 10 mGy to 10 3 Gy in this phosphor. EPR measurements were carried out on unirradiated, gamma irradiated and annealed phosphors to identify the defect centers responsible for thermoluminescence. A TL model is proposed based on the EPR studies in these materials. Kinetic parameters were evaluated for the dosimetric peaks using various methods. The experimental results show that this phosphor can have potential applications in radiation dosimetry applications. -- Highlights: • Polycrystalline powder samples of rare earth doped zinc borates were synthesized. • Thulium was observed to be the most efficient dopant in ZnB 2 O 4 lattice. • TL intensity of the dosimetric peak is around 20 times that of TLD-100. • Based on EPR studies a TL mechanism is proposed in zinc borate. • Deconvolution of the glow curve carried out

  9. Thermoluminescence dosimetric characteristics of thulium doped ZnB{sub 2}O{sub 4} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Annalakshmi, O. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Jose, M.T., E-mail: mtj@igcar.gov.in [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Madhusoodanan, U. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Subramanian, J. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai (India); Venkatraman, B. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Amarendra, G. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Mandal, A.B. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai (India)

    2014-02-15

    Polycrystalline powder samples of rare earth doped Zinc borates were synthesized by high temperature solid state diffusion technique. Dosimetric characteristics of the phosphor like thermoluminescence glow curve, TL emission spectra, dose–response, fading studies, reproducibility and reusability studies were carried out on the synthesized phosphors. Among the different rare earth doped phosphors, thulium doped zinc borate was found to have a higher sensitivity. Hence detailed dosimetric characteristics of this phosphor were carried out. It is observed that the dose–response is linear from 10 mGy to 10{sup 3} Gy in this phosphor. EPR measurements were carried out on unirradiated, gamma irradiated and annealed phosphors to identify the defect centers responsible for thermoluminescence. A TL model is proposed based on the EPR studies in these materials. Kinetic parameters were evaluated for the dosimetric peaks using various methods. The experimental results show that this phosphor can have potential applications in radiation dosimetry applications. -- Highlights: • Polycrystalline powder samples of rare earth doped zinc borates were synthesized. • Thulium was observed to be the most efficient dopant in ZnB{sub 2}O{sub 4} lattice. • TL intensity of the dosimetric peak is around 20 times that of TLD-100. • Based on EPR studies a TL mechanism is proposed in zinc borate. • Deconvolution of the glow curve carried out.

  10. Spectral properties of Dy3+ doped ZnAl2O4 phosphor

    Science.gov (United States)

    Prakash, Ram; Kumar, Sandeep; Mahajan, Rubby; Khajuria, Pooja; Kumar, Vinay; Choudhary, R. J.; Phase, D. M.

    2018-05-01

    Herein, Dy3+ doped ZnAl2O4 phosphor was synthesized by the solution combustion method. The synthesized phosphor was characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The phase purity of the phosphor was confirmed by the XRD studies that showed cubic symmetry of the synthesized phosphor. Under UV excitation (388 nm) the PL emission spectrum of the phosphor shows characteristic transition from the Dy3+ ion. A band gap of 5.2 eV was estimated from the diffused reflectance spectroscopy. The surface properties of the phosphor were studied using the X-ray photoelectron spectroscopy.

  11. Pyroelectric properties of phosphoric acid-doped TGS single crystals

    International Nuclear Information System (INIS)

    Saxena, Aparna; Fahim, M; Gupta, Vinay; Sreenivas, K

    2003-01-01

    Pyroelectric properties of phosphoric acid (H 3 PO 4 )-doped triglycine sulfate (TGSP) single crystals grown from solutions containing 0.1-0.5 mol of H 3 PO 4 have been studied. Incorporation of H 3 PO 4 into the crystal lattice is found to induce an internal bias field (E b ) and is observed through the presence of a sustained polarization and pyroelectricity beyond the transition temperature. The internal bias field has been estimated theoretically by fitting the experimentally measured data on temperature dependence of the pyroelectric coefficient (λ), dielectric constant (ε') and polarization (P). A high E b value in the range 9 x 10 3 -15.5 x 10 4 V m -1 is obtained for crystals grown with 0.1-0.5 mol of H 3 PO 4 in the solution, and a specific concentration of 0.2-0.25 mol of H 3 PO 4 in the solution during crystal growth is found to be optimum for a high figure of merit for detectivity, F d = 428 μC m -2 K -1

  12. Pyroelectric properties of phosphoric acid-doped TGS single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Aparna; Fahim, M; Gupta, Vinay; Sreenivas, K [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2003-12-21

    Pyroelectric properties of phosphoric acid (H{sub 3}PO{sub 4})-doped triglycine sulfate (TGSP) single crystals grown from solutions containing 0.1-0.5 mol of H{sub 3}PO{sub 4} have been studied. Incorporation of H{sub 3}PO{sub 4} into the crystal lattice is found to induce an internal bias field (E{sub b}) and is observed through the presence of a sustained polarization and pyroelectricity beyond the transition temperature. The internal bias field has been estimated theoretically by fitting the experimentally measured data on temperature dependence of the pyroelectric coefficient ({lambda}), dielectric constant ({epsilon}') and polarization (P). A high E{sub b} value in the range 9 x 10{sup 3}-15.5 x 10{sup 4} V m{sup -1} is obtained for crystals grown with 0.1-0.5 mol of H{sub 3}PO{sub 4} in the solution, and a specific concentration of 0.2-0.25 mol of H{sub 3}PO{sub 4} in the solution during crystal growth is found to be optimum for a high figure of merit for detectivity, F{sub d} = 428 {mu}C m{sup -2} K{sup -1}.

  13. Emission spectra of phosphor MgSO4 doped with Dy and Mn

    International Nuclear Information System (INIS)

    Zhang Chunxiang; Chen Lixin; Tang Qiang; Luo Daling; Qiu Zhiren

    2001-01-01

    Emission spectra of phosphor MgSO 4 doped with Dy and Dy/Mn were measured with an optical multichannel analyzer and a linear heating system whose temperature was controlled by a microcomputer. The emission spectrum bands at 480 nm and 580 nm of phosphor MgSO 4 doped with Dy were observed in the three dimensional (3D) glow curves. Compared with the 3D spectrum of CaSO 4 :Dy and the spectrum bands of MgSO 4 :Dy shows the same wavelengths which resulted from the quantum transitions among the energy levels of Dy 3 '+ ions. The intensities of the glow peaks in both spectrum bands (480 nm and 580 nm) of phosphor MgSO 4 doped with Dy/Mn were dramatically reduced except the 380 degree C glow peak

  14. Doping phosphoric acid in polybenzimidazole membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Jensen, Jens Oluf

    2007-01-01

    Polybenzimidazole (PBI) membranes were doped in phosphoric acid solutions of different concentrations at room temperature. The doping chemistry was studied using the Scatchard method. The energy distribution of the acid complexation in polymer membranes is heterogeneous, that is, there are two...... different types of sites in PBI for the acid doping. The protonation constants of PBI by phosphoric acid are found to be 12.7 L mol(-1) (K-1) for acid complexing sites with higher affinity, and 0.19 L mol(-1) (K-2) for the sites with lower affinity. The dissociation constants for the complexing acid onto...... these two types of PBI sites are found to be 5.4 X 10(-4) and 3.6 X 10(-2), respectively, that is, about 10 times smaller than that of aqueous phosphoric acid in the first case but 5 times higher in the second. The proton conducting mechanism is also discussed....

  15. Photoluminescent and Thermoluminescent Studies of Dy3+ and Eu3+ Doped Y2O3 Phosphors.

    Science.gov (United States)

    Verma, Tarkeshwari; Agrawal, Sadhana

    2018-01-01

    Eu 3+ doped and Dy 3+ codoped yttrium oxide (Y 2 O 3 ) phosphors have been prepared using solid-state reaction technique (SSR). The prepared phosphors were characterized by X-ray diffractometer (XRD), energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR) techniques. Photoluminescence (PL) and Thermoluminescence (TL) properties were studied in detail. PL emission spectra were recorded for prepared phosphors under excitation wavelength 254 nm, which show a high intense peak at 613 nm for Y 2 O 3 :Dy 3+ , Eu 3+ (1:1.5 mol %) phosphor. The correlated color temperature (CCT) and CIE analysis have been performed for the synthesized phosphors. TL glow curves were recorded for Eu 3+ doped and Dy 3+ codoped phosphors to study the heating rate effect and dose response. The kinetic parameters were calculated using peak shape method for UV and γ exposures through computerized glow curve deconvolution (CGCD) technique. The phosphors show second order kinetics and activation energies varying from 5.823 × 10 - 1 to 18.608 × 10 - 1  eV.

  16. Co-doping with antimony to control phosphorous diffusion in germanium

    KAUST Repository

    Tahini, H. A.

    2013-02-15

    In germanium, phosphorous and antimony diffuse quickly and as such their transport must be controlled in order to design efficient n-typed doped regions. Here, density functional theory based calculations are used to predict the influence of double donor co-doping on the migration activation energies of vacancy-mediated diffusion processes. The migration energy barriers for phosphorous and antimony were found to be increased significantly when larger clusters involving two donor atoms and a vacancy were formed. These clusters are energetically stable and can lead to the formation of even larger clusters involving a number of donor atoms around a vacancy, thereby affecting the properties of devices.

  17. Rare-earth doped phosphors: oldies or goldies?

    International Nuclear Information System (INIS)

    Moine, B.; Bizarri, G.

    2003-01-01

    The scientific research on phosphors has a long history starting more than 100 years ago. But recently the appearance of new kinds of displays and lighting devices (plasma display, fluorescent lamp without mercury, etc.) induced an increase of the research of new phosphors with better luminous efficiency than those available up to now. It has been shown that the behavior of 'classical' phosphors in a plasma display panel is quite different than in a cathode ray tube and that the vacuum ultraviolet (VUV) excitation process has to be studied with care in order to improve the phosphors efficiency. That is particularly true in PDPs. It is well established now that a good phosphor for electronic or ultraviolet excitation is not necessarily a good choice for excitation in VUV. This is probably due to the fact that the excitation process is very different in that case and also because the penetration depth of the VUV photons is extremely small inducing a large contribution of the surface of the phosphor. We will illustrate this with some examples. Methods to accelerate luminous intensity decrease under VUV excitation will be described. Low efficiency, fast aging process are both drawbacks that can be solved only in the framework of fundamental studies. Quantum cutting emission may be a solution for the first one but no satisfactory process was proposed for the moment to solve the second

  18. Phosphors

    International Nuclear Information System (INIS)

    1975-01-01

    This invention relates to phosphors that can be used in fluorescent lamps and display devices. The phosphor is comprised of a halophosphate of calcium and/or strontium of apatite crystal structure activated with trivalent cerium and trivalent terbium. The phosphor can further include manganese. Preferably, the phosphor includes up to 10% by weight of one or more of the alkali metals lithium, sodium and potassium in the form of a compound or compounds thereof. The emissions appear as a number of fairly narrow discrete bands. The temperature of preparation is 1000degC (as opposed to the usual 1450degC), therefore reducing costs (less energy is needed, more crucibles are readily obtainable and there is no need for special conditions to enable crucibles to overcome thermal shock)

  19. Proton conductivity of phosphoric acid doped polybenzimidazole and its composites with inorganic proton conductors

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Gang, Xiao

    2003-01-01

    Phosphoric acid doped polybenzimidazole (PBI) and PBI composite membranes have been prepared in the present work. The PBI composites contain inorganic proton conductors including zirconium phosphate (ZrP), (Zr(HPO4)2·nH2O), phosphotungstic acid (PWA), (H3PW12O40·nH2O) and silicotungstic acid (Si...

  20. Phosphoric acid doped imidazolium polysulfone membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Qingfeng; Jensen, Jens Oluf

    2012-01-01

    A novel acid–base polymer membrane is prepared by doping of imidazolium polysulfone with phosphoric acid for high temperature proton exchange membrane fuel cells. Polysulfone is first chloromethylated, followed by functionalization of the chloromethylated polysulfone with alkyl imidazoles i.e. me...

  1. Ce3+-Doped garnet phosphors : Composition modification, luminescence properties and applications

    NARCIS (Netherlands)

    Xia, Zhiguo; Meijerink, Andries

    2017-01-01

    Garnets have the general formula of A3B2C3O12 and form a wide range of inorganic compounds, occurring both naturally (gemstones) and synthetically. Their physical and chemical properties are closely related to the structure and composition. In particular, Ce3+-doped garnet phosphors have a long

  2. Phosphoric acid doped AB-PBI membranes and its applications in high temperature PEMFC

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Bjerrum, Niels

    2005-01-01

    Poly(2,5-benzimidazole) (ab-PBI) was prepared from 3,4-diaminobenzoic acid via a polymerisation reaction. The obtained polymer exhibits excellent thermal stability in a temperature range ….. The membrane of ab-PBI when doped with phosphoric acid at room temperaturepresents high proton conductivity...

  3. Spectrophotometric Analysis of Phosphoric Acid Leakage in High-Temperature Phosphoric Acid-Doped Polybenzimidazole Membrane Fuel Cell Application

    Directory of Open Access Journals (Sweden)

    Seungyoon Han

    2016-01-01

    Full Text Available High-temperature proton exchange membrane fuel cells (HT-PEMFCs utilize a phosphoric acid- (PA- doped polybenzimidazole (PBI membrane as a polymer electrolyte. The PA concentration in the membrane can affect fuel cell performance, as a significant amount of PA can leak from the membrane electrode assembly (MEA by dissolution in discharged water, which is a byproduct of cell operation. Spectrophotometric analysis of PA leakage in PA-doped polybenzimidazole membrane fuel cells is described here. This spectrophotometric analysis is based on measurement of absorption of an ion pair formed by phosphomolybdic anions and the cationoid color reagent. Different color reagents were tested based on PA detection sensitivity, stability of the formed color, and accuracy with respect to the amount of PA measured. This method allows for nondestructive analysis and monitoring of PA leakage during HT-PEMFCs operation.

  4. Photoluminescence properties of Li{sup +}-doped KNbO{sub 3}: Eu{sup 3+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnaiah, R.; Kim, Dongwoo; Yi, Soungsoo; Kim, Sunghoon [Silla University, Busan (Korea, Republic of); Jang, Kiwan; Lee, Hosueb [Changwon National University, Changwon (Korea, Republic of); Moon, Byungkee; Jeong, Junghyun [Pukyong National University, Busan (Korea, Republic of)

    2010-12-15

    Different concentrations of Li{sup +}-ions doped KNbO{sub 3}:Eu polycrystalline powder phosphors were prepared by using the conventional solid state reaction method and were characterized by using X-ray diffraction, field emission scanning electron microscopy, and by using photoluminescence excitation and emission measurements. The morphological and the photoluminescence properties of the phosphors were effectively improved with Li-doping. The PL properties as a function of Li concentration in the Li-doped KNbO{sub 3}:Eu phosphors using different excitation wavelengths, along with a comparison of results with these in similar reported works, are discussed in the present work.

  5. Enhanced red emission of LaVO4:Eu3+ phosphors by Li-doping

    International Nuclear Information System (INIS)

    Park, Sung Wook; Yang, Hyun Kyoung; Chung, Jong Won; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun; Jang, Ki Wan; Lee, Ho Sueb; Yi, Soung Soo

    2010-01-01

    LaVO 4 phosphors were synthesized by using a solid state reaction, and were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL). The XRD patterns of the Li-doped LaVO 4 :Eu 3+ powder phosphors revealed a mixture of tetragonal and monoclinic phases. The tetragonal phase of the LaVO 4 :Eu 3+ phosphor showed a higher PL intensity than the monoclinic one, despite the presence of both monoclinic and tetragonal structures. The Li-doped LaVO 4 :Eu 3+ powder phosphors absorbed strongly at 396 nm and exhibited strong red emission at approximately 619.5 nm due to the 5 D 0 → 7 F 2 transition. The incorporation of Li + ions into the LaVO 4 :Eu 3+ powder can lead to a remarkable increase in photoluminescence. The enhanced luminescence is attributed to the incorporation of Li + ions that may act as a sensitizers for effective energy transfer. This phosphor has promising applications in near-UV light-emitting diodes(LEDs).

  6. Luminescence in Eu2+ and Ce3+ doped SrCaP2O7 phosphors

    Directory of Open Access Journals (Sweden)

    K.N. Shinde

    Full Text Available Eu2+ and Ce3+ doped SrCaP2O7 has been achieved by modified solid state diffusion in reducing atmosphere. The prepared phosphor powders have been identified by their characteristic X-ray diffraction patterns. The mixed phases of α-Sr2P2O7 type with orthorhombic and α-Ca2P2O7 type with monoclinic form were investigated. Its excitation wavelength ranging from 250 to 430 nm fits well with the characteristic emission of UV light-emitting diode (LED. The excitation and emission spectra indicate that these phosphors can be effectively excited by the near-UV light, and emits blue (visible range due to 4f7 → 4f65d1 transition of Eu2+ particularly, SrCaP2O7: Eu2+ whereas, photoluminescence excitation spectrum measurements of Ce3+ activated SrCaP2O7 shows that the phosphor can be efficiently excited by UV–Vis light from 280 to 310 nm to realize emission in the near visible range due to the 5d–4f transition of Ce3+ ions which is applicable for scintillation purpose. The impacts of doping of divalent europium and trivalent cerium on photoluminescence properties on SrCaP2O7 pyrophosphate phosphors were investigated and I propose a feasible interpretation. Keywords: Phosphor, Luminescence, XRD, LED, FTIR

  7. Eu/Tb ions co-doped white light luminescence Y2O3 phosphors

    International Nuclear Information System (INIS)

    Tu Dong; Liang Yujun; Liu Rong; Li Daoyi

    2011-01-01

    Y 2 O 3 :Eu 3+ , Tb 3+ phosphors with white emission are prepared with different doping concentration of Eu 3+ and Tb 3+ ions and synthesizing temperatures from 750 to 950 deg. C by the co-precipitation method. The resulted phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy. The results of XRD indicate that the crystallinity of the synthesized samples increases with enhancing the firing temperature. The photoluminescence spectra indicate the Eu 3+ and Tb 3+ co-doped Y 2 O 3 phosphors show five main emission peaks: three at 590, 611 and 629 nm originate from Eu 3+ and two at 481 and 541 nm originate from Tb 3+ , under excitation of 250-320 nm irradition. The white light luminescence color could be changed by varying the excitation wavelength. Different concentrations of Eu 3+ and Tb 3+ ions were induced into the Y 2 O 3 lattice and the energy transfer from Tb 3+ →Eu 3+ ions in these phosphors was found. The Commission International de l'Eclairage (CIE) chromaticity shows that the Y 2 O 3 :Eu 3+ , Tb 3+ phosphors can obtain an intense white emission. - Highlights: → Novel phosphors Y 2 O 3 :Eu 3+ , Tb 3+ have been synthesized by co-precipitation method. → Samples emit white light with excellent color coordinates under UV excitation. → Luminescence color could be changed by varying the excitation wavelength. → Energy transfer from Tb 3+ →Eu 3+ ions in these phosphors was found.

  8. Photoluminescence in Sm3+ doped Ba2P2O7 phosphor prepared by solution combustion method

    Science.gov (United States)

    Ghawade, Sonal P.; Deshmukh, Kavita A.; Dhoble, S. J.; Deshmukh, Abhay D.

    2018-05-01

    In this paper, Sm3+ doped Ba2P2O7 phosphors were synthesized via a Solution combustion method. The crystal structure of the phosphor was characterized by XRD. Orange-red emission was observed from these phosphors under near-ultraviolet (UV) excitation at 404 nm. The luminescence properties of the obtained phosphors were characterized by different techniques. The Ba2P2O7:Sm3+ phosphor can be efficiently excited by near-UV and blue light, and their emission spectrum consists of three emission peaks, at 564, 602, and 646 nm, respectively. Based on the results, the as prepared Ba2P2O7:Sm3+ phosphors are promising orange-red-emitting phosphors exhibit great potential may be applicable as a spectral convertor in c-Si solar cell to enhance the efficiency of solar cell in future.

  9. TL process in europium doped alkaline earth sulphate phosphors- a review

    International Nuclear Information System (INIS)

    Bhatt, B.C.

    2003-01-01

    CaSO 4 doped with the rare earth (RE) ion dysprosium or thulium is used routinely as a thermoluminescent dosimeter (TLD) to monitor personal exposure to x- and γ-radiation. The CaSO 4 :Eu phosphor is potentially important for radio photoluminescence (RPL) and ultraviolet (UV) dosimetry. Eu 3+ → Eu 2+ conversion is suggested to play a pivotal role in UV and γ-ray induced thermoluminescence. However, there is disagreement among different workers on the mechanism of gamma and UV induced TL in this phosphor system. This paper will review the work reported on CaSO 4 :Eu and make effects to project overall picture on this phosphor system. (author)

  10. Luminescence properties of dysprosium doped calcium magnesium silicate phosphor by solid state reaction method

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, Ishwar Prasad, E-mail: ishwarprasad1986@gmail.com [School of Studies in Physics & Astrophysics, Pt. Ravishankar Shukla University, Raipur, C.G. 492010 (India); Chandrakar, Priya; Baghel, R.N.; Bisen, D.P.; Brahme, Nameeta [School of Studies in Physics & Astrophysics, Pt. Ravishankar Shukla University, Raipur, C.G. 492010 (India); Tamrakar, Raunak Kumar [Department of Applied Physics, Bhilai Institute of Technology, Durg, C.G. 491001 (India)

    2015-11-15

    Dysprosium doped calcium magnesium silicate (CaMgSi{sub 2}O{sub 6}:Dy{sup 3+}) white light emitting phosphor was synthesized by solid state reaction process. The crystal structure of sintered phosphor was monoclinic structure with space group C2/c. Chemical composition of the sintered CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor was confirmed by EDX. The prepared CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor was excited from 352 nm and their corresponding emission spectra were recorded at blue (470 nm), yellow (570 nm) and red (675 nm) line due to the {sup 4}F{sub 9/2} → {sup 6}H{sub 15/2}, {sup 4}F{sub 9/2} → {sup 6}H{sub 13/2}, {sup 4}F{sub 9/2} → {sup 6}H{sub 11/2} transitions of Dy{sup 3+} ions. The combination of these three emissions constituted as white light confirmed by the Commission Internationale de L'Eclairage (CIE) chromatic coordinate diagram. The possible mechanism of the white light emitting long lasting CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor was also investigated. Investigation on afterglow property show that phosphor held fast and slow decay process. The peak of mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the local piezoelectricity-induced electron bombardment model is responsible to produce ML in prepared CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor. - Highlights: • The crystal structure of CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor is consistent with standard monoclinic structure. • CIE coordinates of CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor is suitable as white light emitting phosphor. • The local piezoelectricity-induced electron bombardment model is responsible to produce ML in CaMgSi{sub 2}O{sub 6}:Dy{sup 3+} phosphor.

  11. Synthesis and characterization of europium doped LiF phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Villalobos, M. L.; Vallejo, M. A.; Sosa A, M. [Universidad de Guanajuato, Division de Ciencias e Ingenierias, Loma del Bosque No. 103, Lomas del Campestre, 37150 Leon, Guanajuato (Mexico); Diaz T, L. A., E-mail: villaloboscm2010@licifug.ugto.mx [Centro de Investigaciones en Optica, A. C., Loma del Bosque No. 115, Lomas del Campestre, 37150 Leon, Guanajuato (Mexico)

    2015-10-15

    LiF with different dopants has been one of the most investigated materials to use as thermoluminescent dosimeter. In this paper, we present the preparation method, the characterization and the thermoluminescent response of Eu doped LiF irradiated with X-rays. Pure and Eu doped LiF samples with different dopant concentration (0, 0.25, 0.5, 0.75 and 1 % mol) were synthesized using the precipitation method. The samples were structurally characterized by X-ray diffraction (XRD), the diffraction patterns showed a main cubic crystalline structure and a secondary hexagonal structure. The photoluminescence spectrum exhibited four well defined peaks characteristic of the Eu{sup 3+} ion. Thermoluminescent (Tl) glow curves of x-ray irradiated samples showed a well-defined single peak around 200 degrees C, except for the pure and 0.25% Eu doped samples. (Author)

  12. Proton conductivity of phosphoric acid doped polybenzimidazole and its composites with inorganic protontic conductors

    DEFF Research Database (Denmark)

    Li, Qingfeng

    2003-01-01

    contain inorganic protonic conductors including zirconium phosphate (ZrP), (Zr(HPO4)2. nH2O); phosphotungstic acid (PWA), (H3PW12O40. nH2O); and silicotungstic acid (SiWA), (H4SiW12O40 . nH2O). The conductivity of phosphoric acid doped PBI and PBI composite membranes was found to be dependent on the acid...

  13. Long afterglow property of Er"3"+ doped Ca_2SnO_4 phosphor

    International Nuclear Information System (INIS)

    Zhang, Dongyun; Shi, Mingming; Sun, Yiwen; Guo, Yunyun; Chang, Chengkang

    2016-01-01

    A novel green emitting long afterglow phosphor, Er"3"+ -doped Ca_2SnO_4 (Ca_2SnO_4:Er"3"+), was prepared successfully via a traditional high temperature solid–state reaction method. Its properties have been characterized and analyzed by utilizing x-ray diffraction (XRD), photoluminescence spectroscope (PLS), afterglow decay curve (ADC) and thermal luminescence spectroscope (TLS). Three main emission peaks of PLS locate at 524, 550 and 668 nm, corresponding to CIE chromaticity coordinates of x = 0.326, y = 0.6592. An optimal doping concentration of Er"3"+ of 2% was determined. The Ca_2SnO_4:Er"3"+ phosphors showed a typical triple-exponential afterglow decay behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of Ca_2SnO_4:2 mol% Er"3"+ phosphors was generated by the suitable electron or hole traps which were resulted from the doping the Ca_2SnO_4 host with rare-earth ions (Er"3"+). - Highlights: • A novel green emitting long afterglow phosphor, Ca_2SnO_4:Er"3"+, was prepared. • An optimal doping concentration of Er"3"+ of 2% was determined. • After the UV source was turned off, the Ca_2SnO_4:Er"3"+ showed a typical triple-exponential afterglow decay behavior. • CIE chromaticity coordinates results confirmed a green light emitting of the Ca_2SnO_4:Er"3"+. • The persistent afterglow of the Ca_2SnO_4:Er"3"+ was attributed to suitable electron or hole traps.

  14. Color tunability of Sm{sup 3+} doped antimony–phosphate glass phosphors showing broadband fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, P. [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Zhang, J.J., E-mail: zhangjj@dlpu.edu.cn [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Shen, L.F. [Department of Electronic Engineering and State Key Laboratory of Millimeter Waves, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wang, Z.Q. [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Pun, E.Y.B. [Department of Electronic Engineering and State Key Laboratory of Millimeter Waves, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Lin, H., E-mail: lhai8686@yahoo.com [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Department of Electronic Engineering and State Key Laboratory of Millimeter Waves, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2016-10-15

    Sm{sup 3+} doped multicomponent antimony phosphate (MSP) luminescent glasses were prepared and tunable white fluorescence has been investigated. Broad visible emission depending on excitation wavelength is validated to be dominated by discrepant Sb{sup 3+} emitting centers. Group of narrow emissions from Sm{sup 3+} is beneficial to adding yellow and red components in Sm{sup 3+} doped MSP glasses, which is strengthened by effective energy transfer from Sb{sup 3+} to Sm{sup 3+}. Excitation wavelength selection and Sm{sup 3+} concentration adjustment are two feasible routes to optimize luminescence color in Sm{sup 3+} doped MSP glasses and the color tunability of fluorescence indicates that amorphous Sm{sup 3+} doped MSP glass phosphors possess potential for ideal white light devices.

  15. Radiation-induced defects in manganese-doped lithium tetraborate phosphor.

    Science.gov (United States)

    Annalakshmi, O; Jose, M T; Madhusoodanan, U; Sridevi, J; Venkatraman, B; Amarendra, G; Mandal, A B

    2015-01-01

    Lithium tetraborate doped with manganese synthesised by solid-state sintering technique exhibits a dosimetric peak at 280°C. The high-temperature glow curve results in no fading for three months. The sensitivity of Li2B4O7:Mn is determined to be 0.9 times that of TLD-100. The infrared spectrum of this phosphor indicates the presence of bond vibrations corresponding to BO4 tetrahedral and BO3 triangles. The mechanism for thermoluminescence in this phosphor was proposed based on the thermoluminescence (TL) emission spectra, kinetic analysis of TL glow curves and electron paramagnetic resonance (EPR) measurements on non-irradiated and gamma-irradiated phosphors. It was identified that oxygen vacancies and Boron oxygen hole centre (BOHC) are the electron and hole trap centres for TL in this phosphor. When the phosphor is heated, the electrons are released from the electron trap and recombine with the trapped holes. The excitation energy during the recombination is transferred to the nearby Mn(2+) ions, which emit light at 580 nm. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Host sensitized near-infrared emission in Nd3+ doped different alkaline-sodium-phosphate phosphors

    Science.gov (United States)

    Balakrishna, A.; Swart, H. C.; Kroon, R. E.; Ntwaeaborwa, O. M.

    2018-04-01

    Near-infrared (NIR) emitting phosphors of different alkaline based sodium-phosphate (MNa[PO4], where M = Mg, Ca, Sr and Ba were prepared by a conventional solution combustion method with fixed doping concentration of Nd3+ (1.0 mol%). The phosphors were characterized by powder X-ray diffraction, field emission scanning electron microscope, Fourier transform infrared spectroscopy, UV-vis spectroscopy and fluorescent spectrophotometry. The optical properties including reflectance, excitation and emission were investigated. The excitation spectra of the phosphors were characterized by a broadband extending from 450 to 900 nm. Upon excitation with a wavelength of 580 nm, the phosphor emits intensely infrared region at 872 nm, 1060 nm and 1325 nm which correspond to the 4F3/2 → 4I9/2, 4F3/2 → 4I11/2 and 4F3/2 → 4I13/2 transitions of Nd3+ ions and were found to vary for the different hosts. The strongest emission wavelength reaches 1060 nm. The most intense emission of Nd3+ was observed from Ca2+ incorporated host. The down conversion emissions of the material fall in the NIR region suggesting that the prepared phosphors have potential application in the development of photonic devices emitting in the NIR.

  17. Silver lead borate glasses doped with europium ions for phosphors ...

    Indian Academy of Sciences (India)

    2017-07-25

    Jul 25, 2017 ... C. The investigation of Fourier transformer infrared spectra shows the presence of ... around the ions, these kinds of Eu3+ doped glasses find wide range of ... is attributed to hydroxyl (OH) or water group [12]. The broad water ...

  18. On the symmetry of phosphorous doped ZnSe

    Indian Academy of Sciences (India)

    The site symmetry of P doped ZnSe is analysed in detail here, as the recent experiments suggest two possible symmetries T d and C 3 V . The reduction to C 3 V is attributed to the presence of natural impurity, Ga. Our calculations based on molecular model and Green's functions suggest that the symmetry C 3 V is possible ...

  19. On the symmetry of phosphorous doped ZnSe

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The site symmetry of P doped ZnSe is analysed in detail here, as the recent experiments suggest two possible symmetries Td and C3V. The reduction to C3V is attributed to the presence of natural impurity,. Ga. Our calculations based on molecular model and Green's functions suggest that the symmetry C3V is.

  20. Effect of Er doping on optical transmission and EL spectra of (Zn, Cd)S:Cu phosphors

    International Nuclear Information System (INIS)

    Patil, P.K.; Nandgave, J.K.; Lawangar Pawar, R.D.

    1991-01-01

    Powder phosphors((Znsub(0.4)Cdsub(0.6))S)doped with Cu and Er have been prepared under the inert atmosphere of argon. The optical transmission spectra of Cu doped phosphors have been investigated and explained on the basis of copper associated defect states. The improvement of optical transmission of the phosphors due to Er doping has been reported and explained. The EL emission spectrum of (Znsub(0.4)Cdsub(0.6))S:Cu:Er phosphors exhibits two broad bands characteristic of Cu. The absence of characteristic Er bands has been explained as an effect of thermal quenching of Er donor levels. (author). 9 refs., 2 figs

  1. Recent advances in enhanced luminescence upconversion of lanthanide-doped NaYF4 phosphors

    Science.gov (United States)

    Kumar, Deepak; Verma, Kartikey; Verma, Shefali; Chaudhary, Babulal; Som, Sudipta; Sharma, Vishal; Kumar, Vijay; Swart, Hendrik C.

    2018-04-01

    NaYF4 is regarded as the best upconversion (UC) matrix owing to its low phonon energy, more chemical stability, and a superior refractive index. This review reports on the various synthesis techniques of lanthanide-doped NaYF4 phosphors for UC application. The UC intensity depends on different properties of the matrix and those are discussed in detail. Plasmon-enhanced luminescence UC of the lanthanide-doped NaYF4 core-shells structure is discussed based on a literature survey. The present review provides the information about how the UC intensity can be enhanced. The idea about the UC is then deliberately used for versatile applications such as luminescent materials, display devices, biomedical imaging and different security appliances. In addition, the present review demonstrates the recent trends of NaYF4 UC materials in solar cell devices. The role of NaYF4 phosphor to eradicate the spectral variance among the incident solar spectrum, semiconductor as well as the sub-band gap nature of the semiconductor materials is also discussed in detail. Considering the fact that the research status on NaYF4 phosphor for photovoltaic application is now growing, the present review is therefore very important to the researchers. More importantly, this may promote more interesting research platforms to investigate the realistic use of UC nanophosphors as spectral converters for solar cells.

  2. Thermoluminescent phosphor

    Science.gov (United States)

    Lasky, Jerome B.; Moran, Paul R.

    1978-01-01

    A thermoluminescent phosphor comprising LiF doped with boron and magnesium is produced by diffusion of boron into a conventional LiF phosphor doped with magnesium. Where the boron dopant is made to penetrate only the outer layer of the phosphor, it can be used to detect shallowly penetrating radiation such as tritium beta rays in the presence of a background of more penetrating radiation.

  3. Luminescence characteristics and glow curves analysis of Cu"+ doped Li_3PO_4 phosphor

    International Nuclear Information System (INIS)

    Aghalte, G.A.; Dhoble, S.J.; Pawar, N.R.

    2016-01-01

    Li_3PO_4:Cu exhibits useful TL properties in personnel dosimetry of ionizing radiations. Cu is known to be one of the most efficient activator. The PL intensity is found to increase consistently with the increasing quenching temperature. Cu"+ doped Li_3PO_4 phosphor was synthesized by the wet chemical co-precipitation method. The crystal structure and particle morphology of the phosphor was investigated by using X-ray diffraction and scanning electron microscopy. Li_3PO_4:Cu is excellent phosphor for TL dosimetry. For the synthesis of Li_3PO_4:Cu phosphor the stoichiometric amounts of LiOH·H_2O and CuSO_4·"5H_2O were dissolved separately and then the solutions were mixed together. It was precipitated by using concentrated H_3PO_4. The precipitate was filtered out immediately and kept 12 hours below IR lamp. Prepared dry Li_3PO_4:Cu powder was then put on 2.5 wt% NH_4Cl in graphite crucible in preheated furnace at 800°C and was kept for 1 hour. It was then rapidly quenched to room temperature. Thermoluminescence (TL) glow curves were recorded on Nucleonix TL Reader with a heating rate of 2°C per second in the temperature range of 50-250°C. The PMT voltage was 750 volts. Photoluminescence (PL) studies were carried out by Hitachi F-4000 spectrophotometer with a spectral slit width of 1.5 nm

  4. Effect of annealing on structural and luminescence properties of Eu3+ doped NaYF4 phosphor

    Science.gov (United States)

    Pathak, Trilok K.; Kumar, Ashwini; Swart, H. C.; Kroon, R. E.

    2018-04-01

    Eu3+ doped NaYF4 phosphors have been synthesized by the combustion method. The effect of annealing on the structural, morphological and luminescence properties has been investigated. X-ray diffraction analysis revealed that the Eu3+ doped NaYF4 phosphors consisted of mixed phases: α-phase and β-phase which were affected by the annealing of the phosphor. The surface morphology showed a significant change with annealing in the Eu3+ doped NaYF4 phosphors. The elemental mapping and energy dispersive X-ray spectroscopy spectra proved the formation of the desired materials. The photoluminescence spectra illustrated the optical properties of Eu3+ in the as-prepared and annealed Eu3+ doped NaYF4 phosphors. The intensity of the peaks 5D0 → 7F2 and 5D0 → 7F1 varied in as-prepared and annealed samples. The lifetime of the Eu3+ luminescence at 615 nm was also weakly affected by the Eu3+ doping and annealing temperature.

  5. Thermoluminescence glow curve of CaZrO3 phosphor doped with Eu3+

    International Nuclear Information System (INIS)

    Tiwari, Neha; Kuraria, R.K.; Kuraria, S.R.

    2014-01-01

    Behaviour displayed by thermoluminescence analysis of Eu 3+ doped CaZrO 3 phosphor prepared by combustion synthesis technique. The sample was synthesized by combustion method because it is less time taking method as well as low temperature synthesis. For the thermoluminescence study the prepared sample irradiated by UV lamp the wavelength is 254 nm. Every time 2 mg of sample used for TL record at fixed heating rate 5℃ s -1 , sample shows well resolved higher temperature peak at 273℃. The high temperature peak shows more stability and less fading in prepared phosphor which is suitable for TL dosimetry. Also the variation with UV dose (5 to 30 min) shows sublinear response with dose

  6. UV induced thermoluminescence in rare earth oxide doped phosphors: possible use for UV dosimetry

    International Nuclear Information System (INIS)

    Yeh, S.-M.; Su, C.-S.

    1996-01-01

    UV induced thermoluminescent (TL) phenomena in some phosphors doped with rare earth oxides (Gd 2 O 3 :Eu, Gd 2 O 3 :Tb, Gd 2 O 3 :Dy and Y 2 O 3 :EU) have been investigated. Gd 2 O 3 :Eu and Y 2 O 3 :Eu have been found to possess prominent TL phenomena. A stable high temperature glow peak has been found at 345 o C in the cubic (C type) crystalline structure of Gd 2 O 3 :Eu. A more stable high temperature glow peak has also been found at about 380 o C in Y 2 O 3 :Eu. The sensitivity is high enough to be used as UV sensors. TL phenomena in Gd 2 O 3 :Tb and Gd 2 O 3 :Dy have also been investigated, but their TL intensities are much weaker than that of Gd 2 O 3 :Eu or Y 2 O 3 :Eu. On the other hand, all glow peaks of Gd 2 O 3 :Tb and Gd 2 O 3 :Dy are unstable at room temperature, therefore, Gd 2 O 3 :Tb and Gd 2 O 3 :Dy are not suitable for use as UV detectors. According to the above properties, the C type (cubic) crystalline structure of the Gd 2 O 3 :Eu phosphor seems to possess the potential of being the TL material for UV measurement. The position of the high temperature glow peak depends on the total UV exposure. It locates at about 380 o C when this phosphor was irradiated by 302 nm UV at 2.4 mJ.cm -2 exposure, but it shifts to 345 o C at 19.2 mJ.cm -2 or higher exposure. The response curves of this phosphor for various wavelengths, e.g. 253.7 nm, 302 nm, and 365 nm, were also measured. This phosphor is sensitive enough to measure background UV radiations, such as sunlight, bulb light etc. (author)

  7. Synthesis and luminescent properties of Sm3+ doped zinc aluminate phosphor

    Science.gov (United States)

    Mahajan, Rubby; Kumar, Sandeep; Prakash, Ram; Kumar, Vinay

    2018-05-01

    Zinc Aluminate (ZnAl2O4) is a well-known wide band gap oxide that belongs to a class of mixed-metal oxides knows as spinels (AB2O4) where A and B are divalent and trivalent cations. Herein, the structural and photoluminescence properties of Sm3+ ion doped with ZnAl2O4 phosphors are reported. The nanophosphors were synthesized via solution combustion synthesis route at temperature 570 °C. The synthesized samples were characterized by X-ray powder diffraction (XRD), Photoluminescence (PL) spectroscopy, and Ultraviolet-visible spectroscopy. The XRD pattern confirms the cubic phase of phosphor. The calculated lattice parameter were found as a = b = c = 8.0517Å and V = 521.85Å3. The crystallite size of the phosphor was calculated using the Debye-Scherrer formula and found to be ˜19 nm. The emission spectrum at excitation wavelength of 401 nm gave the emission peaks at 563 nm, 601 nm, 648 nm, 697 nm corresponding to the transitions 4G5/2→ 6H5/2, 4G5/2→6H7/2, 4G5/2→6H9/2, 4G5/2 → 6H11/2 of Sm3+ ions, respectively. The diffuse reflectance spectrum was used to calculate the band gap of material and found to be 5.12 eV. The CIE coordinates were found to be (x = 0.56, y = 0.40) that falls in the orange red region of the color gamut. The present phosphor may have potential applications as phosphor for near UV WLED for solid state lighting.

  8. Synthesis and photoluminescence properties of Eu{sup 3+}, Sm{sup 3+} and Pr{sup 3+} doped Ca{sub 2}ZnWO{sub 6} phosphors for phosphor converted LED

    Energy Technology Data Exchange (ETDEWEB)

    Dabre, K.V. [Department of Physics, Arts, Commerce and Science College, Koradi, Nagpur-441111, Maharashtra (India); Dhoble, S.J., E-mail: sjdhoble@rediffmail.com [Department of Physics, R.T.M. Nagpur University, Nagpur-440033, Maharashtra (India)

    2014-06-01

    In this work, we report on the synthesis and photoluminescence (PL) properties of rare earth (Eu{sup 3+}, Sm{sup 3+} and Pr{sup 3+}) doped double perovskite tungstate Ca{sub 2}ZnWO{sub 6} phosphor. The phosphors were synthesized by two step modified solid state method. Phase purity and formation of phosphor were confirmed by XRD technique. PL spectra of Eu{sup 3+}, Sm{sup 3+} and Pr{sup 3+} doped phosphor show intense emission peaks in red region at 615, 604 and 650 nm respectively, upon the visible excitation of 466 nm (Eu{sup 3+}), 410 nm (Sm{sup 3+}) and 491 nm (Pr{sup 3+}). The CIE coordinates of the phosphors are in the yellow (Sm{sup 3+} doped sample) and orange (Eu{sup 3+} and Pr{sup 3+} doped sample) regions near the edge of color space which confirms their applicability in LEDs. -- Highlights: •Eu{sup 3+}, Sm{sup 3+} and Pr{sup 3+} doped and undoped samples of Ca{sub 2}ZnWO{sub 6} phosphor synthesized by Solid state method. •The phosphors have intense excitation in violet and blue region of visible spectrum. •Phosphors show intense emission peaks in red region. •CIE coordinates of phosphors are lie in yellow (Sm{sup 3+} doped phosphor) and orange (Eu{sup 3+} and Pr{sup 3+} doped phosphor) region near to edge of color space.

  9. Solvothermally synthesized europium-doped CdS nanorods: applications as phosphors

    International Nuclear Information System (INIS)

    Kumar, Sunil; Jindal, Zinki; Kumari, Nitu; Verma, Narendra Kumar

    2011-01-01

    To exploit the photoluminescent behavior of CdS at nanoscale with different doping concentration of europium—a rare earth element, we report the synthesis of Eu-doped CdS nanorods by using low temperature solvothermal process by using ethylenediamine. The outcomes can have future applications as phosphors, photovoltaic cells, lasers, light emitting diodes, bio-imaging, and sensors. The doping was confirmed by electron dispersive spectroscopy supported by X-ray diffraction. From scanning electron microscopy and transmission electron microscopy analysis it was observed that the average diameter of the Cd 1−x Eu x S nanorods is about 10–12 nm having lengths in the range of 50–100 nm. UV–Visible spectroscopy study was carried out to determine the band gap of the nanorods and the absorbance peaks showed blue shift with respect to the bulk CdS. The blue shift was also observed as the doping concentration of Eu increases. From photoluminescence (PL) studies at λ ex = 450 nm, peaks at 528 and 540 nm were observed due to CdS, peak at 570 nm is due to defects related transitions, while the peak at 613 nm is due to Eu. As the doping concentration of Eu is increased the intensity of the luminescent peak at 613 nm is increased. Thermogravimetric analysis showed the nanorods are thermally stable up to 300 °C. The traces of impurities adsorbed on the nanorods were confirmed by Fourier transform infrared spectroscopy.

  10. Thermoluminescence glow curve analysis and CGCD method for erbium doped CaZrO{sub 3} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, Ratnesh, E-mail: 31rati@gmail.com [Department of Physics, Bhilai Institute of Technology, Raipur, 493661 (India); Chopra, Seema [Department Physics, G.D Goenka Public School (India)

    2016-05-06

    The manuscript report the synthesis, thermoluminescence study at fixed concentration of Er{sup 3+} (1 mol%) doped CaZrO{sub 3} phosphor. The phosphors were prepared by modified solid state reaction method. The powder sample was characterized by thermoluminescence (TL) glow curve analysis. In TL glow curve the optimized concentration in 1mol% for UV irradiated sample. The kinetic parameters were calculated by computerized glow curve deconvolution (CGCD) techniaue. Trapping parameters gives the information of dosimetry loss in prepared phosphor and its usability in environmental monitoring and for personal monitoring. CGCD is the advance tool for analysis of complicated TL glow curves.

  11. Study of effect of co-doping on CIE coordinates of strontium cerium oxide phosphor (Sr_2CeO_4)

    International Nuclear Information System (INIS)

    Zambare, Pradip Z.; Ahirrao, P.B.; Chaudhari, D.B.; Zambare, A.P.; Mahajan, O.H.

    2016-01-01

    The phosphors Sr_2CeO_4 doped europium and gadolinium were synthesized by modified solid state diffusion method. From emission spectra, the CIE coordinates (x, y) of x% Eu"3"+ and 0.5 %Gd"3"+ doped Sr_2CeO_4 phosphors was calculated. In present paper, we investigate luminescence properties and colorimetric study of Sr_2CeO_4 doped 0.5% Gd"3"+, x% Eu"3"+. The phosphors Sr_2CeO_4 doped europium and gadolinium were successfully synthesized by modified solid state diffusion method. X-ray diffraction (XRD) profile confirms the orthorhombic nature of Eu"3"+ and 0.5% Gd"3"+ doped Sr_2CeO_4 phosphors. In addition, scanning electron Microscopy (SEM), Fourier-Transformation IR spectroscopy (FTIR), was also used to study the synthesized phosphors

  12. Eu2+-doped OH− free calcium aluminosilicate glass: A phosphor for smart lighting

    International Nuclear Information System (INIS)

    Lima, S.M.; Andrade, L.H.C.; Rocha, A.C.P.; Silva, J.R.; Farias, A.M.; Medina, A.N.; Baesso, M.L.; Nunes, L.A.O.; Guyot, Y.; Boulon, G.

    2013-01-01

    In this paper, a broad emission band from Eu 2+ -doped OH − free calcium aluminosilicate glass is reported. By changing the excitation wavelengths, the results showed it is possible to tune the emission from green to orange, what combined with the scattered light from the same blue LED used for excitation, provided a color rendering index of 71 and a correlated color temperature of 6550 K. Our preliminary tests indicate this material as a promising phosphor towards the development of smart lighting devices. -- Highlights: • We report a broad emission band from Eu 2+ -doped OH − free calcium aluminosilicate glass. • The maximum emission peak can be tune from green to orange region. • The test with a LED provided a color rendering index of 71 and a correlated color temperature of 6550 K

  13. Synthesis, structural and luminescent aspect of Tb3+ doped Sr2SnO4 phosphor

    International Nuclear Information System (INIS)

    Taikar, Deepak R.

    2016-01-01

    A novel green emitting, Tb 3+ doped Sr 2 SnO 4 phosphor was synthesized by the co-precipitation method and its photoluminescence characterization was performed. Sr 2 SnO 4 has an ordered tetragonal K 2 NiF 4 -type structure with space group I4/mmm. The structure of Sr 2 SnO 4 consists of SnO 6 octahedra. From the structure of Sr 2 SnO 4 , it was observed that the sites of Sn 4+ ions have inverse symmetry while the Sr 2+ ions have the low symmetry. X-ray powder diffraction (XRD) analysis confirmed the formation of Sr 2 SnO 4 :Tb 3+ . Photoluminescence measurements showed that the phosphor exhibited bright green emission at about 543 nm attributed to 5 D 4 à 7 F 5 transition of Tb 3+ ion under UV excitation. The emission spectra did not exhibit conventional blue emission peaks of Tb 3+ ions due to 5 D 3 → 7 F J transitions in the spectral region 350-470 nm. The excitation spectra indicate that this compound may be useful as a lamp phosphor. (author)

  14. Photoluminescence study of Dy3+ doped SrCeVO5 phosphor

    International Nuclear Information System (INIS)

    Suresh, K.; Dai, Ch. Vijay Anil; Murthy, K.V.R.

    2016-01-01

    Dy 3+ doped SrCeVO 5 phosphor was synthesized by the solid-state reaction method. Photoluminescence (PL) technique was performed to characterize the sample. The excitation spectra monitored under 520 nm and 610 nm wavelength was characterized by a broad band ranging from 220-400 nm. From the excitation spectra two main bands at 265 nm and 325 nm were observed. The PLE intensity of 520 nm monitored shows high intensity than 610 nm spectrum. The emission spectra of SrCeVO 5 phosphor under excitations at 265 nm and 325 nm exhibited main peak at 515 nm (cyan) which is a strong, intense well resolved peak with FWHM (full width at half maximum) of 130 nm is observed. This emission is mainly may be due to Ce ion but not Dy ion. The same emission under 640 and 670 nm excitations (up conversion) with good intensity was also observed. Commission international de l'eclairage (CIE) co-ordinates under these excitations revealed that this phosphor emit cyan colour and could be used for the generation of white light in display and lamp devices. (author)

  15. Structural and optical investigation in Er3+ doped Y2MoO6 phosphors

    Science.gov (United States)

    Mondal, Manisha; Rai, Vineet Kumar

    2018-05-01

    The Er3+ doped Y2MoO6 phosphors have been structurally and optically characterized by X-ray Diffraction (XRD), Field emission scanning electron microscopy (FESEM), UV-Vis absorption spectroscopy and frequency upconversion (UC) emission studies. The crystal and the particles size are found to be ˜ 85 nm and ˜ 200 nm from XRD and FESEM analysis. The intense peak at ˜ 206 nm in the UV-Vis absorption spectroscopy is attributed due to the charge transfer transition between the Mo6+ and the O2- ions in the MoO4 group in the host molybdate. The frequency UC emission studies of the prepared phosphors under 980 nm diode laser excitation shows the intense UC emission in the 0.3 mol% concentrations for the Er3+ ions. In the UC emission spectra, the emission peaks at green (˜ 525 nm and ˜ 546 nm) and red (˜ 656 nm) bands are corresponding to the 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+ ions. The mechanisms involved in the UC process have been explored with the help of energy level diagram. Moreover, the CIE point (0.31, 0.60) lie in the green colour region which indicates that the developed phosphor have suitable applications in NIR to visible upconverter and in making green light display devices.

  16. Structure, electronic properties, luminescence and chromaticity investigations of rare earth doped KMgBO{sub 3} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jianghui; Cheng, Qijin [School of Energy Research, Xiamen University, Xiamen 361005 (China); Wu, Shunqing [Department of Physics, Xiamen University, Xiamen, 361005 (China); Zhuang, Yixi [College of Materials, Xiamen University, Xiamen 361005 (China); Guo, Ziquan; Lu, Yijun [Department of Electronic Science, Fujian Engineering Research Center for Solid-state Lighting, Xiamen University, Xiamen 361005 (China); Chen, Chao, E-mail: cchen@xmu.edu.cn [School of Energy Research, Xiamen University, Xiamen 361005 (China); Department of Physics, Xiamen University, Xiamen, 361005 (China); Department of Electronic Science, Fujian Engineering Research Center for Solid-state Lighting, Xiamen University, Xiamen 361005 (China)

    2015-09-01

    In this work, the optimization of the geometry and the electronic properties of the host matrix KMgBO{sub 3} were investigated using density functional theory, and the comprehensive photoluminescence and chromaticity properties on five rare earth ion-doped (RE = Ce{sup 3+}, Tm{sup 3+}, Tb{sup 3+}, Eu{sup 3+}, Dy{sup 3+}) KMgBO{sub 3} phosphors were also studied. By introducing RE ions into the KMgBO{sub 3} host, excellent purple, blue, green, red and white emitting light could be obtained under the near-ultraviolet light excitation. The results suggest that rare earth doped KMgBO{sub 3} phosphors are potential luminescence materials for the application in the near-ultraviolet white light-emitting diodes. - Highlights: • The electronic properties of the host matrix KMgBO{sub 3} were investigated. • The PL properties on rare earth ions doped KMgBO{sub 3} phosphors were studied. • The chromaticity properties on rare earth ions doped KMgBO{sub 3} samples were studied. • Tm{sup 3+} and Eu{sup 3+} doped KMgBO{sub 3} samples show higher color purity than commercial phosphors.

  17. TL characterization of Ag co-doped SrSO{sub 4}:Eu phosphor for gamma dosimetry applications

    Energy Technology Data Exchange (ETDEWEB)

    Jayasudha, S., E-mail: jsnair.india@gmail.com [Mahatma Gandhi College, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Madhukumar, K.; Nair, C.M.K.; Nair, Resmi G.; Anandakumar, V.M. [Mahatma Gandhi College, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Elias, T.S. [State Institute of Cancer Research, Medical College P.O., Thiruvananthapuram 695011 (India); Rajesh, S. [Campus Universitario de Santiago, Aveiro (Portugal)

    2017-04-15

    High temperature thermoluminescence (TL) emissions and improvement in fading due to the co-doping ofr Ag in the SrSO{sub 4}:Eu phosphor synthesized through chemical precipitation technique when subjected to γ-excitation is discussed. The dopant concentrations were tuned for optimum TL sensitivity. Preliminary crystallographic and structural studies of the phosphors were done using PXRD, SEM, and TEM. The phosphor has a single phase orthorhombic lattice structure and the crystallites are found to be nanostructured. The presence of dopants in the host matrix is established through EDS and ICP-AES studies. The TL glow curve shows a single intense emission at 314 ├ó┬ü┬░C under γ- exposure of dose 1 Gy, which is given from a {sup 60}Co build-up. The dosimetric properties such as sensitivity, dose dependence, fading and reusability of SrSO{sub 4}:Eu,Ag phosphor were also studied. It is observed that co-doping with Ag improves the fading rate of the SrSO{sub 4}:Eu phosphor by about 5%. Even though the luminescence intensity is found to be less than that of SrSO{sub 4}:Eu phosphor, the Ag co-doped phosphor becomes significant owing to its improved fading rate and high temperature afterglow. The gamma sensitivity of the SrSO{sub 4}:Eu,Ag(0.5,0.5 mol%) phosphor is compared to that of the standard CaSO{sub 4}:Dy TLD phosphor. The TL kinetic parameters were calculated using IR, Chen's peak shape method and verified by the theoretical fit using GCD functions. - Highlights: • A High temperature TL emission is observed for the SrSO{sub 4}:Eu,Ag phosphor. • TL intensity is 10 times higher than that of standard CaSO{sub 4}:Dy. • Fading rate of SrSO{sub 4}:Eu phosphor is improved by 5% with Ag co-doping. • Linear dose response in the range 10mGy-10Gy. • t .

  18. Studies in crystal structure and luminescence properties of Eu3+-doped metal tungstate phosphors for white LEDs

    International Nuclear Information System (INIS)

    Lee, Gwan-Hyoung; Kang, Shinhoo

    2011-01-01

    The correlation between the crystal structure and luminescent properties of Eu 3+ -doped metal tungstate phosphors for white LEDs was investigated. Red-emitting A 4-3x (WO 4 ) 2 :Eu x 3+ (A=Li, Na, K) and B (4-3x)/2 (WO 4 ) 2 :Eu x 3+ (B=Mg, Ca, Sr) phosphors were synthesized by solid-state reactions. The findings confirmed that these phosphors exhibited a strong absorption in the near UV to green range, due to the intra-configurational 4f-4f electron transition of Eu 3+ ions. The high doping concentration of Eu 3+ enhanced the absorption of near UV light and red emission without any detectable concentration quenching. Based on the results of a Rietveld refinement, it was attributed to the unique crystal structure. In the crystal structure of the Eu 3+ -doped metal tungstate phosphor, the critical energy transfer distance is larger than 5 A so that exchange interactions between Eu 3+ ions would occur with difficulty, even at a high doping concentration. The energy transfer between Eu 3+ ions, which causes a decrease in red emission with increasing concentration of Eu 3+ , appears to be due to electric multi-polar interactions. In addition, the Eu-O distance in the host lattice affected the shape of emission spectrum by splitting of emission peak at the 5 D 0 → 7 F 2 transition of Eu 3+ . - Highlights: → Eu 3+ -doped metal tungstate was synthesized as a red phosphor for white LEDs. → Crystal structure is tetragonal with a space group of I4 1 /c. → A strong absorption in the near UV to green range was observed. → High doping of Eu 3+ enhanced the absorption of near UV light and red emission.

  19. Using rare earth doped thiosilicate phosphors in white light emitting LEDs: Towards low colour temperature and high colour rendering

    International Nuclear Information System (INIS)

    Smet, P.F.; Korthout, K.; Haecke, J.E. van; Poelman, D.

    2008-01-01

    Rare earth doped thiosilicates are promising materials for use in phosphor converted light emitting diodes (pcLEDs). These phosphors (including the hosts Ca 2 SiS 4 , BaSi 2 S 5 and Ba 2 SiS 4 in combination with Ce 3+ and/or Eu 2+ doping) cover the entire visible part of the spectrum, as the emission colour can be changed from deep blue to red. The photoluminescence emission spectrum and the overlap of the excitation spectrum with the emission of pumping LEDs is evaluated. The trade-off between high colour rendering and high electrical-to-optical power efficiency is discussed by simulation with both blue and UV emitting LEDs. Finally, a phosphor combination with low colour temperature (3000 K) and high colour rendering (CRI = 93) is proposed

  20. Synthesis and thermoluminescence behavior of ZrO2:Eu3+ with variable concentration of Eu3+ doped phosphor

    Directory of Open Access Journals (Sweden)

    Raunak Kumar Tamrakar

    2014-10-01

    Full Text Available Cubical ZrO2 phosphor doped with the europium synthesized by conventional solid state synthesis method. The prepared phosphor was characterized by X-ray diffraction (XRD technique, field emission gun scanning electron microscopy (FEGSEM and transmission electron microscopy (TEM. In this paper, we focused on the thermoluminescence glow curves and kinetic parameters, activation energy, order of kinetics, and the frequency factor of ZrO2:Eu3+ phosphor under different doses of UV irradiations at a heating rate of 6.7 °C/s. The kinetic parameters activation energy E, the order of kinetics b, and the frequency factor s of synthesized phosphor of ZrO2:Eu3+ have been calculated by using a peak shape method.

  1. Performance Degradation Tests of Phosphoric Acid Doped Polybenzimidazole Membrane Based High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

    2015-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2 and meth...

  2. Transition of Emission Colours as a Consequence of Heat-Treatment of Carbon Coated Ce3+-Doped YAG Phosphors

    NARCIS (Netherlands)

    Yin, L.J.; Dierre, B.F.P.R.; Sekiguchi, Takashi; van Ommen, J.R.; Hintzen, H.T.J.M.; Cho, Yujin

    2017-01-01

    To modify the luminescence properties of Ce3+-doped Y3Al5O12 (YAG) phosphors, they have been coated with a carbon layer by chemical vapor deposition and subsequently heat-treated at high temperature under N2 atmosphere. Luminescence of the

  3. Trivalent europium-doped strontium molybdate red phosphors in white light-emitting diodes: Synthesis, photophysical properties and theoretical calculations

    International Nuclear Information System (INIS)

    Yang, W.-Q.; Liu, H.-G.; Liu, G.-K.; Lin, Y.; Gao, M.; Zhao, X.-Y.; Zheng, W.-C.; Chen, Y.; Xu, J.; Li, L.-Z.

    2012-01-01

    Eu 3+ -doped strontium molybdate red phosphors (Sr 1−x MoO 4 :Eu x (x = 0.01–0.2)) for white light-emitting diodes (LED) were synthesized by the solid-state reaction method. The fluorescent intensities of the as-prepared phosphors were remarkably improved. The excitation and emission spectra demonstrate that these phosphors can be effectively excited by the near-UV light (395 nm) and blue light (466 nm). Their emitted red light peaks are located at 613 nm, and the highest quantum yield value (η) of the as-grown red phosphor, which is 95.85%, is much higher than that of commercial red phosphor (77.53%). These red phosphors plus commercial yellow powers (1:10) were successfully packaged with the GaN-based blue chips on a piranha frame by epoxy resins. The encapsulated white LED lamps show high performance of the CIE chromaticity coordinates and color temperatures. Moreover, to explain the fluorescent spectra of these phosphors, a complete 3003 × 3003 energy matrix was successfully built by an effective operator Hamiltonian including free ion and crystal field interactions. For the first time, the fluorescent spectra for Eu 3+ ion at the tetragonal (S 4 ) Sr 2+ site of SrMoO 4 crystal were calculated from a complete diagonalization (of energy matrix) method. The fitting values are close to the experimental results.

  4. The doping sites in Eu2+-doped AIBIIPO4 phosphors and their consequence on the photoluminescence excitation spectra

    Science.gov (United States)

    Amer, M.; Boutinaud, P.

    2018-02-01

    The energy corresponding to the excitation edge in Eu2+-doped phosphate phosphors of the type AIBIIPO4 (AI = monovalent cation, BII = divalent cation) is calculated from the knowledge of two crystal-structure-related factors he(X(i)) and Fc(X(i)) which are connected respectively to the crystal field splitting (CFS) and the centroid energy (Ec) of the excited 4f65d1 electron configuration of Eu2+. The calculation is carried out for each cation site X(i) available for Eu2+ in 25 different compositions of AIBIIPO4 including NaZnPO4-Eu2+ for which the luminescence is firstly reported. Our results indicate (1) that is it possible to identify the nature of the cation site that contributes to the excitation edge of Eu2+ in AIBIIPO4 within an accuracy of±1000 cm-1 and (2) that the method can be used as a tool for the predictive design of AIBIIPO4 - Eu2+ phosphors applicable in solid state LED-based lighting.

  5. Enhanced luminescence properties of YBO{sub 3}:Eu{sup 3+} phosphors by Li-doping

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnaiah, R. [Department of Electronic Materials Engineering, Silla University, Busan 617-736 (Korea, Republic of); Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Yi, Soung Soo, E-mail: ssyi@silla.ac.kr [Department of Electronic Materials Engineering, Silla University, Busan 617-736 (Korea, Republic of); Jang, Kiwan; Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Moon, Byung Kee; Jeong, Jung Hyun [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2011-04-15

    Different concentrations of Li-doped YBO{sub 3}:Eu{sup 3+} phosphors have been prepared by the conventional solid state reaction method and were characterized by X-ray diffraction, field emission scanning electron microscopy, photoluminescence excitation and emission measurements. An intense reddish orange emission is observed under UV excitation and the emitted radiation was dominated by an orange peak at 594 nm resulted from the {sup 5}D{sub 0} {yields} {sup 7}F{sub 1} transitions of Eu{sup 3+} ions. The brightness of the YBO{sub 3}:Eu{sup 3+} phosphor was found greatly improved with Li-doping accompanied by slight improvement in the purity of the color which might be attributed to improvement in crystallinity, grain sizes and creation of oxygen vacancies with Li-doping. The observed results have been discussed in comparison with similar reported works.

  6. Luminescence properties of Nd{sup 3+}-doped (Y,Gd)BO{sub 3} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Soung Soo; Kim, Ji-Chul; Kim, Dong Woo [Department of Electronic Materials Engineering, Silla University, Busan 617-736 (Korea, Republic of); Balakrishnaiah, R. [Department of Electronic Materials Engineering, Silla University, Busan 617-736 (Korea, Republic of); Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Kim, Sung Hoon [Department of Engineering in Energy and Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of); Jang, Kiwan, E-mail: kwjang@changwon.ac.k [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Moon, Byung Kee; Jeong, Jung Hyun [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2010-09-01

    A system of 0.03 mol Nd{sup 3+}-doped (Y,Gd)BO{sub 3} phosphors were prepared by the conventional solid state reaction method for different concentrations of Gd{sup 3+} ions and were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and NIR emission measurements. The emitted radiation was dominated by 1057 nm peak in the NIR region as a result of {sup 4}F{sub 3/2} {yields} {sup 4}I{sub 11/2} transitions of Nd{sup 3+} ions. As the concentration of Gd{sup 3+} ions increases from 0.00 to 0.57 mol, the grain sizes and the intensity of NIR emission peaks were improved. The results are discussed in comparison with similar reported works.

  7. Performance Degradation Tests of Phosphoric Acid Doped PBI Membrane Based High Temperature PEM Fuel Cells

    DEFF Research Database (Denmark)

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

    2014-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation. Continuous tests with H2 and simulated reformate which was composed...... of H2, water steam and methanol as the fuel were performed on both single cells. 12-h-startup/12-h-shutdown dynamic tests were performed on the first single cell with pure dry H2 as the fuel and on the second single cell with simulated reformate as the fuel. Along with the tests electrochemical...... techniques such as polarization curves and electrochemical impedance spectroscopy (EIS) were employed to study the degradation mechanisms of the fuel cells. Both single cells showed an increase in the performance in the H2 continuous tests, because of a decrease in the ORR kinetic resistance probably due...

  8. Enhanced red emission of LaVO{sub 4}:Eu{sup 3+} phosphors by Li-doping

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Wook; Yang, Hyun Kyoung; Chung, Jong Won; Moon, Byung Kee; Choi, Byung Chun; Jeong, Jung Hyun [Pukyoung National University, Busan (Korea, Republic of); Jang, Ki Wan; Lee, Ho Sueb [Changwon National University, Changwon (Korea, Republic of); Yi, Soung Soo [Silla University, Busan (Korea, Republic of)

    2010-12-15

    LaVO{sub 4} phosphors were synthesized by using a solid state reaction, and were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL). The XRD patterns of the Li-doped LaVO{sub 4}:Eu{sup 3+} powder phosphors revealed a mixture of tetragonal and monoclinic phases. The tetragonal phase of the LaVO{sub 4}:Eu{sup 3+} phosphor showed a higher PL intensity than the monoclinic one, despite the presence of both monoclinic and tetragonal structures. The Li-doped LaVO{sub 4}:Eu{sup 3+} powder phosphors absorbed strongly at 396 nm and exhibited strong red emission at approximately 619.5 nm due to the {sup 5}D{sub 0} {yields} {sup 7}F{sub 2} transition. The incorporation of Li{sup +} ions into the LaVO{sub 4}:Eu{sup 3+} powder can lead to a remarkable increase in photoluminescence. The enhanced luminescence is attributed to the incorporation of Li{sup +} ions that may act as a sensitizers for effective energy transfer. This phosphor has promising applications in near-UV light-emitting diodes(LEDs).

  9. Photovoltaic Performance Enhancement of Silicon Solar Cells Based on Combined Ratios of Three Species of Europium-Doped Phosphors

    Directory of Open Access Journals (Sweden)

    Wen-Jeng Ho

    2018-05-01

    Full Text Available This paper presents a scheme for the enhancement of silicon solar cells in terms of luminescent emission band and photovoltaic performance. The proposed devices are coated with an luminescent down-shifting (LDS layer comprising three species of europium (Eu-doped phosphors mixed within a silicate film (SiO2 using a spin-on film deposition. The three species of phosphor were mixed at ratios of 0.5:1:1.5, 1:1:1, or 1.5:1:0.5 in weight percentage (wt %. The total quantity of Eu-doped phosphors in the silicate solution was fixed at 3 wt %. The emission wavelengths of the Eu-doped phosphors were as follows: 518 nm (specie-A, 551 nm (specie-B, and 609 nm (specie-C. We examined the extended luminescent emission bands via photoluminescence measurements at room temperature. Closely matching the luminescent emission band to the high responsivity band of the silicon semiconductor resulted in good photovoltaic performance. Impressive improvements in efficiency were observed in all three samples: 0.5:1:1.5 (20.43%, 1:1:1 (19.67%, 1.5:1:0.5 (16.81%, compared to the control with a layer of pure SiO2 (13.80%.

  10. Improved efficiency of dye-sensitized solar cells by doping of strontium aluminate phosphor in TiO2 photoelectrode

    Directory of Open Access Journals (Sweden)

    Hwangbo Seung

    2015-06-01

    Full Text Available SrAl2O4:Eu2+, Dy3+ phosphor was synthesized by chemical solution route to use as a dopant in TiO2 layer employed as a photoelectrode for down conversion of ultraviolet and near-ultraviolet to visible and near-infrared light in a dye-sensitized solar cell. Nano-crystalline structure of the SrAl2O4:Eu2+, Dy3+ powder was confirmed by X-ray diffraction analysis and field emission scanning electron microscopy. Monitored at 520 nm, SrAl2O4:Eu2+, Dy3+ phosphor showed emission peaks at 460 to 610 nm due to 4f6 4f7 transitions of Eu2+ ions. For the study, SrAl2O4:Eu2+, Dy3+ phosphor-doped TiO2 layer was deposited on fluorine-doped tin oxide coated glass by electrostatic spray deposition. The short circuit current, open circuit voltage, fill factor, and conversion efficiency of the cells were measured. Experimental results revealed that the device efficiency for the SrAl2O4:Eu2+, Dy3+ phosphor-doped TiO2 layer increased to 7.20 %, whereas that of the pure-TiO2 photoelectrode was 4.13 %.

  11. Photovoltaic Performance Enhancement of Silicon Solar Cells Based on Combined Ratios of Three Species of Europium-Doped Phosphors.

    Science.gov (United States)

    Ho, Wen-Jeng; You, Bang-Jin; Liu, Jheng-Jie; Bai, Wen-Bin; Syu, Hong-Jhang; Lin, Ching-Fuh

    2018-05-18

    This paper presents a scheme for the enhancement of silicon solar cells in terms of luminescent emission band and photovoltaic performance. The proposed devices are coated with an luminescent down-shifting (LDS) layer comprising three species of europium (Eu)-doped phosphors mixed within a silicate film (SiO₂) using a spin-on film deposition. The three species of phosphor were mixed at ratios of 0.5:1:1.5, 1:1:1, or 1.5:1:0.5 in weight percentage (wt %). The total quantity of Eu-doped phosphors in the silicate solution was fixed at 3 wt %. The emission wavelengths of the Eu-doped phosphors were as follows: 518 nm (specie-A), 551 nm (specie-B), and 609 nm (specie-C). We examined the extended luminescent emission bands via photoluminescence measurements at room temperature. Closely matching the luminescent emission band to the high responsivity band of the silicon semiconductor resulted in good photovoltaic performance. Impressive improvements in efficiency were observed in all three samples: 0.5:1:1.5 (20.43%), 1:1:1 (19.67%), 1.5:1:0.5 (16.81%), compared to the control with a layer of pure SiO₂ (13.80%).

  12. White- and blue-light-emitting dysprosium(III) and terbium(III)-doped gadolinium titanate phosphors.

    Science.gov (United States)

    Antić, Ž; Kuzman, S; Đorđević, V; Dramićanin, M D; Thundat, T

    2017-06-01

    Here we report the synthesis and structural, morphological, and photoluminescence analysis of white- and blue-light-emitting Dy 3 + - and Tm 3 + -doped Gd 2 Ti 2 O 7 nanophosphors. Single-phase cubic Gd 2 Ti 2 O 7 nanopowders consist of compact, dense aggregates of nanoparticles with an average size of ~25 nm for Dy 3 + -doped and ~50 nm for Tm 3 + -doped samples. The photoluminescence results indicated that ultraviolet (UV) light excitation of the Dy 3 + -doped sample resulted in direct generation of white light, while a dominant yellow emission was obtained under blue-light excitation. Intense blue light was obtained for Tm 3 + -doped Gd 2 Ti 2 O 7 under UV excitation suggesting that this material could be used as a blue phosphor. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Rare earths (Ce, Eu, Tb) doped Y2Si2O7 phosphors for white LED

    International Nuclear Information System (INIS)

    Sokolnicki, Jerzy

    2013-01-01

    Nanocrystalline yttrium pyrosilicate Y 2 Si 2 O 7 (YPS) singly, doubly or triply doped with Ce 3+ , Eu 3+ , Tb 3+ was obtained by the reaction of nanostructured Y 2 O 3 :Ln 3+ and colloidal SiO 2 at high temperatures. X-ray diffraction analysis confirmed the formation of a single phase of α-YPS at 1200 °C. Two series of YPS samples doped with Eu 3+ or Eu 3+ /Tb 3+ were obtained by applying the reducing atmosphere (75%N 2 +25%H 2 ) at different temperatures. The luminescence and excitation spectra are reported. The singly Eu 3+ doped YPS emit from both Eu 3+ and Eu 2+ ions, with the spectral position and width of the Eu 2+ emission different in both series. The presence of Eu 2+ in the samples was confirmed by electron paramagnetic resonance (EPR) spectra. A broadband emission of Eu 2+ (380–650 nm), combined with the red emission of Eu 3+ is perceived by the naked eye as white light. Co-doping of YPS:Eu 3+ with Tb 3+ results in enhancement of the green component of the emission, and well-balanced white luminescence. The colour of this emission is tunable, and it is possible to get Commission International de I'Eclairage (CIE) chromaticity coordinates of (0.327, 0.327), colour-rendering index (CRI) of 85, and quantum efficiency (QE) of 71%. These phosphors are efficiently excited in the wavelength range of 300–420 nm, which perfectly matches a near UV-emitting InGaN chip. It was shown that for triply (Ce 3+ , Eu 3+ and Tb 3+ ) doped samples the three emissions from the particular activators can be generated using one excitation wavelength. The white light resulting from the superposition of the blue (Ce 3+ ), green (Tb 3+ ) and red (Eu 3+ ) emissions can be obtained by varying the concentration of the active ions and the treating atmosphere, i.e. reducing or oxidising. Eu 2+ was not detected in the triply doped samples, and hence line emissions mostly exhibit CRI values equal to or below 30. - Highlights: ► Nanocrystalline Y 2 Si 2 O 7 was obtained by the

  14. Energy transfer and colorimetric properties of Eu3+/Dy3+ co-doped Gd2(MoO4)3 phosphors

    International Nuclear Information System (INIS)

    Wan Jing; Cheng Lihong; Sun Jiashi; Zhong Haiyang; Li Xiangping; Lu Weili; Tian Yue; Lin Hai; Chen Baojiu

    2010-01-01

    Dy 3+ single-doped and Eu 3+ /Dy 3+ co-doped gadolinium molybdate (Gd 2 (MoO 4 ) 3 ) phosphors were synthesized by a traditional solid-state reaction method. The XRD was used to confirm the crystal structure of the phosphors. The energy transfer between Eu 3+ and Dy 3+ was observed and studied. The Eu 3+ concentration can hardly affect the blue and yellow emission intensities of Dy 3+ , and the Eu 3+ emission intensity increases with the increase of Eu 3+ concentration. Co-doping with Eu 3+ compensated the red emission component of the Dy 3+ doped Gd 2 (MoO 4 ) 3 phosphor. Introducing proper amount of Eu 3+ can improve the colorimetric performance of the phosphors.

  15. Thermal properties of phosphoric acid-doped polybenzimidazole membranes in water and methanol-water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Nores-Pondal, Federico J.; Corti, Horacio R. [Grupo de Pilas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica (CNEA), Av. General Paz 1499, B1650KNA San Martin, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Buera, M. Pilar [Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Av. Cantilo s/n, Ciudad Universitaria (1428) Buenos Aires (Argentina)

    2010-10-01

    The thermal properties of phosphoric acid-doped poly[2-2'-(m-phenylene)-5-5' bi-benzimidazole] (PBI) and poly[2,5-benzimidazole] (ABPBI) membranes, ionomeric materials with promising properties to be used as electrolytes in direct methanol and in high temperature polymer electrolyte membrane (PEM) fuel cells, were studied by means of differential scanning calorimetry (DSC) technique in the temperature range from -145 C to 200 C. The DSC scans of samples equilibrated in water at different relative humidities (RH) and in liquid water-methanol mixtures were analyzed in relation to glass transition, water crystallization/melting and solvent desorption in different temperature regions. The thermal relaxation observed in the very low temperature region could be ascribed to the glass transition of the H{sub 3}PO{sub 4}-H{sub 2}O mixture confined in the polymeric matrix. After cooling the samples up to -145 C, frozen water was detected in PBI and ABPBI at different RH, although at 100% RH less amount of water had crystallized than that observed in Nafion membranes under the same conditions. Even more important is the fact that the freezing degree of water is much lower in ABPBI membranes equilibrated in liquid water-methanol mixtures than that observed for PBI and, in a previous study, for Nafion. Thus, apart from other well known properties, acid-doped ABPBI emerges as an excellent ionomer for applications in direct methanol fuel cells working in cold environments. (author)

  16. Radioluminescence of red-emitting Eu-doped phosphors for fiberoptic dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Molina, P.; Santiago, M.; Marcazzo, J.; Caselli, E. [Universidad Nacional del Centro de la Provincia de Buenos Aires, Instituto de Fisica Arroyo Seco, Pinto 399, 7000 Tandil (Argentina); Spano, F. [Autoridad Regulatoria Nuclear, Av. del Libertador 8250, 1429 Buenos Aires (Argentina); Henniger, J. [Institut fur Kern-und Teilchenphysik, Zellescher Weg 19, 01069 Dresden (Germany); Cravero, W., E-mail: pmolina@exa.unicen.edu.ar [Universidad Nacional del Sur, Departamento de Fisica, Av. Colon 80, 8000FTN Bahia Blanca, Buenos Aires (Argentina)

    2011-10-15

    The fiberoptic dosimetry technique (FOD) has become an attractive method for in-vivo real-time dosimetry in radiotherapy. It is based on the use of a tiny piece of scintillator coupled to the end of an optical fiber, which collects the light emitted by the scintillator during irradiation (radioluminescence). Carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) is one of the most radioluminescence materials for FOD due to its high efficiency but it presents the drawback of emitting in the spectral region, where spurious luminescence is also important. Spurious luminescence from optical fiber, termed stem effect, is the main problem afflicting FOD. Several techniques have been applied to remove the stem effect. Optical filtering, which consists in using long-pass filters, is the simplest one. This technique is useful when red-emitting scintillators are employed. In this work, the feasibility of using red-emitting Eu-doped phosphors as FOD scintillators has been investigated. (Author)

  17. Optical properties, luminescence quenching mechanism and radiation hardness of Eu-doped GaN red powder phosphor

    International Nuclear Information System (INIS)

    Jadwisienczak, W.; Wisniewski, K.; Spencer, M.; Thomas, T.; Ingram, D.

    2010-01-01

    We report on the luminescence quenching mechanism of Eu-doped GaN powder phosphor produced with a low-cost, high yield rapid-ammonothermal method. We have studied as-synthesized and acid rinsed Eu-doped GaN powders with the Eu concentration of ∼0.5 at.%. The Eu-doped GaN photoluminescence (PL) was investigated with 325 nm excitation wavelength at hydrostatic pressures up to 7.7 GPa in temperature range between 12 K and 300 K. The room temperature integrated Eu 3+ ion PL intensity from acid rinsed material is a few times stronger than from the as-synthesized material. The temperature dependent PL studies revealed that the thermal quenching of the dominant Eu 3+ ion transition ( 5 D 0 → 7 F 2 ) at 622 nm is stronger in the chemically modified phosphor indicating more efficient coupling between the Eu 3+ ion and passivated GaN powder grains. Furthermore, it was found that thermal quenching of Eu 3+ ion emission intensity can be completely suppressed in studied materials by applied pressure. This is due to stronger localization of bound exciton on Eu 3+ ion trap induced by hydrostatic pressure. Furthermore, the effect of 2 MeV oxygen irradiation on the PL properties has been investigated for highly efficient Eu-doped GaN phosphor embedded in KBr-GaN:Eu 3+ composite. Fairly good radiation damage resistance was obtained for 1.7 x 10 12 to 5 x 10 13 cm -2 oxygen fluence. Preliminary data indicate that Eu-doped GaN powder phosphor can be considered for devices in a radiation environment.

  18. Photovoltaic Performance Characterization of Textured Silicon Solar Cells Using Luminescent Down-Shifting Eu-Doped Phosphor Particles of Various Dimensions.

    Science.gov (United States)

    Ho, Wen-Jeng; Deng, Yu-Jie; Liu, Jheng-Jie; Feng, Sheng-Kai; Lin, Jian-Cheng

    2017-01-01

    This paper reports on efforts to enhance the photovoltaic performance of textured silicon solar cells through the application of a layer of Eu-doped silicate phosphor with particles of various dimensions using the spin-on film technique. We examined the surface profile and dimensions of the Eu-doped phosphors in the silicate layer using optical microscopy with J-image software. Optical reflectance, photoluminescence, and external quantum efficiency were used to characterize the luminescent downshifting (LDS) and light scattering of the Eu-doped silicate phosphor layer. Current density-voltage curves under AM 1.5G simulation were used to confirm the contribution of LDS and light scattering produced by phosphor particles of various dimensions. Experiment results reveal that smaller phosphor particles have a more pronounced effect on LDS and a slight shading of incident light. The application of small Eu-doped phosphor particles increased the conversion efficiency by 9.2% (from 12.56% to 13.86%), far exceeding the 5.6% improvement (from 12.54% to 13.32%) achieved by applying a 250 nm layer of SiO₂ and the 4.5% improvement (from 12.37% to 12.98%) observed in cells with large Eu-doped phosphor particles.

  19. NIR to visible upconversion in Er3+/Yb3+ co-doped CaYAl3O7 phosphor obtained by solution combustion process

    International Nuclear Information System (INIS)

    Singh, Vijay; Rai, Vineet Kumar; Al-Shamery, Katharina; Nordmann, Joerg; Haase, Markus

    2011-01-01

    Using the combustion synthesis, CaYAl 3 O 7 :Er 3+ phosphor powders co-doped with Yb 3+ have been prepared at low temperatures (550 o C) in a few minutes. Formation of the compound was confirmed by X-ray powder diffraction. Near-infrared to visible upconversion fluorescence emission in the Er 3+ doped CaYAl 3 O 7 phosphor powder has been observed. The effect of co-doping with triply ionized ytterbium in the CaYAl 3 O 7 :Er 3+ phosphor has been studied and the process involved is discussed. - Highlights: → The green emitting up-conversion CaYAl 3 O 7 :Er 3+ phosphor powders co-doped with Yb 3+ have been prepared by easy combustion method. → The combustion method is a simple, energy saving, fast and economical viable process. → The luminescence intensity in the co-doped phosphor is enhanced by several times compared to that of the singly (Er 3+ ) doped phosphor.

  20. Long afterglow property of Er{sup 3+} doped Ca{sub 2}SnO{sub 4} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dongyun, E-mail: dyz@sit.edu.cn; Shi, Mingming; Sun, Yiwen; Guo, Yunyun; Chang, Chengkang

    2016-05-15

    A novel green emitting long afterglow phosphor, Er{sup 3+} -doped Ca{sub 2}SnO{sub 4} (Ca{sub 2}SnO{sub 4}:Er{sup 3+}), was prepared successfully via a traditional high temperature solid–state reaction method. Its properties have been characterized and analyzed by utilizing x-ray diffraction (XRD), photoluminescence spectroscope (PLS), afterglow decay curve (ADC) and thermal luminescence spectroscope (TLS). Three main emission peaks of PLS locate at 524, 550 and 668 nm, corresponding to CIE chromaticity coordinates of x = 0.326, y = 0.6592. An optimal doping concentration of Er{sup 3+} of 2% was determined. The Ca{sub 2}SnO{sub 4}:Er{sup 3+} phosphors showed a typical triple-exponential afterglow decay behavior when the UV source was switched off. Thermal simulated luminescence study indicated that the persistent afterglow of Ca{sub 2}SnO{sub 4}:2 mol% Er{sup 3+} phosphors was generated by the suitable electron or hole traps which were resulted from the doping the Ca{sub 2}SnO{sub 4} host with rare-earth ions (Er{sup 3+}). - Highlights: • A novel green emitting long afterglow phosphor, Ca{sub 2}SnO{sub 4}:Er{sup 3+}, was prepared. • An optimal doping concentration of Er{sup 3+} of 2% was determined. • After the UV source was turned off, the Ca{sub 2}SnO{sub 4}:Er{sup 3+} showed a typical triple-exponential afterglow decay behavior. • CIE chromaticity coordinates results confirmed a green light emitting of the Ca{sub 2}SnO{sub 4}:Er{sup 3+}. • The persistent afterglow of the Ca{sub 2}SnO{sub 4}:Er{sup 3+} was attributed to suitable electron or hole traps.

  1. A novel red phosphor Mg2GeO4 doped with Eu3+ for PDP applications

    International Nuclear Information System (INIS)

    Yang Hongmei; Shi Jianxin; Liang Hongbin; Gong Menglian

    2006-01-01

    A novel red emitting phosphor, Eu 3+ -doped Mg 2 GeO 4 , was prepared by the solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the formation of Mg 2 GeO 4 :Eu 3+ . Field-emission-scanning electron microscopy (FE-SEM) observation indicated a narrow size-distribution of about 0.5-2 μm nm for the particles with spindle-like shape. Photoluminescence (PL) and vacuum ultraviolet (VUV) excitation characteristics of the phosphor Mg 2 GeO 4 :Eu 3+ were studied. We have also studied the effect of preparation conditions such as temperature, heating time on the PL data. Photoluminescence measurements indicated that the phosphor exhibits bright red emission at about 609 nm under UV excitation. And the vacuum ultraviolet spectra present that the novel red phosphor Mg 2 GeO 4 :Eu 3+ shows strong absorption in the VUV region, which ensures the efficient absorption of the Xe plasma emission lines. The phosphor Mg 2 GeO 4 :Eu 3+ shows the strongest emission at 613 nm corresponding to the electric dipole 5 D - 7 F 2 transition of Eu 3+ excited at 147 nm. The optical properties study suggests that it is a potential candidate for plasma display panels (PDPs) application

  2. Photoionization behavior of Eu2+-doped BaMgSiO4 long-persisting phosphor upon UV irradiation

    International Nuclear Information System (INIS)

    Li, Y.; Wang, Y.; Gong, Y.; Xu, X.; Zhang, F.

    2011-01-01

    Highlights: → Photoionization behavior of BaMgSiO 4 :Eu 2+ long persistent phosphor upon UV irradiation. → Green phosphorescence was obtained from BaMgSiO 4 :Eu 2+ . → The ionization of Eu 2+ to Eu 3+ was observed in BaMgSiO 4 :Eu 2+ . → The photogenerated Eu 3+ cannot change back to its divalent state at room temperature. → The phosphorescence is associated with the formation forming Eu 3+ -e - pairs. - Abstract: The fluorescence, phosphorescence and thermoluminescence properties of Eu-doped BaMgSiO 4 phosphors sintered in air and in a reducing atmosphere were investigated. Phosphorescence of phosphor sintered in a reducing atmosphere can last for 1.5 h at a recognizable intensity level, whereas phosphorescence of air-sintered phosphor can only persist for 6 min. In addition, a distinction between the shape of the fluorescence spectrum and its corresponding phosphorescence spectrum is observed in the former case. Ionization of Eu 2+ to Eu 3+ upon UV irradiation is observed in the phosphor prepared in a reducing atmosphere, but there is no indication that the photogenerated Eu 3+ cannot change back to its divalent state at room temperature after the excitation source is switched off. In addition, phosphor sintered in a reducing atmosphere shows photochromism upon UV irradiation. No such photoionization and photochromism behavior is observed for the air-sintered phosphor. A possible Eu 2+ photoionization mechanism is constructed on the basis of these experimental observations. The photoionization mechanism presented can also successfully explain the fluorescence and phosphorescence behavior of Eu in BaMgSiO 4 .

  3. NIR optimized dual mode photoluminescence in Nd doped Y{sub 2}O{sub 3} ceramic phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Sukul, Prasenjit Prasad; Mahata, Manoj Kumar; Kumar, Kaushal, E-mail: kumar.bhu@gmail.com

    2017-05-15

    Authors here report the dual mode photo luminescence emission in neodymium doped yttrium oxide ceramic phosphor upon 808 nm diode laser excitation. Single cubic phase Nd{sup 3+} doped Y{sub 2}O{sub 3} phosphor was synthesized using urea assisted combustion route. Nd{sup 3+} doped Y{sub 2}O{sub 3} ceramic phosphor has given photoluminescence in a wide wavelength range covering near infrared window (850–1100 nm) to the visible region i.e. green (525 nm) and red (680 nm) upon 808 nm diode laser excitation. The two most intense bands on 808 nm excitation were observed at 750 nm and 1064 nm due to the upconversion and downconversion emission processes. The sample was also tested for emission using 980 nm and intense green emission due to the trace presence of Er{sup 3+} in the raw materials was seen in the sample. The excitation power dependent upconversion measurements have shown that transitions {sup 4}F{sub 9/2}→{sup 4}I{sub 9/2} and {sup 4}S{sub 3/2}→{sup 4}I{sub 9/2} are thermally coupled and can be used to estimate the sample temperature using Boltzmann relation.

  4. The effect of grain size and phosphorous-doping of polycrystalline 3C–SiC on infrared reflectance spectra

    International Nuclear Information System (INIS)

    Rooyen, I.J. van; Engelbrecht, J.A.A.; Henry, A.; Janzén, E.; Neethling, J.H.; Rooyen, P.M. van

    2012-01-01

    Highlights: ► IR is investigated as a technique to measure grain size and P-doping of polycrystalline SiC. ► Infrared plasma minima can be used to determine doping levels in 3C–SiC for doping levels greater than 5 × 10 17 cm −3 . ► A linear relationship is found between FWHM and the inverse of grain size of 3C–SiC irrespective of P-doping level. ► It is further found that ω p is not influenced by the grain size. ► P-doping level has no significant effect on the linear relationship between grain size and surface roughness. - Abstract: The effect of P-doping and grain size of polycrystalline 3C–SiC on the infrared reflectance spectra is reported. The relationship between grain size and full width at half maximum (FWHM) suggest that the behavior of the 3C–SiC with the highest phosphorous doping level (of 1.2 × 10 19 at. cm −3 ) is different from those with lower doping levels ( 18 at. cm −3 ). It is also further demonstrated that the plasma resonance frequency (ω p ) is not influenced by the grain size.

  5. The effect of grain size and phosphorous-doping of polycrystalline 3C-SiC on infrared reflectance spectra

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: Isabella.vanRooyen@inl.gov [Fuel Performance and Design Department, Idaho National Laboratory, Idaho Falls, ID 83415-6188 (United States); Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Engelbrecht, J.A.A. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Henry, A.; Janzen, E. [Department of Physics, Chemistry and Biology, Semiconductor Materials, Linkoeping University, Linkoeping 58183 (Sweden); Neethling, J.H. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Rooyen, P.M. van [Philip M van Rooyen Network Consultants, Midlands Estates (South Africa)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer IR is investigated as a technique to measure grain size and P-doping of polycrystalline SiC. Black-Right-Pointing-Pointer Infrared plasma minima can be used to determine doping levels in 3C-SiC for doping levels greater than 5 Multiplication-Sign 10{sup 17} cm{sup -3}. Black-Right-Pointing-Pointer A linear relationship is found between FWHM and the inverse of grain size of 3C-SiC irrespective of P-doping level. Black-Right-Pointing-Pointer It is further found that {omega}{sub p} is not influenced by the grain size. Black-Right-Pointing-Pointer P-doping level has no significant effect on the linear relationship between grain size and surface roughness. - Abstract: The effect of P-doping and grain size of polycrystalline 3C-SiC on the infrared reflectance spectra is reported. The relationship between grain size and full width at half maximum (FWHM) suggest that the behavior of the 3C-SiC with the highest phosphorous doping level (of 1.2 Multiplication-Sign 10{sup 19} at. cm{sup -3}) is different from those with lower doping levels (<6.6 Multiplication-Sign 10{sup 18} at. cm{sup -3}). It is also further demonstrated that the plasma resonance frequency ({omega}{sub p}) is not influenced by the grain size.

  6. Photoluminescence and thermoluminescence properties of Eu2+ doped and Eu2+ ,Dy3+ co-doped Ba2 MgSi2 O7 phosphors.

    Science.gov (United States)

    Sao, Sanjay Kumar; Brahme, Nameeta; Bisen, D P; Tiwari, Geetanjali

    2016-11-01

    In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu 2 + -doped and Eu 2 + ,Dy 3 + -co-doped Ba 2 MgSi 2 O 7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid-state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba 2 MgSi 2 O 7 :Eu 2 + showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba 2 MgSi 2 O 7 :Eu 2 + Dy 3 + showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f 6 5d 1 to 4f 7 transition of Eu 2 + . TL analysis revealed that the maximum TL intensity was found at 5 mol% of Eu 2 + doping in Ba 2 MgSi 2 O 7 phosphors after 15 min of ultraviolet (UV) light exposure. TL intensity was increased when Dy 3 + ions were co-doped in Ba 2 MgSi 2 O 7 :Eu 2 + and maximum TL intensity was observed for 2 mol% of Dy 3 + . TL emission spectra of Ba 1.95 MgSi 2 O 7 :0.05Eu 2 + and Ba 1.93 MgSi 2 O 7 :0.05Eu 2 + ,0.02Dy 3 + phosphors were found at 500 nm. TL intensity increased with UV exposure time up to 15 min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co-doping. The trap depths were calculated to be 0.54 eV for Ba 1.95 MgSi 2 O 7 :0.05Eu 2 + and 0.54 eV and 0.75 eV for Ba 1.93 MgSi 2 O 7 :0.05Eu 2 + ,0.02Dy 3 + phosphors. It was observed that co-doping with small amounts of Dy 3 + enhanced the thermoluminescence properties of Ba 2 MgSi 2 O 7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The

  7. Study on luminescence characteristics of blue OLED with phosphor-doped host-guest structure

    Science.gov (United States)

    Wang, Zhen; Liu, Fei; Zheng, Xin; Chen, Ai; Xie, Jia-feng; Zhang, Wen-xia

    2018-05-01

    In this study, we design and fabricate phosphor-doped host-guest structure organic light-emitting diodes (OLEDs), where the blue-ray iridium complex electrophosphorescent material FIrpic acts as object material. Properties of the device can be accommodated by changing the host materials, dopant concentration and thickness of the light-emitting layer. The study shows that the host material N,N'-dicarbazolyl-3,5-benzene (mCP) has a higher triplet excited state energy level, which can effectively prevent FIrpic triplet excited state energy backtracking to host material, thus the luminous efficiency is improved. When mCP is selected as the host material, the thickness of the light-emitting layer is 30 nm and the dopant concentration is 8 wt%, the excitons can be effectively confined in the light-emitting region. As a result, the maximum current efficiency and the maximum brightness of the blue device can reach 15.5 cd/A and 7 196.3 cd/m2, respectively.

  8. Phosphorus and Cu2+ removal by periphytic biofilm stimulated by upconversion phosphors doped with Pr3+-Li.

    Science.gov (United States)

    Zhu, Yan; Zhang, Jianhong; Zhu, Ningyuan; Tang, Jun; Liu, Junzhuo; Sun, Pengfei; Wu, Yonghong; Wong, Po Keung

    2018-01-01

    Upconversion phosphors (UCPs) can convert visible light into luminescence, such as UV, which can regulate the growth of microbes. Based on these fundamentals, the community composition of periphytic biofilms stimulated by UCPs doped with Pr 3+ -Li + was proposed to augment the removal of phosphorus (P) and copper (Cu). Results showed that the biofilms with community composition optimized by UCPs doped with Pr 3+ -Li + had high P and Cu 2+ removal rates. This was partly due to overall bacterial and algal abundance and biomass increases. The synergistic actions of algal, bacterial biomass and carbon metabolic capacity in the Pr-Li stimulated biofilms facilitated the removal of P and Cu 2+ . The results show that the stimulation of periphytic biofilms by lanthanide-doped UCPs is a promising approach for augmenting P and Cu 2+ removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Co-operative energy transfer in Yb3+-Er3+ co-doped SrGdxOy upconverting phosphor

    Science.gov (United States)

    Kumar, Ashwini; Pathak, Trilok K.; Dhoble, S. J.; . Terblans, J. J.; Swart, H. C.

    2018-04-01

    Upconversion nanoparticles (UCNPs) have shown considerable interest in many fields; however, low upconversion efficiency of UCNPs is still the most severe limitation of their applications. Yb3+ and Er3+ co-doped SrGd4O7/Gd2O3(SGO) upconversion (UC) phosphors were synthesized by a modified co-precipitation process. The UC properties were investigated by direct excitation with a 980 nm laser. It was observed that the as prepared materials showed relatively strong green emission, while upon the incorporation of the Er3+ ion, there was an increase in the upconversion luminescence intensity for the red component. The effect of different doping concentration of Er3+on the emission spectra and X-ray diffraction patterns of the UC materials have also been studied. The luminescence lifetimes and Commission Internationale de L'Eclairage coordinates for these as prepared samples were determined to understand the energy transfer (ET) mechanisms occurring between Yb3+ and Er3+ in the SGO host matrix. The UC luminescence intensity as a function of laser pump power was monitored and it was confirmed that the UC process in SGO:Yb3+/Er3+is a two-photon absorption process. The findings reported here are expected to provide a better approach for understanding of the ET mechanisms in the oxide based Yb3+/Er3+ co-doped UC phosphors. This study might be helpful in precisely defined applications where optical transitions are essential criterion and this can be easily achieved by smart tuning of the emission properties of Yb3+/Er3+ co-doped UC phosphors.

  10. Luminescence properties of Y2O3:Bi3+, Yb3+ co-doped phosphor for application in solar cells

    Science.gov (United States)

    Lee, E.; Kroon, R. E.; Terblans, J. J.; Swart, H. C.

    2018-04-01

    Bismuth (Bi3+) and ytterbium (Yb3+) co-doped yttrium oxide (Y2O3) phosphor powder was successfully synthesised using the co-precipitation technique. The X-ray diffraction (XRD) patterns confirmed that a single phase cubic structure with a Ia-3 space group was formed. The visible emission confirmed the two symmetry sites, C2 and S6, found in the Y2O3 host material and revealed that Bi3+ ions preferred the S6 site as seen the stronger emission intensity. The near-infrared (NIR) emission of Yb3+ increased significantly by the presence of the Bi3+ ions when compared to the singly doped Y2O3:Yb3+ phosphor with the same Yb3+ concentration. An increase in the NIR emission intensity was also observed by simply increasing the Yb3+ concentration in the Y2O3:Bi3+, Yb3+ phosphor material where the intensity increased up to x = 5.0 mol% of Yb3+ before decreasing due to concentration quenching.

  11. Tunable photoluminescence and magnetic properties of Dy(3+) and Eu(3+) doped GdVO4 multifunctional phosphors.

    Science.gov (United States)

    Liu, Yanxia; Liu, Guixia; Dong, Xiangting; Wang, Jinxian; Yu, Wensheng

    2015-10-28

    A series of Dy(3+) or/and Eu(3+) doped GdVO4 phosphors were successfully prepared by a simple hydrothermal method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectrometry (EDS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). The results indicate that the as-prepared samples are pure tetragonal phase GdVO4, taking on nanoparticles with an average size of 45 nm. Under ultraviolet (UV) light excitation, the individual Dy(3+) or Eu(3+) ion activated GdVO4 phosphors exhibit excellent emission properties in their respective regions. The mechanism of energy transfer from the VO4(3-) group and the charge transfer band (CTB) to Dy(3+) and Eu(3+) ions is proposed. Color-tunable emissions in GdVO4:Dy(3+),Eu(3+) phosphors are realized through adopting different excitation wavelengths or adjusting the appropriate concentration of Dy(3+) and Eu(3+) when excited by a single excitation wavelength. In addition, the as-prepared samples show paramagnetic properties at room temperature. This kind of multifunctional color-tunable phosphor has great potential applications in the fields of photoelectronic devices and biomedical sciences.

  12. Effect of killer impurities on laser-excited barium-doped ZnS phosphors at liquid nitrogen temperature

    Science.gov (United States)

    Kumar, Sunil; Verma, N. K.; Bhatti, H. S.

    Zinc sulphide phosphors doped with Ba, as well as killer impurities of Fe, Co and Ni, having variable concentrations, were synthesized; and using an ultraviolet laser as the excitation source, decay-curve analyses were done. Various strong emissions in these phosphors were detected and the corresponding excited-state life times were measured at liquid nitrogen temperature. Studies were carried out to see the effect of killer impurities on the phosphorescence excited-state life times. Excited-state life times were found to decrease appreciably (microsecond to nanosecond) with the addition of quenchers. These studies are quite useful and find applications in areas such as optical memories, sensors, luminescent screens, laser-beam detection and alignment, color displays, printing, etc.

  13. Effect of Thermal Annealing on Carbon in In-situ Phosphorous-Doped Si1-xCx films

    International Nuclear Information System (INIS)

    Adam, Thomas; Loubet, Nicolas; Reznicek, Alexander; Paruchuri, Vamsi; Sampson, Ron; Sadana, Devendra

    2012-01-01

    The effect of thermal heat treatment on carbon in in-situ phosphorous-doped silicon-carbon is studied as a function of annealing temperature and type. Films of 0 to 2% carbon were deposited using cyclic chemical vapor deposition at reduced pressures. Secondary ion-mass spectroscopy and high-resolution X-ray diffraction were employed to extract the total and substitutional carbon concentration in samples with phosphorous levels of mid-10 20 cm -3 . It was found that millisecond laser annealing drastically improves substitutionality while high thermal budget treatments (furnace, rapid-thermal, or spike annealing) resulted in an almost complete loss of substitutional carbon, independent of preceding or subsequent laser heat treatments.

  14. Upconversion emission study of Er3+/Yb3+ doped barium titanate phosphor prepared by co-precipitation method

    International Nuclear Information System (INIS)

    Mahata, M.K.; Dey, R.; Kumar, K.; Rai, V.K.; Rai, S.B.

    2012-01-01

    In the present work we have successfully synthesized the Er 3+ , Yb 3+ doped barium titanate phosphor via co-precipitation synthesis method. Under 980 nm excitation, tri-color upconversion fluorescence has been observed. The Fourier Transform Infrared measurement was done to check the presence of organic impurities. In order to find out how many photons are involved in each emission band, the variation of UC emission intensity of the codoped phosphor is studied with increase in excitation power. Upconversion emission spectra show that as the annealing temperature of the powder is increased, intensity of red emission decreases and intensity of green emission increases due to the decrease in maximum phonon frequency of the host material. (author)

  15. Doping efficiency analysis of highly phosphorous doped epitaxial/amorphous silicon emitters grown by PECVD for high efficiency silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    El-Gohary, H.G.; Sivoththaman, S. [Waterloo Univ., ON (Canada). Dept. of Electrical and Computer Engineering

    2008-08-15

    The efficient doping of hydrogenated amorphous and crystalline silicon thin films is a key factor in the fabrication of silicon solar cells. The most popular method for developing those films is plasma enhanced chemical vapor deposition (PECVD) because it minimizes defect density and improves doping efficiency. This paper discussed the preparation of different structure phosphorous doped silicon emitters ranging from epitaxial to amorphous films at low temperature. Phosphine (PH{sub 3}) was employed as the doping gas source with the same gas concentration for both epitaxial and amorphous silicon emitters. The paper presented an analysis of dopant activation by applying a very short rapid thermal annealing process (RTP). A spreading resistance profile (SRP) and SIMS analysis were used to detect both the active dopant and the dopant concentrations, respectively. The paper also provided the results of a structural analysis for both bulk and cross-section at the interface using high-resolution transmission electron microscopy and Raman spectroscopy, for epitaxial and amorphous films. It was concluded that a unity doping efficiency could be achieved in epitaxial layers by applying an optimized temperature profile using short time processing rapid thermal processing technique. The high quality, one step epitaxial layers, led to both high conductive and high doping efficiency layers.

  16. PEM steam electrolysis at 130 °C using a phosphoric acid doped short side chain PFSA membrane

    DEFF Research Database (Denmark)

    Hansen, Martin Kalmar; Aili, David; Christensen, Erik

    2012-01-01

    Steam electrolysis test with a phosphoric acid doped Aquivion™ membrane was successfully conducted and current densities up to 775 mA cm-2 at 1.8 V was reached at 130 ºC and ambient pressure. A new composite membrane system using a perfluorosulfonic acid membrane (Aquivion™) as matrix and phospho...... implied that a new and highly corrosion resistant construction material was needed. Tantalum coated stainless steel felt was tested and found suitable as the anode gas diffusion layer. Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved....

  17. NIR to VIS frequency upconversion luminescence properties of Er{sup 3+}-doped YPO{sub 4} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnaiah, R. [Department of Electronic Materials Engineering, Silla University, Busan 617-736 (Korea, Republic of); Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Kim, Dong Woo [Department of Electronic Materials Engineering, Silla University, Busan 617-736 (Korea, Republic of); Yi, Soung Soo, E-mail: ssyi@silla.ac.k [Department of Electronic Materials Engineering, Silla University, Busan 617-736 (Korea, Republic of); Kim, Sung Hoon [Department of Engineering in Energy and Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of); Jang, Kiwan; Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Moon, Byung Kee; Jeong, Jung Hyun [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2010-09-01

    Different concentrations of Er{sup 3+}-doped YPO{sub 4}:Er powder phosphors have been synthesized by the conventional solid state reaction method and are characterized by X-ray diffraction (XRD), field emission scanning electronic microscopy (FESEM), and upconversion emission measurements. An intense red emission band and a weak green emission band are observed under NIR excitation at 975 nm in case of samples with high dopant concentration while no upconversion emission was observed at lower Er{sup 3+} ion concentrations. The possible mechanisms involved in the upconversion process have been discussed in comparison to results with similar reported works.

  18. Color tunable emission through energy transfer from Yb3+ co-doped SrSnO3: Ho3+ perovskite nano-phosphor

    Science.gov (United States)

    Jain, Neha; Singh, Rajan Kr.; Sinha, Shriya; Singh, R. A.; Singh, Jai

    2018-04-01

    First time color tunable lighting observed from Ho3+ and Yb3+ co-doped SrSnO3 perovskite. Down-conversion and up-conversion (UC) photoluminescence emission spectra were recorded to understand the whole mechanism of energy migration between Ho3+ and Yb3+ ions. The intensity of green and red emission varies with Yb3+ doping which causes multicolour emissions from nano-phosphor. The intensity of UC red emission (654 nm) obtained from 1 at.% Ho3+ and 3 at.% Yb3+ co-doped nano-phosphor is nine times higher than from 1 at.% Ho3+ doped SrSnO3 nano-phosphor. Enhanced brightness of 654 nm in UC process belongs in biological transparency window so that it might be a promising phosphor in the bio-medical field. Moreover, for the other Yb3+ co-doped nano-phosphor, Commission Internationale de l'Éclairage chromaticity co-ordinates were found near the white region and their CCT values lie in the range 4900-5100 K indicating cool white. Decay time was measured for 545 nm emission of Ho3+ ion found in 7.652 and 8.734 µs at 355 nm excitation. The variation in lifetime was observed in ascending order with increasing Yb3+ concentration which supports PL emission spectra observation that with increasing Yb3+ concentration, rate of transition has changed. These studies reveal that Ho3+ and Yb3+ co-doped phosphor is useful for fabrication of white LEDs.

  19. Eu{sup 2+}-doped OH{sup −} free calcium aluminosilicate glass: A phosphor for smart lighting

    Energy Technology Data Exchange (ETDEWEB)

    Lima, S.M., E-mail: smlima@uems.br [Grupo de Espectroscopia Óptica e Fototérmica, Universidade Estadual de Mato Grosso do Sul, C. P. 351, CEP 79804-970 Dourados, MS (Brazil); Andrade, L.H.C.; Rocha, A.C.P. [Grupo de Espectroscopia Óptica e Fototérmica, Universidade Estadual de Mato Grosso do Sul, C. P. 351, CEP 79804-970 Dourados, MS (Brazil); Silva, J.R.; Farias, A.M.; Medina, A.N.; Baesso, M.L. [Departamento de Física, Universidade Estadual de Maringá, Av. Colombo 5790, 87020-900 Maringá, PR (Brazil); Nunes, L.A.O. [Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos, SP (Brazil); Guyot, Y.; Boulon, G. [Laboratoire de Physico-Chimie des Matériaux Luminescents, Université de Lyon 1, UMR 5620 CNRS, 69622 Villeurbanne (France)

    2013-11-15

    In this paper, a broad emission band from Eu{sup 2+}-doped OH{sup −} free calcium aluminosilicate glass is reported. By changing the excitation wavelengths, the results showed it is possible to tune the emission from green to orange, what combined with the scattered light from the same blue LED used for excitation, provided a color rendering index of 71 and a correlated color temperature of 6550 K. Our preliminary tests indicate this material as a promising phosphor towards the development of smart lighting devices. -- Highlights: • We report a broad emission band from Eu{sup 2+}-doped OH{sup −} free calcium aluminosilicate glass. • The maximum emission peak can be tune from green to orange region. • The test with a LED provided a color rendering index of 71 and a correlated color temperature of 6550 K.

  20. Luminescence properties of terbium-doped Li3PO4 phosphor for ...

    Indian Academy of Sciences (India)

    ... of faster and multiple readout, very high sensitivity, absence of thermal quenching and possible use of phosphor in plastic binders [3–15]. ... synthesis technique was developed to reduce the time required for the synthesis, which was about.

  1. Porous polybenzimidazole membranes doped with phosphoric acid: Preparation and application in high-temperature proton-exchange-membrane fuel cells

    International Nuclear Information System (INIS)

    Li, Jin; Li, Xiaojin; Yu, Shuchun; Hao, Jinkai; Lu, Wangting; Shao, Zhigang; Yi, Baolian

    2014-01-01

    Highlights: • Porous polybenzimidazole membrane was prepared with glucose as porogen. • Phosphoric acid content was as high as 15.7 mol H 3 PO 4 per PBI repeat unit. • 200 h Constant current density test was carried out at 150 °C. • Degradation was due to the gap between membrane and catalyst layer. - Abstract: In this paper, the preparation and characterization of porous polybenzimidazole membranes doped with phosphoric acid were reported. For the preparation of porous polybenzimidazole membranes, glucose and saccharose were selected as porogen and added into PBI resin solution before solvent casting. The prepared porous PBI membranes had high proton conductivity and high content of acid doping at room temperature with 15.7 mol H 3 PO 4 per PBI repeat unit, much higher than pure PBI membrane at the same condition. Further, the performance and stability of the porous PBI membrane in high-temperature proton-exchange-membrane fuel cells was tested. It was found that the cell performance remained stable during 200 h stability test under a constant current discharge of 0.5 A cm −2 except for the last fifty hours. The decay in the last fifty hours was ascribed to the delamination between the catalyst layer and membrane increasing the charge-transfer resistance

  2. Transition of Emission Colours as a Consequence of Heat-Treatment of Carbon Coated Ce3+-Doped YAG Phosphors

    Directory of Open Access Journals (Sweden)

    Liang-Jun Yin

    2017-10-01

    Full Text Available To modify the luminescence properties of Ce3+-doped Y3Al5O12 (YAG phosphors, they have been coated with a carbon layer by chemical vapor deposition and subsequently heat-treated at high temperature under N2 atmosphere. Luminescence of the carbon coated YAG:Ce3+ phosphors has been investigated as a function of heat-treatment at 1500 and 1650 °C. The 540 nm emission intensity of C@YAG:Ce3+ is the highest when heated at 1650 °C, while a blue emission at 400–420 nm is observed when heated at 1500 °C but not at 1650 °C. It is verified by X-ray diffraction (XRD that the intriguing luminescence changes are induced by the formation of new phases in C@YAG:Ce3+-1500 °C, which disappear in C@YAG:Ce3+-1650 °C. In order to understand the mechanisms responsible for the enhancement of YAG:Ce3+ emission and the presence of the blue emission observed for C@YAG:Ce3+-1500 °C, the samples have been investigated by a combination of several electron microscopy techniques, such as HRTEM, SEM-CL, and SEM-EDS. This local and cross-sectional analysis clearly reveals a gradual transformation of phase and morphology in heated C@YAG:Ce3+ phosphors, which is related to a reaction between C and YAG:Ce3+ in N2 atmosphere. Through reaction between the carbon layer and YAG host materials, the emission colour of the phosphors can be modified from yellow, white, and then back to yellow under UV excitation as a function of heat-treatment in N2 atmosphere.

  3. Transition of Emission Colours as a Consequence of Heat-Treatment of Carbon Coated Ce3+-Doped YAG Phosphors.

    Science.gov (United States)

    Yin, Liang-Jun; Dierre, Benjamin; Sekiguchi, Takashi; van Ommen, J Ruud; Hintzen, Hubertus T Bert; Cho, Yujin

    2017-10-16

    To modify the luminescence properties of Ce 3+ -doped Y₃Al₅O 12 (YAG) phosphors, they have been coated with a carbon layer by chemical vapor deposition and subsequently heat-treated at high temperature under N₂ atmosphere. Luminescence of the carbon coated YAG:Ce 3+ phosphors has been investigated as a function of heat-treatment at 1500 and 1650 °C. The 540 nm emission intensity of C@YAG:Ce 3+ is the highest when heated at 1650 °C, while a blue emission at 400-420 nm is observed when heated at 1500 °C but not at 1650 °C. It is verified by X-ray diffraction (XRD) that the intriguing luminescence changes are induced by the formation of new phases in C@YAG:Ce 3+ -1500 °C, which disappear in C@YAG:Ce 3+ -1650 °C. In order to understand the mechanisms responsible for the enhancement of YAG:Ce 3+ emission and the presence of the blue emission observed for C@YAG:Ce 3+ -1500 °C, the samples have been investigated by a combination of several electron microscopy techniques, such as HRTEM, SEM-CL, and SEM-EDS. This local and cross-sectional analysis clearly reveals a gradual transformation of phase and morphology in heated C@YAG:Ce 3+ phosphors, which is related to a reaction between C and YAG:Ce 3+ in N₂ atmosphere. Through reaction between the carbon layer and YAG host materials, the emission colour of the phosphors can be modified from yellow, white, and then back to yellow under UV excitation as a function of heat-treatment in N₂ atmosphere.

  4. Tunable Luminescence of CeAl11O18 Based Phosphors by Replacement of (AlO)+ by (SiN)+ and Co-Doping with Eu

    NARCIS (Netherlands)

    Yin, L.J.; Chen, G.Z; Wang, C.; Xu, X.; Hao, L.Y.; Hintzen, H.T.J.M.

    2014-01-01

    A series of Si-N or Eu-Li doped CeAl11O18 and CeAl12O18N phosphors are prepared by solid–state reaction. Their structure and luminescence are researched carefully. Si-N doping with the concentration less than 8% can be successfully dissolved into CeAl11O18 crystal lattice and doesn't change the

  5. Luminescence properties of Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Lei Bingfu, E-mail: tleibf@jnu.edu.cn [Department of Physics, Jinan University, Guangzhou 510632 (China); Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Man Shiqing [Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Department of Electronic Engineering, Jinan University, Guangzhou 510632 (China); Liu Yingliang [Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Yue Song [Department of Physics, Jinan University, Guangzhou 510632 (China)

    2010-12-01

    We report on a luminescent phenomenon in Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} afterglow phosphor. XRD, photoluminescence, afterglow emission spectra and long-lasting phosphorescence decay curve are used to characterize this phosphor. After irradiation by a 267-nm UV light for 5 min, the Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor emits intense reddish-orange emitting afterglow from the {sup 4}G{sub 5/2} to {sup 6}H{sub J} (J = 5/2, 7/2, 9/2) transitions, and its afterglow can be seen with the naked eye in the dark clearly for more than 1 h after removal of the excitation source. Photoluminescence spectra reveal that the reddish-orange light-emitting long-lasting phosphorescence originate from the mixture of Sm{sup 3+} characteristic transitions. The afterglow decay curve of the Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor contains a fast decay component and another slow decay one. The possible mechanism of this reddish-orange light-emitting LLP phosphor is also discussed based on the experiment results.

  6. Phosphorous-doped TiO2 nanoparticles: synthesis, characterization, and visible photocatalytic evaluation on sulfamethazine degradation.

    Science.gov (United States)

    Mendiola-Alvarez, Sandra Yadira; Hernández-Ramírez, Ma Aracely; Guzmán-Mar, Jorge Luis; Garza-Tovar, Lorena Leticia; Hinojosa-Reyes, Laura

    2018-05-24

    Mesoporous phosphorous-doped TiO 2 (TP) with different wt% of P (0.5, 1.0, and 1.5) was synthetized by microwave-assisted sol-gel method. The obtained materials were characterized by XRD with cell parameters refinement approach, Raman, BET-specific surface area analysis, SEM, ICP-OES, UV-Vis with diffuse reflectance, photoluminescence, FTIR, and XPS. The photocatalytic activity under visible light was evaluated on the degradation of sulfamethazine (SMTZ) at pH 8. The characterization of the phosphorous materials (TP) showed that incorporation of P in the lattice of TiO 2 stabilizes the anatase crystalline phase, even increasing the annealing temperature. The mesoporous P-doped materials showed higher surface area and lower average crystallite size, band gap, and particle size; besides, more intense bands attributed to O-H bond were observed by FTIR analysis compared with bare TiO 2 . The P was substitutionally incorporated in the TiO 2 lattice network as P 5+ replacing Ti 4+ to form Ti-O-P bonds and additionally present as PO 4 3-  on the TiO 2 surface. All these characteristics explain the observed superior photocatalytic activity on degradation (100%) and mineralization (32%) of SMTZ under visible radiation by TP catalysts, especially for P-doped TiO 2 1.0 wt% calcined at 450 °C (TP1.0-450). Ammonium, nitrate, and sulfate ions released during the photocatalytic degradation were quantified by ion chromatography; the nitrogen and sulfur mass balance evidenced the partial mineralization of this recalcitrant molecule.

  7. Structural and luminescence effects of Ga co-doping on Ce-doped yttrium aluminate based phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Ayvacikli, M. [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Canimoglu, A. [Nigde University, Faculty of Arts and Sciences, Physics Department, Nigde (Turkey); Muresan, L.E., E-mail: laura_muresan2003@yahoo.com [Babes Bolyai University, Raluca Ripan Institute for Research in Chemistry, Fantanele 30, 400294 Cluj-Napoca (Romania); Barbu Tudoran, L. [Babes Bolyai University, Electronic Microscopy Centre, Clinicilor 37, 400006 Cluj Napoca (Romania); Garcia Guinea, J. [Museo Nacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Karabulut, Y. [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Jorge, A. [Museo Nacional Ciencias Naturales, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Karali, T. [Ege University, Institute of Nuclear Sciences, 35100 Bornova, İzmir (Turkey); Can, N., E-mail: cannurdogan@yahoo.com [Celal Bayar University, Faculty of Arts and Sciences, Department of Physics, Muradiye, Manisa (Turkey); Jazan University, Physics Department, P.O. Box 114, 45142 Jazan (Saudi Arabia)

    2016-05-05

    Herein, we primarily focus on luminescence spectrum measurements of various types of green emitting yttrium aluminate phosphors modified with gallium (Y{sub 3}Al{sub 5-x}Ga{sub x}O{sub 12}) synthesised by solid state reaction. The luminescent emission of samples depends on sample temperature and excitation radiation such as incident X-ray, electron and laser beam. Here, we measured radioluminescence (RL), cathodoluminescence (CL), photoluminescence (PL) along with XRD in order to clarify relationship between lattice defects and the spectral luminescence emissions. The RL and CL spectra of YAG:Ce exhibit an emission band ranging from 300 to 450 nm related to Y{sub Al} antisite defects. The broad emission band of garnet phosphors is shifted from 526 nm to 498 nm with increasing of Ga{sup 3+} content, while full width at half maximum (FWHM) of the band tends to be greater than the width of unmodified YAG:Ce garnet. Deconvolution of the spectrum reveals that three emission bands centred at 139, 234 and 294 °C occur in aluminate host garnets. - Highlights: • We present preparation of YAG:Ce{sup 3+}, Ga{sup 3+} phosphors by a solid state reaction method. • The shape and size of phosphor particles were investigated. • The luminescence properties were studied by different excitation sources.

  8. Luminescence enhancement in Eu3+, Sm3+ co-doped liy(MoO4)2 nano-phosphors by sol-gel process.

    Science.gov (United States)

    Zhou, Xianju; Wang, Guangchuan; Zhou, Tonghui; Zhou, Kaining; Li, Qingxu; Wang, Zhongqing

    2014-05-01

    A series of LiY(0.95-x)Eu(0.05)Sm(x)(MoO4)2 red light emitting phosphors were synthesized by sol-gel technique. The phase impurity and spectroscopic properties were characterized by X-ray Diffraction (XRD), Photo-Luminescence (PL) and Photo-Luminescence Excitation (PLE) spectra, respectively. It is found that the PLE spectra of the Eu3+, Sm3+ co-doped nanoparticles are enhanced and broadened as compared with the solely doped samples, which will make the co-doped phosphors match better with blue and/or UV GaN based LED chips. The red emission intensity of Eu3+ is largely enhanced by the energy transfer from Sm3+. The mechanism of the enhancement is clearly proven to be the increase in the quantum efficiency of 5D0 state of Eu3+ rather than the increase in the absorption of Eu3+. Meanwhile, the characteristic f-f transitions of Sm3+ are greatly reduced, resulting in little influence in the color purity of the co-doped phosphors. The present material is an amendatory promising red light emitting phosphor for white LEDs.

  9. Considerable photoluminescence enhancement of LiEu(MoO4)2 red phosphors via Bi and/or Si doping for white LEDs

    International Nuclear Information System (INIS)

    Wang, Qing-Feng; Liu, Ying; Wang, Yu; Wang, Wenxi; Wan, Yi; Wang, Gui-Gen; Lu, Zhou-Guang

    2015-01-01

    Graphical abstract: Doping of Bi and Si into the lattice leads to an considerable increase of the excitation efficiency and luminous intensity, and obvious movement of the CIE chromaticity coordinates to the NTSC standard values of the LiEu(MoO 4 ) 2 , a promising red phosphors suitable for near UV excited white-light emitting diodes. - Highlights: • High performance red phosphors for near UV light excited white LEDs. • Lithium lanthanide molybdate red phosphors. • Bi and Si substitution. • Considerable enhancement of luminescence intensity and excitation efficiency. • CIE chromaticity coordinates very close to the NTSC standard values. - Abstract: Novel Bi and/or Si substituted LiEu(MoO 4 ) 2 phosphors, where Bi was used as sensitizer to enhance the emission intensity and Si was used as substitution to improve the excitation efficiency, were prepared using the sol–gel method, and the photoluminescent properties of the resulting phosphors were intensively investigated. All samples can be excited efficiently by UV (395 nm) light and emit bright red light at 614 nm, which are coupled well with the characteristic emission from a UV-LED. In the Bi 3+ -doped samples, the intensities of the main emission line ( 5 D 0 – 7 F 2 transition at 614 nm) are strengthened because of the energy transition from Bi 3+ to Eu 3+ . With the substitution of Mo 4+ by Si 4+ , there are no significant changes in the emission peak positions, but the emission intensity was significantly enhanced under 395 nm excitation. Particularly, the LiEu 0.9 Bi 0.1 (Mo 0.97 Si 0.03 O 4 ) 2 phosphor doped with both Bi and Si demonstrates superior comprehensive photoluminescence properties with an excellent combination of easy excitation in the near UV range, bright emission intensity, high PL quantum efficiency as well as suitable decay time, which are very suitable for application as red phosphor for near UV type LEDs

  10. Synthesis and Luminescence Properties of Novel Ce(3+)- and Eu(2+)-Doped Lanthanum Bromothiosilicate La3Br(SiS4)2 Phosphors for White LEDs.

    Science.gov (United States)

    Lee, Szu-Ping; Liu, Shuang-De; Chan, Ting-Shan; Chen, Teng-Ming

    2016-04-13

    Novel Ce(3+)- and Eu(2+)-doped lanthanum bromothiosilicate La3Br(SiS4)2:Ce(3+)and La3Br(SiS4)2:Eu(2+) phosphors were prepared by solid-state reaction in an evacuated and sealed quartz glass ampule. The La3Br(SiS4)2:Ce(3+) phosphor generates a cyan emission upon excitation at 375 nm, whereas the La3Br(SiS4)2:Eu(2+) phosphor could be excited with extremely broad range from UV to blue region (300 to 600 nm) and generates a reddish-orange broadband emission centered at 640 nm. In addition, thermal luminescence properties of La3Br(SiS4)2:Ce(3+)and La3Br(SiS4)2:Eu(2+) phosphors from 20 to 200 °C were investigated. The combination of a 450 nm blue InGaN-based LED chip with the red-emitting La3Br(SiS4)2:Eu(2+) phosphor, and green-emitting BOSE:Eu(2+) commercial phosphor produced a warm-white light with the CRI value of ∼95 and the CCT of 5,120 K. Overall, these results show that the prepared phosphors may have potential applications in pc-WLED.

  11. Luminescence and electron degradation properties of Bi doped CaO phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Yousif, A. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Department of Physics, Faculty of Education, University of Khartoum, P.O. Box 321, 11115 Omdurman (Sudan); Kroon, R.E.; Coetsee, E.; Ntwaeaborwa, O.M. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Seed Ahmed, H.A.A. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Department of Physics, Faculty of Education, University of Khartoum, P.O. Box 321, 11115 Omdurman (Sudan); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa)

    2015-11-30

    Graphical abstract: - Highlights: • Blue emitting Ca{sub 1−x}O:Bi{sub x=0.5%} phosphor powder was successfully prepared. • Strong blue near-UV emission was obtained. • Electron beam induced cathodoluminescence intensity degradation occurred. • XPS was successfully used to explain the degradation process. - Abstract: Ca{sub 1−x}O:Bi{sub x=0.5%} phosphor powder was successfully synthesized by the sol-gel combustion method. The structure, morphology and luminescent properties of the phosphor were characterized by X-ray diffraction, scanning electron microscopy, photoluminescence and cathodoluminescence (CL) spectroscopy. The results showed that the Ca{sub 1−x}O:Bi{sub x=0.5%} consisted of single face-centred cubic crystals and that the phosphor particles were uniformly distributed. When the phosphor was excited by a xenon lamp at 355 nm, or a 325 nm He–Cd laser, or electron beam, it emitted strongly in the blue near-UV range with a wavelength of 395 nm ({sup 3}P{sub 1} → {sup 1}S{sub 0} transition of Bi{sup 3+}). The CL intensity was monitored as a function of the accelerating voltage and also as a function of the beam current. The powder was also subjected to a prolonged electron beam irradiation to study the electron beam induced CL intensity degradation. X-ray photoelectron spectroscopy was used to analyze the Ca{sub 1−x}O:Bi{sub x=0.5%} phosphor sample surface before and after degradation.

  12. Rare-earth doped gadolinia based phosphors for potential multicolor and white light emitting deep UV LEDs.

    Science.gov (United States)

    Bedekar, Vinila; Dutta, Dimple P; Mohapatra, M; Godbole, S V; Ghildiyal, R; Tyagi, A K

    2009-03-25

    Gadolinium oxide host and europium/dysprosium/terbium doped gadolinium oxide nanoparticles were synthesized using the sonochemical technique. Gadolinium oxide nanocrystals were also co-doped with total 2 mol% of Eu(3+)/Dy(3+),Eu(3+)/Tb(3+),Dy(3+)/Tb(3+), and also Eu(3+)/Dy(3+)/Tb(3+) ions, by the same method. The nanoparticles obtained were characterized using powder x-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) techniques. The size of the particles ranged from 15 to 30 nm. The triple doped samples showed multicolor emission on single wavelength excitation. The photoluminescence results were correlated with the lifetime data to get an insight into the luminescence and energy transfer processes taking place in the system. On excitation at 247 nm, the novel nanocrystalline Gd(2)O(3):RE (RE = Dy, Tb) phosphor resulted in having very impressive CIE chromaticity coordinates of x = 0.315 and y = 0.316, and a correlated color temperature of 6508 K, which is very close to standard daylight.

  13. Luminescence properties of terbium-doped Li 3 PO 4 phosphor for ...

    Indian Academy of Sciences (India)

    A polycrystalline sample of Li 3 PO 4 :Tb 3 + phosphor was successfully synthesized using solid-state diffusion method. This synthesis method is of low cost, low temperature and does not require any other atmospheres for the synthesis. The powder X-ray diffraction (PXRD), photoluminescence (PL) emission and excitation ...

  14. Phosphoric acid doped polysulfone membranes with aminopyridine pendant groups and imidazole cross-links

    DEFF Research Database (Denmark)

    Hink, Steffen; Elsøe, Katrine; Cleemann, Lars Nilausen

    2015-01-01

    Udel polysulfone based membranes with 4-aminopyridine pendant groups and cross-linking imidazole units are synthesized in a simple two step reaction. The ratio of 4-aminopyridine and imidazole is varied and the materials are extensively characterized. The average phosphoric acid uptake (in 85 wt%...

  15. Advances in the synthesis of new Europium doped CaSO4 phosphors and their thermoluminescence characterization

    International Nuclear Information System (INIS)

    Bernal, R.; Garcia-Haro, A.R.; Machi, L.; Brown, F.; Perez-Salas, R.; Castano, V.M.; Cruz-Vazquez, C.

    2008-01-01

    Novel self-agglomerating Eu doped CaSO 4 phosphors were synthesized by a cheap, easy, and environmental friendly chemical route. Pellet-shaped sintered samples were obtained without any binding material, and exposed to beta particle irradiation. The thermoluminescence (TL) response in the 0.08-2.6 Gy dose range increased linearly as the radiation dose increased. Glow curves exhibit the most intense maximum close to 200 deg. C, and two much less intense maxima at 250 and 330 deg. C when a 5 deg. C/s heating rate is used. No TL peaks shift is observed when dose changes, which is characteristic of first order kinetics TL processes. The whole glow curve displays a remarkable stability under storage at room temperature. The main peak intensity is 2.5 times greater than that of the TLD-100. The method here reported can be used to synthesize CaSO 4 with other dopants

  16. Photoluminescence, reddish orange long persistent luminescence and photostimulated luminescence properties of praseodymium doped CdGeO3 phosphor

    International Nuclear Information System (INIS)

    Jin, Yahong; Hu, Yihua; Chen, Li; Fu, Yinrong; Mu, Zhongfei; Wang, Tao; Lin, Jun

    2014-01-01

    Highlights: • A novel phosphor CdGeO 3 :Pr 3+ was synthesized successfully. • The persistent luminescence properties of CdGeO 3 :Pr 3+ were studied. • The photostimulated luminescence properties of CdGeO 3 :Pr 3+ were investigated. • The persistent and photostimulated luminescence mechanisms were discussed in detail. - Abstract: Praseodymium doped CdGeO 3 phosphors were prepared successfully by a conventional high temperature solid-state reaction method. It showed reddish orange long persistent luminescence (LPL) after the short UV-irradiation. The reddish orange photostimulated luminescence (PSL) was also observed upon near infrared stimulation at 980 nm after per-exposure into UV light. The origin of LPL and PSL was identified with the emission from Pr 3+ ions with the aid of traps in host lattice. The optimal concentration of Pr 3+ ions for the brightest photoluminescence (PL) emission and the best LPL characteristic were experimentally to be about 3% and 0.5 mol%, respectively. The trapping and de-trapping processes of charge carriers between shallower and deep traps were illustrated. A model was proposed on the basis of experimental results to study the mechanisms of LPL and PSL

  17. Possibility of RGB emission by Eu2+ ion doped MIIMIIIMVI phosphors for color inorganic electro- luminescent displays

    International Nuclear Information System (INIS)

    Jabbarov, R.B.; Tagiev, B.G.; Tagiev, O.B.; Musaeva, N.N.; Benalloul, P.; Barthou, C.

    2004-01-01

    Full text: Eu 2+ ion give broad-band emission due to f-d transitions. The 5d orbital are not shelled from the host lattice by any occupied orbital. Therefore the wavelength positions of the emission bands depend on host and change from hear UV to red. With increasing crystal field strength, the emission bands shift to longer wavelength. The broad band absorption and luminescence of Eu 2+ is parity-and spin-allowed and lifetime is sub-microseconds. In resent years, many efforts have been devoted to luminescence studies of thio gallates and thio-aluminates doped with rare-earth ions because of their chemical stability in ambient environments. In ternary compounds both the ligand field at the divalent cation site and the nephelauxetic effect are reduced by the presence of trivalent or tetravalent ions. This effect is more pronounced with Al than with Ga. In a same family of compounds, the emission band generally shifts to shorter wavelengths with increasing M II /M IV or M VI /M III ratio. In this paper we revisited the luminescence of the phosphors CaGa 2 S 4 , BaGa 2 S 4 , BaAl 2 S 4 activated by Eu 2+ ion. Influence of temperature and Eu 2+ concentration on the luminescence characteristics of these phosphors are studied. These dates will be useful to evaluate the quality oi the powder or thin films prepared for devices

  18. Photocatalytic characteristics for the nanocrystalline TiO{sub 2} on the Ag-doped CaAl{sub 2}O{sub 4}:(Eu,Nd) phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung-Sik, E-mail: jskim@uos.ac.kr; Sung, Hyun-Je; Kim, Bum-Joon

    2015-04-15

    Highlights: • The photocatalytic reactivity of the TiO{sub 2}-coated on the Ag-doped long-lasting phosphor (CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+}). • The photodecomposition of benzene gas under visible light irradiation. • The TiO{sub 2}-coated on the Ag-doped long-lasting phosphor showed much higher photocatalytic reactivity. • The light emitted from the long-lasting phosphors contributed to the photo generation of TiO{sub 2}. - Abstract: This study investigated the photocatalytic behavior of nanocrystalline TiO{sub 2} deposited on Ag-doped long-lasting phosphor (CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+}). The CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} phosphor powders were prepared via conventional sintering using CaCO{sub 3}, Al{sub 2}O{sub 3}, Eu{sub 2}O{sub 3}, and Nd{sub 2}O{sub 3} as raw materials according to the appropriate molar ratios. Silver nanoparticles were loaded on the phosphor by mixing with an aqueous Ag-dispersion solution. Nanocrystalline TiO{sub 2} was deposited on Ag-doped CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} powders via low-pressure chemical vapor deposition (LPCVD). The TiO{sub 2} coated on the phosphor was actively photo-reactive under irradiation with visible light and showed much faster benzene degradation than pure TiO{sub 2}, which is almost non-reactive. The coupling of TiO{sub 2} with phosphor may result in an energy band bending in the junction region, which then induces the TiO{sub 2} crystal at the interface to be photo-reactive under irradiation with visible light. In addition, the intermetallic compound of CaTiO{sub 3} that formed at the interface between TiO{sub 2} and the CaAl{sub 2}O{sub 4}:(Eu{sup 2+},Nd{sup 3+}) phosphor results in the formation of oxygen vacancies and additional electrons that promote the photodecomposition of benzene gas. The addition of Ag nanoparticles enhanced the photocatalytic reactivity of the TiO{sub 2}/CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} phosphor. TiO{sub 2} on the Ag-doped

  19. Phosphoric acid doped polybenzimidazole membranes: Physiochemical characterization and fuel cell applications [PEM fuel cells

    DEFF Research Database (Denmark)

    Qingfeng, Li; Hjuler, Hans Aage; Bjerrum, Niels

    2001-01-01

    A polymer electrolyte membrane fuel cell operational at temperatures around 150-200 degrees C is desirable for fast electrode kinetics and high tolerance to fuel impurities. For this purpose polybenzimidazole (PBI) membranes have been prepared and H/sub 3/PO/sub 4/-doped in a doping range from 300...... doping level. At 160 degrees C a conductivity as high as 0.13 S cm/sup -1/ is obtained for membranes of high doping levels. Mechanical strength measurements show, however, that a high acid doping level results in poor mechanical properties. At operational temperatures up to 190 degrees C, fuel cells...... based on this polymer membrane have been tested with both hydrogen and hydrogen containing carbon monoxide....

  20. Synthesis and luminescence properties of Ce{sup 3+} doped MWO{sub 4} (M=Ca, Sr and Ba) microcrystalline phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Dabre, K.V. [Department of Physics, Arts, Commerce and Science College, Koradi, Nagpur (India); Dhoble, S.J., E-mail: sjdhoble@rediffmail.com [Department of Physics, R.T.M. Nagpur University, Nagpur 440033 (India); Lochab, Jyoti [Radiotherapy Department, Safdarjung Hospital, New Delhi (India)

    2014-05-01

    The Ce{sup 3+} doped and undoped samples of alkali earth metal tungstate MWO{sub 4} (M=Ca, Sr, and Ba) phosphors are synthesized by a co-precipitation method in controlled pH environment. The resulting phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), photoluminescence (PL) and thermoluminescence (TL). XRD pattern and SEM micrographs reveal the formation of agglomerated microcrystalline phosphor. FTIR spectra show the strong absorption around 821 cm{sup −1} due to characteristic vibrations of (WO{sub 4}){sup 2−} complex. PL excitation spectra show broadband in the UV region having peak at 280 nm, and the emission spectrum shows broadband in the visible region with peak in the blue region. The PL emission intensity increases with Ce{sup 3+} concentration with the most effective concentration at 5 mol%. The complex TL glow curve of Ce{sup 3+} doped phosphors is deconvoluted by using a TLAnal computer program. The trap parameters obtained by TLAnal were compared with those calculated by Chen's method and a possible model for TL is discussed. - Highlights: • M{sub 1−x}WO{sub 4}:Ce{sub x} (M=Ca, Sr, and Ba) phosphors are synthesized by the co-precipitation method in controlled pH environment. • Phosphor exhibits broad emission band with maximum in the blue region. • Enhancement of PL emission intensity due to doping of Ce in a host lattice. • The complex TL glow curves were deconvoluted by TLAnal. • FTIR spectra show the main transmittance peaks related to v{sub 3} and v{sub 4} vibration modes of W–O bonds.

  1. Structural and optical analysis on europium doped AZrO{sub 3} (A=Ba, Ca, Sr) phosphor for display devices application

    Energy Technology Data Exchange (ETDEWEB)

    Dubey, Vikas, E-mail: jsvikasdubey@gmail.com [Department of Physics, Bhilai Institute of Technology Raipur, 493661 (India); Tiwari, Neha [Department of Physics, Govt. Model Science College, Jabalpur (India)

    2016-05-06

    Behavior displayed by europium doped AZrO{sub 3} phosphor which was synthesized by solid state reaction method. For synthesis of BaZrO{sub 3}, SrZrO{sub 3} and CaZrO{sub 3} phosphor with fixed concentration of europium ion was calcination at 1000°C and sintered at 1300°C following intermediate grinding. Synthesized sample was characterized by X-ray diffraction analysis and crystallite sized was calculated by Scherer’s formula. From PL spectra of prepared phosphors shows intense emission centred at 612nm (red emission) with high intensity for SrZrO{sub 3}:Eu{sup 3+}. For europium doped BaZrO{sub 3} and CaZrO{sub 3} (613nm) phosphor shows less intense PL spectra as compared to SrZrO{sub 3}:Eu{sup 3+}. The strong emission peak of AZrO{sub 3}:Eu{sup 3+} phosphor is due to forced electric dipole transition of {sup 5}D{sub 0} to {sup 7}F{sub 2} centered at 612 and 613nm. It is characteristic red emission for europium ion. The excitation spectra of AZrO{sub 3}:Eu{sup 3+} phosphor mainly consists of the charge transfer and (CTB) of Eu{sup 3+} located in 200–350 nm centred at 254nm. The present phosphors can act as single host for red light emission in display devices. The CIE coordinates were calculated by Spectrophotometric method using the spectral energy distribution of the AZrO{sub 3}:Eu{sup 3+} sample.

  2. Structural characterization and optical properties of Eu"2"+ and Dy"2"+ doped Sr_2SiO_4 phosphor by solid state reaction method

    International Nuclear Information System (INIS)

    Verma, Durga; Verma, Mohan L.; Upma; Patel, R.P.

    2016-01-01

    Thermoluminescence, SEM, FTIR Divalent dysprosium and europium doped strontium silicate (Sr_2SiO_4) phosphors were synthesized with the high-temperature solid-state reaction technique. The obtained phosphor was well characterized by powder X-ray diffraction, scanning electron microscopy, FTIR, UV-visible spectroscopy and thermoluminescence. The crystal structure of the prepared phosphor has an orthorhombic structure with space group Pnma. From scanning electron microscopy (SEM), agglomerations of particles were observed due to the high temperature synthesis process. The chemical composition of the sintered Sr_2SiO_4:Dy"2"+ and Sr_2SiO_4: Eu"2"+ phosphor was confirmed by energy dispersive X-ray spectroscopy (EDX). The UV-VIS analysis can be thought as a good quality check for the optical behavior of materials. The Fourier transmission infrared spectroscopy (FTIR) confirms the present elements in phosphor. Thermoluminescence study was carried out for the phosphor with UV irradiation show one glow peak. The trapping parameters associated with the prominent glow peak of Sr_2SiO_4:Dy"2"+ and Sr_2SiO_4:Eu"2"+ are calculated using Chen's glow curve method. The release of holes/electrons from defect centers at the characteristic trap site initiates the luminescence process in this material. (author)

  3. Fracto- mechanoluminescence and thermoluminescence properties of orange-red emitting Eu3+ doped Ca2Al2SiO7 phosphors

    International Nuclear Information System (INIS)

    Tiwari, Geetanjali; Brahme, Nameeta; Sharma, Ravi; Bisen, D.P.; Sao, Sanjay K.; Khare, Ayush

    2017-01-01

    The suitability of nano-structured Ca 2 Al 2 SiO 7 :Eu 3+ phosphors for thermoluminescence and mechanoluminescence dosimeter were investigated. Europium doped di-calcium di-aluminum silicate phosphor was synthesised by the combustion assisted method and annealed at 1100 °C for 4 h in reducing and oxidizing environments. The prepared Ca 2 Al 2 SiO 7 :Eu 3+ phosphor was characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDX), photoluminescence (PL) and decay characteristics. The phase structure of sintered phosphor has akermanite type which belongs to the tetragonal crystallography; this structure is a member of the melilite group and forms a layered compound. The chemical composition of the sintered Ca 2 Al 2 SiO 7 :Eu 3+ phosphor was confirmed by EDX spectra. Mechanoluminescence (ML) and thermoluminescence (TL) studies revealed that the ML and TL intensity increases with activator concentration. Optimum ML was observed for the sample having 2 mol% of Eu ions. The TL intensity of Ca 2 Al 2 SiO 7 :Eu 3+ was recorded for different exposure times of γ -irradiation and it was observed that TL intensity is maximum for γ dose of 1770 Gy. The PL spectra indicated that Ca 2 Al 2 SiO 7 :Eu 3+ could be excited effectively by near ultraviolet (NUV) light and exhibited bright orange-red emission with excellent colour stability. CIE colour coordinates of the prepared Ca 2 Al 2 SiO 7 :Eu 3+ phosphor was found suitable as orange-red light emitting phosphor with a CIE value of (x=0.6142, y=0.3849) and correlated colour temperature (CCT) is 1250 K. Therefore, it is considered to be a new promising orange-red emitting phosphor for white light emitting diode (LED) application.

  4. Red emitting phosphors of Eu3+ doped Na2Ln2Ti3O10 (Ln = Gd, Y) for white light emitting diodes

    International Nuclear Information System (INIS)

    Zhang, Niumiao; Guo, Chongfeng; Yin, Luqiao; Zhang, Jianhua; Wu, Mingmei

    2015-01-01

    Highlights: • Layered red phosphors Na 2 Ln 2 Ti 3 O 10 (Ln = Gd, Y):Eu 3+ were prepared. • The synthesis parameters of phosphors were optimized. • PL and thermal stability of the samples were investigated. • LED devices were also fabricated including the present red phosphor. - Abstract: A series of Eu 3+ doped Na 2 Ln 2 Ti 3 O 10 (Ln = Gd, Y) red-emitting phosphors for application in ultraviolet based light emitting diodes (LEDs) were successfully synthesized by a modified sol–gel method. Their structure and luminescent properties were characterized by powder X-ray diffraction (XRD), photoluminescence excitation (PLE) and emission (PL) spectra and absorption spectra, according to these results the optimal compositions and synthesis parameters were determined. In addition, the thermal stabilities of the phosphors were investigated according to the temperature-dependent PL spectra. The red and white-LEDs (W-LEDs) comprising the Na 2 Ln 2 Ti 3 O 10 :Eu 3+ (Ln = Gd, Y) red emitting phosphors were fabricated with a near-ultraviolet (n-UV) chip. In comparison with Na 2 Y 1.4 Eu 0.6 Ti 3 O 10 , the Na 2 Gd 0.6 Eu 1.4 Ti 3 O 10 phosphor offers higher brightness, quantum efficiency, and excellent thermal stability. W-LEDs comprising Na 2 Gd 0.6 Eu 1.4 Ti 3 O 10 showed bright white emission with a color rendering index (Ra) of 82, a color temperature of 2151 K, and Commission Internationale de I’Eclairage (CIE) color coordinates of (0.34, 0.37). The phosphor Na 2 Gd 0.6 Eu 1.4 Ti 3 O 10 is more suitable candidate for application in LEDs

  5. Luminescence characteristic of YVO{sub 4}:Eu{sup 3+} thin film phosphors by Li doping

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hyun Kyoung; Shim, Kyoo Sung; Moon, Byung Kee; Choi, Byung Chun [Department of Physics, Pukyong National University, Busan 608-737, Republic Korea (Korea, Republic of); Jeong, Jung Hyun [Department of Physics, Pukyong National University, Busan 608-737, Republic Korea (Korea, Republic of)], E-mail: jhjeong@pknu.ac.kr; Yi, Soung Soo [Department of Electronic Materials Engineering, Silla University, Busan 608-736, Republic Korea (Korea, Republic of); Kim, Jung Hwan [Department of Physics, Dong Eui University, Busan 614-714, Republic Korea (Korea, Republic of)

    2008-06-30

    YVO{sub 4}:Eu{sup 3+} and Li-doped YVO{sub 4}:Eu{sup 3+} thin film phosphors have been deposited on Al{sub 2}O{sub 3} (0001) substrate using a pulsed laser deposition technique. The Li{sup +} ions concentration was varied from 0 to 3 wt.% and Li{sup +} doping influenced crystallinity and surface morphology of YVO{sub 4}:Eu{sup 3+} films.. As Li{sup +} content increases from 0 wt.% to 2 wt.%, not only crystallinity was improved, but also the shape of grains was rounded. However, Li{sup +} content, increases further to 3 wt.% the shape of grains was changed to elliptical. The emitted radiation was dominated by a red emission peak at 619 nm radiated from the {sup 5}D{sub 0}-{sup 7}F{sub 2} transition of Eu{sup 3+} ions. In particular, the incorporation of Li{sup +} ions into YVO{sub 4} lattice could induce an increase of photoluminescence. The enhanced luminescence results not only from the improved crystallinity but also from the enhanced surface roughness. The luminescent intensity and surface roughness exhibited similar behavior as a function of Li{sup +} ions concentration.

  6. Structural and optical properties of Tb and Na-Tb co-doped Ca3V2O8 phosphors prepared by sol-gel process

    Science.gov (United States)

    Parab, Shambhu S.; Salker, A. V.

    2018-01-01

    A malic acid assisted sol-gel route was successfully employed to prepare two distinct series of green emitting Ca3V2O8 phosphors. In the first series, Tb was solely doped whereas in the second series Na and Tb were doped simultaneously in the Ca3V2O8 crystal lattice. X-ray diffraction studies proved the utility of adopted preparative method by confirming the monophasic formation of all compounds from both the series. Spectral analysis like Raman spectroscopy, UV-DRS were undertaken to analyse the local structure, crystallinity and absorptive characteristics. XPS validated the presence of desired oxidation states of all the elements present. Finally, photoluminescence studies were done to elucidate the scope of prepared compounds as green emitting phosphors and also to understand the effect of both doping schemes on the luminescence. Intense green emission was observed in both the cases. Tb concentration of 0.08 was found to be optimum in case of Tb singly doped compounds whereas Tb = 0.12 showed highest intensity among the Na-Tb co-doped samples. Moreover, a red shift in the excitation wavelength was observed after Na doping signifying a change in the local electronic environment which in turn has affected the luminescence pattern. Local crystallinity and vacancy concentrations were found to have a major say on the emission intensities.

  7. Investigation of thermal quenching and abnormal thermal quenching in mixed valence Eu co-doped LaAlO{sub 3} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jingjing [Tianjin Key Laboratory for Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China); Zhao, Yang [China academy of civil aviation science and technology, Beijing 100028 (China); Mao, Zhiyong, E-mail: mzhy1984@163.com [Tianjin Key Laboratory for Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China); Wang, Dajian [Tianjin Key Laboratory for Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China); Bie, Lijian, E-mail: ljbie@tjut.edu.cn [Tianjin Key Laboratory for Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 (China)

    2017-06-15

    Temperature dependent luminescence of mixed valence Eu co-doped LaAlO{sub 3} phosphors are deeply investigated in this work. Different temperature properties of Eu{sup 2+} and Eu{sup 3+} luminescence are observed as the phosphor excited by different incident light. Eu{sup 3+} luminescence shows normal thermal quenching when excited at 320 nm and abnormal thermal quenching as the excitation light changed into 365 nm, while Eu{sup 2+} luminescence exhibits a normal thermal quenching independent on the incident excitation lights. The origin of these novel normal/abnormal thermal quenching phenomena are analyzed and discussed by the excitation-emission processes in terms of the configuration coordinate model. The presented important experimental and analysis results give insights into the temperature properties of phosphors.

  8. Synthesis and characterization of phosphors based on calcium and magnesium silicates doped with europium and dysprosium

    International Nuclear Information System (INIS)

    Misso, Agatha Matos

    2016-01-01

    Ca and Mg silicates based phosphors were prepared by sol-gel method combined with the molten salts process. The gel of silica was obtained from Na 2 SiO 3 solution by using europium, dysprosium, calcium and magnesium chloride solutions. Therefore, those chlorides were homogeneously dispersed into the gel. The obtained gel was dried and heat treated to 900° C for 1h to allow the fusion of the present salts. Then it was water washed until negative test for Cl - , and dried. The reduction of the europium to Eu 2+ was performed under atmosphere of 5% of H 2 and 95% of Ar to 900° C for 3h, to reach CaMgSi 2 O 6 :Eu 2+ and CaMgSi 2 O 6 :Eu 2+ :Dy 3+ phosphors. Diopside was identified as main crystalline phase and quartz, as secondary phase from XRD (X-ray diffraction) patterns. SEM (scanning electron microscopy) micrographs, of the samples showed needles, spheres, leaves and rods of particles and agglomerates. Thermal analysis (TGA-DTGA) curves revealed that the crystallization temperature of CaMgSi 2 O 6 :Eu 2+ lies around 765° C. Photoluminescence spectroscopy of the phosphors was studied based on interconfigurational 4f N → 4f N-1 5d transition of Eu 2+ ion. The spectra of excitation showed 4f N → 4f N-1 5d transition of Eu 2+ ion broad band, related to the ligand to metal charge transfer transition (LMCT) O 2- (2p) → Eu 3+ in the 250 nm region, when the emission is monitored at 583,5 nm. It also presents the 4f ↔ 4f transitions of Eu 3+ ion bands, showing the 7 F 0 → 5 L 6 transition at 393 nm. From emission spectra with excitation monitored at 393 nm, it can be observed fine peaks between 570 and 750 nm which are characteristics of 5 D 0 → 7 F J (J = 0 - 5) transition of Eu 3+ ion, indicating that the Eu 3+ ion occupies a site with center of inversion. Finally, the obtained results indicate that the developed method is suitable to synthesize CaMgSi 2 O 6 :Eu 2+ and CaMgSi 2 O 6 :Eu 2+ :Dy 3+ phosphors, as it has been proposed. (author)

  9. The synthesis and luminescence properties of a novel red-emitting phosphor: Eu3+-doped Ca9La(PO4)7

    Science.gov (United States)

    Liang, Zehui; Mu, Zhongfei; Wang, Qiang; Zhu, Daoyun; Wu, Fugen

    2017-10-01

    A series of novel red-emitting phosphors Ca9La1- x (PO4)7: xEu3+ were synthesized by high-temperature solid state reactions. The photoluminescence excitation and photoluminescence spectra of these phosphors were investigated in detail. O2--Eu3+ charge transfer band peaking at about 261 nm is dominant in the PLE spectra of Eu3+-doped Ca9La(PO4)7, indicating that the phosphors are suitable for tricolor fluorescent lamps. The phosphors also show a good absorption in near ultraviolet (around 395 nm) and blue (around 465 nm) spectral region, which indicates that it can be pumped with NUV and blue chips for white light-emitting diodes. The transition of 5D0 → 7F2 of Eu3+ in this lattice can emit bright red light. Ca9La(PO4)7 could accommodate a large amount of Eu3+ with an optimal concentration of 60 mol%. The dipole-dipole interaction between Eu3+ is the dominant mechanism for concentration quenching of Eu3+. The calculated color coordinates lie in red region ( x = 0.64, y = 0.36), which is close to Y2O3: 0.05Eu3+ ( x = 0.65, y = 0.34). The integral emission intensity of Ca9La0.4(PO4)7: 0.6Eu3+ is 1.9 times stronger than that of widely used commercial red phosphor Y2O3: 0.05Eu3+. All these results indicate that Eu3+-doped Ca9La(PO4)7 is a promising red-emitting phosphor which can be used in tricolor fluorescent lamps and white light-emitting diodes.

  10. Luminescent features of sol–gel derived rare-earth multi-doped oxyfluoride nano-structured phosphors for white LED application

    International Nuclear Information System (INIS)

    Gouveia-Neto, A.S.; Silva, A.F. da; Bueno, L.A.; Costa, E.B. da

    2012-01-01

    Rare-earth doped oxyfluoride 75SiO 2 :25PbF 2 nano-structured phosphors for white-light-emitting diodes were synthesized by thermal treatment of precursor sol–gel derived glasses. Room temperature luminescence features of Eu 3+ , Sm 3+ , Tb 3+ , Eu 3+ /Tb 3+ , and Sm 3+ /Tb 3+ ions incorporated into low-phonon-energy PbF 2 nanocrystals dispersed in the aluminosilicate glass matrix and excited with UV light emitting diode were investigated. The luminescence spectra exhibited strong emission signals in the red (600, 610, 625, and 646 nm), green (548 and 560 nm), and blue (485 nm) wavelength regions. White-light emission was observed in Sm/Tb and Eu/Tb double-doped activated phosphors employing UV-LED excitation at 395 nm. The dependence of the luminescence emission intensities upon annealing temperature and rare-earth concentration was also examined. The results indicated that there exist optimum annealing temperature and activator ion concentration in order to obtain intense visible emission light with high color rendering index. The study suggests that the nanocomposite phosphor based upon 75SiO 2 :25PbF 2 host herein reported is a promising contender for white-light LED applications. - Highlights: ► White-light emission in double-doped activated phosphors employing UV-LED excitation. ► Luminescent features of europium, samarium, and terbium in nanocrystals dispersed in aluminosilicate glass. ► New nanocomposite phosphor host for white-light LED applications.

  11. Synthesis and luminescence characterization of Pr3+ doped Sr1.5Ca0.5SiO4 phosphor

    Science.gov (United States)

    Vidyadharan, Viji; Mani, Kamal P.; Sajna, M. S.; Joseph, Cyriac; Unnikrishnan, N. V.; Biju, P. R.

    2014-12-01

    Luminescence properties of Pr3+ activated Sr1.5Ca0.5SiO4 phosphors synthesized by solid state reaction method are reported in this work. Blue, orange red and red emissions were observed in the Pr3+ doped sample under 444 nm excitation and these emissions are assigned as 3P0 → 3H4, 3P0 → 3H6 and 3P0 → 3F4 transitions. The emission intensity shows a maximum corresponding to the 0.5 wt% Pr3+ ion. The decay analysis was done for 0.05 and 0.5 wt% Pr3+ doped samples for the transition 3P0 → 3H6. The life times of 0.05 and 0.5 wt% Pr3+ doped samples were calculated by fitting to exponential and non-exponential curve respectively, and are found to be 156 and 105 μs respectively. The non-exponential behaviour arises due to the statistical distribution of the distances between the ground state Pr3+ ions and excited state Pr3+ ions, which cause the inhomogeneous energy transfer rate. The XRD spectrum confirmed the triclinic phase of the prepared phosphors. The compositions of the samples were determined by the energy dispersive X-ray spectra. From the SEM images it is observed that the particles are agglomerated and are irregularly shaped. IR absorption bands were assigned to different vibrational modes. The well resolved peaks shown in the absorption spectra are identical to the excitation spectra of the phosphor samples. Pr3+ activated Sr1.5Ca0.5SiO4 phosphors can be efficiently excited with 444 nm irradiation and emit multicolour visible emissions. From the CIE diagram it can be seen that the prepared phosphor samples give yellowish-green emission.

  12. Synthesis and effect of Ce and Mn co-doping on photoluminescence characteristics of Ca6AlP5O20:Eu novel phosphors.

    Science.gov (United States)

    Shinde, K N; Dhoble, S J

    2013-01-01

    A series of Ca6AlP5O20 doped with rare earths (Eu and Ce) and co-doped (Eu, Ce and Eu,Mn) were prepared by combustion synthesis. Under Hg-free excitation, Ca6AlP5O20:Eu exhibited Eu(2+) (486 nm) emission in the blue region of the spectrum and under near Hg excitation (245 nm), Ca6AlP5O20:Ce phosphor exhibited Ce(3+) emission (357 nm) in the UV range. Photoluminescence (PL) peak intensity increased in Ca6AlP5O20:Eu,Ce and Ca6AlP5O20:Eu, Mn phosphors due to co-activators of Ce(3+) and Mn(2+) ions. As a result, these ions played an important role in PL emission in the present matrix. Ca6AlP5O20:Eu, Ce and Ca6AlP5O20:Eu, Mn phosphors provided energy transfer mechanisms via Ce(3+) → Eu(2+) and Eu(2+) → Mn(2+), respectively. Eu ions acted as activators and Ce ions acted as sensitizers. Ce emission energy was well matched with Eu excitation energy in the case of Ca6AlP5O20:Eu, Ce and Eu ions acted as activators and Mn ions acted as sensitizers in Ca6AlP5O20:Eu, Mn. This study included synthesis of new and efficient phosphate phosphors. The impact of doping and co-doping on photoluminescence properties and energy transfer mechanisms were investigated and we propose a feasible interpretation. Copyright © 2012 John Wiley & Sons, Ltd.

  13. Enhancement of the mechanoluminescence properties on Ca2MgSi2O7:Dy3+ phosphor by co-doping of charge compensator ions

    Science.gov (United States)

    Sahu, Ishwar Prasad

    2016-08-01

    In the present article, effect of charge compensator ions (R+ = Li+, Na+ and K+) on dysprosium-doped di-calcium magnesium di-silicate (Ca2MgSi2O7:Dy3+) phosphors were investigated. The Ca2MgSi2O7:Dy3+ and Ca2MgSi2O7:Dy3+, R+ phosphors, were prepared by solid-state reaction method. The crystal structures of sintered phosphors were an akermanite-type structure which belongs to the tetragonal crystallography. The peaks of mechanoluminescence (ML) intensity were increased linearly with increasing impact velocity of the moving piston. Thus, present investigation indicates that the piezoelectricity was responsible to produce ML in prepared phosphors. The time of the peak ML intensity and the decay rate did not change significantly with respect to increasing impact velocity. Addition of charge compensator ions enhances the luminescence intensity of prepared Ca2MgSi2O7:Dy3+ phosphors, because they neutralize the charge generated by Dy3+ substitution for Ca2+ ions. The role of Li+ ions among all charge compensator ions (Na+ or K+) used was found to be most effective for enhanced Dy3+ ion emission. These ML materials can be used in the devices such as stress sensor, fracture sensor, impact sensor, damage sensors, safety management monitoring system and fuse system for army warheads.

  14. A novel double perovskite tellurate Eu3+-doped Sr2MgTeO6 red-emitting phosphor with high thermal stability

    Science.gov (United States)

    Liang, Jingyun; Zhao, Shancang; Yuan, Xuexia; Li, Zengmei

    2018-05-01

    A series of novel double perovskite tellurate red-emitting phosphors Sr2MgTeO6:xEu3+ (x = 0.05-0.40) were successfully synthesized by a high-temperature solid-state reaction method. The phase structure, photoluminescence properties and thermal stability of the phosphor were investigated in detail. The phosphor shows dominant emission peak at 614 nm belonging to the 5D0 → 7F2 electric dipole transition under 465 nm excitation. The luminescence intensity keeps increasing with increasing the content of Eu3+ to 25 mol%, and the critical transfer distance of Eu3+ was calculated to be 12 Å. The quenching temperature for Sr2MgTeO6:0.25Eu3+ was estimated to be above 500 K. This spectral feature reveals high color purity and excellent chromaticity coordinate characteristics. Therefore, Eu3+-doped Sr2MgTeO6 phosphors are potential red phosphors for blue chip-based white light-emitting diode and display devices.

  15. Photoluminescence characteristics of Sm{sup 3+} doped Ba{sub 3}La(PO{sub 4}){sub 3} as new orange-red emitting phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ruijin [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Mi Noh, Hyeon; Kee Moon, Byung; Chun Choi, Byung [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Hyun Jeong, Jung, E-mail: jhjeong@pknu.ac.kr [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Sueb Lee, Ho [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Jang, Kiwan, E-mail: kwjang@changwon.ac.kr [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Soo Yi, Soung [Department of Electronic Material Engineering, Silla University, Busan 617-736 (Korea, Republic of)

    2014-01-15

    A series of orange-red emitting Ba{sub 3}La(PO{sub 4}){sub 3}:xSm{sup 3+} (0.01≤x≤0.30) phosphors was synthesized by the convenient solid-state reaction. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of the as-synthesized phosphors. The emission spectra of the Ba{sub 3}La(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors consisted of some sharp emission peaks of Sm{sup 3+} ions centered at 563 nm, 600 nm, 647 nm, 710 nm. The strongest one is located at 600 nm due to {sup 4}G{sub 5/2}–{sup 6}H{sub 7/2} transition of Sm{sup 3+}, generating bright orange-red light. The optimum dopant concentration of Sm{sup 3+} ions in Ba{sub 3}La(PO{sub 4}):xSm{sup 3+} is around 5 mol% and the critical transfer distance of Sm{sup 3+} is calculated as 22 Å. The CIE chromaticity coordinates of the Ba{sub 3}La(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphors was is located in the orange reddish region. The Ba{sub 3}La(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors may be potentially used as red phosphors for white light-emitting diodes. -- Highlights: • A new Sm{sup 3+}-doped Ba{sub 3}La(PO{sub 4}){sub 3} phosphor was firstly synthesized. • Its structure, luminescent properties are well studied and characterized. • The Ba{sub 3}La(PO{sub 4}){sub 3}:Sm{sup 3+} shows bright orange reddish emissions under UV excitation.

  16. Tunable emission in Ln3+ (Ce3+/Dy3+, Ce3+/Tb3+) doped KNa3Al4Si4O16 phosphor synthesized by combustion method

    Science.gov (United States)

    Kolte, M. M.; Pawade, V. B.; Bhattacharya, A. B.; Dhoble, S. J.

    2018-05-01

    Ln3+ (Ln = Ce3+/Dy3+, Ce3+/Tb3+) doped KNa3Al4Si4O16 phosphor has been synthesized by Combustion method (CS) at 550° C successfully. Ln3+ (Ln = Ce3+, Dy3+, Tb3+) ions when doped in KNa3Al4Si4O16 host lattice, it shows blue and green emission band under the near Ultraviolet (NUV) excitation wavelength. The Photoluminescence excitation (PLE) and emission spectra are observed due to f-f and d-f transition of rare earth ions. Also, an effective energy transfer (ET) study from Ce3+ → Dy3+ and Ce3+ → Tb3+ ions has been studied and confirmed on the basis of Dexter-Foster theory. Further synthesized phosphor is well characterized by XRD, SEM, TEM and decay time measurement. However, the analysis of crystallite size, lattice strain has been studied by using theoretical as well as experimental techniques. Hence, the observed tunable emission in Ln3+ doped KNa3Al4Si4O16 phosphor may be applicable for solid state lighting technology.

  17. Considerable photoluminescence enhancement of LiEu(MoO{sub 4}){sub 2} red phosphors via Bi and/or Si doping for white LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qing-Feng [Department of Materials Science and Engineering, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong 518055 (China); Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Liu, Ying [Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Wang, Yu [Department of Physics and Materials Science, City University of Hong Kong, Hong Kong Special Administrative Region (Hong Kong); Wang, Wenxi; Wan, Yi [Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Wang, Gui-Gen [Department of Materials Science and Engineering, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen, Guangdong 518055 (China); Lu, Zhou-Guang [Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China)

    2015-03-15

    Graphical abstract: Doping of Bi and Si into the lattice leads to an considerable increase of the excitation efficiency and luminous intensity, and obvious movement of the CIE chromaticity coordinates to the NTSC standard values of the LiEu(MoO{sub 4}){sub 2}, a promising red phosphors suitable for near UV excited white-light emitting diodes. - Highlights: • High performance red phosphors for near UV light excited white LEDs. • Lithium lanthanide molybdate red phosphors. • Bi and Si substitution. • Considerable enhancement of luminescence intensity and excitation efficiency. • CIE chromaticity coordinates very close to the NTSC standard values. - Abstract: Novel Bi and/or Si substituted LiEu(MoO{sub 4}){sub 2} phosphors, where Bi was used as sensitizer to enhance the emission intensity and Si was used as substitution to improve the excitation efficiency, were prepared using the sol–gel method, and the photoluminescent properties of the resulting phosphors were intensively investigated. All samples can be excited efficiently by UV (395 nm) light and emit bright red light at 614 nm, which are coupled well with the characteristic emission from a UV-LED. In the Bi{sup 3+}-doped samples, the intensities of the main emission line ({sup 5}D{sub 0}–{sup 7}F{sub 2} transition at 614 nm) are strengthened because of the energy transition from Bi{sup 3+} to Eu{sup 3+}. With the substitution of Mo{sup 4+} by Si{sup 4+}, there are no significant changes in the emission peak positions, but the emission intensity was significantly enhanced under 395 nm excitation. Particularly, the LiEu{sub 0.9}Bi{sub 0.1}(Mo{sub 0.97}Si{sub 0.03}O{sub 4}){sub 2} phosphor doped with both Bi and Si demonstrates superior comprehensive photoluminescence properties with an excellent combination of easy excitation in the near UV range, bright emission intensity, high PL quantum efficiency as well as suitable decay time, which are very suitable for application as red phosphor for near UV

  18. Synthesis of Eu3+-doped calcium and strontium carbonate phosphors at room temperature

    International Nuclear Information System (INIS)

    Pan Yuexiao; Wu Mingmei; Su Qiang

    2003-01-01

    Red phosphors CaCO 3 :Eu 3+ and SrCO 3 :Eu 3+ have been prepared by co-precipitation with ammonium bicarbonate (NH 4 HCO 3 ) at room temperature. Pure calcite CaCO 3 can be obtained by prolonging the reaction time at 220 deg. C and it decomposes to cubic CaO at 1000 deg. C. Trivalent Eu 3+ acts as a luminescent probe to determine both the calcite and the mixed phase of calcite and vaterite phase of CaCO 3 host and to analyze its decomposition process. High temperature sintering improved both the crystallization and luminescence of SrCO 3 :Eu 3+ in aragonite phase

  19. Electrocatalytic and supercapacitor performance of Phosphorous and Nitrogen co-doped Porous Carbons synthesized from Aminated Tannins

    International Nuclear Information System (INIS)

    Bairi, Venu Gopal; Nasini, Udaya B.; Kumar Ramasahayam, Sunil; Bourdo, Shawn E.; Viswanathan, Tito

    2015-01-01

    Highlights: • Microwave Synthetic technique using aminated tannins is reported for the first time. • P,N doped carbon was characterized extensively for physico-chemical properties. • Cyclic Voltammetry, RDE and RRDE studies were investigated for O 2 reduction capability. • O 2 reduction occurred by a kinetically favored one step four electron reduction pathway. • The charge storage capacity was found to be 161 F/g at 5 mV/S in alkaline conditions. - Abstract: A phosphorus and nitrogen co-doped carbon material (PNDC) was synthesized from aminated tannin and polyphosphoric acid by a rapid and highly efficient microwave synthetic technique. X-ray photoelectron spectroscopy study was useful in the identification of nitrogen and phosphorous environments in a sp 2 hybridized carbon lattice. The PNDC was found to be a porous material with a surface area of 433 m 2 g −1 . PNDC sample exhibited excellent thermal stability and the Raman spectroscopic studies were used for analyzing defects in the sp 2 hybridized carbon lattice. This material has promising electrochemical applications, especially for catalyzing oxygen reduction reaction in fuel cells and for charge storage in supercapacitors. The oxygen reduction capability of PNDC was investigated in 0.1 M KOH solution, and rotating disk and ring disk electrode studies were performed to identify the mechanism of oxygen reduction. The capacitative behavior of the PNDC was investigated in 6 M KOH and specific capacitance was determined to be 161 F g −1 due to the electric double layer charge storage phenomenon.

  20. Nitrogen-Doped Carbon for Red Phosphorous Based Anode Materials for Lithium Ion Batteries

    Directory of Open Access Journals (Sweden)

    Jiaoyang Li

    2018-01-01

    Full Text Available Serving as conductive matrix and stress buffer, the carbon matrix plays a pivotal role in enabling red phosphorus to be a promising anode material for high capacity lithium ion batteries and sodium ion batteries. In this paper, nitrogen-doping is proved to effective enhance the interface interaction between carbon and red phosphorus. In detail, the adsorption energy between phosphorus atoms and oxygen-containing functional groups on the carbon is significantly reduced by nitrogen doping, as verified by X-ray photoelectron spectroscopy. The adsorption mechanisms are further revealed on the basis of DFT (the first density functional theory calculations. The RPNC (red phosphorus/nitrogen-doped carbon composite material shows higher cycling stability and higher capacity than that of RPC (red phosphorus/carbon composite anode. After 100 cycles, the RPNC still keeps discharge capacity of 1453 mAh g−1 at the current density of 300 mA g−1 (the discharge capacity of RPC after 100 cycles is 1348 mAh g−1. Even at 1200 mA g−1, the RPNC composite still delivers a capacity of 1178 mAh g−1. This work provides insight information about the interface interactions between composite materials, as well as new technology develops high performance phosphorus based anode materials.

  1. Characterisation and luminescence studies of Tm and Na doped magnesium borate phosphors.

    Science.gov (United States)

    Ekdal, E; Garcia Guinea, J; Karabulut, Y; Canimoglu, A; Harmansah, C; Jorge, A; Karali, T; Can, N

    2015-09-01

    In this study, structural and luminescence properties of magnesium borate of the form MgB4O7 doped with Tm and Na were investigated by X-ray diffraction (XRD), Raman spectroscopy and cathodoluminescence (CL). The morphologies of the synthetised compounds exhibit clustered granules and road-like materials. As doping trivalent ions into a host with divalent cations requires charge compensation, this effect is discussed. The CL spectra of undoped MgB4O7 shows a broad band emission centred around 350 nm which is postulated to be produced by self-trapped excitons and some other defects. From the CL emission spectrum, main emission bands centred at 360, 455, 475 nm due to the respective transitions of (1)D2→(3)H6,(1)D2→(3)F4 and (1)G4→(3)H6 suggest the presence of Tm(3+) ion in MgB4O7 lattice site. CL mechanism was proposed to explain the observed phenomena which are valuable in possibility of the developing new luminescent materials for different applications. In addition, the experimental Raman spectrum of doped and undoped MgB4O7 were reported and discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Upconversion luminescence of Er3+/Yb3+ doped Sr5(PO4)3OH phosphor powders

    Science.gov (United States)

    Mokoena, P. P.; Swart, H. C.; Ntwaeaborwa, O. M.

    2018-04-01

    Sr5(PO4)3OH co-doped with Er3+and Yb3+ powder phosphors were synthesized by urea combustion method. The crystal structure was analyzed using X-ray diffraction (XRD). Particle morphology was analyzed using a Jeol JSM 7800F thermal field emission scanning electron microscope (FE-SEM) and the chemical composition analysis was carried out using an Oxford Instruments AzTEC energy dispersive spectrometer (EDS) attached to the FE-SEM. Upconversion emission was measured by using a FLS980 Spectrometer equipped with a 980 nm NIR laser as the excitation source, and a photomultiplier (PMT) detector. The XRD data of the Sr5(PO4)3OH powder exhibited characteristic diffraction patterns of the hexagonal structure referenced in the standard JCPDS card number 00-033-1348. The sharp peaks revealed the formation of crystalline Sr5(PO4)3OH. The powders were made up of hexagonal nanospheres. The enhanced red emission due to the 4F9/2 → 4I15/2 transitions of Er3+ was observed and was attributed to up conversion (UC) energy transfer from Yb3+. The upconversion energy transfer mechanism from Yb3+ to Er3+ is discussed.

  3. A single-phase white light emitting Pr3+ doped Ba2CaWO6 phosphor: synthesis, photoluminescence and optical properties

    Science.gov (United States)

    Sreeja, E.; Vidyadharan, Viji; Jose, Saritha K.; George, Anns; Joseph, Cyriac; Unnikrishnan, N. V.; Biju, P. R.

    2018-04-01

    Pr3+ doped Ba2CaWO6 phosphor were prepared by traditional high-temperature solid-state reaction technique. The structure evolution was systematically investigated by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The X-ray powder diffraction patterns indicate that the prepared phosphors crystallized in the cubic double-perovskite structure. The functional groups were identified using FTIR spectra and the elements present in the composition were confirmed by the EDS profile. The morphology of the phosphor was identified using SEM and TEM analysis. The PL spectra illustrated that these phosphors could be efficiently excited by charge transfer band of host and the maximum luminescence intensity was observed at 0.06 wt% of Pr3+ ion. Upon the charge transfer band excitation, emission spectra showed peaks at 489, 532, 647, 685 and 737 nm corresponding to 3P0→3H4, 3P1→3H5, 3P0→3F2, 3P0→3F3 and 3P0→3F4 transitions respectively. The concentration quenching of Ba2CaWO6:Pr3+ phosphor can be mainly attributed to dipole-dipole interaction. The CIE coordinates were estimated to be close to the white region. The decay curves are well fitted with double exponential decay models. The standard and modified Judd-Ofelt (JO) theories were used to determine the Judd-Ofelt intensity parameters, radiative transition probabilities and branching ratios. The optical properties indicate that Ba2CaWO6:Pr3+ phosphors can produce white light emission from a single phase host and its potential application for solid-state lighting and display devices.

  4. Thermoluminescence of rare earth doped BaSO/sub 4/ phosphors and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Nagpal, J.S.; Varadharajan, G. (Bhabha Atomic Research Centre, Bombay (India). Div. of Radiological Protection)

    1982-03-01

    Thermoluminescence of synthetic BaSO/sub 4/ samples individually doped with Y, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy and Tm has been studied after ..gamma..- and microwave irradiations. BaSO/sub 4/:Eu has the highest response for ..gamma..-radiation while BaSO/sub 4/:Tb exhibits highest reduction in its ..gamma..-induced TL after exposure to microwave radiation (2425 +- 25 MHz). The reduction depends on the microwave radiant exposure and is independent of the irradiance level in the range 25-200 mW . cm/sup -2/ and hence can be useful for microwave dosimetry.

  5. Photoluminescence characteristics of reddish-orange Eu{sup 3+} or Sm{sup 3+} singly-doped and Eu{sup 3+} and Sm{sup 3+} co-doped KZnGd(PO{sub 4}){sub 2} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jun Ho; Bandi, Vengala Rao; Grandhe, Bhaskar Kumar; Jang, Ki Wan; Lee, Ho Sueb [Changwon National University, Changwon (Korea, Republic of); Yi, Soung Soo [Silla University, Busan (Korea, Republic of); Jeong, Jung Hyun [Pukyong National University, Busan (Korea, Republic of)

    2011-02-15

    Eu{sup 3+} or Sm{sup 3+} singly-doped and Eu{sup 3+} and Sm{sup 3+} co-doped KZnGd(PO{sub 4}){sub 2} phosphors were synthesized by using a conventional solid state reaction method at 750 .deg. C. The emission spectra of KZnGd{sub 1-x}(PO{sub 4}){sub 2}:Eu{sup 3+}{sub x} with {lambda}{sub ex} = 395 nm and KZnGd{sub 1-y}(PO{sub 4}){sub 2}:Sm{sup 3+}{sub y} with {lambda}{sub ex} = 403 nm phosphors showed intense {sup 5}D{sub 0} {yields} {sup 7}F{sub 1}, {sup 4}G{sub 5/2} {yields} {sup 6}H{sub 7/2} emission transitions at 595 nm and 599 nm, respectively. The optimum relative intensity of the KZnGd{sub 1-x-y}(PO{sub 4}){sub 2}:Eu{sup 3+}{sub x} , Sm{sup 3+}{sub y} phosphor was obtained for the doping concentrations of (x = 0.09, y = 0.01). In addition, the temperature dependent luminescence intensity of the synthesized phosphors was investigated and the thermal stability of the KZnGd(PO{sub 4}){sub 2}:Eu{sup 3+} phosphor was found to be higher than that of standard YAG:Ce{sup 3+} and KZnGd{sub 1-x-y}(PO{sub 4}){sub 2}:Eu{sup 3+}{sub x} Sm{sup 3+}{sub y} under near ultra-violet (NUV) light emitting diode excitation (LED). Therefore, we suggest that Eu{sup 3+} or Sm{sup 3+} singly-doped and Eu{sup 3+} and Sm{sup 3+} co-doped KZnGd(PO{sub 4}){sub 2} phosphors should be efficient for different red-color-emitting display device applications and NUV-LED-based white-light-emitting diodes.

  6. Luminescent Enhancement of Na+ and Sm3+ Co-doping Reddish Orange SrCa3Si2O8 Phosphors

    Science.gov (United States)

    Chun, Fengjun; Zhang, Binbin; Li, Wen; Liu, Honggang; Deng, Wen; Chu, Xiang; Osman, Hanan; Zhang, Haitao; Yang, Weiqing

    2018-04-01

    Reddish orange SrCa3Si2O8 phosphors, prepared by the facile solid state reaction method, are a luminescent enhancement of Na+ and Sm3+ co-doping luminescent material. Na+ was designed to compensate the charge imbalance of Sm3+ ion substituting for the Sr2+ ion of orthorhombic SrCa3Si2O8 crystals. The results suggest that Na+ can effectively enhance the luminescent intensity of the reddish orange light peaked at about 562 nm (4 G 5/2 → 6 H 5/2), 600 nm (4 G 5/2 → 6 H 7/2) and 645 nm (4 G 5/2 → 6 H 9/2) excited by the near ultraviolet excited light 404 nm (4 L 13/2 → 6 H 5/2). The energy transfer has been further verified by the florescence lifetime. Additionally, the luminescent lifetime τ of as-grown phosphors was separated into two parts, a rapid lifetime and a slow lifetime. The average lifetime results ranged from 2.098 to 1.329 ms which were influenced by the concentration of Sm3+ doping. The systematic researches of as-grown phosphors have clearly suggested a potential application for white-light-emitting diodes ( w-LEDs).

  7. Synthesis and photoluminescence properties of Pb{sup 2+} doped inorganic borate phosphor NaSr{sub 4}(BO{sub 3}){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, A. O., E-mail: abhi2718@gmail.com; Koparkar, K. A.; Omanwar, S. K. [Department of Physics, SantGadge Baba Amravati University, Amravati MH, 444602 (India); Bajaj, N. S. [Department of Physics, Toshniwal Art, Commerce and Science College, Sengoan, Hingoli MH (India)

    2016-05-06

    A series of Inorganic borate phosphors NaSr{sub 4}(BO{sub 3}){sub 3} doped with Pb{sup 2+} was successfully synthesized by modified solid state diffusion method. The crystal structure and the phase purity of sample were characterized by powder X-ray diffraction (XRD). The photoluminescence properties of synthesized materials were investigated using spectrofluorometer at room temperature. The phosphor show strong broad band emission spectra in UVA region maximum at 370 nm under the excitation of 289 nm. The dependence of the emission intensity on the Pb{sup 2+} concentration for the NaSr{sub 4}(BO{sub 3}){sub 3} were studied in details. The concentration quenching of Pb{sup 2+} doped NaSr{sub 4}(BO{sub 3}){sub 3} was observed at 0.02 mol. The Stokes shifts of NaSr{sub 4}(BO{sub 3}){sub 3}: Pb{sup 2+} phosphor was calculated to be 7574 cm{sup −1}.

  8. Energy transfer and color tunable emission in Tb3+,Eu3+ co-doped Sr3LaNa(PO4)3F phosphors.

    Science.gov (United States)

    Li, Shuo; Guo, Ning; Liang, Qimeng; Ding, Yu; Zhou, Huitao; Ouyang, Ruizhuo; Lü, Wei

    2018-02-05

    A group of color tunable Sr 3 LaNa(PO 4 ) 3 F:Tb 3+ ,Eu 3+ phosphors were prepared by conventional high temperature solid state method. The phase structures, luminescence properties, fluorescence lifetimes and energy transfer were investigated in detail. Under 369nm excitation, owing to efficient energy transfer of Tb 3+ →Eu 3+ , the emission spectra both have green emission of Tb 3+ and red emission of Eu 3+ . An efficient energy transfer occur in Tb 3+ , Eu 3+ co-doped Sr 3 LaNa(PO 4 ) 3 F phosphors. The most possible mechanism of energy transfer is dipole-dipole interaction by Dexter's theoretical model. The energy transfer of Tb 3+ and Eu 3+ was confirmed by the variations of emission and excitation spectra and Tb 3+ /Eu 3+ decay lifetimes in Sr 3 LaNa(PO 4 ) 3 F:Tb 3+ ,Eu 3+ . The color tone can tuned from yellowish-green through yellow and eventually to reddish-orange with fixed Tb 3+ content by changing Eu 3+ concentrations. The results show that the prepared Tb 3+ , Eu 3+ co-doped color tunable Sr 3 LaNa(PO 4 ) 3 F phosphor can be used for white LED. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Energy transfer and color tunable emission in Tb3 +,Eu3 + co-doped Sr3LaNa(PO4)3F phosphors

    Science.gov (United States)

    Li, Shuo; Guo, Ning; Liang, Qimeng; Ding, Yu; Zhou, Huitao; Ouyang, Ruizhuo; Lü, Wei

    2018-02-01

    A group of color tunable Sr3LaNa(PO4)3F:Tb3 +,Eu3 + phosphors were prepared by conventional high temperature solid state method. The phase structures, luminescence properties, fluorescence lifetimes and energy transfer were investigated in detail. Under 369 nm excitation, owing to efficient energy transfer of Tb3 + → Eu3 +, the emission spectra both have green emission of Tb3 + and red emission of Eu3 +. An efficient energy transfer occur in Tb3 +, Eu3 + co-doped Sr3LaNa(PO4)3F phosphors. The most possible mechanism of energy transfer is dipole-dipole interaction by Dexter's theoretical model. The energy transfer of Tb3 + and Eu3 + was confirmed by the variations of emission and excitation spectra and Tb3 +/Eu3 + decay lifetimes in Sr3LaNa(PO4)3F:Tb3 +,Eu3 +. The color tone can tuned from yellowish-green through yellow and eventually to reddish-orange with fixed Tb3 + content by changing Eu3 + concentrations. The results show that the prepared Tb3 +, Eu3 + co-doped color tunable Sr3LaNa(PO4)3F phosphor can be used for white LED.

  10. An investigation on photoluminescence and energy transfer of Eu{sup 3+}/Sm{sup 3+} single-doped and co-doped Ca{sub 4}YO(BO{sub 3}){sub 3} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Bandi, Vengala Rao; Grandhe, Bhaskar Kumar [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Jang, Kiwan, E-mail: kwjang@changwon.ac.kr [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Shin, Dong-Soo [Department of Chemistry, Changwon National University, Changwon (Korea, Republic of); Yi, Soung-Soo [Department of Photonics, Silla University, Busan (Korea, Republic of); Jeong, Jung-Hyun [Department of Physics, Pukyong National University, Busan (Korea, Republic of)

    2013-07-15

    The present investigation aims to demonstrate the potentiality of Eu{sup 3+}/Sm{sup 3+} single-doped and co-doped Ca{sub 4}YO(BO{sub 3}){sub 3} phosphors, which were prepared by a sol–gel method. The X-ray diffraction (XRD) profiles showed that all the observed peaks could be attributed to the monoclinic phase of Ca{sub 4}YO(BO{sub 3}){sub 3}. From the measured emission profiles, we have noticed that both the single-doped Eu{sup 3+}/Sm{sup 3+} phosphors shows four emission transitions of {sup 5}D{sub 0} → {sup 7}F{sub 0,1,2,3} and {sup 4}G{sub 5/2} → {sup 6}H{sub 5/2,7/2,9/2,11/2} respectively. Among them, the {sup 5}D{sub 0} → {sup 7}F{sub 2} of Eu{sup 3+} and {sup 4}G{sub 5/2} → {sup 6}H{sub 7/2} of Sm{sup 3+} are intense emission transitions, leading to an intense red color emission from the prepared phosphors. The excitation spectra showed that Eu{sup 3+}/Sm{sup 3+} doped samples can be excited efficiently by 394 nm and 402 nm respectively, incidentally which matches well with the characteristic emission from UVLED. The co-doping of Sm{sup 3+} ions can broaden and strengthen the absorption of near UV region and to be efficient to sensitize the emission of the Ca{sub 4}YO(BO{sub 3}){sub 3}:Eu{sup 3+} phosphor. The mechanism involved in the energy transfer between Eu{sup 3+} and Sm{sup 3+} has been explained and elucidated by an energy level diagram. - Highlights: • Eu{sup 3+} or/and Sm{sup 3+}:Ca{sub 4}YO(BO{sub 3}){sub 3} phosphors were prepared by sol–gel method. • The co-doping of Sm{sup 3+} to Ca{sub 4}YO(BO{sub 3}){sub 3}:Eu{sup 3+} extends its absorption of NUV region. • It has intense absorption in NUV region, which is suitable for NUV LED. • The energy transfer process between Eu{sup 3+} and Sm{sup 3+} ions were discussed.

  11. Tunable emission and the systematic study on energy-transfer properties of Ce3+- and Tb3+-co-doped Sr3(PO4)2 phosphors

    International Nuclear Information System (INIS)

    Liu, Zhijun

    2015-01-01

    An emitting color tunable phosphor Sr 3 (PO 4 ) 2 :Ce 3+ , Tb 3+ was synthesized by the traditional high-temperature solid-state reaction method. The photoluminescence and energy-transfer (ET) properties of Ce 3+ - and Tb 3+ -doped Sr 3 (PO 4 ) 2 host were studied in detail. The obtained phosphors show both a blue emission from Ce 3+ and a yellowish green emission from Tb 3+ with considerable intensity under ultraviolet (UV) excitation (∝311 nm). When the content of Ce 3+ was fixed at 0.03, the emission chromaticity coordinates could be adjusted from blue to green region by tuning the contents of Tb 3+ ions with the aid of ET process. The critical distance between Ce 3+ and Tb 3+ is 14.69 A. The ET mechanism from Ce 3+ to Tb 3+ ions was identified with dipole-dipole interaction. The obtained phosphor exhibits a strong excitation in UV spectral region and high-efficient ET from Ce 3+ to Tb 3+ ions. It may find applications as a green light-emitting UV-convertible phosphor in white LED devices. (orig.)

  12. Physicochemical properties of phosphoric acid doped polybenzimidazole membranes for fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Bach, Anders

    2006-01-01

    of the polymer, a level necessary to obtain high enough proton conductivity for fuel cell uses, the polymer membrane exhibits a volume swelling by 118%, resulting in separation of the polymer backbones. The separation in turn reduces the mechanical strength of the membrane especially at high temperatures....... Another consequence is the increased H2 and O2 permeability through the membrane. In the temperature range from 120 to 180 ◦C, the hydrogen permeability was found to be 1.6–4.3×10−17 and 1.2–4.0×10−15 mol cm cm−2 s−1 Pa−1 for pristine and acid doped PBI membranes, respectively, while for oxygen it was 5...

  13. ZnMoO4:Er3+,Yb3+ phosphor with controlled morphology and enhanced upconversion through alkali ions doping

    Science.gov (United States)

    Luitel, Hom Nath; Chand, Rumi; Watari, Takanori

    2018-04-01

    A facile hydrothermal method was used to synthesize ZnMoO4:Er3+,Yb3+ nanoparticles. The shapes and sizes of the nanoparticles were well tuned by simply monitoring the pH of the starting solution. Microballs consisting of agglomerated nanograins were observed at strong acidic condition. At mild pH, plates and rectangular particles were realized, while strong basic pH stabilized rods. Further increasing pH to extremely basic conditions (pH > 13), rods changed to fragile hairy structures. The nucleation and growth mechanism of nanograins to form different morphology nanoparticles were studied and illustrated. XRD patterns confirmed well crystalline, triclinic structure despite small amount of aliovalent metal ions doping. Under 980 nm excitation, the ZnMoO4:Er3+,Yb3+ nanophosphor exhibited strong green (centered at 530 and 560 nm) and weak red (centered at 660 nm) upconversion (UC) emissions. Substitution of part of the Zn2+ ions by monovalent alkali ions intensified the UC emission intensities drastically. The order of intensification was K+>Na+>Li+>Rb+>no alkali ion. When Zn2+ ions were substituted with 10 at% K+ ions, the green and red UC emissions intensities increased by more than 50 and 15 folds, respectively. Time dependent measurements confirmed efficient Yb to Er energy transfer in the ZnMoO4:Er3+,Yb3+,K+ nanophosphor. The optimized ZnMoO4:Er3+,Yb3+,K+ phosphor exhibited intense UC emissions with 0.31% quantum yield. The upconverted light is visible to naked eye while pumping by laser of less than 1 mW power and opens door for variety of novel applications.

  14. Infrared emissions in MgSrAl10O17:Er3+ phosphor co-doped with Yb3+/Ba2+/Ca2+ obtained by solution combustion route

    International Nuclear Information System (INIS)

    Singh, Vijay; Kumar Rai, Vineet; Venkatramu, V.; Chakradhar, R.P.S.; Hwan Kim, Sang

    2013-01-01

    An intense infrared emitting MgSrAl 10 O 17 :Er 3+ phosphor co-doped with Yb 3+ , Ba 2+ and Ca 2+ ions have been prepared by a solution combustion method. Phase purity of the derived compounds was confirmed by X-ray diffraction technique. The vibrational properties of MgSrAl 10 O 17 phosphor was studied by Fourier transform infrared spectroscopy. The broad and strong infrared emission of Er 3+ ions at around 1.53 μm was observed upon excitation at 980 nm. Effect of co-doping with the Yb 3+ , Ba 2+ and Ca 2+ ions on the infrared luminescence intensity of Er 3+ ions and the mechanism responsible for the variation in the infrared intensity have been discussed. The results indicate that these materials may be suitable for the optical telecommunication window and wavelength division multiplexing applications. - Highlights: ► The hexagonal phase of MgSrAl 10 O 17 could be obtained by the low temperature combustion method. ► The broad and strong infrared emission of Er 3+ ions at around 1.53 μm was observed. ► Effect of co-doping with the Yb 3+ , Ba 2+ and Ca 2+ ions on the infrared luminescence intensity of Er 3+ were reported.

  15. Structural and optical characterization of nanoparticulate manganese doped zinc silicate phosphors prepared by sol–gel and combustion methods

    Energy Technology Data Exchange (ETDEWEB)

    Mbule, P.S., E-mail: mbuleps@gmail.com [Department of Physics, CSET, University of South Africa, Johannesburg, 1710 (South Africa); Ntwaeaborwa, O.M. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa); Mothudi, B.M.; Dhlamini, M.S. [Department of Physics, CSET, University of South Africa, Johannesburg, 1710 (South Africa)

    2016-11-15

    The present study reports the synthesis, crystallographic structure and optical properties of manganese (Mn{sup 2+}) doped zinc silicate (Zn{sub 2}SiO{sub 4}) nanoparticle phosphors prepared by sol–gel and combustion methods. For samples prepared by sol–gel method, the X-ray diffraction results showed phase transformation from amorphous to α-phase Zn{sub 2}SiO{sub 4} due to annealing temperatures at 600 °C to 1100 °C, whereas for combustion samples an admixture of highly crystalline β-phase and hexagonal wurtzite structure of ZnO was observed at annealing temperature of 600 °C. Photoluminescence spectra with Mn{sup 2+} concentrations ranging from 0.015–0.09 mol% were compared for two methods. Emission band assigned to the {sup 4}T{sub 1}({sup 4}G)→{sup 6}A{sub 1}({sup 6}S) electronic transition of Mn{sup 2+} was observed with maximum intensity at ~573 nm for combustion samples and ~532 nm for sol–gel samples upon UV-excitation by a Xenon lamp. Furthermore, the photoluminescence decay curves of annealed Zn{sub 2}SiO{sub 4}:Mn{sup 2+} samples were observed to be bi-exponential. The fast and slow decay components are due to the pair or cluster formation and isolated ions at higher doping concentration, respectively. - Highlights: • Synthesis, crystallographic and optical properties of Zn{sub 2}SiO{sub 4}:Mn{sup 2+} are presented. • XRD shows amorphous diffraction peak and crystallinity improved by increase of annealing temperature. • Crystallite and particle size from XRD and SAXS techniques, respectively, are compared. • Photoluminescence (PL) spectra are compared for sol-gel and combustion method. • The photoluminescence decay curves of annealed Zn{sub 2}SiO{sub 4}:Mn{sup 2+} samples were observed to be bi-exponential.

  16. TL and OSL properties of Mn2+-doped MgGa2O4 phosphor

    Science.gov (United States)

    Luchechko, A.; Zhydachevskyy, Ya; Maraba, D.; Bulur, E.; Ubizskii, S.; Kravets, O.

    2018-04-01

    The oxide MgGa2O4 spinel ceramics doped with Mn2+ ions was synthesized by a solid-state reaction at 1200 °C in air. The activator concentration was equal 0.05 mol% of MnO. Phase purity of the synthesized samples was analyzed by X-ray diffraction technique. This spinel ceramics show efficient green emission in the range from 470 to 550 nm with a maximum at about 505 nm under UV or X-ray excitations, which is due to Mn2+ ions. MgGa2O4: Mn2+ exhibits intense thermoluminescence (TL) and optically stimulated luminescence (OSL) after influence of ionizing radiation. Are complex nature of the TL glow curves is associated with a significant number of structural defects that are responsible for the formation of shallow and deep electron traps. In this work, time-resolved OSL characteristics of the samples exposed to beta particles are reported for the first time. A light from green LED was used for optical stimulation. Obtained TL and OSL results suggest MgGa2O4:Mn2+ as perspective material for further research and possible application in radiation dosimetry.

  17. Phosphor Dysprosium-Doped Layered Double Hydroxides Exchanged with Different Organic Functional Groups

    Directory of Open Access Journals (Sweden)

    David Ricardo Martínez Vargas

    2013-01-01

    Full Text Available The layers of a Zn/Al layered double hydroxide (LDH were doped with Dy3+ cations. Among some compositions, the Zn2+ : Al3+ : Dy3+ molar ratio equal to 30 : 9 : 1 presented a single crystalline phase. Organic anions with carboxylic, amino, sulfate, or phosphate functional groups were intercalated as single layers between LDH layers as confirmed by X-ray diffraction and infrared spectroscopy. Photoluminescence spectra of the nitrate intercalated LDH showed a wide emission band with strong intensity in the yellow region (around 574 nm, originated due to symmetry distortion of the octahedral coordination in dysprosium centers. Moreover, a broad red band emission was also detected apparently due to the presence of zinc oxide. The distorted symmetry of the dysprosium coordination environment, also confirmed by X-ray photoelectron spectroscopy analysis, was modified after the intercalation with phenyl phosphonate (PP, aspartate (Asp, adipate (Adip, and serinate (Ser anions; the emission as measured from PL spectra of these LDH was more intense in the blue region (ca. 486 nm, thus indicating an increase in symmetry of dysprosium octahedrons. The red emission band from zinc oxide kept the same intensity after intercalation of dodecyl sulfate (DDS. An additional emission of unknown origin at λ = 767 nm was present in all LDHs.

  18. The effect of porosity on performance of phosphoric acid doped polybenzimidazole polymer electrolyte membrane fuel cell

    Directory of Open Access Journals (Sweden)

    Celik Muhammet

    2016-01-01

    Full Text Available A polybenzimidazole (PBI based polymer electrolyte fuel cells, which called high temperature polymer electrolyte fuel cells (HT-PEMS, operate at higher temperatures (120-200°C than conventional PEM fuel cells. Although it is known that HT-PEMS have some of the significant advantages as non-humidification requirements for membrane and the lack of liquid water at high temperature in the fuel cell, the generated water as a result of oxygen reduction reaction causes in the degradation of these systems. The generated water absorbed into membrane side interacts with the hydrophilic PBI matrix and it can cause swelling of membrane, so water transport mechanism in a membrane electrode assembly (MEA needs to be well understood and water balance must be calculated in MEA. Therefore, the water diffusion transport across the electrolyte should be determined. In this study, various porosity values of gas diffusion layers are considered in order to investigate the effects of porosity on the water management for two phase flow in fuel cell. Two-dimensional fuel cell with interdigitated flow-field is modelled using COMSOL Multiphysics 4.2a software. The operating temperature and doping level is selected as 160°C and 6.75mol H3PO4/PBI, respectively.

  19. Size limit on the phosphorous doped silicon nanocrystals for dopant activation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, P., E-mail: pengyuan.yang@surrey.ac.uk [Surrey Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 5XH (United Kingdom); Gwilliam, R.M. [Surrey Ion Beam Centre, Advanced Technology Institute, University of Surrey, Guildford GU2 5XH (United Kingdom); Crowe, I.F.; Papachristodoulou, N.; Halsall, M.P. [Photon Science Institute, School of Electrical and Electronic Engineering, Alan Turing Building, University of Manchester, Manchester M13 9PL (United Kingdom); Hylton, N.P. [Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom); Hulko, O.; Knights, A.P. [Department of Engineering Physics and the Centre for Emerging Device Technologies, McMaster University, 1280 Main Street West, Hamilton L8S 4L7, Ontario (Canada); Shah, M.; Kenyon, A.J. [Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE (United Kingdom)

    2013-07-15

    We studied the photoluminescence spectra of silicon nanocrystals doped with and without phosphorus as a function of isothermal annealing time. Silicon nanocrystals were prepared by the implantation of 80 keV Si{sup +} into a 500 nm SiO{sub 2} film to an areal density of 8 × 10{sup 16} at/cm{sup 2}. Half of the samples were co-implanted with P{sup +} at 80 keV to 5 × 10{sup 15} at/cm{sup 2}. The photoluminescence of the annealed samples were photo-excited at wavelength of 405 nm. For short anneal times, when the nanocrystal size distribution has a relatively small mean diameter, formation in the presence of phosphorus yields an increase in the luminescence intensity and a blue shift in the emission peak compared with intrinsic nanocrystals. As the mean size increases with annealing time, this enhancement rapidly diminishes and the peak energy shifts to the red. Our results indicate the donor electron generation depends strongly on the nanocrystal size. We also found a critical limit above which it allows dopant activation.

  20. The synthesis and luminescence properties of a novel red-emitting phosphor. Eu{sup 3+}-doped Ca{sub 9}La(PO{sub 4}){sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Zehui [Guangdong University of Technology, Experimental Teaching Department, Guangzhou (China); Guangdong University of Technology, School of Chemical Engineering and Light Industry, Guangzhou (China); Mu, Zhongfei; Zhu, Daoyun [Guangdong University of Technology, Experimental Teaching Department, Guangzhou (China); Wang, Qiang; Wu, Fugen [Guangdong University of Technology, School of Materials and Energy, Guangzhou (China)

    2017-10-15

    A series of novel red-emitting phosphors Ca{sub 9}La{sub 1-x}(PO{sub 4}){sub 7}: xEu{sup 3+} were synthesized by high-temperature solid state reactions. The photoluminescence excitation and photoluminescence spectra of these phosphors were investigated in detail. O{sup 2-}-Eu{sup 3+} charge transfer band peaking at about 261 nm is dominant in the PLE spectra of Eu{sup 3+}-doped Ca{sub 9}La(PO{sub 4}){sub 7}, indicating that the phosphors are suitable for tricolor fluorescent lamps. The phosphors also show a good absorption in near ultraviolet (around 395 nm) and blue (around 465 nm) spectral region, which indicates that it can be pumped with NUV and blue chips for white light-emitting diodes. The transition of {sup 5}D{sub 0} → {sup 7}F{sub 2} of Eu{sup 3+} in this lattice can emit bright red light. Ca{sub 9}La(PO{sub 4}){sub 7} could accommodate a large amount of Eu{sup 3+} with an optimal concentration of 60 mol%. The dipole-dipole interaction between Eu{sup 3+} is the dominant mechanism for concentration quenching of Eu{sup 3+}. The calculated color coordinates lie in red region (x = 0.64, y = 0.36), which is close to Y{sub 2}O{sub 3}: 0.05Eu{sup 3+} (x = 0.65, y = 0.34). The integral emission intensity of Ca{sub 9}La{sub 0.4}(PO{sub 4}){sub 7}: 0.6Eu{sup 3+} is 1.9 times stronger than that of widely used commercial red phosphor Y{sub 2}O{sub 3}: 0.05Eu{sup 3+}. All these results indicate that Eu{sup 3+}-doped Ca{sub 9}La(PO{sub 4}){sub 7} is a promising red-emitting phosphor which can be used in tricolor fluorescent lamps and white light-emitting diodes. (orig.)

  1. Luminescence properties of Eu{sup 2+} doped SrB{sub 4}O{sub 7} phosphor for radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Palan, C.B., E-mail: chetanpalan27@yahoo.in; Bajaj, N.S.; Omanwar, S.K.

    2016-04-15

    Highlights: • Report TL/OSL properties of SrB{sub 4}O{sub 7}:Eu{sup 2+} under beta irradiations. • OSL Sensitivity was about 33% than that of commercially available α-Al{sub 2}O{sub 3.} • TL glow peaks was appear at 305° C and TL sensitivity about 200 times higher than TLD-500. • OSL decay pattern was faster than α- Al{sub 2}O{sub 3}:C and dose response was linear nature. - Abstract: In this report, we presented the TL/OSL properties of Eu doped SrB{sub 4}O{sub 7} phosphor under β-irradiation. This phosphor was synthesized by using solid state method. The phosphor shows OSL sensitivity about 33% than that of commercially available α-Al{sub 2}O{sub 3}: C phosphor. CW-OSL curve possess two components having photoionization cross-sections 0.707 × 10{sup −17} and 18.58 × 10{sup −17} cm{sup 2} respectively and TL sensitivity about 200 times higher than TLD-500. The kinetic parameters such as activation energy, frequency factor and order of kinetics of TL curve were calculated by using peak shape method. In TL/OSL mode dose-response was almost linear in the range of measurements. The MDD was found to be 1.26 mGy with 3σ of background. Also reusability studies showed the phosphor can be reused for 10 cycles with 1% change in the OSL output. The PL spectra of SrB{sub 4}O{sub 7} showed emission in NUV region when excited with 318 nm under UV source.

  2. Eu-doped barium aluminium oxynitride with the ß-alumina-type structure as new blue-emitting phosphor

    NARCIS (Netherlands)

    Jansen, S.R.; Migchels, J.M.; Hintzen, H.T.J.M.; Metselaar, R.

    1999-01-01

    Attractive new blue-emitting phosphors for use in low-pressure mercury gas discharge lamps are synthesized by Eu-substitution in the barium aluminum oxynitride host lattice with the -alumina-type structure. The emission spectra of these phosphors for 254 nm excitation show a band at about 450 nm

  3. Phosphoric acid doped membranes based on Nafion®, PBI and their blends – Membrane preparation, characterization and steam electrolysis testing

    DEFF Research Database (Denmark)

    Aili, David; Hansen, Martin Kalmar; Pan, Chao

    2011-01-01

    Proton exchange membrane steam electrolysis at temperatures above 100 °C has several advantages from thermodynamic, kinetic and engineering points of view. A key material for this technology is the high temperature proton exchange membrane. In this work a novel procedure for preparation of Nafion......® and polybenzimidazole blend membranes was developed. Homogeneous binary membranes covering the whole composition range were prepared and characterized with respect to chemical and physiochemical properties such as water uptake, phosphoric acid doping, oxidative stability, mechanical strength and proton conductivity...

  4. Drastic reduction in the surface recombination velocity of crystalline silicon passivated with catalytic chemical vapor deposited SiNx films by introducing phosphorous catalytic-doped layer

    International Nuclear Information System (INIS)

    Thi, Trinh Cham; Koyama, Koichi; Ohdaira, Keisuke; Matsumura, Hideki

    2014-01-01

    We improve the passivation property of n-type crystalline silicon (c-Si) surface passivated with a catalytic chemical vapor deposited (Cat-CVD) Si nitride (SiN x ) film by inserting a phosphorous (P)-doped layer formed by exposing c-Si surface to P radicals generated by the catalytic cracking of PH 3 molecules (Cat-doping). An extremely low surface recombination velocity (SRV) of 2 cm/s can be achieved for 2.5 Ω cm n-type (100) floating-zone Si wafers passivated with SiN x /P Cat-doped layers, both prepared in Cat-CVD systems. Compared with the case of only SiN x passivated layers, SRV decreases from 5 cm/s to 2 cm/s. The decrease in SRV is the result of field effect created by activated P atoms (donors) in a shallow P Cat-doped layer. Annealing process plays an important role in improving the passivation quality of SiN x films. The outstanding results obtained imply that SiN x /P Cat-doped layers can be used as promising passivation layers in high-efficiency n-type c-Si solar cells.

  5. Strong blue and white photoluminescence emission of BaZrO{sub 3} undoped and lanthanide doped phosphor for light emitting diodes application

    Energy Technology Data Exchange (ETDEWEB)

    Romero, V.H. [Centro de Investigaciones en Optica, A. P. 1-948, Leon Gto., 37160 (Mexico); De la Rosa, E., E-mail: elder@cio.mx [Centro de Investigaciones en Optica, A. P. 1-948, Leon Gto., 37160 (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro, Qro. 76000 (Mexico); Velazquez-Salazar, J.J. [Department of Physics and Astronomy, The University of Texas at San Antonio One UTSA Circle, San Antonio TX 78249 (United States)

    2012-12-15

    In this paper, we report the obtained strong broadband blue photoluminescence (PL) emission centered at 427 nm for undoped BaZrO{sub 3} observed after 266 nm excitation of submicron crystals prepared by hydrothermal/calcinations method. This emission is enhanced with the introduction of Tm{sup 3+} ions and is stronger than the characteristic PL blue emission of such lanthanide. The proposed mechanism of relaxation for host lattice emission is based on the presence of oxygen vacancies produced during the synthesis process and the charge compensation due to the difference in the electron valence between dopant and substituted ion in the host. Brilliant white light emission with a color coordinate of (x=0.29, y=0.32) was observed by combining the blue PL emission from the host with the green and red PL emission from Tb{sup 3+} and Eu{sup 3+} ions, respectively. The color coordinate can be tuned by changing the ratio between blue, green and red band by changing the concentration of lanthanides. - Graphical abstract: Strong blue emission from undoped BaZrO{sub 3} phosphor and white light emission by doping with Tb{sup 3+} (green) and Eu{sup 3+} (red) after 266 nm excitation. Highlights: Black-Right-Pointing-Pointer Blue emission from BaZrO{sub 3} phosphor. Black-Right-Pointing-Pointer Blue emission enhanced with Tm{sup 3+}. Black-Right-Pointing-Pointer White light from BaZrO{sup 3+} phosphor.

  6. Effects of phosphorous-doping and high temperature annealing on CVD grown 3C-SiC

    International Nuclear Information System (INIS)

    Rooyen, I.J. van; Neethling, J.H.; Henry, A.; Janzén, E.; Mokoduwe, S.M.; Janse van Vuuren, A.; Olivier, E.

    2012-01-01

    The integrity and property behavior of the SiC layer of the Tri-isotropic (TRISO) coated particle (CP) for high temperature reactors (HTR) are very important as the SiC layer is the main barrier for gaseous and metallic fission product release. This study describes the work done on un-irradiated SiC samples prepared with varying phosphorus levels to simulate the presence of phosphorus due to transmutation. 30 Si transmutes to phosphorous ( 31 P) and other transmutation products during irradiation, which may affect the integrity of the SiC layer. The P-doping levels of the SiC samples used in this study cover the range from 1.1 × 10 15 to 1.2 × 10 19 atom/cm 3 and are therefore relevant to the PBMR operating conditions. Annealing from 1000 °C to 2100 °C was performed to study the possible changes in nanostructures and various properties due to temperature. Characterization results by X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), are reported in this article. As grain boundary diffusion is identified as a possible mechanism by which 110m Ag, one of the fission activation products, might be released through intact SiC layer, grain size measurements is also included in this study. Temperature is evidently one of the factors/parameters amongst others known to influence the grain size of SiC and therefore it is important to investigate the effect of high temperature annealing on the SiC grain size. The ASTM E112 method as well as electron back scatter diffraction (EBSD) was used to determine the grain size of various commercial SiC samples and the SiC layer in experimental PBMR Coated Particles (CPs) after annealing at temperatures ranging from 1600 °C to 2100 °C. The HRTEM micrograph of the decomposition of SiC at 2100 °C are shown and discussed. Nanotubes were not identified during the TEM and HRTEM analysis

  7. Effects of phosphorous-doping and high temperature annealing on CVD grown 3C-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: Isabella.vanrooyen@inl.gov [CSIR, National Laser Centre, PO Box 395, Pretoria 0001 (South Africa); Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Fuel Design, PBMR, 1279 Mike Crawford Avenue, Centurion 0046 (South Africa); Neethling, J.H. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Henry, A.; Janzen, E. [Department of Physics, Chemistry and Biology, Semiconductor Materials, Linkoeping University, Linkoeping 58183 (Sweden); Mokoduwe, S.M. [Fuel Design, PBMR, 1279 Mike Crawford Avenue, Centurion 0046 (South Africa); Janse van Vuuren, A.; Olivier, E. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

    2012-10-15

    The integrity and property behavior of the SiC layer of the Tri-isotropic (TRISO) coated particle (CP) for high temperature reactors (HTR) are very important as the SiC layer is the main barrier for gaseous and metallic fission product release. This study describes the work done on un-irradiated SiC samples prepared with varying phosphorus levels to simulate the presence of phosphorus due to transmutation. {sup 30}Si transmutes to phosphorous ({sup 31}P) and other transmutation products during irradiation, which may affect the integrity of the SiC layer. The P-doping levels of the SiC samples used in this study cover the range from 1.1 Multiplication-Sign 10{sup 15} to 1.2 Multiplication-Sign 10{sup 19} atom/cm{sup 3} and are therefore relevant to the PBMR operating conditions. Annealing from 1000 Degree-Sign C to 2100 Degree-Sign C was performed to study the possible changes in nanostructures and various properties due to temperature. Characterization results by X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), are reported in this article. As grain boundary diffusion is identified as a possible mechanism by which {sup 110m}Ag, one of the fission activation products, might be released through intact SiC layer, grain size measurements is also included in this study. Temperature is evidently one of the factors/parameters amongst others known to influence the grain size of SiC and therefore it is important to investigate the effect of high temperature annealing on the SiC grain size. The ASTM E112 method as well as electron back scatter diffraction (EBSD) was used to determine the grain size of various commercial SiC samples and the SiC layer in experimental PBMR Coated Particles (CPs) after annealing at temperatures ranging from 1600 Degree-Sign C to 2100 Degree-Sign C. The HRTEM micrograph of the decomposition of Si

  8. Preparation and luminescence properties of Eu2+-doped CaSi2O2-dN2+2/3d phosphors

    International Nuclear Information System (INIS)

    Gu Yunxin; Zhang Qinghong; Wang Hongzhi; Li Yaogang

    2009-01-01

    Eu 2+ -doped CaSi 2 O 2-d N 2+2/3d phosphors for white LED lamps were prepared by solid-state reaction, and the effects of heat-treatment conditions and the overall composition of host lattice on the optical properties have been discussed. Eu 2+ -doped CaSi 2 O 2-d N 2+2/3d displayed a single broad emission band peak at 540 nm, which could be assigned to the allowed transition of Eu 2+ from the lowest crystal field component of 4f 6 5d to 4f 7 ground-state level. The excitation band of samples, extending from UV to blue, is extremely wide, so the phosphors are suitable for white LED lamps in combination with a UV or blue LED dies. The highest PL intensity is found for the sample sintered at 1400 0 C. Moreover, the emission intensity decreases when N partially replaces O. A red shift of emission wavelength did not occur with increasing of the N content.

  9. High-Throughput Synthesis and Characterization of Eu Doped Ba xSr2- xSiO4 Thin Film Phosphors.

    Science.gov (United States)

    Frost, Sara; Guérin, Samuel; Hayden, Brian E; Soulié, Jean-Philippe; Vian, Chris

    2018-06-20

    High-throughput techniques have been employed for the synthesis and characterization of thin film phosphors of Eu-doped Ba x Sr 2- x SiO 4 . Direct synthesis from evaporation of the constituent elements under a flux of atomic oxygen on a sapphire substrate at 850 °C was used to directly produce thin film libraries (415 nm thickness) of the crystalline orthosilicate phase with the desired compositional variation (0.24 > x > 1.86). The orthosilicate phase could be synthesized as a pure, or predominantly pure, phase. Annealing the as synthesized library in a reducing atmosphere resulted in the reduction of the Eu while retaining the orthosilicate phase, and resulted in a materials thin film library where fluorescence excited by blue light (450 nm) was observable by the naked eye. Parallel screening of the fluorescence from the combinatorial libraries of Eu doped Ba x Sr 2- x SiO 4 has been implemented by imaging the fluorescent radiation over the library using a monochrome digital camera using a series of color filters. Informatics tools have been developed to allow the 1931 CIE color coordinates and the relative quantum efficiencies of the materials library to be rapidly assessed and mapped against composition, crystal structure and phase purity. The range of compositions gave values of CIE x between 0.17 and 0.52 and CIE y between 0.48 and 0.69 with relative efficiencies in the range 2.0 × 10 -4 -7.6 × 10 -4 . Good agreement was obtained between the thin film phosphors and the fluorescence characteristics of a number of corresponding bulk phosphor powders. The thermal quenching of fluorescence in the thin film libraries was also measured in the temperature range 25-130 °C: The phase purity of the thin film was found to significantly influence both the relative quantum efficiency and the thermal quenching of the fluorescence.

  10. Photoluminescence characteristics of Sm{sup 3+}-doped Ba{sub 2}CaWO{sub 6} as new orange–red emitting phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ruiijn [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Mi Noh, Hyeon; Kee Moon, Byung; Chun Choi, Byung [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Hyun Jeong, Jung, E-mail: jhjeong@pknu.ac.kr [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of); Sueb Lee, Ho [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Jang, Kiwan, E-mail: kwjang@changwon.ac.kr [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Soo Yi, Soung [Department of Electronic Material Engineering, Silla University, Busan 617-736 (Korea, Republic of)

    2014-08-01

    The orange–red emitting Ba{sub 2}CaWO{sub 6}:xSm{sup 3+} (0.01≤x≤0.25) phosphors were synthesized via solid state reaction process. The crystal structure of the phosphor was characterized by XRD. The photoluminescence excitation and emission spectra, concentration effect were investigated. The results show an efficient energy transfer from WO{sub 6}{sup 6−} group to Sm{sup 3+} occurs. The emission spectra of the Ba{sub 2}CaWO{sub 6}:Sm{sup 3+} phosphors consisted of some sharp emission peaks of Sm{sup 3+} ions centre at 579 nm, 618 nm, 625 nm, and 675 nm. The strongest one is located at 610 nm due to {sup 4}G{sub 5/2}→{sup 6}H{sub 7/2} transition of Sm{sup 3+}, generating bright orange–red light. The optimum dopant concentration of Sm{sup 3+} ions in Ba{sub 2}CaWO{sub 6}:xSm{sup 3+} is around 5 mol% and the critical transfer distance of Sm{sup 3+} is calculated as 18 Å. The fluorescence lifetime of Sm{sup 3+} in Ba{sub 2}CaWO{sub 6}:0.05Sm{sup 3+} is 2.36 ms. The Ba{sub 2}CaWO{sub 6}:Sm{sup 3+} phosphors may be potentially used as orange–red phosphors for white light-emitting diodes. - Highlights: • A new host-sensitized Sm{sup 3+}-doped Ba{sub 2}CaWO{sub 6} phosphor was firstly synthesized. • Its structure, luminescent properties are well studied and characterized. • There exists an efficient energy transfer from WO{sub 6}{sup 6−} group to Sm{sup 3+}. • The thermal quenching properties of Ba{sub 2}CaWO{sub 6}:Sm{sup 3+} was firstly evaluated.

  11. Long-wave UVA radiation excited warm white-light emitting NaGdTiO4: Tm3+/Dy3+/Eu3+ ions tri-doped phosphors: Synthesis, energy transfer and color tunable properties

    International Nuclear Information System (INIS)

    Bharat, L. Krishna; Du, Peng; Yu, Jae Su

    2016-01-01

    NaGdTiO 4 (NGT) phosphors doped with different activator ions (Tm 3+ , Dy 3+ , and Eu 3+ ) were synthesized by a conventional solid-state reaction method in an ambient atmosphere. These phosphors were characterized by scanning electron microscope images, transmission electron microscope images, X-ray diffraction patterns, Fourier transform infrared spectra, and photoluminescence spectra. All the samples were crystallized in an orthorhombic phase with a space group of Pbcm (57). In Tm 3+ /Dy 3+ ions co-doped samples, white-light emission was observed under near-ultraviolet (NUV) excitation. In addition, the energy transfer between Tm 3+ and Dy 3+ ions was proved to be a resonant type via an electric dipole–dipole mechanism and the critical distance of energy transfer was calculated to be 19.91 Å. Furthermore, Tm 3+ /Dy 3+ /Eu 3+ ions tri-doped NGT phosphors demonstrated warm white-light emission by appropriately tuning the activator content, based on the principle of energy transfer. These NUV wavelength excitable phosphors exhibit great potential as a single-phase full-color emitting phosphor for white light-emitting diode applications. - Highlights: • The pebble shaped NaGdTiO 4 particles were prepared by solid-state reaction method. • Tm 3+ and Dy 3+ single doping gives respective blue and cool white light emission. • The Tm 3+ /Dy 3+ ions co-doped samples give CIE values near to standard white light. • Addition of Eu 3+ ions shifts the CIE values towards warm white light region. • This single phase white light emitting phosphors have lower CCT values (<5000 K).

  12. Enhanced Ce{sup 3+} photoluminescence by Li{sup +} co-doping in CaO phosphor and its use in blue-pumped white LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Zhendong, E-mail: haozd@ciomp.ac.cn; Zhang, Xia; Luo, Yongshi; Zhang, Ligong; Zhao, Haifeng; Zhang, Jiahua, E-mail: zhangjh@ciomp.ac.cn

    2013-08-15

    In this paper, we demonstrate a method to improve the photoluminescence of CaO: Ce{sup 3+} phosphor and delineate its first use in blue-pumped white LEDs. The results show that the yellow emission of Ce{sup 3+} is enhanced by a factor of 1.88 by adding Li{sup +} into CaO host at 474 nm blue light excitation. On analyzing the diffuse reflection spectra and fluorescence decay curves, we reveal that the photoluminescence enhancement is originated from the rise of absorbance to the excitation photons but not from the improvement of the luminescent efficiency. Li{sup +}-improved CaO: Ce{sup 3+} exhibits more red component when it is compared with the commercial Y{sub 3}Al{sub 5}O{sub 12}: Ce{sup 3+} (YAG: Ce{sup 3+}) phosphor, indicating its potential application for high color rendering white LEDs. Thus, a white LED is fabricated by combining blue InGaN LED chip with CaO: Ce{sup 3+}, Li{sup +} phosphor and a warm white light with high color rendering index (R{sub a}) of 80, low correlated color temperature (T{sub c}) of 4524 K, and sufficient luminous efficiency of 50 lm W{sup −1} is obtained. -- Highlights: • The photoluminescence of Ce{sup 3+} in CaO host was enhanced by Li{sup +} co-doping. • A CaO: Ce{sup 3+}, Li{sup +} based white LED was fabricated for the first time. • An efficient warm white light was obtained. • CaO: Ce{sup 3+}, Li{sup +} is expected to be used as a yellow phosphor for blue-pumped white LEDs.

  13. Spectral-converting behaviors of Er{sup 3+} and Er{sup 3+}–Yb{sup 3+} doped YOCl phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sangmoon, E-mail: spark@silla.ac.kr [Center for Green Fusion Technology and Department of Engineering in Energy and Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of); Cho, So-Hye [Center for Materials Architecturing, Institute of Multidisciplinary Convergence of Materials, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of)

    2014-01-25

    Highlights: • Luminescent materials of YOCl:Er,Yb were prepared using NH{sub 4}Cl flux. • Interesting spectral-converting behaviors were observed in the phosphors. • 980 or 1550 nm diode laser was irradiated for up-converting study. • A multi-photon process in the phosphors was calculated. -- Abstract: Luminescent materials composed of Y{sub 1−m−n}Er{sub m}Yb{sub n}OCl (m = 0.001–0.1, n = 0.005–0.1) were prepared via a solid-state reaction using NH{sub 4}Cl flux. Photoluminescence spectra, the dependence of the luminescent intensity as a function of Er{sup 3+} content, and their CIE coordinates of the Er{sup 3+}-doped layered YOCl compounds were also investigated under near-ultraviolet (NUV) and visible lights. The spectral up-converting properties of Er{sup 3+} and Er{sup 3+}–Yb{sup 3+} in YOCl phosphors were elucidated under 980 and 1550 nm diode laser irradiations. This up-conversion emission spectra and the pump power dependence versus emission intensity observed in the Y{sub 0.9}Er{sub 0.1}OCl up-conversion phosphors gave rise to one- and two-photon processes. The up-conversion mechanism of Er{sup 3+} and Yb{sup 3+} ions in YOCl was described by a schematic energy-level diagram. Through the use of these up-conversion luminescent materials, the desired emitting lights throughout the orange and red regions of the spectra were achieved.

  14. White phosphor using Yb3+-sensitized Er3+-and Tm3+-doped sol-gel derived lead-fluorosilicate transparent glass ceramic excited at 980 nm

    Science.gov (United States)

    Tavares, M. C. P.; da Costa, E. B.; Bueno, L. A.; Gouveia-Neto, A. S.

    2018-01-01

    Generation of primary colors and white light through frequency upconversion using sol-gel derived 80SiO2:20PbF2 vitroceramic phosphors doped with Er3+, Er3+/Yb3+, Tm3+/Yb3+, and Er3+/Tm3+/Yb3+ excited at 980 nm is demonstrated. For Er3+ and Er3+/Yb3+ doped samples emissions were obtained in the blue (410 nm), green (530, and 550 nm) and red (670 nm) regions, corresponding to the 2H9/2 → 4I15/2,2H11/2 → 4I15/2, 4S3/2 → 4I152 and 4F9/2 → 4I15/2 transitions of Er3+, respectively. The codoping with Yb3+ ions altered the spectral profile of most of the emissions compared to the single doped samples, resulting in changes in the emitted color, in addition to a significant increase in the emission intensity. In Tm3+/Yb3+ co-doped samples visible emissions in the blue (480 nm), and red (650 nm), corresponding to transitions 1G4 → 3H6 and 1G4 → 3F4 of Tm3+, respectively, were obtained. The emission intensity around 480 nm overcome the red emission, and luminescence showed a predominantly blue tone. White light with CIE-1931 coordinates (0.36; 0.34) was produced by homogeneously mixing up powders of heat treated at 400 °C co-doped samples 5.0Er3+/5.0Yb3+ and 0.5Tm3+/2.5Yb3+ in the mass ratio of 13%, and 87%, respectively. The measured emission spectrum for a sample resulting from the mixture showed a profile with very good agreement with the spectrum found from the superimposition of the spectra of the co-doped samples.

  15. Generation of White Light from Dysprosium-Doped Strontium Aluminate Phosphor by a Solid-State Reaction Method

    Science.gov (United States)

    Sahu, Ishwar Prasad; Bisen, D. P.; Brahme, N.; Tamrakar, Raunak Kumar

    2016-04-01

    A single-host lattice, white light-emitting SrAl2O4:Dy3+ phosphor was synthesized by a solid-state reaction method. The crystal structure of prepared SrAl2O4:Dy3+ phosphor was in a monoclinic phase with space group P21. The chemical composition of the sintered SrAl2O4:Dy3+ phosphor was confirmed by the energy dispersive x-ray spectroscopy technique. Under ultra-violet excitation, the characteristic emissions of Dy3+ are peaking at 475 nm, 573 nm and 660 nm, originating from the transitions of 4F9/2 → 6H15/2, 4F9/2 →&!nbsp; 6H13/2 and 4F9/2 → 6H11/2 in the 4f9 configuration of Dy3+ ions. Commission International de I'Eclairage color coordinates of SrAl2O4:Dy3+ are suitable for white light-emitting phosphor. In order to investigate the suitability of the samples as white color light sources for industrial uses, correlated color temperature (CCT) and color rendering index (CRI) values were calculated. Values of CCT and CRI were found well within the defined acceptable range. Mechanoluminescence (ML) intensity of SrAl2O4:Dy3+ phosphor increased linearly with increasing impact velocity of the moving piston. Thus, the present investigation indicates piezo-electricity was responsible for producing ML in sintered SrAl2O4:Dy3+ phosphor. Decay rates of the exponential decaying period of the ML curves do not change significantly with impact velocity. The photoluminescence and ML results suggest that the synthesized SrAl2O4:Dy3+ phosphor was useful for the white light-emitting diodes and stress sensor respectively.

  16. Luminescence characterization of sol-gel derived Pr{sup 3+} doped NaGd(WO{sub 4}){sub 2} phosphors for solid state lighting applications

    Energy Technology Data Exchange (ETDEWEB)

    Durairajan, A., E-mail: durairajan.a@gmail.com [Crystal Growth Centre, Anna University, Chennai, 600025 (India); I3N-Aveiro, Department of Physics, University of Aveiro, Aveiro, 3810 193 (Portugal); Thangaraju, D. [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka, 432-8011 (Japan); Moorthy Babu, S. [Crystal Growth Centre, Anna University, Chennai, 600025 (India); Valente, M.A. [I3N-Aveiro, Department of Physics, University of Aveiro, Aveiro, 3810 193 (Portugal)

    2016-08-15

    In the present work, xPr{sup 3+}:NaGd(WO{sub 4}){sub 2} (0.5 ≤ x ≤ 5.0 mol%) sub-micron phosphors were synthesised by sol-gel method. Low cost precursors of metal nitrates and low temperature thermal treatment was used compared to conventional solid state reaction. The formation of highly crystalline phosphors with tetragonal structure was confirmed by XRD and increase of Pr{sup 3+} ions content in host matrix leads to expansion of the unit cell volume. The surface morphology, size and particle distribution of the phosphors were observed by field emission scanning electron microscopy (FE-SEM). A rectangular shape particle with a size distribution ranging from 400 to 600 nm and tightly packed surface was seen in FE-SEM micrographs. The various internal and external phonon modes vibration corresponding to double tungstate structure was observed in Raman spectra. The optical properties of the synthesised phosphors were explored by ultraviolet visible (UV–Vis) absorption in diffuse reflectance and photoluminescence (PL) measurements. UV–Vis measurements distinguished the host and Pr{sup 3+} absorption and also reveal an increase in optical band gap values with an increase of Pr{sup 3+}. The PL measurements show various emissions from green and red regions under 450 nm. The maximum intensity emission at 489 nm is due to {sup 3}P{sub 0} → {sup 3}H{sub 4} transition of Pr{sup 3+}. From the maximum emission the critical doping concentration was calculated to be at 3.5 mol% and critical distance between two adjacent Pr{sup 3+} ions as 20.43 Å. - Highlights: • A sol-gel method was used to prepare Pr{sup 3+} doped NaGd(WO{sub 4}){sub 2} at low temperature. • Structural, spectroscopic, morphological, and optical and luminescence properties were studied. • The praseodymium ions are in trivalent state, the site symmetry is distorted and S{sub 4} local symmetry with Na{sup +} ions. • Strong green emission was observed under UV and visible excitation.

  17. Luminescence characterization of sol-gel derived Pr"3"+ doped NaGd(WO_4)_2 phosphors for solid state lighting applications

    International Nuclear Information System (INIS)

    Durairajan, A.; Thangaraju, D.; Moorthy Babu, S.; Valente, M.A.

    2016-01-01

    In the present work, xPr"3"+:NaGd(WO_4)_2 (0.5 ≤ x ≤ 5.0 mol%) sub-micron phosphors were synthesised by sol-gel method. Low cost precursors of metal nitrates and low temperature thermal treatment was used compared to conventional solid state reaction. The formation of highly crystalline phosphors with tetragonal structure was confirmed by XRD and increase of Pr"3"+ ions content in host matrix leads to expansion of the unit cell volume. The surface morphology, size and particle distribution of the phosphors were observed by field emission scanning electron microscopy (FE-SEM). A rectangular shape particle with a size distribution ranging from 400 to 600 nm and tightly packed surface was seen in FE-SEM micrographs. The various internal and external phonon modes vibration corresponding to double tungstate structure was observed in Raman spectra. The optical properties of the synthesised phosphors were explored by ultraviolet visible (UV–Vis) absorption in diffuse reflectance and photoluminescence (PL) measurements. UV–Vis measurements distinguished the host and Pr"3"+ absorption and also reveal an increase in optical band gap values with an increase of Pr"3"+. The PL measurements show various emissions from green and red regions under 450 nm. The maximum intensity emission at 489 nm is due to "3P_0 → "3H_4 transition of Pr"3"+. From the maximum emission the critical doping concentration was calculated to be at 3.5 mol% and critical distance between two adjacent Pr"3"+ ions as 20.43 Å. - Highlights: • A sol-gel method was used to prepare Pr"3"+ doped NaGd(WO_4)_2 at low temperature. • Structural, spectroscopic, morphological, and optical and luminescence properties were studied. • The praseodymium ions are in trivalent state, the site symmetry is distorted and S_4 local symmetry with Na"+ ions. • Strong green emission was observed under UV and visible excitation.

  18. Thermoluminescence properties of Eu-doped and Eu/Dy-codoped Sr2 Al2 SiO7 phosphors.

    Science.gov (United States)

    Jadhaw, Akhilesh; Sonwane, Vivek D; Gour, Anubha S; Jha, Piyush

    2017-11-01

    We report the thermoluminescence properties of Sr 1.96 Al 2 SiO 7 :Eu 0.04 and Sr 1.92 Al 2 SiO 7 :Eu 0.04 Dy 0.04 phosphors. These phosphors were prepared by a high-temperature solid-state reaction method. The prepared phosphors were characterized by X-ray diffraction. A 254 nm source was used for ultraviolet (UV) irradiation and a 60 Co source was used for γ-irradiation. The effect of heating rate and UV-exposure were examined. The thermoluminescence temperature shifts to higher values with increasing heating rate and thermoluminescence intensity increases with increasing UV exposure time. The trapping parameters such as activation energy (E), order of kinetics and frequency factor (s) were calculated by peak shape method. The effect of γ- and UV-irradiation on thermoluminescence studies was also examined. Copyright © 2017 John Wiley & Sons, Ltd.

  19. Orange and reddish-orange light emitting phosphors: Sm{sup 3+} and Sm{sup 3+}/Eu{sup 3+} doped zinc phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Meza-Rocha, A.N., E-mail: ameza@fis.cinvestav.mx [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 México D.F., México (Mexico); Speghini, A. [Dipartimento di Biotecnologie, Universita di Verona and INSTM, UdR Verona, Strada Le Grazie 15, I-37314 Verona (Italy); IFAC CNR, Nello Carrara Institute of Applied Physics, MDF Lab, I-50019 Sesto Fiorentino, FI (Italy); Bettinelli, M. [Dipartimento di Biotecnologie, Universita di Verona and INSTM, UdR Verona, Strada Le Grazie 15, I-37314 Verona (Italy); Caldiño, U. [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 México D.F., México (Mexico)

    2015-11-15

    A spectroscopy study of Sm{sup 3+} and Sm{sup 3+}/Eu{sup 3+} doped zinc phosphate glasses is performed through photoluminescence spectra and decay time profile measurements. Under Sm{sup 3+} excitation at 344 nm, the Sm{sup 3+} singly doped glass shows an orange global emission with x=0.579 and y=0.414 CIE1931 chromaticity coordinates, whereas the Sm{sup 3+}/Eu{sup 3+} co-doped sample exhibits orange overall emissions (x=0.581 and y=0.398, and x=0.595 and y=0.387) and reddish-orange overall emission (x=0.634 and y=0.355) upon excitations at 344, 360 and 393 nm, respectively. Such luminescence from the co-doped sample is originated by the simultaneous emission of Sm{sup 3+} and Eu{sup 3+}. Under Sm{sup 3+} excitation at 344 and 360 nm, the Eu{sup 3+} emission is sensitized and enhanced by Sm{sup 3+} through a non-radiative energy transfer process. The non-radiative nature was inferred from the shortening of the Sm{sup 3+} lifetime observed in the Sm{sup 3+}/Eu{sup 3+} co-doped sample. An analysis of the Sm{sup 3+} emission decay time profiles using the Inokuti–Hirayama model suggests that an electric quadrupole–quadrupole interaction into Sm–Eu clusters might dominate the energy transfer process, with an efficiency of 0.17. - Highlights: • Zinc phosphate glasses are optically activated with Sm{sup 3+}/Eu{sup 3+} (ZPOSmEu). • Non-radiative energy transfer Sm{sup 3+}→Eu{sup 3+} takes place in ZPOSmEu. • ZPOSmEu overall emission can be modulated with the excitation wavelength. • ZPOSmEu might be useful as orange/reddish-orange phosphor for UV-white LEDs.

  20. The development of new phosphors of Tb3+/Eu3+ co-doped Gd3Al5O12 with tunable emission

    Science.gov (United States)

    Teng, Xin; Wang, Wenzhi; Cao, Zhentao; Li, Jinkai; Duan, Guangbin; Liu, Zongming

    2017-07-01

    The gadolinium aluminum garnets Gd3Al5O12 (GdAG) activated with Tb3+/Eu3+ were successfully prepared via co-precipitation method at 1500 °C in this work. The crystal structure stabilization, elements analysis, microphotograph, PL/PLE spectra, decay behavior and quantum efficiency were discussed in detail. The metastable GdAG compounds been effectively stabilized by doping with smaller 10 at.% Tb3+, which then allows the development of new phosphors of (Gd0.9-xTb0.1Eux)3Al5O12 (GdAG:Tb3+/Eu3+, x = 0-0.03) for opto-functionality explorations. The PLE/PL spectra displays that the strongest PLE peak was located at ∼276 nm, which overlaps the 8S7/2 → 6IJ transition of Gd3+. Under 276 nm excitation, the phosphors exhibited both Tb3+ and Eu3+ emissions at 548 nm (green, 5D4 → 7F5 transition of Tb3+) and 592 nm (orange-red, 5D0 → 7F1 transition of Eu3+), respectively. The emission intensities of Tb3+ and Eu3+ remarkably varied with the Eu3+ incorporation. As a consequence, the emission color can be readily tuned from approximately green to orange-red. Fluorescence decay analysis found that the lifetime for the Tb3+ emission rapidly decreased conforming to the Tb3+ → Eu3+ energy transfer, and the energy transfer efficiency was calculated. Owing to the Gd3+ → Eu3+ and Gd3+ → Tb3+ energy transfer, the emission intensities of Tb3+ and Eu3+ in (Gd0.9-xTb0.1Eux)AG phosphor were higher than (Y0.87Tb0.1Eu0.03)AG and (Lu0.87Tb0.1Eu0.03)AG system. The (Gd0.9-xTb0.1Eux)AG garnet phosphors developed in this work may serve as a new type of phosphor which hopefully meets the requirements of various lighting and optical display applications.

  1. Lanthanide doped BaTiO{sub 3}−SrTiO{sub 3} solid-solution phosphors: Structure, optical spectroscopy and upconverted temperature sensing behavior

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Daqin, E-mail: dqchen@hdu.edu.cn; Xu, Wei; Zhou, Yang; Chen, Yan, E-mail: chenyan@hdu.edu.cn

    2016-08-15

    Lanthanide doped Ba{sub 1-x}Sr{sub x}TiO{sub 3} (x = 0–1) solid-solution phosphors were successfully prepared by a conventional solid-state reaction. Using Eu{sup 3+} dopants as the structural probe, the variation of {sup 5}D{sub 0} → {sup 7}F{sub 2}/{sup 5}D{sub 0} → {sup 7}F{sub 1} emission intensity ratio with increase of Eu{sup 3+} content and the excitation-wavelength-dependent luminescence in the Ba{sub 1-x}Sr{sub x}TiO{sub 3} sample were demonstrated to be originated from the different emission behaviors of Eu{sup 3+} in Ba{sup 2+}/Sr{sup 2+} site and Ti{sup 4+} site. Furthermore, upconversion luminescence for the Yb{sup 3+}/Er{sup 3+} co-doped Ba{sub 1-x}Sr{sub x}TiO{sub 3} samples were investigated, and it was found that the emission intensity of Yb{sup 3+}/Er{sup 3+}: Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} phosphor was about 5 and 2 times as high as those of Yb{sup 3+}/Er{sup 3+}: BaTiO{sub 3} and Yb{sup 3+}/Er{sup 3+}: SrTiO{sub 3} ones. Using the investigated Yb{sup 3+}/Er{sup 3+}: Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} solid-solution as the optical thermometric medium, the temperature sensitivity was determined to be 0.76% K{sup −1} at the temperature of 610 K based on the temperature-dependent fluorescence intensity ratio of the thermally coupled {sup 2}H{sub 11/2} and {sup 4}S{sub 3/2} emitting-states of Er{sup 3+}. - Highlights: • Lanthanide doped Ba{sub 1-x}Sr{sub x}TiO{sub 3} (x = 0–1) solid-solutions were fabricated. • Excitation-wavelength-dependent Eu{sup 3+} emissions were recorded. • Enhanced Er{sup 3+} luminescence was realized by partial substitution of Ba{sup 2+} by Sr{sup 2+}. • T-sensitive emissions of two Er{sup 3+} thermally coupled states were observed. • The upconversion phosphor exhibited a high sensitivity of 0.76% K{sup −1}.

  2. Luminescent properties of Eu2+-doped BaGdF5 glass ceramics a potential blue phosphor for ultra-violet light-emitting diode

    International Nuclear Information System (INIS)

    Zhang, Weihuan; Zhang, Yuepin; Ouyang, Shaoye; Zhang, Zhixiong; Wang, Qian; Xia, Haiping

    2015-01-01

    Eu 2+ doped transparent oxyfluoride glass ceramics containing BaGdF 5 nanocrystals were successfully fabricated by melt-quenching technique under a reductive atmosphere. The structure of the glass and glass ceramics were investigated by differential scanning calorimetry, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The luminescent properties were investigated by transmission, excitation, and emission spectra. The decay time of the Gd 3+ ions at 312 nm excited with 275 nm were also investigated. The results of XRD and TEM indicated the existence of BaGdF5 nanocrystals in the transparent glass ceramics. The excitation spectra of Eu 2+ doped glass ceramics showed an excellent overlap with the main emission region of an ultraviolet light-emitting diode (UV-LED). Compared with the as-made glass, the emission of glass ceramics is much stronger by a factor of increasing energy transfer efficiency from Gd 3+ to Eu 2+ ions, the energy transfer efficiency from Gd 3+ to Eu 2+ ions was discussed. In addition, the chromaticity coordinates of glass and glass ceramics specimens were also discussed, which indicated that the Eu 2+ doped BaGdF 5 glass ceramics may be used as a potential blue-emitting phosphor for UV-LED

  3. Method of preparing a thermoluminescent phosphor

    Science.gov (United States)

    Lasky, Jerome B.; Moran, Paul R.

    1979-01-01

    A thermoluminescent phosphor comprising LiF doped with boron and magnesium is produced by diffusion of boron into a conventional LiF phosphor doped with magnesium. Where the boron dopant is made to penetrate only the outer layer of the phosphor, it can be used to detect shallowly penetrating radiation such as tritium beta ays in the presence of a background of more penetrating radiation.

  4. The zombie thermographer apocalypse preparedness 101: zombie thermographer pandemic

    Science.gov (United States)

    Colbert, Fred

    2013-05-01

    Fact: The U.S Government Centers for Disease Control and Prevention (CDC), Office of Public Health Preparedness and Response, rather remarkably has dedicated part of their web site to" Zombie Preparedness". See: http://www.cdc.gov/phpr/zombies.htm for more information. This is a tongue-incheek campaign with messages to engage audiences with the hazards of unpreparedness. The CDC director, U.S. Assistant Surgeon General Ali S. Khan (RET), MD, MPH notes, "If you are generally well equipped to deal with a zombie apocalypse you will be prepared for a hurricane, pandemic, earthquake, or terrorist attack. Make a plan, and be prepared!" (CDC Website, April 26th, 2013). Today we can make an easy comparison between the humor that the CDC is bringing to light, and what is actually happening in the Thermographic Industry. It must be acknowledge there are "Zombie Thermographers" out there. At times, it can be observed from the sidelines as a pandemic apocalypse attacking the credibility and legitimacy of the science and the industry that so many have been working to advance for over 30 years. This paper outlines and explores the trends currently taking place, the very real risks to facility plant, property, and human life as a result, and the strategies to overcome these problems.

  5. The Role of Activator-Activator Interactions In Reducing in Low-Voltage-Cathodoluminescence Efficiency in Eu and Tb Doped Phosphors

    International Nuclear Information System (INIS)

    SEAGER, CARLETON H.; TALLANT, DAVID R.

    1999-01-01

    High resolution measurements of spectrally resolved cathodoluminescence (CL) decay have been made in several commercial and experimental phosphors doped with Eu and Tb at beam energies ranging from 0.8 to 4 keV. CL emission from the lowest two excited states of both rare earth activators was compared to the decay of photoluminescence (PL) after pulsed laser excitation. We find that, at long times after the cessation of electron excitation, the CL decay rates are comparable to those measured in PL, at short times, the decay process is considerably faster and has a noticeable dependence on the energy of the electron beam. These beam energy effects are largest for the higher excited states and for phosphors with larger activator concentrations. Measurements of the experimental phosphors over a range of activator fractions from 0.1 to 0.002 show that the beam energy dependence of the steady-state CL efficiency is larger for higher excited states and weakens as the activator concentration is reduced. The latter effect is strongest for Y 2 SiO 5 :Tb, but also quite evident in Y 2 O 3 :Eu. We suggest that the electron beam dependence of both the decay lifetimes and the steady state CL efficiency may be due to interaction of nearby excited states which occurs as a result of the large energy deposition rate for low energy electrons. This picture-for non-radiative quenching of rare earth emission is an excited state analog of the well-known (ground state-excited state) concentration quenching mechanism

  6. New Ce{sup 3+} doped Ca{sub 2}YMgScSi{sub 3}O{sub 12} garnet ceramic phosphor for white LED converters

    Energy Technology Data Exchange (ETDEWEB)

    Khaidukov, N. [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation); Zorenko, Yu.; Zorenko, T.; Iskaliyeva, A.; Paprocki, K. [Institute of Physics, Kazimierz Wielki University Bydgoszcz (Poland); Zhydachevskii, Y.; Suchocki, A. [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland); Deun, R. van [L3 - Luminescent Lanthanide Lab, Department of Inorganic and Physical Chemistry, Ghent University (Belgium); Batentschuk, M. [Department of Materials Science and Engineering VI, Institute of Materials for Energy and Electronic Technology (i-IMEET), University of Erlangen-Nuremberg, Erlangen (Germany)

    2017-05-15

    The results on crystallization and investigation of the luminescent properties of a new prospective ceramic phosphor based on the Ce{sup 3+} doped Ca{sub 2}YMgScSi{sub 3}O{sub 12} silicate garnet are presented for the first time in this work. The luminescent properties of Ca{sub 2}YMgScSi{sub 3}O{sub 12}:Ce were compared with the properties of the reference Ca{sub 3}Sc{sub 2}Si{sub 3}O{sub 12}:Ce ceramic sample. Without any doubt, the results of this research can be suitable for the development of a new generation of white converters based on the Ca{sup 2+}-Si{sup 4+} garnet compounds. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Dependence of upconversion emission intensity on Yb3+ concentration in Er3+/Yb3+ co-doped flake shaped Y2(MoO4)3 phosphors

    International Nuclear Information System (INIS)

    Lu Weili; Cheng Lihong; Zhong Haiyang; Sun Jiashi; Wan Jing; Tian Yue; Chen Baojiu

    2010-01-01

    Yttrium molybdate phosphors with fixed Er 3+ and various Yb 3+ concentrations were synthesized via a co-precipitation method. The crystal structure and the morphology of the phosphor were characterized by means of x-ray diffraction and field-emission scanning electron microscopy. Under 980 nm excitation, red and green upconversion emissions centred at 660, 553 and 530 nm were observed. Quantitative analyses on the dependence of upconversion emission intensity on the working current of a laser diode (LD) indicated that two-photon processes are responsible for both red and green upconversion emissions in both cases of low and high Yb 3+ concentrations. The relationship between the emission intensity ratio of 2 H 11/2 → 4 I 15/2 to 4 S 3/2 → 4 I 15/2 and the working current of the LD was studied for the samples doped with low and high Yb 3+ concentrations. Finally, a set of rate equations was established based on the possible upconversion mechanism, and an empirical formula was proposed to describe the Yb 3+ concentration dependence of upconversion emission intensity; the empirical formula fits well with the experimental data.

  8. Influence of Pr doping on the thermal, structural and optical properties of novel SLS-ZnO glasses for red phosphor

    Science.gov (United States)

    Mohamed, Nurzilla; Hassan, Jumiah; Matori, Khamirul Amin; Azis, Raba'ah Syahidah; Wahab, Zaidan Abdul; Ismail, Zamratul Maisarah Mohd; Baharuddin, Nur Fadilah; Rashid, Siti Syuhaida Abdul

    A novel environmental friendly strategy towards red phosphors in optoelectronic applications employing Pr6O11 doped SLS-ZnO with chemical composition x(Pr6O11)·100-x(SLS·ZnO) where x = 0, 1, 2, 3, 4 and 5 wt% via melt-quenching technique was successfully synthesized. The X-ray Diffraction (XRD) patterns of all these glasses show broad and diffused humps, which confirm the amorphous structure of samples. The Differential Thermal Calorimetry (DSC) indicated that the value of glass transition is higher from 625 °C to 637 °C with increasingly of Pr6O11 content. Fourier Transform Infrared Spectra (FTIR) spectra display a decreasing trend towards a smaller wavenumber with the increase of Pr content is due to the formation of non-bridging oxygen (NBO) in SLS-ZnO host matrix. The absorption spectra had revealed the most intense absorption band at ∼444 nm, which was assigned as excitation wavelength to determine the photoluminescence (PL) emission intensity of the glass. The indirect band gap values varies from ∼2.44 eV to ∼3.02 eV as a function of Pr6O11 concentration. The PL emission bands at ∼530 (blue), ∼556 (green), ∼613 (red) and ∼650 (red) nm increases from 0 wt% to 4 wt% and slightly decreases as Pr6O11 increases with a maximum at 5 wt%. Therefore, the SLS-ZnO doped with Pr6O11 as a good potential as red phosphors in an optoelectronic application in accordance with the highest red emission intensity at ∼613 nm and ∼650 nm.

  9. Advances in thermographic signal reconstruction

    Science.gov (United States)

    Shepard, Steven M.; Frendberg Beemer, Maria

    2015-05-01

    Since its introduction in 2001, the Thermographic Signal Reconstruction (TSR) method has emerged as one of the most widely used methods for enhancement and analysis of thermographic sequences, with applications extending beyond industrial NDT into biomedical research, art restoration and botany. The basic TSR process, in which a noise reduced replica of each pixel time history is created, yields improvement over unprocessed image data that is sufficient for many applications. However, examination of the resulting logarithmic time derivatives of each TSR pixel replica provides significant insight into the physical mechanisms underlying the active thermography process. The deterministic and invariant properties of the derivatives have enabled the successful implementation of automated defect recognition and measurement systems. Unlike most approaches to analysis of thermography data, TSR does not depend on flawbackground contrast, so that it can also be applied to characterization and measurement of thermal properties of flaw-free samples. We present a summary of recent advances in TSR, a review of the underlying theory and examples of its implementation.

  10. Enhancement of encaged electron concentration by Sr(2+) doping and improvement of Gd(3+) emission through controlling encaged anions in conductive C12A7 phosphors.

    Science.gov (United States)

    Zhang, Meng; Liu, Yuxue; Zhu, Hancheng; Yan, Duanting; Yang, Jian; Zhang, Xinyang; Liu, Chunguang; Xu, Changshan

    2016-07-28

    Conductive C12A7:0.1%Gd(3+),y%Sr(2+) powders with different Sr(2+) doping concentrations have been prepared in a H2 atmosphere by a solid state method in combination with subsequent UV-irradiation. The encaged electron concentration could be modulated through tuning Sr(2+) doping and its maximum value reaches 2.3 × 10(19) cm(-3). This is attributed to the competition between enhanced uptake and the release of the encaged anions during their formation and diffusion processes and the suppression of encaged electrons generation due to the increased encaged OH(-) anions and the decreased encaged O(2-) anions. Although there exists encaged electrons and different encaged anions (O(2-), H(-) and OH(-)) in C12A7 conductive powders prepared through the hydrogen route, a dominant local environment around Gd(3+) could be observed using electron spin resonance (ESR) detection. It can be ascribed to the stronger coupling of the encaged OH(-) to the framework of C12A7 than those of the encaged electrons, O(2-) and H(-) anions. In addition, emission of Gd(3+) ions is enhanced under UV or low voltage electron beam excitation and a new local environment around Gd(3+) ions appears through the thermal annealing in air because of the decrease of the encaged OH(-) anions and the increase of the encaged O(2-) anions. Our results suggested that Sr(2+) doping in combination with thermal annealing in air is an effective strategy for increasing the conductive performance and enhancing the emission of rare earth ions doped into C12A7 conductive phosphors for low-voltage field emission displays (FEDs).

  11. Sol–gel synthesis and photoluminescence studies on colour tuneable Dy3+/Tm3+ co-doped NaGd(WO4)2 phosphor for white light emission

    International Nuclear Information System (INIS)

    Durairajan, A.; Balaji, D.; Rasu, K. Kavi; Moorthy Babu, S.; Hayakawa, Y.; Valente, M.A.

    2015-01-01

    A series of Dy 3+ /Tm 3+ ion co-doped NaGd(WO 4 ) 2 (NGW) phosphors were synthesised by a sol–gel method at low temperature for white light emission. The structural and luminescence properties of the synthesised phosphors were studied by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman and photoluminescence techniques. In Dy 3+ /Tm 3+ :NGW phosphors, the dopant ions substituted Gd 3+ ions that are located in S 4 sites of NGW host lattice. In NGW host, under UV excitation the Dy 3+ ions have shown strong yellow ( 4 F 9/2 → 6 H 13/2 ) and comparatively weak blue ( 4 F 9/2 → 6 H 15/2 ) emission transitions at 575 and 488 nm, respectively. Due to deficient blue colour the overall emission falls in yellow region. Hence, Tm 3+ ions having strong blue emission at 455 nm corresponding to the transition 1 D 2 → 3 F 4 were co-activated along with Dy 3+ ions in NGW matrix. By changing the doping concentrations of Tm 3+ and Dy 3+ ions in NGW, white light emission was tuned by 353 nm excitation wavelength. Their corresponding colour co-ordinates were calculated and found to be very close to the white colour chromaticity co-ordinates (0.333, 0.333). - Highlights: • Dy 3+ and Dy 3+ /Tm 3+ :NGW phosphors were synthesised by sol–gel methods. • The excitation spectrum confirmed the strong absorption in near-UV region. • The emission spectrum shows the yellow and white emission to doped and co-doped phosphors respectively. • The CIE co-ordinate conforms close to daylight emission

  12. High-pressure liquid chromatography of trace elements: Determination of terbium in terbium doped gadolinium oxide sulphide phosphors

    International Nuclear Information System (INIS)

    Mazzucotelli, A.; Dadone, A.; Frache, R.; Baffi, F.; Genoa Univ.

    1982-01-01

    A detailed study of isocratic and gradient elution separations of lanthanides has been carried out. Analyses of industrially and scientifically interesting products such as luminescent phosphors have been carried out by gradient elution with DL-2-hydroxyisobutyric acid. The determination of small amounts of terbium in gadolinium oxide sulphide phosphors is described in which an HCl solution was eluted through a stainless steel column packed with microparticulate silica, with bonded cation-exchange groups. Complete separation of gadolinium and terbium is achieved. Detection is with a variable wavelength detector following post-column complex formation with 4-(2-pyridylazo)-resorcinol monosodium salt. Results obtained on test solutions show good reproducilbity and sensitivtiy and the method may be considered sufficiently reliable to be used in routine quality control procedures. (orig.)

  13. Investigation of holmium-doped zirconium oxide ceramic phosphor as an ultraviolet wavelength-discriminating laser beam viewer

    Science.gov (United States)

    Yamanoi, Kohei; Hori, Tatsuhiro; Minami, Yuki; Empizo, Melvin John F.; Luong, Mui Viet; Shiro, Atsushi; Watanabe, Jun; Iwano, Keisuke; Iwasa, Yuki; Cadatal-Raduban, Marilou; Gabayno, Jacque Lynn; Shimizu, Toshihiko; Sarukura, Nobuhiko; Norimatsu, Takayoshi

    2018-01-01

    We report the fluorescence spectra of ZrO2 and trivalent Ho-doped ZrO2 ceramics under ultraviolet (UV) excitation at 213, 266, and 355 nm wavelengths. The Ho3+-doped ZrO2 ceramics exhibited varying fluorescence color tones depending on the excitation wavelength used. The different color tones match the fluorescence spectrum characteristics at each excitation wavelength. Our results demonstrate that Ho3+-doped ZrO2 ceramics can discriminate between UV light, specifically the third, fourth, and fifth harmonics of a Nd:YAG laser. It can potentially be used for developing UV laser beam viewers to aid laser alignment.

  14. Effect of ultrasound treatment on the morpho-structural and luminescent characteristics of cerium doped yttrium silicate phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Muresan, L.E., E-mail: laura_muresan2003@yahoo.com [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Cadis, A.I.; Perhaita, I. [“Raluca Ripan” Institute for Research in Chemistry, Babeş Bolyai University, Fântânele 30, 400294 Cluj-Napoca (Romania); Silipas, D.T. [National Institute for R& D of Isotopic and Molecular Technologies, Donath 67-103, 400293 Cluj-Napoca (Romania); Tudoran, L. Barbu [Electronic Microscopy Centre, Babeş Bolyai University, Clinicilor 37, 400006 Cluj-Napoca (Romania)

    2015-08-15

    Highlights: • Y{sub 2}SiO{sub 5}:Ce is prepared by gel combustion in ultrasound conditions (US). • Morpho-structural characteristics are revealed based on FTIR, SEM, XRD, BET. • Incorporation of Ce{sup 3+} in X1/X2 type centers depends on preparative conditions. • US treatment increases the luminescent performances up to 151%. - Abstract: Cerium activated yttrium silicate (Y{sub 2}SiO{sub 5}:Ce) phosphors were prepared by gel-combustion, using yttrium–cerium nitrate as oxidizer, aspartic acid as fuel and TEOS as source of silicon. Two modalities for samples preparation were approached namely: the classical gel-combustion and sonication gel-combustion. The ultrasound treatment during the gelling stage has a positive effect on the structural and luminescent characteristics of the final product. Therefore, a well crystallized single X2–Y{sub 2}SiO{sub 5} phase phosphor was obtained at 1200 °C. Based on FT-IR and XRD investigations, conversion of X1 to X2–Y{sub 2}SiO{sub 5} phases is observed as the firing temperature is varied (1100 °C, 1200 °C, 1300 °C 1400 °C). The ultrasound treatment leads to smaller particle size and enhances the luminescent performances up to 151% in comparison with samples prepared by classical way.

  15. Luminescence and energy transfer of Tm3+ or/and Dy3+ co-doped in Sr3Y(PO4)3 phosphors with UV excitation for WLEDs

    International Nuclear Information System (INIS)

    Wang, Jiyou; Wang, Jianbo; Duan, Ping

    2014-01-01

    Powder samples Sr 3 Y 1−x−y (PO 4 ) 3 :xTm 3+ -yDy 3+ were synthesized by the conventional solid-state reaction method. By appropriate tuning of activator content, the emission color can be adjusted around blue to white and yellow. It was discovered that the energy transfer from Tm 3+ to Dy 3+ was demonstrated to be via the intensity of Dy 3+ emission increase with the increase of Tm 3+ concentration. By changing the doping concentration of Tm 3+ and Dy 3+ in Sr 3 Y(PO 4 ) 3 , white-emitting phosphors are produced by 350 nm excitation wavelength, their corresponding color coordinates are very close to the white color chromaticity coordinates (x=0.33, y=0.33). Finally, Sr 3 Y 1−x−y (PO 4 ) 3 :xTm 3+ −yDy 3+ phosphors could be a good promising single-component white light-emitting UV-convertible phosphor in the field of white LEDs. -- Highlights: • The Sr 3 Y 1−x−y (PO 4 ) 3 :xTm 3+ −yDy 3+ phosphors were synthesized by the conventional solid-state reaction method. • The energy transfer in between Tm 3+ and Dy 3+ was observed and explained. • The phosphors can be efficiently excited by a UV light. • The Sr 3 Y 1−x−y (PO 4 ) 3 :xTm 3+ -yDy 3+ phosphor could be a better candidate white phosphor for UV W-LEDs

  16. Continuous growth of low-temperature Si epitaxial layer with heavy phosphorous and boron doping using photoepitaxy

    International Nuclear Information System (INIS)

    Yamazaki, T.; Minakata, H.; Ito, T.

    1990-01-01

    The authors grew p + -n + silicon epitaxial layers, heavily doped with phosphorus and boron, continuously at 650 degrees C using low-temperature photoepitaxy. Then N + photoepitaxial layer with a phosphorus concentration above 10 17 cm -3 grown on p - substrate shows high-density surface pits, and as a result, poor crystal quality. However, when this n + photoepitaxial layer is grown continuously on a heavily boron-doped p + photoepitaxial layer, these surface pits are drastically decreased, disappearing completely above a hole concentration of 10 19 cm -3 in the p + photoepitaxial layer. The phosphorus activation ratio and electron Hall mobility in the heavily phosphorus-doped n + photoexpitaxial layer were also greatly improved. The authors investigated the cause of the surface pitting using a scanning transmission electron microscope, secondary ion mass spectroscopy, and energy-dispersive x-ray spectroscopy. They characterized the precipitation of phosphorus atoms on the crystal surface at the initial stage of the heavily phosphorus-doped n + photoexpitaxial layer growth

  17. Photoluminescence and photostimulated luminescence in the X-ray storage phosphor BaBr2 doped with cerium

    International Nuclear Information System (INIS)

    Corradi, G.; Secu, M.; Schweizer, S.; Spaeth, J.-M.

    2004-01-01

    In orthorhombic BaBr 2 : Ce 3+ two kinds of luminescence bands at room temperature have been attributed to charge-compensated Ce 3+ centres. One type was associated with potassium (or some other monovalent cation) on a neighbouring Ba site and another one associated with an unidentified defect. A third kind of emission, observed only as low temperature photoluminescence (PL), is ascribed to isolated Ce 3+ ions. The charge-compensated Ce 3+ complexes are active both in PL and photostimulated luminescence (PSL) following X-ray irradiation. The PSL is nearly as efficient as in the case of the commercially used X-ray storage phosphor BaFBr:Eu 2+ . The X-ray induced electrons are trapped in F-type centres whose band position is characteristic for the nearby Ce complex. As shown by the fingerprint character of the PSL itself, the hole partner in the recombination is also associated or identical with the same Ce complex

  18. Synthesis of calcium-phosphorous doped TiO2 nanotubes by anodization and reverse polarization: A promising strategy for an efficient biofunctional implant surface

    International Nuclear Information System (INIS)

    Alves, Sofia A.; Patel, Sweetu B.; Sukotjo, Cortino; Mathew, Mathew T.; Filho, Paulo N.; Celis, Jean-Pierre

    2017-01-01

    Highlights: • A new surface modification methodology for bio-functionalization of TiO2 NTs is addressed • Bone-like structured TiO2 nanotubular surfaces containing Ca and P were synthesized. • Ca/P-doped TiO2 NTs enhanced adhesion and proliferation of osteoblastic-like cells. • The bio-functionalization granted improved bio-electrochemical stability to TiO2 NTs. - Abstract: The modification of surface features such as nano-morphology/topography and chemistry have been employed in the attempt to design titanium oxide surfaces able to overcome the current dental implants failures. The main goal of this study is the synthesis of bone-like structured titanium dioxide (TiO 2 ) nanotubes enriched with Calcium (Ca) and Phosphorous (P) able to enhance osteoblastic cell functions and, simultaneously, display an improved corrosion behavior. To achieve the main goal, TiO 2 nanotubes were synthetized and doped with Ca and P by means of a novel methodology which relied, firstly, on the synthesis of TiO 2 nanotubes by anodization of titanium in an organic electrolyte followed by reverse polarization and/or anodization, in an aqueous electrolyte. Results show that hydrophilic bone-like structured TiO 2 nanotubes were successfully synthesized presenting a highly ordered nano-morphology characterized by non-uniform diameters. The chemical analysis of such nanotubes confirmed the presence of CaCO 3 , Ca 3 (PO 4 ) 2 , CaHPO 4 and CaO compounds. The nanotube surfaces submitted to reverse polarization, presented an improved cell adhesion and proliferation compared to smooth titanium. Furthermore, these surfaces displayed a significantly lower passive current in artificial saliva, and so, potential to minimize their bio-degradation through corrosion processes. This study addresses a very simple and promising multidisciplinary approach bringing new insights for the development of novel methodologies to improve the outcome of osseointegrated implants.

  19. Photoluminescence properties and energy transfer in Ce(3+) /Dy(3+) co-doped Sr(3) MgSi(2) O(8) phosphors for potential application in ultraviolet white light-emitting diodes.

    Science.gov (United States)

    Yu, Hong; Zi, Wenwen; Lan, Shi; Gan, Shucai; Zou, Haifeng; Xu, Xuechun; Hong, Guangyan

    2013-01-01

    Sr(3) MgSi(2) O(8) :Ce(3+) , Dy(3+) phosphors were prepared by a solid-state reaction technique and the photoluminescence properties were investigated. The emission spectra show not only a band due to Ce(3+) ions (403 nm) but also as a band due to Dy(3+) ions (480, 575 nm) (UV light excitation). The photoluminescence properties reveal that effective energy transfer occurs in Ce(3+) /Dy(3+) co-doped Sr(3) MgSi(2) O(8)phosphors, and the co-doping of Ce(3+) could enhance the emission intensity of Dy(3+) to a certain extent by transferring its energy to Dy(3+) . The Ce(3+) /Dy(3+) energy transfer was investigated by emission/excitation spectra, and photoluminescence decay behaviors. In Sr2.94 MgSi2 O8 :0.01Ce(3+) , 0.05Dy(3+) phosphors, the fluorescence lifetime of Dy(3+) (from 3.35 to 27.59 ns) is increased whereas that of Ce(3+) is greatly decreased (from 43.59 to 13.55 ns), and this provides indirect evidence of the Ce(3+) to Dy(3+) energy transfer. The varied emitted color of Sr(3) MgSi(2) O(8):Ce(3+) , Dy(3+) phosphors from blue to white were achieved by altering the concentration ratio of Ce(3+) and Dy(3+) . These results indicate Sr(3) MgSi(2) O(8):Ce(3+) , Dy(3+) may be as a candidate phosphor for white light-emitting diodes. Copyright © 2012 John Wiley & Sons, Ltd.

  20. One-pot electrochemical growth of sponge-like polyaniline-intercalated phosphorous-doped graphene oxide on nickel foam as binder-free electrode material of supercapacitor

    Science.gov (United States)

    Bigdeli, Hadise; Moradi, Morteza; Borhani, Saeid; Jafari, Elnaz Abbasi; Hajati, Shaaker; Kiani, Mohammad Ali

    2018-06-01

    In this work, phosphor-doped graphene oxide (PGO) was synthesized by chemical technique. Also, the sponge-like PGO@polyaniline nanocomposite (PGO@PANI) film was coated on the nickel foam by one-step electropolymerization. The active materials were then characterized by Fourier transforms infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller technique. When PANI/PGO was used as supercapacitor electrode, under current density of 1 A/g, the specific capacitance of the prepared PGO@PANI was measured as 603 F/g, which is 6.0 times higher than that of pure PANI (102 F/g). Moreover, capacity stability of the PANI/PGO increased significantly as compared to PANI (65% vs. 44%) after increasing the current density from 1 to 15 A/g. The clear electrochemical performance of PANI/PGO was enhanced owing to the synergistic effect of PGO and PANI. Our results demonstrate that PANI/PGO nanosheet arrays are promising candidate for electrode supercapacitor applications.

  1. Investigation of electrolyte leaching in the performance degradation of phosphoric acid-doped polybenzimidazole membrane-based high temperature fuel cells

    Science.gov (United States)

    Jeong, Yeon Hun; Oh, Kyeongmin; Ahn, Sungha; Kim, Na Young; Byeon, Ayeong; Park, Hee-Young; Lee, So Young; Park, Hyun S.; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Ju, Hyunchul; Kim, Jin Young

    2017-09-01

    Precise monitoring of electrolyte leaching in high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) devices during lifetime tests is helpful in making a diagnosis of their quality changes and analyzing their electrochemical performance degradation. Here, we investigate electrolyte leaching in the performance degradation of phosphoric acid (PA)-doped polybenzimidazole (PBI) membrane-based HT-PEMFCs. We first perform quantitative analyses to measure PA leakage during cell operation by spectrophotometric means, and a higher PA leakage rate is detected when the current density is elevated in the cell. Second, long-term degradation tests under various current densities of the cells and electrochemical impedance spectroscopy (EIS) analysis are performed to examine the influence of PA loss on the membrane and electrodes during cell performance degradation. The combined results indicate that PA leakage affect cell performance durability, mostly due to an increase in charge transfer resistance and a decrease in the electrochemical surface area (ECSA) of the electrodes. Additionally, a three-dimensional (3-D) HT-PEMFC model is applied to a real-scale experimental cell, and is successfully validated against the polarization curves measured during various long-term experiments. The simulation results highlight that the PA loss from the cathode catalyst layer (CL) is a significant contributor to overall performance degradation.

  2. Methodology, models and algorithms in thermographic diagnostics

    CERN Document Server

    Živčák, Jozef; Madarász, Ladislav; Rudas, Imre J

    2013-01-01

    This book presents  the methodology and techniques of  thermographic applications with focus primarily on medical thermography implemented for parametrizing the diagnostics of the human body. The first part of the book describes the basics of infrared thermography, the possibilities of thermographic diagnostics and the physical nature of thermography. The second half includes tools of intelligent engineering applied for the solving of selected applications and projects. Thermographic diagnostics was applied to problematics of paraplegia and tetraplegia and carpal tunnel syndrome (CTS). The results of the research activities were created with the cooperation of the four projects within the Ministry of Education, Science, Research and Sport of the Slovak Republic entitled Digital control of complex systems with two degrees of freedom, Progressive methods of education in the area of control and modeling of complex object oriented systems on aircraft turbocompressor engines, Center for research of control of te...

  3. Metaheuristics-Assisted Combinatorial Screening of Eu2+-Doped Ca-Sr-Ba-Li-Mg-Al-Si-Ge-N Compositional Space in Search of a Narrow-Band Green Emitting Phosphor and Density Functional Theory Calculations.

    Science.gov (United States)

    Lee, Jin-Woong; Singh, Satendra Pal; Kim, Minseuk; Hong, Sung Un; Park, Woon Bae; Sohn, Kee-Sun

    2017-08-21

    A metaheuristics-based design would be of great help in relieving the enormous experimental burdens faced during the combinatorial screening of a huge, multidimensional search space, while providing the same effect as total enumeration. In order to tackle the high-throughput powder processing complications and to secure practical phosphors, metaheuristics, an elitism-reinforced nondominated sorting genetic algorithm (NSGA-II), was employed in this study. The NSGA-II iteration targeted two objective functions. The first was to search for a higher emission efficacy. The second was to search for narrow-band green color emissions. The NSGA-II iteration finally converged on BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphors in the Eu 2+ -doped Ca-Sr-Ba-Li-Mg-Al-Si-Ge-N compositional search space. The BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphor, which was synthesized with no human intervention via the assistance of NSGA-II, was a clear single phase and gave an acceptable luminescence. The BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphor as well as all other phosphors that appeared during the NSGA-II iterations were examined in detail by employing powder X-ray diffraction-based Rietveld refinement, X-ray absorption near edge structure, density functional theory calculation, and time-resolved photoluminescence. The thermodynamic stability and the band structure plausibility were confirmed, and more importantly a novel approach to the energy transfer analysis was also introduced for BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphors.

  4. Determination of Flaw Size from Thermographic Data

    Science.gov (United States)

    Winfree, William P.; Howell, Patricia A.; Zalameda, Joseph N.

    2014-01-01

    Conventional methods for reducing the pulsed thermographic responses of delaminations tend to overestimate the size of the flaw. Since the heat diffuses in the plane parallel to the surface, the resulting temperature profile over the flaw is larger than the flaw. A variational method is presented for reducing the thermographic data to produce an estimated size for the flaw that is much closer to the true size of the flaw. The size is determined from the spatial thermal response of the exterior surface above the flaw and a constraint on the length of the contour surrounding the flaw. The technique is applied to experimental data acquired on a flat bottom hole composite specimen.

  5. Prominent blue emission through Tb3+ doped La2O3 nano-phosphors for white LEDs

    Science.gov (United States)

    Jain, Neha; Singh, Rajan Kr; Srivastava, Amit; Mishra, S. K.; Singh, Jai

    2018-06-01

    In this article, we report the tunable luminescence emission of Tb3+ doped La2O3 nanophosphors synthesized by a facile and effective Polyol method. The structural and surface morphological studies have been carried out by employing X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The XRD studies elucidate the proper phase formation and the results emanate from Raman spectroscopy of the as synthesized nanophosphor affirms it. The optical properties of the as fabricated nanoparticles have been investigated by Raman and photoluminescence (PL) spectroscopy. The PL spectroscopy shows the occurrence of excitation peaks at 305, 350 and 375 nm for 543 nm emissions, correspond to transition 5D4 →7F5. Emission spectra with 305 nm excitation exhibits characteristic emission peaks of Tb3+ion at 472, 487, 543 and 580 nm. The intensity of emission increases with Tb3+ concentration and is most prominent for 7 at% Tb3+ ion. The characteristic emissions of Tb3+ ion owes to the transition in which intensities of blue and green emission are prominent. The dominant intensity has been found for 472 nm (for blue emission). Commission international d 'Eclairage (CIE) co-ordinates have found in the light blue to green region. The research work provides a new interesting insight dealing with tunable properties with Tb3+ doping in La2O3 nanophosphors, to be useful for display devices, solar cells, LEDs and optoelectronic devices.

  6. High efficiency nitride based phosphores for white LEDs

    NARCIS (Netherlands)

    Li, Yuan Qiang; Hintzen, H.T.J.M.

    2008-01-01

    In this overview paper, novel rare-earth doped silicon nitride based phosphors for white LEDs applications have been demonstrated. The luminescence properties of orange-red-emitting phosphors (M2Si5N8:Eu2+) and green-to-yellow emitting phosphors (MSi2N2O2:Eu2+, M = Ca, Sr, Ba) are discussed in

  7. Eu2+-doped Ba2GaB4O9Cl blue-emitting phosphor with high color purity for near-UV-pumped white light-emitting diodes

    Science.gov (United States)

    Gao, Zhiwen; Deng, Huajuan; Xue, Na; Jeong, Jung Hyun; Yu, Ruijin

    2018-01-01

    Eu2+-doped borate fluoride Ba2GaB4O9Cl was synthesized by the conventional high-temperature solid-state reaction. The crystal structure and luminescence properties of the phosphors, as well as their thermal luminescence quenching capabilities and CIE chromaticity coordinates were systematically investigated. Under the excitation at 340 nm, the phosphor exhibited an asymmetric broad-band blue emission with a peak at 445 nm, which is ascribed to the 4f-5d transition of Eu2+. It was further proved that energy transfer among the nearest neighbor ions is the major mechanism for concentration quenching of Eu2+ in Ba2-xGaB4O9Cl:xEu2+ phosphors. The luminescence quenching temperature is 432 K. The CIE color coordinates are very close to those of BaMgAl10O17:Eu2+ (BAM). All the properties indicated that the blue-emitting Ba2GaB4O9Cl:Eu2+ phosphor has potential application in white LEDs.

  8. Tunable emission and the systematic study on energy-transfer properties of Ce{sup 3+}- and Tb{sup 3+}-co-doped Sr{sub 3}(PO{sub 4}){sub 2} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhijun [Guangzhou Maritime Institute, Department of Shipping Engineering, Guangzhou (China)

    2015-09-15

    An emitting color tunable phosphor Sr{sub 3}(PO{sub 4}){sub 2}:Ce{sup 3+}, Tb{sup 3+} was synthesized by the traditional high-temperature solid-state reaction method. The photoluminescence and energy-transfer (ET) properties of Ce{sup 3+}- and Tb{sup 3+}-doped Sr{sub 3}(PO{sub 4}){sub 2} host were studied in detail. The obtained phosphors show both a blue emission from Ce{sup 3+} and a yellowish green emission from Tb{sup 3+} with considerable intensity under ultraviolet (UV) excitation (∝311 nm). When the content of Ce{sup 3+} was fixed at 0.03, the emission chromaticity coordinates could be adjusted from blue to green region by tuning the contents of Tb{sup 3+} ions with the aid of ET process. The critical distance between Ce{sup 3+} and Tb{sup 3+} is 14.69 A. The ET mechanism from Ce{sup 3+} to Tb{sup 3+} ions was identified with dipole-dipole interaction. The obtained phosphor exhibits a strong excitation in UV spectral region and high-efficient ET from Ce{sup 3+} to Tb{sup 3+} ions. It may find applications as a green light-emitting UV-convertible phosphor in white LED devices. (orig.)

  9. Synthesis and luminescence properties of Ce{sup 3+}-doped Y{sub 3}Al{sub 3.5}Ga{sub 1.5}O{sub 12} green phosphor for white LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Yaochun [Fujian Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Yu, Yuxi, E-mail: yu_heart@xmu.edu.cn [Fujian Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Chen, Guolong [Fujian Engineering Research Center for Solid-state Lighting, Department of Electronic Science, Xiamen University, Xiamen 361005 (China); Fang, Jiyu [Advanced Materials Processing and Analysis Center, Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32816 (United States)

    2016-04-15

    A series of Ce{sup 3+}-doped Y{sub 3}Al{sub 3.5}Ga{sub 1.5}O{sub 12} green phosphors were successfully synthesized by a solid-state reaction method. The microstructure, morphology, luminescence spectra, luminescence quantum yield (QY) and thermal stability of the phosphor were investigated. The critical concentration of Ce{sup 3+} ions in Y{sub 3−m}Al{sub 3.5}Ga{sub 1.5}O{sub 12}:mCe{sup 3+} is m=0.06. The QY of Y{sub 2.94}Al{sub 3.5}Ga{sub 1.5}O{sub 12}:0.06Ce{sup 3+} phosphor is as high as 94% under excitation at 450 nm and its luminescence intensity at 150 °C still maintains 90% of that measured at 25 °C, which are just a little worse than those of commercial Lu{sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+} green phosphor but much better than those of commercial (Sr,Ba){sub 2}SiO{sub 4}:Eu{sup 2+} green phosphor. A white LED lamp was fabricated by employing Y{sub 2.94}Al{sub 3.5}Ga{sub 1.5}O{sub 12}:0.06Ce{sup 3+} as a green phosphor and commercial (Ca,Sr)AlSiN{sub 3}:Eu{sup 2+} as a red phosphor (628 nm), its Ra value, correlated color temperature (CCT), CIE1931 chromaticity coordinates and luminous efficiency is 84, 3081 K, (x=0.4369, y=0.4142) and 102 lm/W, respectively. The experimental results demonstrate that Y{sub 2.94}Al{sub 3.5}Ga{sub 1.5}O{sub 12}:0.06Ce{sup 3+} is a promising green phosphor not only can be used for high color rendering index white LEDs but also for high-power white LEDs.

  10. Red emitting phosphors of Eu{sup 3+} doped Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y) for white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Niumiao [National Key Laboratory of Photoelectric Technology and Functional Materials Culture Base in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069 (China); Guo, Chongfeng, E-mail: guocf@nwu.edu.cn [National Key Laboratory of Photoelectric Technology and Functional Materials Culture Base in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069 (China); Yin, Luqiao; Zhang, Jianhua [Key Laboratory of Advanced Display and System Applications (Shanghai University), Ministry of Education, Shanghai 200072 (China); Wu, Mingmei, E-mail: ceswmm@mail.sysu.edu.cn [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, No. 135, Xingang Xi Road, Guangzhou 510275 (China)

    2015-06-25

    Highlights: • Layered red phosphors Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y):Eu{sup 3+} were prepared. • The synthesis parameters of phosphors were optimized. • PL and thermal stability of the samples were investigated. • LED devices were also fabricated including the present red phosphor. - Abstract: A series of Eu{sup 3+} doped Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y) red-emitting phosphors for application in ultraviolet based light emitting diodes (LEDs) were successfully synthesized by a modified sol–gel method. Their structure and luminescent properties were characterized by powder X-ray diffraction (XRD), photoluminescence excitation (PLE) and emission (PL) spectra and absorption spectra, according to these results the optimal compositions and synthesis parameters were determined. In addition, the thermal stabilities of the phosphors were investigated according to the temperature-dependent PL spectra. The red and white-LEDs (W-LEDs) comprising the Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10}:Eu{sup 3+} (Ln = Gd, Y) red emitting phosphors were fabricated with a near-ultraviolet (n-UV) chip. In comparison with Na{sub 2}Y{sub 1.4}Eu{sub 0.6}Ti{sub 3}O{sub 10}, the Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} phosphor offers higher brightness, quantum efficiency, and excellent thermal stability. W-LEDs comprising Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} showed bright white emission with a color rendering index (Ra) of 82, a color temperature of 2151 K, and Commission Internationale de I’Eclairage (CIE) color coordinates of (0.34, 0.37). The phosphor Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} is more suitable candidate for application in LEDs.

  11. Fracto- mechanoluminescence and thermoluminescence properties of orange-red emitting Eu{sup 3+} doped Ca{sub 2}Al{sub 2}SiO{sub 7} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, Geetanjali, E-mail: geetanjali.tiwari10@gmail.com [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur, C.G., 492010 (India); Brahme, Nameeta, E-mail: namitabrahme@gmail.com [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur, C.G., 492010 (India); Sharma, Ravi [Department of Physics, Govt. Arts and Commerce Girls College, Devendra Nagar, Raipur, C.G. (India); Bisen, D.P.; Sao, Sanjay K. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur, C.G., 492010 (India); Khare, Ayush [Department of Physics, National Institute of Technology, Raipur - 492 010 (India)

    2017-03-15

    The suitability of nano-structured Ca{sub 2}Al{sub 2}SiO{sub 7}:Eu{sup 3+} phosphors for thermoluminescence and mechanoluminescence dosimeter were investigated. Europium doped di-calcium di-aluminum silicate phosphor was synthesised by the combustion assisted method and annealed at 1100 °C for 4 h in reducing and oxidizing environments. The prepared Ca{sub 2}Al{sub 2}SiO{sub 7}:Eu{sup 3+} phosphor was characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDX), photoluminescence (PL) and decay characteristics. The phase structure of sintered phosphor has akermanite type which belongs to the tetragonal crystallography; this structure is a member of the melilite group and forms a layered compound. The chemical composition of the sintered Ca{sub 2}Al{sub 2}SiO{sub 7}:Eu{sup 3+} phosphor was confirmed by EDX spectra. Mechanoluminescence (ML) and thermoluminescence (TL) studies revealed that the ML and TL intensity increases with activator concentration. Optimum ML was observed for the sample having 2 mol% of Eu ions. The TL intensity of Ca{sub 2}Al{sub 2}SiO{sub 7}:Eu{sup 3+} was recorded for different exposure times of γ -irradiation and it was observed that TL intensity is maximum for γ dose of 1770 Gy. The PL spectra indicated that Ca{sub 2}Al{sub 2}SiO{sub 7}:Eu{sup 3+} could be excited effectively by near ultraviolet (NUV) light and exhibited bright orange-red emission with excellent colour stability. CIE colour coordinates of the prepared Ca{sub 2}Al{sub 2}SiO{sub 7}:Eu{sup 3+} phosphor was found suitable as orange-red light emitting phosphor with a CIE value of (x=0.6142, y=0.3849) and correlated colour temperature (CCT) is 1250 K. Therefore, it is considered to be a new promising orange-red emitting phosphor for white light emitting diode (LED) application.

  12. Effective lattice stabilization of gadolinium aluminate garnet (GdAG via Lu3+ doping and development of highly efficient (Gd,LuAG:Eu3+ red phosphors

    Directory of Open Access Journals (Sweden)

    Jinkai Li, Ji-Guang Li, Zhongjie Zhang, Xiaoli Wu, Shaohong Liu, Xiaodong Li, Xudong Sun and Yoshio Sakka

    2012-01-01

    Full Text Available The metastable garnet lattice of Gd3Al5O12 is stabilized by doping with smaller Lu3+, which then allows an effective incorporation of larger Eu3+ activators. The [(Gd1−xLux1−yEuy]3Al5O12 (x = 0.1–0.5, y = 0.01–0.09 garnet solid solutions, calcined from their precursors synthesized via carbonate coprecipitation, exhibit strong luminescence at 591 nm (the 5D0 → 7F1 magnetic dipole transition of Eu3+ upon UV excitation into the charge transfer band (CTB at ~239 nm, with CIE chromaticity coordinates of x = 0.620 and y = 0.380 (orange-red. The quenching concentration of Eu3+ was estimated at ~5 at.% (y = 0.05, and the quenching was attributed to exchange interactions. Partial replacement of Gd3+ with Lu3+ up to 50 at.% (x = 0.5 while keeping Eu3+ at the optimal content of 5 at.% does not significantly alter the peak positions of the CTB and 5D0 → 7F1 emission bands but slightly weakens both bands owing to the higher electronegativity of Lu3+. The effects of processing temperature (1000–1500 °C and Lu/Eu contents on the intensity, quantum efficiency, lifetime and asymmetry factor of luminescence were thoroughly investigated. The [(Gd0.7Lu0.30.95Eu0.05]3Al5O12 phosphor processed at 1500 °C exhibits a high internal quantum efficiency of ~83.2% under 239 nm excitation, which, in combination with the high theoretical density, favors its use as a new type of photoluminescent and scintillation material.

  13. Synthesis of calcium-phosphorous doped TiO{sub 2} nanotubes by anodization and reverse polarization: A promising strategy for an efficient biofunctional implant surface

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Sofia A., E-mail: sofiafonso@msn.com [CMEMS – Center of MicroElectroMechanical Systems, Department of Mechanical Engineering, University of Minho, 4800-058 Guimarães (Portugal); IBTN/US – American Branch of the Institute of Biomaterials, Tribocorrosion and Nanomedicine, UIC College of Dentistry, 60612 Chicago, IL (United States); Patel, Sweetu B. [IBTN/US – American Branch of the Institute of Biomaterials, Tribocorrosion and Nanomedicine, UIC College of Dentistry, 60612 Chicago, IL (United States); Department of Mechanical Engineering, Michigan Technological University, 49931 Houghton, MI (United States); Sukotjo, Cortino [IBTN/US – American Branch of the Institute of Biomaterials, Tribocorrosion and Nanomedicine, UIC College of Dentistry, 60612 Chicago, IL (United States); Departmenmt of Restorative Dentistry, University of Illinois at Chicago, 60612 Chicago, IL (United States); Mathew, Mathew T. [IBTN/US – American Branch of the Institute of Biomaterials, Tribocorrosion and Nanomedicine, UIC College of Dentistry, 60612 Chicago, IL (United States); Department of Orthopedic Surgery, Rush University Medical Center, 60612 Chicago, IL (United States); Department of Biomedical Science, UIC School of Medicine at Rockford, 61107 Rockford, IL (United States); Filho, Paulo N. [IBTN/Br – Brazilian Branch of the Institute of Biomaterials, Tribocorrosion and Nanomedicine, UNESP – Universidade Estadual Paulista, Faculdade de Ciências, 17033-360 Bauru, São Paulo (Brazil); Faculdade de Ciências, Departamento de Física, UNESP - Universidade Estadual Paulista, 17033-360 Bauru, São Paulo (Brazil); Celis, Jean-Pierre [Department of Materials Engineering, KU Leuven, 3001 Leuven (Belgium); and others

    2017-03-31

    Highlights: • A new surface modification methodology for bio-functionalization of TiO2 NTs is addressed • Bone-like structured TiO2 nanotubular surfaces containing Ca and P were synthesized. • Ca/P-doped TiO2 NTs enhanced adhesion and proliferation of osteoblastic-like cells. • The bio-functionalization granted improved bio-electrochemical stability to TiO2 NTs. - Abstract: The modification of surface features such as nano-morphology/topography and chemistry have been employed in the attempt to design titanium oxide surfaces able to overcome the current dental implants failures. The main goal of this study is the synthesis of bone-like structured titanium dioxide (TiO{sub 2}) nanotubes enriched with Calcium (Ca) and Phosphorous (P) able to enhance osteoblastic cell functions and, simultaneously, display an improved corrosion behavior. To achieve the main goal, TiO{sub 2} nanotubes were synthetized and doped with Ca and P by means of a novel methodology which relied, firstly, on the synthesis of TiO{sub 2} nanotubes by anodization of titanium in an organic electrolyte followed by reverse polarization and/or anodization, in an aqueous electrolyte. Results show that hydrophilic bone-like structured TiO{sub 2} nanotubes were successfully synthesized presenting a highly ordered nano-morphology characterized by non-uniform diameters. The chemical analysis of such nanotubes confirmed the presence of CaCO{sub 3}, Ca{sub 3}(PO{sub 4}){sub 2}, CaHPO{sub 4} and CaO compounds. The nanotube surfaces submitted to reverse polarization, presented an improved cell adhesion and proliferation compared to smooth titanium. Furthermore, these surfaces displayed a significantly lower passive current in artificial saliva, and so, potential to minimize their bio-degradation through corrosion processes. This study addresses a very simple and promising multidisciplinary approach bringing new insights for the development of novel methodologies to improve the outcome of osseointegrated

  14. Role of Gd{sup 3+} ion on downshifting and upconversion emission properties of Pr{sup 3+}, Yb{sup 3+} co-doped YNbO{sub 4} phosphor and sensitization effect of Bi{sup 3+} ion

    Energy Technology Data Exchange (ETDEWEB)

    Dwivedi, A.; Rai, S. B., E-mail: sbrai49@yahoo.co.in [Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Mishra, Kavita [Department of Physics, University of Lucknow, Lucknow 226007 (India)

    2016-07-28

    Dual-mode luminescence (downshifting-DS and upconversion-UC) properties of Pr{sup 3+}/Yb{sup 3+} co-doped Y{sub 1−x}Gd{sub x}NbO{sub 4} (x = 0.0, 0.5, and 1.0) phosphors synthesized by solid state reaction technique have been explored with and without Gd{sup 3+} ion. The structural characterizations (XRD, SEM, and FTIR) confirm the pure phase of YNbO{sub 4} phosphor. Further, with the Gd{sup 3+} ion co-doping, the YNbO{sub 4} phosphors having a random shape and the large particle size are found to be transformed into nearly spherical shape particles with the reduced particle size. The optical band gaps (E{sub g}) of Y{sub 1−x}Gd{sub x}NbO{sub 4} (x = 0.00, 0.25, 0.50, and 1.00) calculated from UV-Vis-NIR measurements are ∼3.69, 4.00, 4.38, and 4.44 eV, respectively. Moreover, YNbO{sub 4} phosphor is a promising blue emitting material, whereas Y{sub 1−x−y−z}Pr{sub y}Yb{sub z}Gd{sub x}NbO{sub 4} phosphor gives intense green, blue, and red emissions via dual-mode optical processes. The broad blue emission arises due to (NbO{sub 4}){sup 3−} group of the host with λ{sub ex} = 264 nm, whereas Pr{sup 3+} doped YNbO{sub 4} phosphor gives dominant red and blue emissions along with comparatively weak green emission on excitation with λ{sub ex} = 300 nm and 491 nm. The concentration dependent variation in emission intensity at 491 nm ({sup 3}P{sub 0}→{sup 3}H{sub 4} transition) and 612 nm ({sup 1}D{sub 2}→{sup 3}H{sub 4} transition); at 612 nm ({sup 1}D{sub 2}→{sup 3}H{sub 4} transition) and 658 nm ({sup 3}P{sub 0}→{sup 3}F{sub 2} transition) of Pr{sup 3+} ion in YNbO{sub 4} phosphor with λ{sub ex} = 300 nm and 491 nm excitations, respectively, has been thoroughly explored and explained by the cross-relaxation process through different channels. The sensitization effect of Bi{sup 3+} ion co-doping on DS properties of the phosphor has also been studied. The observed DS results have been optimized by varying the

  15. A facile one-pot hydrothermal method to prepare europium-doped titania hollow phosphors and their sensitized luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Feng Xuan; Yang Ling; Zhang Nianchun [Department of Chemistry and Institute of Nanochemistry, Jinan University, 601 Western Huangpu Road, Guangzhou 510632 (China); Liu Yingliang, E-mail: tliuyl@jnu.edu.c [Department of Chemistry and Institute of Nanochemistry, Jinan University, 601 Western Huangpu Road, Guangzhou 510632 (China)

    2010-09-17

    Research highlights: {yields} The strongest emission intensity was observed with TiO{sub 2}:Eu{sub 0.2} hollow spheres and TiO{sub 2}:Eu{sub 0.2} hollow spheres calcining at 550 {sup o}C. Moreover, the strongest excitation of TiO{sub 2}:Eu{sub 0.2} hollow spheres transferred from 400 to 500 {sup o}C and the effective nonradiative energy transfer from the TiO{sub 2} hollow spheres host matrix to Eu{sup 3+} ions crystal field states was realized due to changes of crystalline field in the environment around Eu{sup 3+} ions occupying Ti{sup 4+} sites. The proposed energy transfer mechanism was that UV light is absorbed in the band of TiO{sub 2} hollow spheres crystal and then the energy is relaxed to the defect states of TiO{sub 2} host. The energy can transfer to the crystal states of Eu{sup 3+} ions ({sup 7}F{sub j}, j = 0, 1, 2, 3 and 4), which results in efficient photoluminescence. The fluorescent intensity of TiO{sub 2}:Eu{sub 0.2} hollow spheres was 2.2 times as strong as that of TiO{sub 2}:Eu{sub 0.2} bulk material. - Abstract: Monodisperse europium-activated titania hollow phosphors had been synthesized by a facile one-pot hydrothermal method using carbon spheres as hard templates. Samples were characterized by X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive spectrometer and photoluminescence spectrum. The strongest emission intensity was observed with TiO{sub 2}:Eu{sub 0.2} hollow spheres and TiO{sub 2}:Eu{sub 0.2} hollow spheres calcining at 550 {sup o}C. Moreover, the strongest excitation of TiO{sub 2}:Eu{sub 0.2} hollow spheres transferred from 400 to 500 {sup o}C and the effective nonradiative energy transfer from the TiO{sub 2} hollow spheres host matrix to Eu{sup 3+} ions crystal field states was realized due to changes of crystalline field in the environment around Eu{sup 3+} ions occupying Ti{sup 4+} sites. The proposed energy transfer mechanism was that UV light is absorbed in the band

  16. Tailored white light emission in Eu3+/Dy3+ doped tellurite glass phosphors containing Al3+ ions

    Science.gov (United States)

    Walas, Michalina; Piotrowski, Patryk; Lewandowski, Tomasz; Synak, Anna; Łapiński, Marcin; Sadowski, Wojciech; Kościelska, Barbara

    2018-05-01

    Tellurite glass systems modified by addition of aluminum fluoride AlF3 have been successfully synthesized as host matrices for optically active rare earth ions RE3+ (RE3+ = Eu3+, Dy3+). Samples with different Eu3+ to Dy3+ molar ratio have been studied in order to determine possibility of white light emission via UV excitation. Structural investigations confirmed amorphous character of materials whereas spectroscopic studies brought more insight into glass network's nature. FTIR results shown presence of two features related to tellurite glass matrix (in 490-935 cm-1 spectral region) and another one (940-1250 cm-1) due to aluminum addition. Especially, Al-O and Te-O-Al bonds of AlO4 tetrahedrons have been found. AlO4 units are considered as glass formers that improve network's strength and thermal resistivity against devitrification. Based on XPS studies of Al3+ photoelectron band the existence of Al-O and also Al-F bonds have been examined. Moreover, signals originating from Eu3+ and Dy3+ have been found confirming their valence state. Luminescence results revealed possibility of simultaneous UV excitation of Eu3+ and Dy3+ ions. Excitation with λexc = 390 and 393 nm resulted in white light generation starting from warm white to neutral and cool white depending on Eu3+ concentration and used excitation wavelength. Additionally, increase of decay lifetime of Eu3+ induced by Al3+ presence have been revealed based on luminescence decay analysis. Thus, tellurite glass systems modified by AlF3 and doped with Eu3+/Dy3+ may be considered as promising candidates for white light emitting sources.

  17. Color-tunable and luminescence properties of phosphors of Ce{sup 3+} and Tb{sup 3+} co-doped La{sub 5}Si{sub 3}O{sub 12}N for UV w-LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Junru; Chen, Jian; Liu, Yangai, E-mail: liuyang@cugb.edu.cn

    2016-02-15

    A series of Ce{sup 3+}, Tb{sup 3+} and Ce{sup 3+}/Tb{sup 3+} co-doped in La{sub 5}Si{sub 3}O{sub 12}N phosphors were synthesized by conventional high temperature solid state reaction method. With the increase of Tb{sup 3+}, the green emission was realized in (La{sub 0.94−y}Ce{sub 0.06}Tb{sub y}){sub 5}Si{sub 3}O{sub 12}N phosphors on the basis of the efficient energy transfer from Ce{sup 3+} to Tb{sup 3+} with an efficiency (η{sub T}) over 58.72%. The room temperature PL decay curves of the Ce{sup 3+} ions in (La{sub 0.94−y}Ce{sub 0.06}Tb{sub y}){sub 5}Si{sub 3}O{sub 12}N phosphors monitored at 460 nm with an excitation at 365 nm indicated that the energy transfer process between Ce{sup 3+} and Tb{sup 3+} indeed took place. The CIE chromaticity diagrams for (La{sub 0.94−y}Ce{sub 0.06}Tb{sub y}){sub 5}Si{sub 3}O{sub 12}N phosphors were also observed, which shows the color tuned from blue to blue-greenish to green with the increase of Tb{sup 3+} concentration from 0.01 to 0.08. These results demonstrated that Tb{sup 3+} ion with low 4f–4f absorption efficiency in near UV region can play the role of an activator in narrow green-emitting phosphor through efficient energy feeding by allowing 4f–5d absorption of Ce{sup 3+} with high oscillator strength. All the results indicated that the Ce{sup 3+} and Tb{sup 3+} activated La{sub 5}Si{sub 3}O{sub 12}N phosphor may be good candidates for blue-green components in n-UV white LEDs. - Highlights: • A series of Ce{sup 3+}, Tb{sup 3+} and Ce{sup 3+}/Tb{sup 3+} co-doped in La{sub 5}Si{sub 3}O{sub 12}N phosphors were synthesized by high temperature solid state reaction method. • The green emission was realized in (La{sub 0.94−y}Ce{sub 0.06}Tb{sub y})Si{sub 3}O{sub 12}N phosphors on the basis of the highly efficient energy transfer. • The Ce{sup 3+} and Tb{sup 3+} activated La{sub 5}Si{sub 3}O{sub 12}N phosphor may be good candidates for blue-green components in n-UV white LEDs.

  18. Radionuclide and thermographic diagnosis of head and neck tumors

    Energy Technology Data Exchange (ETDEWEB)

    Bogdasarov, Yu.B.; Lenskaya, O.P.; Polyakov, B.I.; Belkina, B.M. (Akademiya Meditsinskikh Nauk SSSR, Moscow. Onkologicheskij Nauchnyj Tsentr)

    1983-10-01

    Radionuclide and thermographic studies using /sup 67/Ga-citrate and /sup 111/In-bleomycin were performed in 129 patients with laryngeal cancer, chemodectoma of the neck, retinoblastoma, rhabdomyosarcoma of the orbital and facial soft tissues and cancer of the tongue. Elevated amounts of the radiopharmaceuticals were found in patients with tumors. In thermographic studies higher temperature activity corresponding to the tumor was noted. Radio-nuclide thermographic studies extend diagnostic opportunities for head and neck tumors.

  19. Radionuclide and thermographic diagnosis of head and neck tumors

    International Nuclear Information System (INIS)

    Bogdasarov, Yu.B.; Lenskaya, O.P.; Polyakov, B.I.; Belkina, B.M.

    1983-01-01

    Radionuclide and thermographic studies using 67 Ga-citrate and 111 In-bleomycin were performed in 129 patients with laryngeal cancer, chemodectoma of the neck, retinoblastoma, rhabdomyosarcoma of the orbital and facial soft tissues and cancer of the tongue. Elevated amounts of the radiopharmaceuticals were found in patients with tumors. In thermographic studies higher temperature activity corresponding to the tumor was noted. Radio-nuclide thermographic studies extend diagnostic opportunities for head and neck tumors

  20. Color tunable emission in Ce3+ and Tb3+ co-doped Ba2Ln(BO3)2Cl (Ln=Gd and Y) phosphors for white light-emitting diodes.

    Science.gov (United States)

    Zhang, Niumiao; Guo, Chongfeng; Jing, Heng; Jeong, Jung Hyun

    2013-12-01

    Ce(3+) and Tb(3+) co-doped Ba2Ln(BO3)2Cl (Ln=Y and Gd) green emitting phosphors were prepared by solid state reaction in reductive atmosphere. The emission and excitation spectra as well as luminescence decays were investigated, showing the occurrence of efficient energy transfer from Ce(3+) to Tb(3+) in this system. The phosphors exhibit both a blue emission from Ce(3+) and a green emission from Tb(3+) under near ultraviolet light excitation with 325-375 nm wavelength. Emission colors of phosphors could be tuned from deep blue through cyan to green by adjusting the Tb(3+) concentrations. The energy transfer efficiency and emission intensity of Ba2Y(BO3)2Cl:Ce(3+), Tb(3+) precede those of Ba2Gd(BO3)2Cl:Ce(3+), Tb(3+), and the sample Ba2Y(BO3)2Cl:0.03Ce(3+), 0.10Tb(3+) is the best candidate for n-UV LEDs. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Enhancement of photoluminescence properties and modification of crystal structures of Si3N4 doping Li2Sr0.995SiO4:0.005Eu2+ phosphors

    International Nuclear Information System (INIS)

    Song, Kaixin; Zhang, Fangfang; Chen, Daqin; Wu, Song; Zheng, Peng; Huang, Qingming; Jiang, Jun; Xu, Junming; Qin, Huibin

    2015-01-01

    Highlights: • Si 3 N 4 modified Li 2 Sr 0.995 SiO 4 :0.005Eu 2+ phosphors were prepared. • The luminescence intensity of Li 2 Sr 0.995 SiO 4 :Eu 2+ was enhanced by doping Si 3 N 4 . • The fluorescence decay times and thermal stability were enhanced by doping Si 3 N 4 . - Abstract: Si 3 N 4 modified Li 2 Sr 0.995 SiO 4 :0.005Eu 2+ (Li 2 Sr 0.995 SiO 4−3x/2 N x :0.005Eu 2+ ) phosphors were synthesized with the conventional solid-state reaction in the reduced atmosphere. The crystal structure and vibrational modes were analyzed by X-ray diffraction, Raman scattering spectroscopy and Rietveld crystal structure refinement. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra showed that Li 2 Sr 0.995 SiO 4−3x/2 N x :0.005Eu 2+ powder exhibited a broad yellow emission band centered at 560 nm under the excitation of 460 nm visible light, due to the 4f 6 5d 1 → 4f 7 transition of Eu 2+ . The partial nitridation of Li 2 Sr 0.995 SiO 4−3x/2 N x :0.005Eu 2+ (x = 0.01) phosphors led to a large enhancement in the luminescence intensity, as much as 190%. At the same time, the fluorescence decay behavior curves further showed that the photoluminescence efficiencies of Li 2 Sr 0.995 SiO 4−3x/2 N x :0.005Eu 2+ phosphors were enhanced by addition of Si 3 N 4 . The temperature quenching characteristics confirmed that the oxynitride based Li 2 Sr 0.995 SiO 4−3x/2 N x :0.005Eu 2+ showed slightly higher stability. It is implied that Li 2 Sr 0.995 SiO 4−3x/2 N x :0.005Eu 2+ phosphors had a possible potential application on white LEDs to match blue light chips

  2. Electron-beam-pumped phosphors

    International Nuclear Information System (INIS)

    Goldhar, J.; Krupke, W.F.

    1985-01-01

    Electron-beam excitation of solid-state scintillators, or phosphors, can result in efficient generation of visible light confined to relatively narrow regions of the spectrum. The conversion efficiency can exceed 20%, and, with proper choice of phosphors, radiation can be obtained anywhere from the near infrared (IR) to the near ultraviolet (UV). These properties qualify the phosphors as a potentially useful pump source for new solid-state lasers. New phosphors are being developed for high-brightness television tubes that are capable of higher power dissipation. Here, an epitaxial film of fluorescing material is grown on a crystalline substrate with good thermal properties. For example, researchers at North American Philips Laboratories have developed a cerium-doped yttrium aluminum garnet (YAG) grown on a YAG substrate, which has operated at 1 A/cm 2 at 20 kV without observed thermal quenching. The input power is higher by almost two orders of magnitude than that which can be tolerated by a conventional television phosphor. The authors describe tests of these new phosphors

  3. Implementation of thermographers' certification in Brazil

    Science.gov (United States)

    dos Santos, Laerte; Alves, Luiz M.; da Costa Bortoni, Edson

    2011-05-01

    In recent years Brazil has experienced extraordinary growth despite the recent economic global crisis. The demand for infrared thermography products and services has accompanied this growth. Like other non-destructive testing and inspection, the results obtained by thermography are highly dependent on the skills of thermographer. Therefore, it is very important to establish a serious and recognized process of certification to assess thermographers' qualifications and help services suppliers to establish credibility with their customers and increase the confidence of these costumers on the quality of these services. The Brazilian Society of Non-Destructive Testing and Inspection, ABENDI, a non-profitable, private technical-scientific entity, recognized nationally and internationally, has observed the necessity of starting a process for certification of thermographers in Brazil. With support of a work group composed by experts from oil and energy industries, transportation, universities and manufactures, the activities started in 2005. This paper describes the economic background required for installation of the certification process, its initial steps, the main characteristics of the Brazilian certification and the expectation for initiating the certification process.

  4. The effect of doping Mg2+ on structure and properties of Sr(1.992-x)MgxSiO4: 0.008Eu2+ blue phosphor synthesized by co-precipitation method

    Science.gov (United States)

    Yang, Lingxiang; Wang, Jin-shan; Zhu, Da-chuan; Pu, Yong; Zhao, Cong; Han, Tao

    2018-01-01

    In order to improve the luminescence property of silicate phosphors, a series of Sr(1.992-x)MgxSiO4: 0.008Eu2+(x = 0, 0.25, 0.50, 0.75) blue phosphors have been synthesized using one-step calcination of a precursor prepared by chemical co-precipitation. And then the crystal structure and luminescence properties of the phosphors are investigated by means of X-Ray Diffraction and spectrophotometer. The results show that β-phase existed in the mixed phases of Sr2SiO4 (β+α‧) would transform to α‧-phase with Mg2+ ions doping into the silicate host until it disappeared. On the other hand, the introduction of Mg2+ ions can enhance the intensity of the excitation spectrum and promote the excitation sensitivity of Sr(1.992-x)MgxSiO4: 0.008Eu2+ phosphors in NUV region. Under NUV excitation at 350 nm, all samples exhibit a broadband emission in range of 400-550 nm due to the 4f65d1→4f7(8S7/2) transition of Eu2+ ions. According to Multi-peak fitting to emission spectra by Gauss method, the broad emission band consists of two single bands with peaks Em1 and Em2 locating at 460 and 490 nm, which corresponds to Eu2+ ions occupying the ten-fold oxygen-coordinated Sr1 site and the nine-fold oxygen-coordinated Sr2 site, respectively. The luminescence intensity of Sr(1.992-x)MgxSiO4:0.008Eu2+(x = 0, 0.25, 0.50, 0.75) blue phosphors has been enhanced remarkably after Mg2+ ions are added. Meanwhile, the chromaticity coordinates change from the blue-green region to the blue region as x moves from 0 to 0.75. Moreover, the decay curves are measured and can be well fitted with double exponential decay equation. It shows that the average lifetime is extended with the concentration of Mg2+ ions increasing. These results indicate that Sr(1.992-x)MgxSiO4: 0.008Eu2+(x = 0, 0.25, 0.50, 0.75) can be used as a potential blue phosphor in near UV-excited white LEDs.

  5. Long-wave UVA radiation excited warm white-light emitting NaGdTiO{sub 4}: Tm{sup 3+}/Dy{sup 3+}/Eu{sup 3+} ions tri-doped phosphors: Synthesis, energy transfer and color tunable properties

    Energy Technology Data Exchange (ETDEWEB)

    Bharat, L. Krishna; Du, Peng; Yu, Jae Su, E-mail: jsyu@khu.ac.kr

    2016-05-05

    NaGdTiO{sub 4} (NGT) phosphors doped with different activator ions (Tm{sup 3+}, Dy{sup 3+}, and Eu{sup 3+}) were synthesized by a conventional solid-state reaction method in an ambient atmosphere. These phosphors were characterized by scanning electron microscope images, transmission electron microscope images, X-ray diffraction patterns, Fourier transform infrared spectra, and photoluminescence spectra. All the samples were crystallized in an orthorhombic phase with a space group of Pbcm (57). In Tm{sup 3+}/Dy{sup 3+} ions co-doped samples, white-light emission was observed under near-ultraviolet (NUV) excitation. In addition, the energy transfer between Tm{sup 3+} and Dy{sup 3+} ions was proved to be a resonant type via an electric dipole–dipole mechanism and the critical distance of energy transfer was calculated to be 19.91 Å. Furthermore, Tm{sup 3+}/Dy{sup 3+}/Eu{sup 3+} ions tri-doped NGT phosphors demonstrated warm white-light emission by appropriately tuning the activator content, based on the principle of energy transfer. These NUV wavelength excitable phosphors exhibit great potential as a single-phase full-color emitting phosphor for white light-emitting diode applications. - Highlights: • The pebble shaped NaGdTiO{sub 4} particles were prepared by solid-state reaction method. • Tm{sup 3+} and Dy{sup 3+} single doping gives respective blue and cool white light emission. • The Tm{sup 3+}/Dy{sup 3+} ions co-doped samples give CIE values near to standard white light. • Addition of Eu{sup 3+} ions shifts the CIE values towards warm white light region. • This single phase white light emitting phosphors have lower CCT values (<5000 K).

  6. Structure, luminescence and thermal quenching properties of Eu doped Sr{sub 2−x}Ba{sub x}Si{sub 5}N{sub 8} red phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y.H.; Chen, L.; Zhou, X.F.; Liu, R.H., E-mail: griremlrh@126.com; Zhuang, W.D.

    2017-02-15

    Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were synthesized at 1610 ℃ for 4 h via the solid-state reaction method. The XRD results confirm that the complete solid solutions are formed. With the increase of x, the emission spectra show an obvious blue-shift from 610 nm to 585 nm under the excitation of 460 nm. The color tone can be tuned from yellow to red. The corresponding mechanism for the blue-shift of peak-wavelength is studied in detail. The results of decomposed Gaussian spectra and fluorescence lifetime show that the local coordination structure surrounding activator ions changes with increasing x value. It is found that the probability of Eu occupying Sr1 and Sr2 site is dependent on Ba/Sr ratio. The variation of thermal quenching properties and the corresponding mechanism is discussed in detail. The results indicate that Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} is a promising orange red-emitting phosphor for near UV or blue light-pumped white light-emitting-diodes (wLEDs). - Graphical abstract: Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} solid solutions were prepared by the solid-state reaction method. The structure, luminescence and thermal quenching properties with varying Ba/Sr ratio were investigated in detail. - Highlights: • The stucture and luminescence properties of Eu doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were investigated. • The samples with the intermediate compositions(x=1.0,1.5) show better stability than the end members of both Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} and Ba{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}. • The possible mechanism for the improvement of thermal quenching properties was proposed.

  7. Infrared emissions in MgSrAl{sub 10}O{sub 17}:Er{sup 3+} phosphor co-doped with Yb{sup 3+}/Ba{sup 2+}/Ca{sup 2+} obtained by solution combustion route

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Vijay, E-mail: vijayjiin2006@yahoo.com [Physical Chemistry, Institute for Pure and Applied Chemistry and Center of Interface Science, University of Oldenburg, 26129 Oldenburg (Germany); Kumar Rai, Vineet [Department of Applied Physics, Indian School of Mines, Dhanbad 826 004 (India); Venkatramu, V. [Department of Physics, Yogi Vemana University, Kadapa 516 003 (India); Chakradhar, R.P.S. [CSIR-National Aerospace, Bangalore 560 017 (India); Hwan Kim, Sang [Department of Chemical Engineering, Konkuk University, Seoul 143-701 (Korea, Republic of)

    2013-02-15

    An intense infrared emitting MgSrAl{sub 10}O{sub 17}:Er{sup 3+} phosphor co-doped with Yb{sup 3+}, Ba{sup 2+} and Ca{sup 2+} ions have been prepared by a solution combustion method. Phase purity of the derived compounds was confirmed by X-ray diffraction technique. The vibrational properties of MgSrAl{sub 10}O{sub 17} phosphor was studied by Fourier transform infrared spectroscopy. The broad and strong infrared emission of Er{sup 3+} ions at around 1.53 {mu}m was observed upon excitation at 980 nm. Effect of co-doping with the Yb{sup 3+}{sub ,} Ba{sup 2+} and Ca{sup 2+} ions on the infrared luminescence intensity of Er{sup 3+} ions and the mechanism responsible for the variation in the infrared intensity have been discussed. The results indicate that these materials may be suitable for the optical telecommunication window and wavelength division multiplexing applications. - Highlights: Black-Right-Pointing-Pointer The hexagonal phase of MgSrAl{sub 10}O{sub 17} could be obtained by the low temperature combustion method. Black-Right-Pointing-Pointer The broad and strong infrared emission of Er{sup 3+} ions at around 1.53 {mu}m was observed. Black-Right-Pointing-Pointer Effect of co-doping with the Yb{sup 3+}{sub ,} Ba{sup 2+} and Ca{sup 2+} ions on the infrared luminescence intensity of Er{sup 3+} were reported.

  8. Investigation of Upconversion, downshifting and quantum –cutting behavior of Eu3+, Yb3+, Bi3+ co-doped LaNbO4 phosphor as a spectral conversion material

    Science.gov (United States)

    Dwivedi, A.; Mishra, K.; Rai, S. B.

    2018-06-01

    This work presents the spectral conversion characteristics [upconversion (UC), downshifting (DS) and quantum–cutting (QC) optical processes] of Eu3+, Yb3+ and Bi3+ co-doped LaNbO4 (LBO) phosphor samples synthesized by solid state reaction technique. The crystal structure and the pure phase formation have been confirmed by x-ray diffraction (XRD) measurements. The surface morphology and particle size are studied by scanning electron microscopy (SEM). The rarely observed intense red UC emission from Eu3+ ion has been successfully obtained in Eu3+/Yb3+ co-doped LaNbO4 phosphor (on excitation with 980 nm) by optimizing the concentrations of Eu3+ and Yb3+ ions. The downshifting (DS) behavior has been studied by photoluminescence (PL) measurements on excitation with 265 nm wavelength from a Xe lamp source. A broad blue emission in the region 300–550 nm with its maximum ∼415 nm due to charge transfer band (CTB) of the host and large number of sharp peaks due to f-f transitions of Eu3+ ion have been observed. The energy transfer has been observed from (NbO4)3‑ to Eu3+ ion and the fluorescence emission has been optimized by varying the concentration of Eu3+ ion. An intense red emission has also been observed corresponding to 5D0 → 7F2 transition of Eu3+ ion at 611 nm in LBO: 0.09Eu3+ phosphor on excitation with 394 nm. The luminescence properties of Eu3+ ion are enhanced further through the sensitization effect of Bi3+ ion. The near infra-red (NIR) quantum cutting (QC) behavior due to Yb3+ ion has been monitored on excitation with 265 as well as 394 nm. The NIR QC is observed due to 2F5/2 → 2F7/2 transition of Yb3+ ion via co-operative energy transfer (CET) process from (NbO4)3‑ as well as Eu3+ ions to Yb3+ ion. This multimodal behavior (UC, DS and QC) makes this a promising phosphor material for multi-purpose spectral converter.

  9. Luminescence properties of cerium-doped di-strontium magnesium di-silicate phosphor by the solid-state reaction method

    Science.gov (United States)

    Prasad Sahu, Ishwar

    2016-05-01

    A series of Sr2MgSi2O7:xCe3+ (x = 1.0%, 2.0%, 3.0%, 4.0% and 5.0%) phosphors were synthesized by the solid-state reaction method. The phosphor with optimum thermoluminescence, photoluminescence and mechanoluminescence (ML) intensity was characterized by X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared techniques. The trapping parameters (i.e. activation energy, frequency factor and order of the kinetics) of each synthesized phosphor have been calculated using the peak shape method and the results have been discussed. Under ultraviolet excitation (325 nm), Sr2MgSi2O7:xCe3+ phosphors were composed of a broad band peaking at 385 nm, belonging to the broad emission band which emits violet-blue color. Commission International de I'Eclairage coordinates have been calculated for each sample and their overall emission is near violet-blue light. In order to investigate the suitability of the samples for industrial uses, color purity and color rendering index were calculated. An ML intensity of optimum [Sr2MgSi2O7:Ce3+ (3.0%)] phosphor increases linearly with increasing impact velocity of the moving piston which suggests that these phosphors can be used as fracto-ML-based devices. The time of the peak ML intensity and the decay rate did not change significantly with respect to increasing impact velocity of the moving piston.

  10. Formation of Deep Electron Trap by Yb3+ Codoping Leads into Super-Long Persistent Luminescence in Ce3+-doped Yttrium Aluminum Gallium Garnet Phosphors.

    Science.gov (United States)

    Ueda, Jumpei; Miyano, Shun; Tanabe, Setsuhisa

    2018-05-23

    The Y 3 Al 2 Ga 3 O 12 :Ce 3+ -Cr 3+ compound is one of the brightest persistent phosphors, but its persistent luminescence (PersL) duration is not so long due to the relatively shallow Cr 3+ electron trap. Comparing the vacuum referred binding energy of the electron trapping state by Cr 3+ and those by lanthanide ions, we selected Yb 3+ as a deeper electron trapping center. The Y 3 Al 2 Ga 3 O 12 :Ce 3+ -Yb 3+ phosphors show Ce 3+ :5d→4f green persistent luminescence after ceasing blue light excitation. The formation of Yb 2+ was confirmed by the increased intensity of absorption at 585 nm during the charging process. This result indicates that the Yb 3+ ions act as electron traps by capturing an electron. From the thermoluminescence glow curves, it was found the Yb 3+ trap makes much deeper electron trap with 1.01 eV depth than the Cr 3+ electron trap with 0.81 eV depth. This deeper Yb 3+ trap provides much slower detrapping rate of filled electron traps than the Cr 3+ -codoped persistent phosphor. In addition, by preparing transparent ceramics and optimizing Ce 3+ and Yb 3+ concentrations, the Y 3 Al 2 Ga 3 O 12 :Ce 3+ (0.2%)-Yb 3+ (0.1%) as-made transparent ceramic phosphor showed super long persistent luminescence for over 138.8 hours after ceasing blue light charging.

  11. Structural and optical properties of Vernier phase lutetium oxyfluorides doped with lanthanide ions: interesting candidates as scintillators and X-Ray phosphors

    Czech Academy of Sciences Publication Activity Database

    Passuello, T.; Piccinelli, M.; Trevisani, M.; Giarola, M.; Mariotto, G.; Marciniak, L.; Hreniak, D.; Guzik, M.; Fasoli, M.; Vedda, A.; Jarý, Vítězslav; Nikl, Martin; Causin, V.; Bettinelli, M.; Speghini, A.

    2012-01-01

    Roč. 22, č. 21 (2012), s. 10639-10649 ISSN 0959-9428 R&D Projects: GA AV ČR KAN300100802 Institutional research plan: CEZ:AV0Z10100521 Keywords : oxyfluoride * luminescence * scintillator * phosphor * Eu3+ * Ce3+ * Pr3+ Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.968, year: 2011

  12. Co-precipitation synthesis and luminescence behavior of Ce-doped yttrium aluminum garnet (YAG:Ce) phosphor: The effect of precipitant

    International Nuclear Information System (INIS)

    Zhang Kai; Liu Hezhou; Wu Yating; Hu Wenbin

    2008-01-01

    YAG:Ce precursors were co-precipitated using ammonia water and ammonium hydrogen carbonate as precipitants, respectively. Phase transition of the precursors during sintering was compared between the two precipitants. The precursors synthesized with ammonia water transformed to YAG at about 1000 deg. C via YAlO 3 phase. The precursors synthesized with ammonium hydrogen carbonate directly converted to pure YAG at about 900 deg. C. Comparing the powders produced with the two precipitants, the powders produced with ammonia hydrogen carbonate showed good dispersity. When sintered at 1600 deg. C, aggregation of the powders synthesized with the two precipitants both became severe. With increase the sintering temperature, the maximum wavelength of excitation and emission spectra of the phosphors synthesized with ammonium water hardly varied. While the maximum wavelength of excitation spectra of the phosphors synthesized with ammonium hydrogen carbonate unchanged, and the emission spectra showed red shift. Because of size effect and higher loss of cerium content, the emission intensity of phosphors prepared with ammonium hydrogen carbonate was lower than the phosphors prepared with ammonium water, when sintered at the same temperature

  13. Oxidizer in phosphoric reactors

    International Nuclear Information System (INIS)

    Santos Benedetto, J. dos

    1985-01-01

    Oxidation during the manufacture of wet-process phosphoric acid affected the distribution of uranium and impurities between phosphoric acid and gypsum, by decreasing the uranium loss to gypsum and the impurities solubilization in phosphoric acid. (Author) [pt

  14. Enhancement of CdSiO3: Tb3+ green long-lasting phosphors by co-doping with Re3+ (Re3+=Gd3+, Y3+, La3+) ions

    International Nuclear Information System (INIS)

    Zeng, Wei; Wang, Yuhua; Han, Shaochun; Chen, Wenbo; Li, Gen

    2014-01-01

    CdSiO 3 : Tb 3+ , Re 3+ long-lasting phosphors were synthesized by the conventional high temperature solid-state method. A green-light phosphorescence phenomenon, which was associated with the 5 D 4 → 7 F J (J=6, 5, 4, 3) transitions of the Tb 3+ ion, was observed. Introduction of Re 3+ (Re 3+ =Gd 3+ , Y 3+ , La 3+ ) ions, which deepens the depth (E t ) or/and increases the density (n 0 ) of traps, greatly improved the afterglow properties of CdSiO 3 : Tb 3+ . Possible mechanism of CdSiO 3 : Tb 3+ , Re 3+ was discussed in this work. - Highlights: • CdSiO 3 : Tb 3+ , Re 3+ samples enrich the color of long-lasting afterglow phosphors in CdSiO 3 host. • Both the afterglow intensity and the lasting time are greatly enhanced for the co-doped samples, especially for Cd 0.96 SiO 3 : Tb 0.03 3+ , La 0.01 3+ . • Introduction of Re 3+ (Re 3+ =Gd 3+ , Y 3+ , La 3+ ) ions, which deepens the depth (E t ) or increase density(n 0 ) of traps, greatly improved the afterglow properties of CdSiO 3 : Tb 3+

  15. Quantitative analysis of UV excitation bands for red emissions in Pr3+-doped CaTiO3, SrTiO3 and BaTiO3 phosphors by peak fitting

    International Nuclear Information System (INIS)

    Fujiwara, Rei; Sano, Hiroyuki; Shimizu, Mikio; Kuwabara, Makoto

    2009-01-01

    A quantitative spectral analysis of the ultraviolet (UV) broad excitation bands, which are located in the range 300-400 nm, for red emissions at around 610 nm in Pr-doped CaTiO 3 , SrTiO 3 :Al and BaTiO 3 :Mg phosphors has been carried out using a peak fitting technique. The obtained results demonstrate that the UV broad band of CaTiO 3 :Pr consists of four primary excitation bands centered around 330, 335, 365 and 380 nm and those of both SrTiO 3 :Al and BaTiO 3 :Mg consist of three primary bands centered around 310, 345 and 370 nm. Based on the behavior patterns and the values of the respective primary excitation bands' parameters, i.e. center gravity (λ top ), maximum height (I max ) and full-width at half-maximum (FWHM), the UV-to-red relaxation processes in these titanate phosphors can be explained to be essentially the same, except for the existence of an additional relaxation pathway via electron-trap states in CaTiO 3 :Pr, which gives a characteristic shape of its UV excitation spectrum in the wavelength range of >360 nm

  16. Pilot Study on The Thermographic Change of Seven Acupoints by Digital Infrared Thermographic Imaging

    Directory of Open Access Journals (Sweden)

    Lee Yun-kyu

    2005-12-01

    Full Text Available Objective : This study was designed to find out the effect of seven acupoints of stroke in cerebrovascular hemiplegia patients. Methods : This study was performed on 6 patients with cerebrovascular hemiplegia (test group and 6 health persons(control group. We measured temperature of skin surface of test and control group using digital infrared thermographic imaging(D.I.T.I. after acupunture on seven acupoints of stroke. And we calculated difference of skin temperature between healthful and affected side for each groups. Results : There was significant difference in area 3 in both two groups between before and after acupuncture. But in general there was no significant difference between two groups on thermographic change. Conclusions : This is pilot study, so further studies are required to find out the effect of seven acupoints of stroke in cerebrovascular hemiplegia patients.

  17. Thermoluminescence properties of Mn-doped CaYAl3O7 phosphor irradiated with ultra-violet, mega-voltage and gamma radiation

    International Nuclear Information System (INIS)

    Pathak, Pushpraj; Selot, Anupam; Kurchania, Rajnish

    2014-01-01

    Low temperature combustion synthesis was employed for the preparation of CaYAl 3 O 7 (Mn 2+ ) phosphor. X-Ray diffraction (XRD) patterns were recorded to confirm the phase formation. Estimated particle size was found to be ∼19.9 nm by using the Debye Scherrer's formula. FTIR study confirms the formation of CaYAl 3 O 7 compound, escape of nitrates and other organic products. Thermoluminescence (TL) glow curves of the prepared phosphor were recorded after exposing the sample with Ultra-violet (UV), 6-Mega-voltage (MV), 16-MV and Co-60(Cobalt-60, 1.25-MeV average gamma energy) radiation. Trapping parameters namely activation energy (E), order of kinetics (b) and frequency factor(s) of main peak, centered around 186 °C in the sample irradiated with UV source for 20 min, were determined using glow curve shape (Chen's) method. It has been observed that the TL peak intensity increases with increasing the exposure from UV source. Also with increases the energy of incident radiation a decrease in TL peak intensity were observed. This could be due to higher penetration power and less absorbance of incident beam in the phosphor material. Analysis suggests that possibility of utilizing this phosphor in futuristic low and high energy dosimetric applications as well as in solid state lighting devices. - Highlights: • The average particle size was found to be 19.9 nm of CaYAl 3 O 7 :Mn 2+ phosphor synthesized by the combustion method. • Two glow peaks were recorded in UV exposed sample. However with Gamma and MV irradiated sample a single glow peak was observed. • TL intensity in the sample irradiated with UV is higher as compared to Gamma and MV. • Glow peaks of the phosphor obeys second order kinetic has 0.637 eV activation energy and 9.9×10 7 S −1 frequency factor. • Useful in radiation dosimetry as well as solid state lighting

  18. Synthesis and Luminescence Characteristics of Cr3+ doped Y3Al5O12 Phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Brenda A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dabestani, Reza T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lewis, Linda A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Thompson, Cyril V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Collins, Case T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Aytug, Tolga [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-10-01

    Luminescence performance of yttrium aluminum garnet (Y3Al5O12) phosphors as a function of Cr3+ concentration has been investigated via two different wet-chemical synthesis techniques, direct- (DP) and hydrothermal-precipitation (HP). Using either of these methods, the red-emitting phosphor [Y3Al5-xCrxO12 (YAG: Cr3+)] showed similar photoluminescence (PL) intensities once the dopant concentration was optimized. Specifically, the YAG: Cr3+ PL emission intensity reached a maximum at Cr3+ concentrations of x = 0.02 (0.4 at.%) and x = 0.13 (2.6 at.%) for DP and HP processed samples, respectively. The results indicated the strong influence of the processing method on the optimized YAG: Cr3+ performance, where a more effective energy transfer rate between a pair of Cr3+ activators at low concentration levels was observed by using the DP synthesis technique. Development of a highly efficient phosphor, using a facile synthesis approach, could significantly benefit consumer and industrial applications by improving the operational efficiency of a wide range of practical devices.

  19. Computer vision syndrome (CVS) - Thermographic Analysis

    Science.gov (United States)

    Llamosa-Rincón, L. E.; Jaime-Díaz, J. M.; Ruiz-Cardona, D. F.

    2017-01-01

    The use of computers has reported an exponential growth in the last decades, the possibility of carrying out several tasks for both professional and leisure purposes has contributed to the great acceptance by the users. The consequences and impact of uninterrupted tasks with computers screens or displays on the visual health, have grabbed researcher’s attention. When spending long periods of time in front of a computer screen, human eyes are subjected to great efforts, which in turn triggers a set of symptoms known as Computer Vision Syndrome (CVS). Most common of them are: blurred vision, visual fatigue and Dry Eye Syndrome (DES) due to unappropriate lubrication of ocular surface when blinking decreases. An experimental protocol was de-signed and implemented to perform thermographic studies on healthy human eyes during exposure to dis-plays of computers, with the main purpose of comparing the existing differences in temperature variations of healthy ocular surfaces.

  20. Evaluation of trapping parameters of thermally stimulated luminescence glow curves in Cu-doped Li2B4O7 phosphor

    International Nuclear Information System (INIS)

    Manam, J.; Sharma, S.K.

    2005-01-01

    Evaluation of trapping parameters, including order of kinetics, activation energy and frequency factor, is one of the most important aspect of studies in the field of thermally stimulated luminescence (TSL). A polycrystalline sample of Cu-doped Li 2 B 4 O 7 was prepared by the melting method. Formation of the doped compound was checked by use of Fourier-transform infrared (FTIR) spectroscopy. TSL studies of the Cu-doped lithium tetraborate sample shows three glow peaks, the maximum emission occurring, respectively, at a temperature of 175 deg. C, 290 deg. C and 350 deg. C, the intensity of the 175 deg. C-glow peak being the maximum. The trapping parameters associated with this prominent glow peak of Cu-doped lithium tetraborate are reported herein, using the isothermal luminescence decay and glow curve shape (Chen's) methods. Our results show very good agreement between the trapping parameters calculated by the two methods

  1. Effects of composition modulation on the luminescence properties of Eu(3+) doped Li1-xAgxLu(MoO4)2 solid-solution phosphors.

    Science.gov (United States)

    Cheng, Fangrui; Xia, Zhiguo; Molokeev, Maxim S; Jing, Xiping

    2015-11-07

    Double molybdate scheelite-type solid-solution phosphors Li1-xAgxLu1-y(MoO4)2:yEu(3+) were synthesized by the solid state reaction method, and their crystal structures and luminescence properties were investigated in detail. The composition modulation and structural evolution of this series of samples were studied and the selected AgEu(MoO4)2, AgLu(MoO4)2, LiLu(MoO4)2 and LiEu(MoO4)2 phases were analyzed based on the Rietveld refinement. Depending on the variation of the Li/Ag ratio in Li1-xAgxLu1-y(MoO4)2:yEu(3+) phosphors, the difference in the luminescence properties of Li1-xAgxLu1-y(MoO4)2:yEu(3+) phosphors was ascribed to two factors, one reason could be assigned to the coupling effect and the nonradiative transition between the energy levels of LixAg1-xLu(MoO4)2 matrices and the activator Eu(3+), another could be due to the near ultraviolet energy absorption and transmission efficiency between the charge-transfer (CT) band of O(2-)-Mo(6+) and the 4f → 4f emissive transitions of Eu(3+). The ultraviolet-visible diffuse reflection spectra (UV-vis DRS) and Raman spectra analysis were also used to verify the above mechanism.

  2. EPR and optical absorption studies of Cu{sup 2+} doped L-histidinium dihydrogen phosphate–phosphoric acid single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Prabakaran, R.; Sheela, K. Juliet; Rosy, S. Margret [Department of Physics, Gandhigram Rural Institute—Deemed University, Gandhigram, Dindigul-624302, Tamilnadu (India); Radha Krishnan, S.; Shanmugam, V.M. [CSIR-Central Electrochemical Research Institute, Karaikudi-630006, Tamilnadu (India); Subramanian, P., E-mail: psmanian_gri@yahoo.com [Department of Physics, Gandhigram Rural Institute—Deemed University, Gandhigram, Dindigul-624302, Tamilnadu (India)

    2014-02-01

    The EPR spectra of Cu{sup 2+} in L-histidinium dihydrogen phosphate phosphoric acid at room temperature reveal the presence of two magnetically inequivalent Cu{sup 2+} sites in the lattice. The principal values of the g- and A-tensors indicate existence of rhombic symmetry around the Cu{sup 2+} ion. From the direction cosines of the principal values of the g- and A-tensors, the locations of Cu{sup 2+} in the lattice have been identified as substitutional sites. Optical absorption study shows four bands confirm the rhombic symmetry. Photoluminescence study also confirms the rhombic symmetry around the ions.

  3. Practical applications of phosphors

    CERN Document Server

    Yen, William M; Yamamoto, Hajime

    2006-01-01

    Drawn from the second edition of the best-selling Phosphor Handbook, Practical Applications of Phosphors outlines methods for the production of various phosphors and discusses a broad spectrum of applications. Beginning with methods for synthesis and related technologies, the book sets the stage by classifying and then explaining practical phosphors according to usage. It describes the operating principle and structure of phosphor devices and the phosphor characteristics required for a given device, then covers the manufacturing processes and characteristics of phosphors. The book discusses research and development currently under way on phosphors with potential for practical usage and touches briefly on phosphors that have played a historical role, but are no longer of practical use. It provides a comprehensive treatment of applications including lamps and cathode-ray tubes, x-ray and ionizing radiation, and for vacuum fluorescent and field emission displays and covers inorganic and organic electroluminescen...

  4. Possibility of RGB emission by Eu{sup 2+} ion doped M{sup II}M{sup III}M{sup VI} phosphors for color inorganic electro- luminescent displays

    Energy Technology Data Exchange (ETDEWEB)

    Jabbarov, R B; Tagiev, B G; Tagiev, O B; Musaeva, N N [Inst. of Physics Azerbaijan National Academy of Sciences, Baku (Azerbaijan); Benalloul, P; Barthou, C [Univ. P. et. M. Curie, Paris (France)

    2004-07-01

    Full text: Eu{sup 2+} ion give broad-band emission due to f-d transitions. The 5d orbital are not shelled from the host lattice by any occupied orbital. Therefore the wavelength positions of the emission bands depend on host and change from hear UV to red. With increasing crystal field strength, the emission bands shift to longer wavelength. The broad band absorption and luminescence of Eu{sup 2+} is parity-and spin-allowed and lifetime is sub-microseconds. In resent years, many efforts have been devoted to luminescence studies of thio gallates and thio-aluminates doped with rare-earth ions because of their chemical stability in ambient environments. In ternary compounds both the ligand field at the divalent cation site and the nephelauxetic effect are reduced by the presence of trivalent or tetravalent ions. This effect is more pronounced with Al than with Ga. In a same family of compounds, the emission band generally shifts to shorter wavelengths with increasing M{sup II}/M{sup IV} or M{sup VI}/M{sup III} ratio. In this paper we revisited the luminescence of the phosphors CaGa{sub 2}S{sub 4}, BaGa{sub 2}S{sub 4}, BaAl{sub 2}S{sub 4} activated by Eu{sup 2+} ion. Influence of temperature and Eu{sup 2+} concentration on the luminescence characteristics of these phosphors are studied. These dates will be useful to evaluate the quality oi the powder or thin films prepared for devices.

  5. Investigation of the mechanism responsible for the photoluminescence enhancement with Li+ co-doping in highly thermally stable white-emitting Sr8ZnSc(PO4)7:Dy3+ phosphor

    International Nuclear Information System (INIS)

    Gou, Jing; Fan, Jingyan; Luo, Meng; Zuo, Shengnan

    2017-01-01

    The strategy of co-doping Li + was used with the aim of enhancing the emission intensities of Sr 8 ZnSc(PO 4 ) 7 under near ultraviolet excitation. The luminescence enhancement was related to the deep defects V O ¨ which were produced by the introduction of Li + ion. Furthermore, much deep V O ¨ were produced with the incorporation amount of Li + ion increasing. As the sensitizer, the produced deep V O ¨ can effectively tunnelling transfer energy to the nearby activator Dy 3+ resulting in the photoluminescence enhancement in SZSPO:1.5%Dy 3+ ,5%Li + . In addition, its yellow/blue emitting ratio and photoluminescent quantum yields both were improved under longer wavelength excitation. Furthermore, the excellent thermal stability of optimal SZSPO:1.5%Dy 3+ ,5%Li + excelled over commercial phosphor DS-200 below 225 °C. The electroluminescence properties of fabricated ABPD-WLED reach the optimum with V=10 V and I=800 mA (λ ex =365 nm) or 700 mA (λ ex =388 nm), then the bright white luminescence can be obviously observed. These photoluminescence, electroluminescence and thermal properties testified the potential application of Sr 8 ZnSc(PO 4 ) 7 :1.5%Dy 3+ ,5%Li + as a new-style warm-white emitting LEDs phosphor. - Graphical abstract: The mechanism of the luminescence enhancement is consider as that a little amount introduction of Li + ion can produce defects Li Zn ′ and oxygen vacancies V O ¨, and with the incorporation amount of Li + increasing, the more deep V O ¨ are produced. As sensitizer, the productive deeper V O ¨ can effectively tunneling transfer energy to nearby activator Dy 3+ inducing its photoluminescence enhancement.

  6. Investigation of saturation effects in ceramic phosphors for laser lighting

    DEFF Research Database (Denmark)

    Krasnoshchoka, Anastasiia; Thorseth, Anders; Dam-Hansen, Carsten

    2017-01-01

    We report observation of saturation effects in a Ce:LuAG and Eu-doped nitride ceramic phosphor for conversion of blue laser light for white light generation. The luminous flux from the phosphors material increases linearly with the input power until saturation effects limit the conversion....... It is shown, that the temperature of the phosphor layer influences the saturation power level and the conversion efficiency. It is also shown that the correlated color temperature (CCT), phosphor conversion efficiency and color rendering index (CRI) are dependent both on incident power and spot size diameter...... of the illumination. A phosphor conversion efficiency up to 140.8 lm/W with CRI of 89.4 was achieved. The saturation in a ceramic phosphor, when illuminated by high intensity laser diodes, is estimated to play the main role in limiting the available luminance from laser based lighting systems....

  7. Influencial factors in thermographic analysis in substations

    Science.gov (United States)

    Zarco-Periñán, Pedro J.; Martínez-Ramos, José L.

    2018-05-01

    Thermography is one of the best predictive maintenance tools available due to its low cost, fast implementation and effectiveness of the results obtained. The detected hot spots enable serious incidents to be prevented, both in the facilities and equipment where they have been located. In accordance with the criticality of such points, the repair is carried out with greater or lesser urgency. However, for detection to remain reliable, the facility must meet a set of requirements that are normally assumed, otherwise hot spots cannot be detected correctly and will subsequently cause unwanted defects. This paper analyses three aspects that influence the reliability of the results obtained: the minimum percentage of load that a circuit must contain in order to be able to locate all the hot spots therein; the minimum waiting time from when an item of equipment or facility is energized until a thermographic inspection can be carried out with a complete guarantee of hot spot detection; and the influence on the generation of hot spots exerted by the tightening torque realized in the assembly process.

  8. Luminescence properties of Eu2+-doped MAl2-xSixO4-xNx (M = Ca, Sr, Ba) conversion phosphor for white LED applications

    NARCIS (Netherlands)

    Li, Y.Q.; With, de G.; Hintzen, H.T.J.M.

    2006-01-01

    Undoped and Eu-doped MAl2-xSixO4-2Nx (M = Ca, Sr, Ba) were synthesized by a solid-state reaction method at 1300 - 1400 ¿C under nitrogen-hydrogen atmosphere. The solubility of (SiN)+, in MAl2O4 was determined. Nitrogen can be incorporated into MAl2O4 by replacement of (AlO)+ by (SiN)+, whose amount

  9. Rare earth phosphors and phosphor screens

    International Nuclear Information System (INIS)

    Buchanan, R.A.; Maple, T.G.; Sklensky, A.F.

    1981-01-01

    Advances in the use of stabilized rare earth phosphors and of conversion screens using these materials are examined. In particular the new phosphors discussed in this invention consist of oxybromides of yttrium, lanthanum and gadolinium with a luminescent activator ion stabilized by an oxychloride or oxyfluoride surface layer and the conversion screens include trivalent cerium as the activator ion. (U.K.)

  10. X-ray absorption spectroscopy on phosphoric-salt pellets. Determination of the geometric and electronic structure of metal-oxide doped sodium-phosphate glasses

    International Nuclear Information System (INIS)

    Brendebach, B.

    2004-02-01

    Sodium metaphosphate glasses doped with transition metal oxides show characteristic colors. X-ray absorption spectroscopy (XAS) investigations provide information whether the coloration stems from different electronic transitions or changes in the geometrical structure of the glasses. Even though the violet color of MnO y -doped glasses is considered as an evidence for Mn 3+ -ions, Mn K-XAS reveals that the majority of the manganese ions are in the oxidation state +II and have a mixed coordination of four and six oxygen atoms, respectively. The oxygen coordination around the nickel ions in NiO-doped glasses with different metall oxide concentrations is always six. The change of color from citreous to auburn with increasing nickel oxide content is attributed to a systematic change in the bonding characteristic from mainly ionic-like to a small but significant contribution of covalent-like bonding. Analysis of higher coordination shells provides no indication of the formation of metal oxide clusters. (orig.)

  11. Tunable luminescence in Bi{sup 3+} and Eu{sup 3+} co-doped Sr{sub 3}AlO{sub 4}F Oxyfluorides phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Minhee [Center for Green Fusion Technology and Department of Engineering in Energy & Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of); Cho, So-Hye [Center for Materials Architecturing, Institute of Multidisciplinary Convergence of Materials, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of); Park, Sangmoon, E-mail: spark@silla.ac.kr [Center for Green Fusion Technology and Department of Engineering in Energy & Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of)

    2015-05-15

    Luminescent materials composed of Sr{sub 3−3(m+n)/2}Bi{sub m}Eu{sub n}AlO{sub 4}F (m=0.001–0.05, n=0–0.1) were prepared by the solid-state reaction method. The excitation and emission spectra of Sr{sub 3−3m/2}Bi{sub m}AlO{sub 4}F (m=0.001–0.05) were investigated using photoluminescence spectroscopy; broad-band emission peaks owing to the {sup 3}P{sub 1}→{sup 1}S{sub 0} transitions of the Bi{sup 3+} activator were observed centered near 427 nm. Critical emission quenching, as a function of Bi{sup 3+} content in Sr{sub 3−3m/2}Bi{sub m}AlO{sub 4}F, was observed at relatively low concentrations of the activator. The quantum efficiency of Sr{sub 2.985}Bi{sub 0.01}AlO{sub 4}F in comparison with sodium salicylate was explored. When Sr{sup 2+} ions in the oxyfluoride host were replaced by Bi{sup 3+} and Eu{sup 3+} ions, the effective s{sup 2}–sp and f–f transitions of the Bi{sup 3+} and Eu{sup 3+} ions, respectively, were simultaneously observed. The diverse excitation and emission photoluminescence spectra and color CIE coordinates, as well as the blue to orange-red emission, obtained using Sr{sub 3−3(m+n)/2}Bi{sub m}Eu{sub n}AlO{sub 4}F (m=0–0.05, n=0–0.1) phosphors are also discussed. - Highlights: • Sr{sub 3−3(m+n)/2}Bi{sub m}Eu{sub n}AlO{sub 4}F (m=0.001–0.05, n=0–0.1) phosphors was prepared. • Emission owing to the {sup 3}P{sub 1}→{sup 1}S{sub 0} transitions of the Bi{sup 3+} activator was observed. • Quantum efficiency of Sr{sub 2.985}Bi{sub 0.01}AlO{sub 4}F was explored. • s{sup 2}–sp and f–f transitions of the Bi{sup 3+} and Eu{sup 3+} ions were simultaneously observed. • CIE values including the emissions from blue to red regions were achieved.

  12. Thermographic survey of two rural buildings in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Martin Ocana, S.; Canas Guerrero, I. [Departamento de Construccion y Vias Rurales, Escuela Tecnica Superior de Ingenieros Agronomos, Universidad Politecnica de Madrid, Madrid (Spain); Gonzalez Requena, I. [Departamento de Materiales y Produccion Aeroespacial, Escuela Tecnica Superior de Ingenieros Aeronauticos, Universidad Politecnica de Madrid, Madrid (Spain)

    2004-07-01

    Two common housing prototypes of existing buildings in Spanish rural areas were surveyed by infrared inspection. The aim of the study is to assess the usefulness of infrared thermography as a technique for the detection of the thermal performance of rural buildings. For the traditional house the best results were obtained in the thermographic survey carried out in the evening. Contrarily, for the modern house the thermographic survey at daybreak provided more information. Infrared thermography allowed the comparison of the thermal performance of two buildings. (author)

  13. Spectrum designation and effect of Al substitution on the luminescence of Cr3+ doped ZnGa2O4 nano-sized phosphors

    International Nuclear Information System (INIS)

    Zhang Weiwei; Zhang Junying; Chen Ziyu; Wang Tianmin; Zheng Shukai

    2010-01-01

    Low-temperature photoluminescent spectra of ZnGa 2 O 4 :Cr 3+ nano-sized phosphors calcined at different temperatures were reported. The fine structure of the emission spectra has been designated to Cr 3+ ions in different sites including ideal octahedral, Zn-interstitial, Ga ZN 4 -Zn Ga 6 sites and Ga 2 O 3 impurity. The vibronic sidebands for both Stokes' and anti-Stokes' sides are related to the host lattice vibrations, which were confirmed by IR and Raman spectra. Al 3+ is substituted in Ga 3+ sites to form Zn(Ga 1-y Al y ) 2 O 4 :Cr 0.01 3+ (0≤y≤0.5). The blue shift and luminescent intensity variations of the charge transfer band and 3d-3d transitions in the spectra caused by Al substitution were related to larger band gap and stronger crystal field, respectively. The calculated crystal-field parameters indicated that Al incorporation enhanced the crystal field strength and induced more trigonal distortion due to different radii of Al 3+ and Ga 3+ .

  14. An investigation of down-conversion luminescence properties of rare earth doped CaMoO4 phosphors for solar cell application

    Science.gov (United States)

    Verma, Akta; Sharma, S. K.

    2018-05-01

    In the present work, we have synthesized a CaMoO4:(1%)Er3+,(1%)Yb3+ down-converting phosphor by hydrothermal method. The primary goal of studying down-conversion is to enhance the conversion efficiency of Si-solar cell by converting one high energy (UV) photon into two low energy (NIR) photons. The various characterization such as XRD, FESEM and Photoluminescence (PL) were carried out. The X-ray diffraction (XRD) pattern exhibit tetragonal crystal structure and has a space group of I41a (88). The FESEM microphotograph shows surface morphology having a abundance of particles in spherical shape. The PL emission spectra were recorded both in Visible and NIR regions. There is hypertensive emission peak at 555 nm in the visible region due to 4S3/2 → 4I15/2 transition of Er3+ ions and an emission at 980 nm (2F5/2 → 2F7/2) due to Yb3+ ions. The result shows a demand of this down-converting material in the field of solar energy to improve the efficiency of Si-solar-cell.

  15. Persistent luminescence of transition metal (Co, Ni...)-doped ZnGa2O4 phosphors for applications in the near-infrared range

    Science.gov (United States)

    Pellerin, Morgane; Castaing, Victor; Gourier, Didier; Chanéac, Corinne; Viana, Bruno

    2018-02-01

    Persistent luminescence materials present many applications including security lighting and bio-imaging. Many progresses have been made in the elaboration of persistent luminescent nanoparticles suitable for the first NIR partial transparency window (650 - 950 nm). Moving to the second and third near-infrared partial transparency windows (1000 nm - 1800 nm) allows further reducing of scattering, absorption and tissue autofluorescence effects. In this work, we present the synthesis of Co2+ and Ni2+ doped zinc-gallate nanoparticles with broad emission covering the NIR-II range. Site occupancy, energy levels, optical features and persistent phenomena are presented.

  16. New Silicate Phosphors for a White LED(Electronic Displays)

    OpenAIRE

    Toda, Kenji; Kawakami, Yoshitaka; Kousaka, Shin-ichiro; Ito, Yutaka; Komeno, Akira; Uematsu, Kazuyoshi; Sato, Mineo

    2006-01-01

    We focus on the development of new silicate phosphors for a white LED. In the europium doped silicate system, four LED phosphor candidates-Li_2SrSiO_4:Eu^, Ba_9Sc_2Si_6O_:Eu^, Ca_3Si_2O_7:Eu^ and Ba_2MgSi_2O_7:Eu^ were found. Luminescent properties under near UV and visible excitation were investigated for the new Eu^ doped LED silicate phosphors. These new phosphors have a relatively strong absorption band in a long wavelength region.

  17. Fundamentals of phosphors

    CERN Document Server

    Yen, William M; Yamamoto, Hajime

    2006-01-01

    Drawing from the second edition of the best-selling Handbook of Phosphors, Fundamentals of Phosphors covers the principles and mechanisms of luminescence in detail and surveys the primary phosphor materials as well as their optical properties. The book addresses cutting-edge developments in phosphor science and technology including oxynitride phosphors and the impact of lanthanide level location on phosphor performance.Beginning with an explanation of the physics underlying luminescence mechanisms in solids, the book goes on to interpret various luminescence phenomena in inorganic and organic materials. This includes the interpretation of the luminescence of recently developed low-dimensional systems, such as quantum wells and dots. The book also discusses the excitation mechanisms by cathode-ray and ionizing radiation and by electric fields to produce electroluminescence. The book classifies phosphor materials according to the type of luminescence centers employed or the class of host materials used and inte...

  18. Structural and luminescence properties of self-yellow emitting undoped and (Ca, Ba, Sr)-doped Zn2V2O7 phosphors synthesized by combustion method

    Science.gov (United States)

    Foka, Kewele E.; Dejene, Birhanu F.; Koao, Lehlohonolo F.; Swart, Hendrik C.

    2018-04-01

    A self-activated yellow emitting Zn2V2O7 was synthesized by combustion method. The influence of the processing parameters such as synthesis temperature and dopants concentration on the structure, morphology and luminescence properties was investigated. The X-ray diffraction (XRD) analysis confirmed that the samples have a tetragonal structure and no significant structural change was observed in varying both the synthesis temperature and the dopants concentration. The estimated average crystallite size was 78 nm for the undoped samples synthesized at different temperatures and 77 nm for the doped samples. Scanning electron microscope (SEM) images showed agglomerated hexagonal-shaped particles with straight edges at low temperatures and the shape of the particles changed to cylindrical structures at moderate temperatures. At higher temperatures, the morphology changed completely. However, the morphologies of the doped samples looked alike. The photoluminescence (PL) of the product exhibited broad emission bands ranging from 400 to 800 nm. The best luminescence intensity was observed for the undoped Zn2V2O7 samples and those synthesized at 600 ℃ . Any further increase in synthesis temperature, type and concentration of dopants led to a decrease in the luminescence intensity. The broad band emission peak of Zn2V2O7 consisted of two broad bands corresponding to emissions from the Em1 (3T2→1A1) and Em2 (3T1→1A1) transitions.

  19. Improvement of photoluminescence intensity of Ce-doped Y{sub 3}Al{sub 5}O{sub 12} phosphor by Si{sub 3}N{sub 4} addition

    Energy Technology Data Exchange (ETDEWEB)

    Shyu, Jiin-Jyh, E-mail: jjshyu@ttu.edu.tw; Yang, Chia-Wei

    2017-06-01

    Yttrium aluminum garnet (Y{sub 3}Al{sub 5}O{sub 12}, YAG) has been widely used as a host for luminescent ions. The present paper describes the effects of Si{sub 3}N{sub 4} addition on the formation and photoluminescence properties of the Ce-doped YAG yellow phosphors. Phosphor powders with the nominal compositions of Y{sub 2.95}Ce{sub 0.05}Al{sub 5-m}Si{sub m}O{sub 12-m}N{sub m} (m = 0–0.6) were prepared by calcining the mixed raw materials at 1500 °C in nitrogen atmosphere. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscope, and transmission electron microscopy equipped with an energy dispersive x-ray spectrometer were used to characterize the structure of the calcined powders. The photoluminescence properties were measured with fluorescence spectrophotometry. It was found that in the range of m = 0–0.27, single phase YAG solid solution (s.s.) in which the Y, Al, and O sites are partially occupied by Ce, Si, and N ions, respectively. The nitrogen ions do not distribute homogeneously over the YAG lattice. The tendency to bond with nitrogen ion for the cations is (Y, Ce) > Si > Al. With the increase in the Si{sub 3}N{sub 4} content, the increase in both the Ce{sup 3+}/(Ce{sup 3+} + Ce{sup 4+}) ratio and the Ce-N bonds improve the intensity of the photoluminescent emission. At m = 0.27, the emission intensity reaches a maximum which is about 2.5 and 1.6 times of that for the Si{sub 3}N{sub 4}-free composition (m = 0) calcined in air and nitrogen, respectively. When the Si{sub 3}N{sub 4} content (m) is higher than 0.27, the emission intensity decreases due to the existence of residual Si{sub 3}N{sub 4} phase. - Highlights: • Addition of Si{sub 3}N{sub 4} can increase the emission intensity of YAG:Ce up to 2.5 times. • Increase in the Ce{sup 3+}/Ce{sup 4+} ratio and the number of Ce-N bonds improve the emission. • The tendency to bond with nitrogen ion for cations in YAG:Ce is (Y, Ce) > Si > Al. • The incomplete dissolution

  20. Synthesis of green emission upconversion phosphor nanosheets (LaNb{sub 2}O{sub 7}) doped with Er{sup 3+} and Yb{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Takasugi, Soichi [Course of Science and Technology, Graduate School of Science and Technology, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Iida, Riku [Department of Chemistry, School of Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Tomita, Koji, E-mail: tomita@keyaki.cc.u-tokai.ac.jp [Department of Chemistry, School of Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Iwaoka, Michio [Course of Science and Technology, Graduate School of Science and Technology, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Department of Chemistry, School of Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Katagiri, Kiyofumi [Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Osada, Minoru [International Center for Materials Nano architectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Kakihana, Masato [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2016-05-15

    LaNb{sub 2}O{sub 7}:Er{sup 3+},Yb{sup 3+} upconversion (UPC) phosphor nanosheets were prepared by exfoliating a KLaNb{sub 2}O{sub 7}:Er{sup 3+},Yb{sup 3+} layered compound. Highly crystalline nanosheets with a thickness and lateral size of 3.91 nm and approximately 300 nm, respectively, were obtained. The UPC emission intensity of the nanosheets was 7.6 times greater than that of mechanically milled particles (100–500 nm) of bulk KLaNb{sub 2}O{sub 7}:Er{sup 3+},Yb{sup 3+}. The UPC emission intensities of the nanosheets dispersed in different solvents (H{sub 2}O, D{sub 2}O, CH{sub 3}OH, CH{sub 2}Cl{sub 2}, and CCl{sub 4}) were measured, and the intensities were observed to decrease in the order CCl{sub 4}>CH{sub 2}Cl{sub 2}>D{sub 2}O>CH{sub 3}OH>H{sub 2}O. Because of the large surface area of the nanosheets, their emission intensity was decreased depending on the solvent's vibrational energy. - Highlights: • La{sub 0.45}Er{sub 0.05}Yb{sub 0.5}Nb{sub 2}O{sub 7} nanosheets were synthesized by a soft breakdown method (exfoliation). • The lateral size and thickness of the nanosheets were approximately 300 nm and approximately 3.91 nm, respectively. • The exfoliated nanosheets exhibited bright upconversion emission 7.6 times more intense than that of the milled sample (100–500 nm). • The nanosheets dispersed in solvents exhibited greatly different upconversion emission intensities depending on the solvent's vibrational energy.

  1. Standardized assessment of infrared thermographic fever screening system performance

    Science.gov (United States)

    Ghassemi, Pejhman; Pfefer, Joshua; Casamento, Jon; Wang, Quanzeng

    2017-03-01

    Thermal modalities represent the only currently viable mass fever screening approach for outbreaks of infectious disease pandemics such as Ebola and SARS. Non-contact infrared thermometers (NCITs) and infrared thermographs (IRTs) have been previously used for mass fever screening in transportation hubs such as airports to reduce the spread of disease. While NCITs remain a more popular choice for fever screening in the field and at fixed locations, there has been increasing evidence in the literature that IRTs can provide greater accuracy in estimating core body temperature if appropriate measurement practices are applied - including the use of technically suitable thermographs. Therefore, the purpose of this study was to develop a battery of evaluation test methods for standardized, objective and quantitative assessment of thermograph performance characteristics critical to assessing suitability for clinical use. These factors include stability, drift, uniformity, minimum resolvable temperature difference, and accuracy. Two commercial IRT models were characterized. An external temperature reference source with high temperature accuracy was utilized as part of the screening thermograph. Results showed that both IRTs are relatively accurate and stable (<1% error of reading with stability of +/-0.05°C). Overall, results of this study may facilitate development of standardized consensus test methods to enable consistent and accurate use of IRTs for fever screening.

  2. Super-resolution thermographic imaging using blind structured illumination

    Science.gov (United States)

    Burgholzer, Peter; Berer, Thomas; Gruber, Jürgen; Mayr, Günther

    2017-07-01

    Using an infrared camera for thermographic imaging allows the contactless temperature measurement of many surface pixels simultaneously. From the measured surface data, the structure below the surface, embedded inside a sample or tissue, can be reconstructed and imaged, if heated by an excitation light pulse. The main drawback in active thermographic imaging is the degradation of the spatial resolution with the imaging depth, which results in blurred images for deeper lying structures. We circumvent this degradation by using blind structured illumination combined with a non-linear joint sparsity reconstruction algorithm. We demonstrate imaging of a line pattern and a star-shaped structure through a 3 mm thick steel sheet with a resolution four times better than the width of the thermal point-spread-function. The structured illumination is realized by parallel slits cut in an aluminum foil, where the excitation coming from a flashlight can penetrate. This realization of super-resolution thermographic imaging demonstrates that blind structured illumination allows thermographic imaging without high degradation of the spatial resolution for deeper lying structures. The groundbreaking concept of super-resolution can be transferred from optics to diffusive imaging by defining a thermal point-spread-function, which gives the principle resolution limit for a certain signal-to-noise ratio, similar to the Abbe limit for a certain optical wavelength. In future work, the unknown illumination pattern could be the speckle pattern generated by a short laser pulse inside a light scattering sample or tissue.

  3. Thermographic and radionuclide investigation in combined diagnosis of breast cancer

    International Nuclear Information System (INIS)

    Abushakhmanov, A.Kh.

    1986-01-01

    The results of examination of 157 women with breast diseases are given. Breast cancer was diagnosed in 94 patients, benign diseases in 63. The combined use of the thermographic and radionuclide methods was shown to raise the accuracy of breast cancer diagnosis

  4. Calibration and verification of thermographic cameras for geometric measurements

    Science.gov (United States)

    Lagüela, S.; González-Jorge, H.; Armesto, J.; Arias, P.

    2011-03-01

    Infrared thermography is a technique with an increasing degree of development and applications. Quality assessment in the measurements performed with the thermal cameras should be achieved through metrology calibration and verification. Infrared cameras acquire temperature and geometric information, although calibration and verification procedures are only usual for thermal data. Black bodies are used for these purposes. Moreover, the geometric information is important for many fields as architecture, civil engineering and industry. This work presents a calibration procedure that allows the photogrammetric restitution and a portable artefact to verify the geometric accuracy, repeatability and drift of thermographic cameras. These results allow the incorporation of this information into the quality control processes of the companies. A grid based on burning lamps is used for the geometric calibration of thermographic cameras. The artefact designed for the geometric verification consists of five delrin spheres and seven cubes of different sizes. Metrology traceability for the artefact is obtained from a coordinate measuring machine. Two sets of targets with different reflectivity are fixed to the spheres and cubes to make data processing and photogrammetric restitution possible. Reflectivity was the chosen material propriety due to the thermographic and visual cameras ability to detect it. Two thermographic cameras from Flir and Nec manufacturers, and one visible camera from Jai are calibrated, verified and compared using calibration grids and the standard artefact. The calibration system based on burning lamps shows its capability to perform the internal orientation of the thermal cameras. Verification results show repeatability better than 1 mm for all cases, being better than 0.5 mm for the visible one. As it must be expected, also accuracy appears higher in the visible camera, and the geometric comparison between thermographic cameras shows slightly better

  5. Study of the recrystallization mechanisms of ultra-high purity iron doped with carbon, manganese and phosphorus; Etude des mecanismes de recristallisation dans le fer de ultra-haute purete dope en carbone, manganese et phosphore

    Energy Technology Data Exchange (ETDEWEB)

    Lesne, L.

    2000-07-04

    High purity steels have the potential to improve deep drawing properties for automotive applications. Understanding the influence of the chemical composition on the recrystallization mechanisms and on texture development should help to improve their properties. We have studied the influence of 10 ppm of carbon, 1000 ppm of manganese and 120 ppm of phosphorus on the recrystallization mechanisms of ultra-high purity iron (UHP iron > 99.997%). For this purpose we used 4 materials: one undoped (UHP), one doped with C, one doped with C, Mn and one doped With C, Mn, P. In order to restrict grain coarsening in the hot strips, hot rolling was performed in the ferritic region, in one pass of 80% thickness reduction. The hot bands were then fully recrystallized but exhibited non-isotropic textures, with in particular an intense Goss [110]<001> component for the doped materials. The hot-bands were subsequently cold rolled down to a thickness of 0.8 mm corresponding to a thickness reduction of 80%, and then continuously annealed at 10 deg. C/s. The recrystallization kinetics are delayed with the addition of doping elements. In particular, the incubation time for nucleation is shifted towards higher temperatures while the recrystallization velocity increases. The textures of the fully recrystallized materials exhibit a strong Goss component prejudicial for deep drawing properties. We have established that this component can only appear if coarse grains and carbon in solid solution were simultaneously present in the material before deformation. Characterisation of the cold deformed state enabled us to evaluate the energy stored during deformation as a function of the material composition and the grain orientation: - the overall stored energy increases with the doping elements content. - the stored energy in the {gamma} fibre grains is greater than in the {alpha} fibre grains: 30 J/mol for the {gamma} fibre instead of 5 J/mol for the {alpha} fibre, in the undoped UHP iron. In the

  6. Phosphor scintillator structure

    International Nuclear Information System (INIS)

    Cusano, D.A.; Prener, J.S.

    1980-01-01

    A method of fabricating scintillators is described in which the phosphor is distributed within the structure in such a way as to enhance the escape of the visible wavelength radiation that would otherwise be dissipated within the scintillator body. Two embodiments of the present invention are disclosed: one in which the phosphor is distributed in a layered structure and another in which the phosphor is dispersed throughout a transparent matrix. (U.K.)

  7. Up-conversion emission of Er{sup 3+}/Yb{sup 3+}co-doped BaBi{sub 2}Nb{sub 2}O{sub 9} (BBN) phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Façanha, M.X., E-mail: marcello.facanha@uece.br [Departamento de Química, Centro de Ciências, Universidade Federal do Ceará (UFC), Fortaleza, Ceará (Brazil); Faculdade de Educação de Crateús (FAEC), Universidade Estadual do Ceará (UECE), Fortaleza, Ceará (Brazil); Laboratório de Telecomunicações e Ciências e Engenharia de Materiais (LOCEM), Universidade Federal do Ceará (UFC), Fortaleza, Ceará (Brazil); Nascimento, J.P.C. do [Departamento de Química, Centro de Ciências, Universidade Federal do Ceará (UFC), Fortaleza, Ceará (Brazil); Laboratório de Telecomunicações e Ciências e Engenharia de Materiais (LOCEM), Universidade Federal do Ceará (UFC), Fortaleza, Ceará (Brazil); Silva, M.A.S., E-mail: marceloassilva@yahoo.com.br [Laboratório de Telecomunicações e Ciências e Engenharia de Materiais (LOCEM), Universidade Federal do Ceará (UFC), Fortaleza, Ceará (Brazil); and others

    2017-03-15

    On this paper, polycrystalline samples of the tetragonal systems BaBi{sub 2}Nb{sub 2}O{sub 9} (BBN) and BBN co-doped with Er{sup 3+}/Yb{sup 3+} (BBN: 0.04Er{sup 3+}yYb{sup 3+}, where y=0.02, 0.04, 0.06 and 0.08 mol%) were synthesized by the solid state method. The crystalline structure and photoluminescent properties of the ceramic phosphors were investigated by powder X-ray diffraction (PXRD), Raman spectroscopy and spectral analysis of up-conversion (UC) emission. The results reveal that all compositions crystallize in the I4/mmm space group at room temperature, and show UC green emissions (centered at 525 nm and 550 nm) and red (around 660 nm) coming from ({sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}→{sup 4}I{sub 15/2}) and ({sup 4}F{sub 9/2}→{sup 4}I{sub 15/2}) transitions, respectively, under excitation at 980 nm. Increasing variations of the Yb{sup 3+} sensitizer concentration in the host BBN, lead to a significant intensity increase in both UC emissions due to the efficiency of the energy-transfer process. The BBN: 0.04 mol%Er{sup 3+}0.08 mol%Yb{sup 3+} composition showed the higher intensity bands, thus establishing the BBN as an alternative host material for luminescent centers.

  8. Effect of grinding on photostimuable phosphors for x-ray screens

    International Nuclear Information System (INIS)

    Rao, R.B.

    1988-01-01

    Luminescence efficiency of a phosphor can be improved by minimizing the energy losses during excitation. The loss of excitation energy in the case of powdered samples is mainly due to scattering of incident radiation by the particles of phosphor. Thus, while considering the industrial applications of polycrystalline phosphors in lamps, screens, paints, etc., the effect of particle size on the light output has to be specially studied. It is very well established that the radiographic imaging with photostimuable (PS) phosphors has many advantages over conventional photographic film screens. In the new type of computer radiography, PS phosphors are to be used as memory materials for temporary storage of the x-ray image. Eu(2+) doped barium fluorohalide phosphors are most suitable for this purpose. The spatial resolution from the image plate can be improved to a certain extent with phosphors comprising fine particles. The fineness of the particles can be achieved by various means such as grinding, fast cooling after firing or incorporation of some flux materials during the firing processes. But the efficiency of the phosphor deteriorates with grinding. Fast cooling is a complicated process in the case of Eu(2+) doped phosphors. Incorporation of flux materials may change the characteristics of phosphor materials. In the present investigation, effect of grinding (ball milling) on particle size distribution, shape of the particles and luminescent properties of BaFCl phosphors have been studied

  9. Study of the Susceptibility of Oxygen-Free Phosphorous Doped Copper to Corrosion in Simulated Groundwater in the Presence of Chloride and Sulfide

    International Nuclear Information System (INIS)

    Escobar, Ivan; Lamas, Claudia; Werme, Lars; Oversby, Virginia

    2007-01-01

    Oxygen free high conductivity copper, doped with phosphorus (Cu OFP) has been chosen as the material for the fabrication of high level nuclear waste containers in Sweden. This material will be the corrosion barrier for spent fuel in the environment of a deep geological repository in granitic rock. The service life of this container is expected to exceed 1,000,000 years. During this time, which includes several glaciations, water of different compositions, including high concentration of chloride ions, will contact the copper surface. This work reports a study of the susceptibility of Cu OFP to corrosion when chloride ions are present, in deionized water (DW) and in synthetic groundwater (SGW). The techniques used were electrochemical methods such as corrosion potential evolution and Tafel curves. The system was studied with Electrochemical Impedance Spectroscopy (EIS). We also used as characterization techniques Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). The main conclusions are that copper is more susceptible to corrosion at high chloride ion concentration. When the chloride concentration is low, it is possible to form copper chloride crystals, but at the highest concentration, copper chloride complexes are formed, leaving the copper surface without deposits. When the chloride concentration is low ( -5 M), copper corrosion in the presence of chloride is controlled by diffusional processes, while at higher concentrations corrosion is controlled by charge transfer processes. (authors)

  10. Enhanced photoluminescence of Sm{sup 3+}/Bi{sup 3+} co-doped Gd{sub 2}O{sub 3} phosphors by combustion synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Liu Guangsheng; Zhang Ying [Institute of Micro-system Physics, School of Physics and Electronics, Henan University, Kaifeng 475001 (China); Yin Jiang [Department of Physics, Nanjing University, Nanjing 210093 (China); Zhang, W.F. [Institute of Micro-system Physics, School of Physics and Electronics, Henan University, Kaifeng 475001 (China)], E-mail: wfzhang@henu.edu.cn

    2008-12-15

    Gd{sub 2}O{sub 3}:Sm{sup 3+} and Gd{sub 2}O{sub 3}:Sm{sup 3+},Bi{sup 3+} powders were prepared by a combustion method. Their structures were determined using X-ray diffraction. UV-visible absorption and photoluminescence spectra were investigated for Gd{sub 2}O{sub 3}:Sm{sup 3+} and Gd{sub 2}O{sub 3}:Sm{sup 3+},Bi{sup 3+} at different annealing temperatures and different doping concentrations. The emission spectra of all samples presented the characteristic emission narrow lines arising from the {sup 4}G{sub 5/2}{yields}{sup 6}H{sub J} transitions (J=5/2, 7/2, and 9/2) of Sm{sup 3+} ions upon excitation with UV irradiation. The emission intensity of Sm{sup 3+} ions was largely enhanced with introducing Bi{sup 3+} ions into Gd{sub 2}O{sub 3}:Sm{sup 3+} and the maximum occurred at a Bi{sup 3+} concentration of 0.5 mol%. The relevant mechanisms were discussed with the sensitization theory by Dexter and the aggregation behavior of Bi{sup 3+} ions.

  11. Photon up-conversion production in Tb{sup 3+}–Yb{sup 3+} co-doped CaF{sub 2} phosphors prepared by combustion synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Rakov, Nikifor, E-mail: nikifor.gomez@univasf.edu.br [PG—Ciência dos Materiais, Universidade Federal do Vale do São Francisco, 48902-300 Juazeiro, BA (Brazil); Guimarães, Renato B. [Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, RJ (Brazil); Maciel, Glauco S., E-mail: glauco@if.uff.br [Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, RJ (Brazil)

    2016-02-15

    Graphical abstract: Up-conversion luminescence from Tb{sup 3+} obtained by energy transfer from Yb{sup 3+} pairs in CaF{sub 2} powder prepared by combustion synthesis. - Highlights: • Calcium fluoride (CaF{sub 2}) powders were prepared by combustion synthesis. • Rare-earth ions doped in this material were found in interstitial sites. • Cooperative up-conversion was observed in Tb{sup 3+}:Yb{sup 3+}:CaF{sub 2} powder. • Energy transfer between Tb{sup 3+} and pairs of Yb{sup 3+} was analyzed using rate equations. - Abstract: Calcium fluoride (CaF{sub 2}) crystalline powders were successfully prepared by the combustion synthesis method. The powder material containing luminescent rare-earth ions, more specifically terbium (Tb{sup 3+}) and ytterbium (Yb{sup 3+}), was studied by X-ray diffraction, scanning electronic microscopy and optical spectroscopy. These ions are allocated in charge compensated interstitial positions of tetragonal (C{sub 4v}) and trigonal (C{sub 3v}) symmetry sites of the cubic (O{sub h}) CaF{sub 2} lattice. Up-conversion (UC) luminescence in Tb{sup 3+} was achieved using a low power diode laser operating at 975 nm. Tb{sup 3+} is insensitive to near-infrared radiation but UC can be achieved via energy transfer from pairs of Yb{sup 3+} ions to Tb{sup 3+} ions. The UC luminescence dynamics of Tb{sup 3+} was used to study the energy transfer mechanism.

  12. Development of some phosphors of high quantic efficiency and their application in radiological image reinforcing screens

    International Nuclear Information System (INIS)

    Caticha-Ellis, S.; Alvarez, A.G.; Torrianni, I.L.; Lluesma, E.G.

    1981-01-01

    The establishment of a methodology for the preparation of phosphors and the study of different physical factors which interfere in the process is presented. Emphasis is given on the use of a method of preparation of modern phosphors based on crystalline substracts doped with rare earths. (A.R.H.) [pt

  13. New NaSrPO4:Sm phosphor as orange-red emitting material

    Indian Academy of Sciences (India)

    Because NaSr1−xPO4:xSm3+ phosphor features a high colour-rendering index and chemical stability, it is potentially ... use blue LED chips (GaN or InGaN) with a yellow phosphor ... excitation by doping Sm3+ rare earth ions into a suitable.

  14. Combustion synthesis of Eu and Dy activated Sr3(VO4)2 phosphor ...

    Indian Academy of Sciences (India)

    phosphor as well as Sr3(VO4)2:Dy is blue and yellow emitting phosphor for solid state lighting i.e. white LEDs. The ... 2004; Pang et al 2004) doped with rare earth has expanded ... controlled since the LED light output (intensity and colour).

  15. Eu and Sr2CeO4 : Eu phosphors suitable for near ultraviolet excitation

    Indian Academy of Sciences (India)

    Administrator

    The study on white light phosphors suitable for near- ultraviolet (nUV) ... Rare earth ion-doped phosphors have been used in varied fields ... practical applications. .... by naked eyes. ... induced by Sr2CeO4 host matrix (Arunachalam Laxmanan.

  16. Thermographic Inspection of Fatigue Crack by Using Contact Thermal Resistance

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Seung Yong; Kim, No Hyu [Korean University of Technology and Education, Cheonan (Korea, Republic of)

    2013-04-15

    Fatigue crack was detected from a temperature change around surface crack using the thermographic technique. Thermal gradient across the crack decreased very much due to thermal resistance of contact surface in the crack. Heat diffusion flow passing through the discontinuity was visualized in temperature by infrared camera to find and locate the crack. A fatigue crack specimen(SM-45C), which was prepared according to KS specification and notched in its center to initiate fatigue crack from the notch tip, was heated by halogen lamp at the end of one side to generate a heat diffusion flow in lateral direction. A abrupt jump in temperature across the fatigue crack was observed in thermographic image, by which the crack could be located and sized from temperature distribution.

  17. Thermographic Inspection of Fatigue Crack by Using Contact Thermal Resistance

    International Nuclear Information System (INIS)

    Yang, Seung Yong; Kim, No Hyu

    2013-01-01

    Fatigue crack was detected from a temperature change around surface crack using the thermographic technique. Thermal gradient across the crack decreased very much due to thermal resistance of contact surface in the crack. Heat diffusion flow passing through the discontinuity was visualized in temperature by infrared camera to find and locate the crack. A fatigue crack specimen(SM-45C), which was prepared according to KS specification and notched in its center to initiate fatigue crack from the notch tip, was heated by halogen lamp at the end of one side to generate a heat diffusion flow in lateral direction. A abrupt jump in temperature across the fatigue crack was observed in thermographic image, by which the crack could be located and sized from temperature distribution.

  18. Thermographic analysis of waveguide-irradiated insect pupae

    Science.gov (United States)

    Olsen, Richard G.; Hammer, Wayne C.

    1982-01-01

    Pupae of the insect Tenebrio molitor L. were thermographically imaged during waveguide irradiation through longitudinal slots. T. molitor pupae have been subjects of microwave-induced teratology for a number of years, but until now the smallness of the insect has prevented detailed dosimetry. High-resolution thermographic imaging equipment was used to obtain the magnitude and spatial distribution of absorbed microwave energy at three frequencies, 1.3, 5.95, and 10 GHz. The detail of the thermal images obtained is sufficient to show the differential heating of structures as small as a single insect leg. Results show that the electrical properties of the head, thorax, and abdomen are sufficiently different to seriously impair the usefulness of any theoretical dosimetric model of homogeneous composition. Some general features of correlation with a slab model in waveguide are given.

  19. The consistency of thermographic findings in breast screening

    International Nuclear Information System (INIS)

    Pflanzer, K.; Kleedorfer, D.; Pflanzer, D.; Fochem, K.

    1983-01-01

    Thermography is a valuable complementary method in breast examination, but is not a suitable screening method. However, the results of control investigations in 200 females who were reexamined after at least two years, showed no change in the thermographic pattern in 87.5% of the women. In 10.5% the change in thermogram was due to pathological changes, whilst no explanation could be found in only 2% of cases. This high stability rate of the thermograms permits an alternative procedure: If, one year after a basic examination which includes clinical investigation, mammography and thermography, the thermographic pattern is identical with the first, no mammography is necessary. On the occasion of the next control, mammography should be carried out again at the time of the subsequent control examination. This schedule permits a reduction in irradiation without reducing the security of diagnosis. (Author)

  20. Electronic structure and luminescence properties of self-activated and Eu{sup 2+}/Ce{sup 3+} doped Ca{sub 3}Li{sub 4-y}Si{sub 2}N{sub 6-y}O{sub y} red-emitting phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Quansheng; Ding, Jianyan; Li, Yanyan; Wang, Xicheng [Key Laboratory for Special Function Materials and Structural Design of the Ministry of the Education (China); Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang, Yuhua, E-mail: wyh@lzu.edu.cn [Key Laboratory for Special Function Materials and Structural Design of the Ministry of the Education (China); Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2017-06-15

    The undoped and Eu{sup 2+}/Ce{sup 3+} doped Ca{sub 3}Li{sub 4-y}Si{sub 2}N{sub 6-y}O{sub y} (0≤y≤1.5) (CLSN) were successfully prepared by solid-state reaction and their luminescence properties were studied. The undoped CLSN shows red defect-related luminescence with maximum emission intensity at 710 nm, Eu{sup 2+} and Ce{sup 3+} doped CLSN also show red emission centered at 702 nm and 673 nm, respectively. The electronic structure and the thermal stability of CLSN were investigated in this work. The results indicate that CLSN:Eu{sup 2+}/Ce{sup 3+} could be conducive to the development of phosphor-converted light-emitting diodes.

  1. Spectral modulation through controlling anions in nanocaged phosphors

    NARCIS (Netherlands)

    Bian, H.; Liu, Y.; Yan, D.; Zhu, H.; Liu, C.; Xu, C.S.; Liu, Y.; Zhang, H.; Wang, X.

    2013-01-01

    A new approach has been proposed and validated to modulate the emission spectra of europium-doped 12CaO center dot 7Al(2)O(3) phosphors by tuning the nonradiative and radiative transition rates, realized by controlling the sort and amount of the encaged anions. A single wavelength at 255 nm can

  2. Unactivated yttrium tantalate phosphor

    International Nuclear Information System (INIS)

    Reddy, V.B.; Cheung, H.K.

    1992-01-01

    This patent describes an unactivated yttrium tantalate phosphor having M prime monoclinic structure and containing one or more additives of Rb and Al in an amount of between about 0.001 to 0.1 moles per mole of yttrium tantalate to improve brightness under X-radiation. This patent also describes an unactivated yttrium tantalate phosphor having M prime monoclinic structure and containing additives of Sr in an amount of between 0.001 to 0.1 moles per mole of yttrium tantalate and one or more of Rb and Al in an amount of between 0.001 to 0.1 moles per mole of yttrium tantalate the phosphor exhibiting a greater brightness under X-radiation than the phosphor absent Rb and Al

  3. Low lag luminescent phosphors

    International Nuclear Information System (INIS)

    1976-01-01

    The addition of potassium or rubidium salts to europium-activated fluorohalide phosphors produces X-ray screens with low lag, even at very low europium concentrations. The chemical preparation and afterglow test results are described

  4. Compact fluorescent lamp phosphors in accidental radiation monitoring

    International Nuclear Information System (INIS)

    Murthy, K. V. R.; Pallavi, S. P.; Ghildiyal, R.; Parmar, M. C.; Patel, Y. S.; Ravi Kumar, V.; Sai Prasad, A. S.; Natarajan, V.; Page, A. G.

    2006-01-01

    The application of lamp phosphors for accidental dosimetry is a new concept. Since the materials used in fluorescent lamps are good photo luminescent materials, if one can either use the inherent defects present in the phosphor or add suitable modifiers to induce thermoluminescence (TL) in these phosphors, then the device (fluorescent lamp) can be used as an accidental dosemeter. In continuation of our search for a suitable phosphor material, which can serve both as an efficient lamp phosphor and as a good radiation monitoring device, detailed examination has been carried out on cerium and terbium-doped lanthanum phosphate material. A 90 Sr beta source with 50 mCi strength (1.85 GBq) was used as the irradiation source for TL studies. The TL response as a function of dose received was examined for all phosphors used and it was observed that the intensity of the TL peak vs. dose received was a linear function in the dose range 0.1-200 Gy in each case. Incidentally LaPO 4 :Ce,Tb is a component of the compact fluorescent lamp marketed recently as an energy bright light source. Besides having very good luminescence efficiency, good dosimetric properties of these phosphors render them useful for their use in accidental dosimetry also. (authors)

  5. TL-OSL study of Li{sub 3}PO{sub 4}: Mg, Cu phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Rahangdale, S. R., E-mail: sachin.rahangdale1@gmail.com; Wankhede, S. P. [Department of Physics, K.D.K.College of Engineering, Nagpur (India); Dhabekar, B. S. [RPAD, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Palikundwar, U. A.; Moharil, S. V. [Department of Physics, RTM Nagpur University, Nagpur, 440010 (India)

    2015-08-28

    In the present work, we report the thermoluminescence and optically stimulated luminescence properties of Mg and Cu doped Li{sub 3}PO{sub 4} phosphor. The phosphor was synthesized by precipitation method. The thermoluminescence dosimetric peak temperature for the phosphor varies with concentrations of Mg and Cu. Li{sub 3}PO{sub 4} shows good response to 470nm optical stimulation. The OSL sensitivity of the phosphor is approximately 12 times than that of standard Lithium magnesium phosphate. This study may help to develop this material for the application in real time dosimetry using optically stimulated luminescence.

  6. Phosphors for LED lamps

    Science.gov (United States)

    Murphy, James Edward; Manepalli, Satya Kishore; Kumar, Prasanth Nammalwar

    2013-08-13

    A phosphor, a phosphor blend including the phosphor, a phosphor prepared by a process, and a lighting apparatus including the phosphor blend are disclosed. The phosphor has the formula (Ca.sub.1-p-qCe.sub.pK.sub.q).sub.xSc.sub.y(Si.sub.1-rGa.sub.r).sub.zO.su- b.12+.delta. or derived from a process followed using disclosed amounts of reactants. In the formula, (0

  7. High temperature thermometric phosphors

    Science.gov (United States)

    Allison, Stephen W.; Cates, Michael R.; Boatner, Lynn A.; Gillies, George T.

    1999-03-23

    A high temperature phosphor consists essentially of a material having the general formula LuPO.sub.4 :Dy.sub.(x),Eu.sub.y) wherein: 0.1 wt %.ltoreq.x.ltoreq.20 wt % and 0.1 wt %.ltoreq.y.ltoreq.20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopent. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions.

  8. A review of thermographic techniques for damage investigation in composites

    Directory of Open Access Journals (Sweden)

    Laura Vergani

    2014-01-01

    Full Text Available The aim of this work is a review of scientific results in the literature, related to the application of thermographic techniques to composite materials. Thermography is the analysis of the surface temperature of a body by infrared rays detection via a thermal-camera. The use of this technique is mainly based on the modification of the surface temperature of a material, when it is stimulated by means of a thermal or mechanical external source. The presence of defects, in fact, induces a localized variation in its temperature distribution and, then, the measured values of the surface temperature can be used to localize and evaluate the dimensions and the evolution of defects. In the past, many applications of thermography were proposed on homogeneous materials, but only recently this technique has also been extended to composites. In this work several applications of thermography to fibres reinforced plastics are presented. Thermographic measurements are performed on the surface of the specimens, while undergoing static and dynamic tensile loading. The joint analysis of thermal and mechanical data allows one to assess the damage evolution and to study the damage phenomenon from both mechanical and energetic viewpoints. In particular, one of the main issues is to obtain information about the fatigue behaviour of composite materials, by following an approach successfully applied to homogenous materials. This approach is based on the application of infrared thermography on specimens subjected to static or stepwise dynamic loadings and on the definition of a damage stress, D, that is correlated to the fatigue strength of the material. A wide series of experimental fatigue tests has been carried out to verify if the value of the damage stress, D, is correlated with the fatigue strength of the material. The agreement between the different values is good, showing the reliability of the presented thermographic techniques, to the study of composite

  9. Fiber Optic Thermographic Detection of Flaws in Composites

    Science.gov (United States)

    Wu, Meng-Chou; Winfree, William P.

    2009-01-01

    Optical fibers with multiple Bragg gratings bonded to surfaces of structures were used for thermographic detection of subsurface defects in structures. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The obtained data were analyzed with thermal modeling to reveal particular characteristics of the interested areas. These results were found to be consistent with the simulation results.

  10. Fluid flow in panel radiator under various conditions - thermographic visualisation

    Directory of Open Access Journals (Sweden)

    Bašta Jiří

    2012-04-01

    Full Text Available Thermographic investigation of a heating panel radiator under various conditions, especially with various heating water volume flow rate is described in this article. For a radiator type 10-500x1000 TBOE and for two levels of inlet water temperature (75 and 55 °C a set of thermal images of surface temperature patterns for various values of heating water volume flow rate was taken. The initial value of flow rate was derived from nominal heating output and recalculated to real conditions. An increase of volume flow rate higher than 15 % over the nominal recalculated value is for the studied cases easily detectable on the resulting thermal images.

  11. Quantitative thermographic imagery in the evaluation of antenna heating patterns

    International Nuclear Information System (INIS)

    Pearce, J.A.; Baughman, R.R.

    1984-01-01

    In quantitative thermographic imaging the temperature distribution of a surface is inferred from measurement of the radiant energy leaving the surface. Digital image processing and calibration methods allow the subtraction of preexisting temperature gradients so that precise heating patterns can be obtained. The primary limitation of quantitative thermography is that noise in the photodetector limits minimum resolvable temperature difference to around 0.5 0 C since frame integration cannot be used on the transient temperature distributions expected. The authors have developed and evaluated nonlinear smoothing operators which reduce the noise variance so that temperature differences of 0.1 0 C can be measured. They have applied digital thermographic imaging in the measurement of heating patterns obtained from two roughly orthogonal microwave antennas: a spiral antenna and a bow-tie antenna. These two antenna types are orthogonal in that the spiral has an H-field essentially normal to the phantom surface and the bow-tie has an E-field essentially normal to the surface. The resulting heating patterns clearly show the effect of non-uniform phantom electrical properties on the heating profiles obtained

  12. Thermographic Inspections And The Residential Conservation Service Program (RCS)

    Science.gov (United States)

    Ward, Ronald J.

    1983-03-01

    Rhode Islanders Saving Energy (RISE) is a non-profit corporation founded in 1977 to provide Rhode Island residents with a variety of energy conservation services. Since January of 1981, it has been performing energy audits in compliance with the Department of Energy's (DOE) Residential Conservation Service Program (RCS). One aspect of the RCS program is the performance of inspections on energy conservation activities completed according to RCS installation guidelines. This paper will describe both the use and results of thermographic inspections within the RISE program. The primary objective of these inspections has been to assure the quality of the building envelope after completion of retrofit measures. Thermal anamolies have been detected that vary in size, location and probable cause. Approximately 37% of all jobs performed through RISE in conjunction with the RCS program have required remedial work as a result of problems that were identi-fied during the thermographic inspection. This percentage was much higher when infra-red inspections were conducted on "Non-RCS" retrofits. Statistics will be presented that provide an interesting insight on the quality of retrofit work when performed in associa-tion with a constant inspection process.

  13. Thermographic inspection of pipes, tanks, and containment liners

    Energy Technology Data Exchange (ETDEWEB)

    Renshaw, Jeremy B., E-mail: jrenshaw@epri.com; Muthu, Nathan [Electric Power Research Institute, 1300 West WT Harris Blvd., Charlotte, NC 28262 (United States); Lhota, James R.; Shepard, Steven M., E-mail: sshepard@thermalwave.com [Thermal Wave Imaging, 845 Livernois St., Ferndale, MI 48220 (United States)

    2015-03-31

    Nuclear power plants are required to operate at a high level of safety. Recent industry and license renewal commitments aim to further increase safety by requiring the inspection of components that have not traditionally undergone detailed inspected in the past, such as tanks and liners. NEI 09-14 requires the inspection of buried pipes and tanks while containment liner inspections are required as a part of license renewal commitments. Containment liner inspections must inspect the carbon steel liner for defects - such as corrosion - that could threaten the pressure boundary and ideally, should be able to inspect the surrounding concrete for foreign material that could be in contact with the steel liner and potentially initiate corrosion. Such an inspection requires a simultaneous evaluation of two materials with very different material properties. Rapid, yet detailed, inspection results are required due to the massive size of the tanks and containment liners to be inspected. For this reason, thermal NDE methods were evaluated to inspect tank and containment liner mockups with simulated defects. Thermographic Signal Reconstruction (TSR) was utilized to enhance the images and provide detailed information on the sizes and shapes of the observed defects. The results show that thermographic inspection is highly sensitive to the defects of interest and is capable of rapidly inspecting large areas.

  14. Preparation and photoluminescence properties of Mn2+-activated M2Si5N8 (M = Ca, Sr, Ba) phosphors

    NARCIS (Netherlands)

    Duan, C.J.; Otten, W.M.; Delsing, A.C.A.; Hintzen, H.T.J.M.

    2008-01-01

    Mn2+-doped M2Si5N8 (M=Ca, Sr, Ba) phosphors have been prepared by a solid-state reaction method at high temperature and their photoluminescence properties were investigated. The Mn2+-activated M2Si5N8 phosphors exhibit narrow emission bands in the wavelength range of 500–700 nm with peak center at

  15. SiO{sub 2} effect on spectral and colorimetric properties of europium doped SrO{sub 2}-MgO-xSiO{sub 2} (0.8 {<=} x {<=} 1.6) phosphor for white LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Chen, B J; Jang, K W; Lee, H S; Jayasimhadri, M; Cho, E J [Department of Physics, Changwon National University, Changwon, 641-773 (Korea, Republic of); Yi, S S [Department of Photonics, Silla University, Pusan 617-736 (Korea, Republic of); Jeong, J H [Department of Physics, Pukyong National University, Pusan 608-737 (Korea, Republic of)], E-mail: kwjang@changwon.ac.kr

    2009-05-21

    Silicate phosphors with compositions 1.99 SrO{sub 2}-1.0 MgO-xSiO{sub 2}-0.01 Eu{sub 2}O{sub 3} (x = 0.8, 1.0, 1.2, 1.4 and 1.6) were prepared in a reducing atmosphere via a solid state reaction. The resultant phosphors were examined by using x-ray diffraction and confirmed to be a mixture of monoclinic Sr{sub 2}SiO{sub 4} and orthorhombic Mg{sub 2}(Si{sub 2}O{sub 4}). The scanning electron microscope images revealed that SiO{sub 2} content does not influence the morphology of the resultant phosphors. It was also observed that the excitation spectra are dependent on the monitored emission wavelength, and the emission spectra are dependent on the excitation wavelength and the SiO{sub 2} content. The energy transfer between Eu{sup 2+} ions occupying different Sr{sup 2+} sites was discussed. The colour coordinates for these phosphors are tunable based on both the excitation wavelength and the SiO{sub 2} content.

  16. Tunable white light of a Ce3+,Tb3+,Mn2+ triply doped Na2Ca3Si2O8 phosphor for high colour-rendering white LED applications: tunable luminescence and energy transfer.

    Science.gov (United States)

    Lü, Wei; Xu, Huawei; Huo, Jiansheng; Shao, Baiqi; Feng, Yang; Zhao, Shuang; You, Hongpeng

    2017-07-18

    A tunable white light emitting Na 2 Ca 3 Si 2 O 8 :Ce 3+ ,Tb 3+ ,Mn 2+ phosphor with a high color rendering index (CRI) has been prepared. Under UV excitation, Na 2 Ca 3 Si 2 O 8 :Ce 3+ phosphors present blue luminescence and exhibit a broad excitation ranging from 250 to 400 nm. When codoping Tb 3+ /Mn 2+ ions into Na 2 Ca 3 Si 2 O 8 , energy transfer from Ce 3+ to Tb 3+ and Ce 3+ to Mn 2+ ions is observed from the spectral overlap between Ce 3+ emission and Tb 3+ /Mn 2+ excitation spectra. The energy-transfer efficiencies and corresponding mechanisms are discussed in detail. The mechanism of energy transfer from Ce 3+ to Tb 3+ is demonstrated to be a dipole-quadrupole mechanism by the Inokuti-Hirayama model. The wavelength-tunable white light can be realized by coupling the emission bands centered at 440, 550 and 590 nm ascribed to the contribution from Ce 3+ , Tb 3+ and Mn 2+ , respectively. The commission on illumination value of color tunable emission can be tuned by controlling the content of Ce 3+ , Tb 3+ and Mn 2+ . Temperature-dependent luminescence spectra proved the good thermal stability of the as-prepared phosphor. White LEDs with CRI = 93.5 are finally fabricated using a 365 nm UV chip and the as-prepared Na 2 Ca 3 Si 2 O 8 :Ce 3+ ,Tb 3+ ,Mn 2+ phosphor. All the results suggest that Na 2 Ca 3 Si 2 O 8 :Ce 3+ ,Tb 3+ ,Mn 2+ can act as potential color-tunable and single-phase white emission phosphors for possible applications in UV based white LEDs.

  17. Infrared Thermographic Diagnosis Mechanism for Fault Detection of Ball Bearing under Dynamic Loading Conditions

    International Nuclear Information System (INIS)

    Seo, Jin Ju; Yoon, Hanvit; Kim, Dong Yeon; Hong, Dong Pyo; Kim, Won Tae

    2011-01-01

    Fault detection for dynamic loading conditions of rotational machineries was considered from the contactless, non-destructive infrared thermographic method, rather than the traditional diagnosis method. In this paper, by applying a rotating deep-grooved ball bearing, passive thermographic experiment was performed as an alternative way proceeding the traditional fault monitoring. In addition, the thermographic experiments were compared with the vibration spectrum analysis to evaluate the efficiency of the proposed method. Based on the results, it was concluded the temperature characteristics of the ball bearing under dynamic loading conditions were analyzed thoroughly

  18. Phosphates and phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Becker, P [Compagnie Francaise de l' Azote, Paris (France)

    1983-01-01

    In chapter 8.5 the following aspects of uranium recovery are treated: basis of extraction process, extraction principle, solvents, strength of the acid to be treated, technology, main processes in use, impact of uranium recovery on phosphoric acid plants, and economics of uranium recovery plants.

  19. Aerial thermography from low-cost UAV for the generation of thermographic digital terrain models

    Science.gov (United States)

    Lagüela, S.; Díaz-Vilariño, L.; Roca, D.; Lorenzo, H.

    2015-03-01

    Aerial thermography is performed from a low-cost aerial vehicle, copter type, for the acquisition of data of medium-size areas, such as neighbourhoods, districts or small villages. Thermographic images are registered in a mosaic subsequently used for the generation of a thermographic digital terrain model (DTM). The thermographic DTM can be used with several purposes, from classification of land uses according to their thermal response to the evaluation of the building prints as a function of their energy performance, land and water management. In the particular case of buildings, apart from their individual evaluation and roof inspection, the availability of thermographic information on a DTM allows for the spatial contextualization of the buildings themselves and the general study of the surrounding area for the detection of global effects such as heat islands.

  20. Photoluminescence of Eu{sup 2+}-doped CaMgSi{sub 2x}O{sub 6+2x} (1.00{<=}x{<=}1.20) phosphors in UV-VUV region

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhiya [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang Yuhua [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)], E-mail: wyh@lzu.edu.cn

    2008-03-15

    Alkaline-earth silicate phosphors CaMgSi{sub 2x}O{sub 6+2x}:Eu{sup 2+} (1.00{<=}x{<=}1.20) were prepared by traditional solid-state reaction. The phosphors showed an intense blue emission centered around 453 nm, with both 254 and 147 nm excitations. The host absorption below 200 nm in the excitation spectra consisted of two bands around 160 and 190 nm. The band around 160 nm was ascertained to be associated with the SiO{sub 4}-tetrahedra and MgO{sub 6}-polyhedra, and that around 190 nm was due to the CaO{sub 8}-polyhedra or some impurities. The incorporation of excess Si of less than 15% would not lead to formation of impurities and the results indicated that an appropriate Si excess could improve the Photoluminescence (PL) intensity in both ultraviolet (UV) and vacuum ultraviolet (VUV) regions.

  1. Photoluminescence of Eu2+-doped CaMgSi2xO6+2x (1.00≤x≤1.20) phosphors in UV-VUV region

    International Nuclear Information System (INIS)

    Zhang Zhiya; Wang Yuhua

    2008-01-01

    Alkaline-earth silicate phosphors CaMgSi 2x O 6+2x :Eu 2+ (1.00≤x≤1.20) were prepared by traditional solid-state reaction. The phosphors showed an intense blue emission centered around 453 nm, with both 254 and 147 nm excitations. The host absorption below 200 nm in the excitation spectra consisted of two bands around 160 and 190 nm. The band around 160 nm was ascertained to be associated with the SiO 4 -tetrahedra and MgO 6 -polyhedra, and that around 190 nm was due to the CaO 8 -polyhedra or some impurities. The incorporation of excess Si of less than 15% would not lead to formation of impurities and the results indicated that an appropriate Si excess could improve the Photoluminescence (PL) intensity in both ultraviolet (UV) and vacuum ultraviolet (VUV) regions

  2. Assessment of lower extremity ischemia using smartphone thermographic imaging

    Directory of Open Access Journals (Sweden)

    Peter H. Lin, MD

    2017-12-01

    Full Text Available Conventional diagnostic modalities for assessing arterial circulation or tissue perfusion include blood pressure measurement, ultrasound evaluation, and contrast-based angiographic assessment. An infrared thermal camera can detect infrared radiation energy from the human body, which generates a thermographic image to allow tissue perfusion analysis. We describe a smartphone-based miniature thermal imaging system that can be used as an adjunctive imaging modality to assess tissue perfusion. This smartphone-based camera device is noninvasive, simple to use, and cost-effective in assessing patients with lower extremity tissue perfusion. Assessment of patients with lower extremity arterial ischemia can be performed by a variety of diagnostic modalities, including ankle-brachial index, absolute systolic ankle or toe pressure, transcutaneous oximetry, arterial Doppler waveform, arterial duplex ultrasound, computed tomography scan, arterial angiography, and thermal imaging. We herein describe a noninvasive imaging modality using smartphone-based infrared thermography.

  3. Characterization of Photovoltaic Panels by means of Thermograph Analysis

    Directory of Open Access Journals (Sweden)

    Noe Samano

    2016-01-01

    Full Text Available Solar panels have become attractive in order to generate and supply electricity in commercial and residential applications. Their increased module efficiencies have caused not only a massive production but also a sensible drop on sale prices. Methods of characterization, instrumentation for in situ measurements, defect monitoring, process control, and performance are required. A temperature characterization method by means of thermograph analysis is exposed in this paper. The method was applied to multicrystalline modules, and the characterization was made with respect to two different variables, first a thermal transient and second a characterization with respect to the current. The method is useful in order to detect hot spots caused by mismatch conditions in electrical parameters. The description, results, and limitations of the proposed method are discussed.

  4. Ultraviolet /UV/ sensitive phosphors for silicon imaging detectors

    Science.gov (United States)

    Viehmann, W.; Cowens, M. W.; Butner, C. L.

    1981-01-01

    The fluorescence properties of UV sensitive organic phosphors and the radiometric properties of phosphor coated silicon detectors in the VUV, UV, and visible wavelengths are described. With evaporated films of coronene and liumogen, effective quantum efficiencies of up to 20% have been achieved on silicon photodiodes in the vacuum UV. With thin films of methylmethacrylate (acrylic), which are doped with organic laser dyes and deposited from solution, detector quantum efficiencies of the order of 15% for wavelengths of 120-165 nm and of 40% for wavelengths above 190 nm have been obtained. The phosphor coatings also act as antireflection coatings and thereby enhance the response of coated devices throughout the visible and near IR.

  5. Enhancement of photoluminescence properties and modification of crystal structures of Si{sub 3}N{sub 4} doping Li{sub 2}Sr{sub 0.995}SiO{sub 4}:0.005Eu{sup 2+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Song, Kaixin, E-mail: kxsong@hdu.edu.cn [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhang, Fangfang [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Chen, Daqin [College of Materials Sciences and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Song; Zheng, Peng [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Huang, Qingming [Instrument Analysis and Testing Center, Fuzhou University, Fuzhou 350002 (China); Jiang, Jun [Ningbo Institute of Materials Technologies and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Xu, Junming; Qin, Huibin [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2015-10-15

    Highlights: • Si{sub 3}N{sub 4} modified Li{sub 2}Sr{sub 0.995}SiO{sub 4}:0.005Eu{sup 2+} phosphors were prepared. • The luminescence intensity of Li{sub 2}Sr{sub 0.995}SiO{sub 4}:Eu{sup 2+} was enhanced by doping Si{sub 3}N{sub 4}. • The fluorescence decay times and thermal stability were enhanced by doping Si{sub 3}N{sub 4}. - Abstract: Si{sub 3}N{sub 4} modified Li{sub 2}Sr{sub 0.995}SiO{sub 4}:0.005Eu{sup 2+} (Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+}) phosphors were synthesized with the conventional solid-state reaction in the reduced atmosphere. The crystal structure and vibrational modes were analyzed by X-ray diffraction, Raman scattering spectroscopy and Rietveld crystal structure refinement. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra showed that Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+} powder exhibited a broad yellow emission band centered at 560 nm under the excitation of 460 nm visible light, due to the 4f{sup 6}5d{sup 1} → 4f{sup 7} transition of Eu{sup 2+}. The partial nitridation of Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+} (x = 0.01) phosphors led to a large enhancement in the luminescence intensity, as much as 190%. At the same time, the fluorescence decay behavior curves further showed that the photoluminescence efficiencies of Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+} phosphors were enhanced by addition of Si{sub 3}N{sub 4}. The temperature quenching characteristics confirmed that the oxynitride based Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+} showed slightly higher stability. It is implied that Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+} phosphors had a possible potential application on white LEDs to match blue light chips.

  6. Spectral downshifting in MBO{sub 3}:Nd{sup 3+} (M=Y, La) phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Omanwar, S.K.; Sawala, N.S. [Sant Gadge Baba Amravati University, Department of Physics, Amravati, MH (India)

    2017-11-15

    The spectral downshifting (DS) from ultra-violet (UV)/visible (VIS) light to near infra-red (NIR) radiation in Nd{sup 3+} doped YBO{sub 3} and LaBO{sub 3} phosphors is reported. The prepared materials were characterized by X-ray powder diffraction (XRD) and photoluminescence (PL) properties along with time-decay curves were studied which confirmed the spectral DS from VIS to NIR radiation. This can be employed to overcome the spectral mismatch of crystalline silicon (c-Si) solar cell with solar spectrum. The prepared Nd{sup 3+} doped as prepared phosphors provide NIR emission (1052 nm) at excitation of 586 nm where response of c-Si solar cell was optimum. Thus spectral modification by mentioned phosphor can be utilized to improve solar cells performance. Hence these phosphors have potential application for photovoltaic (PV) technology. (orig.)

  7. Certification of building thermographers: experiences after three courses

    Science.gov (United States)

    Kauppinen, Timo; Hekkanen, Martti; Paloniitty, Sauli; Krankka, Juha

    2006-04-01

    The certification procedure of building thermographers was started in 2003, even though thermography has been used in Finland in building survey since late 70's. There has been about a 25 years' unorganized and more or less wild period, without any generally accepted rules for interpretation, as well as how to order thermography services, how to report the results, how to do the practical work in the buildings etc. The service was provided by consultants with varied backgrounds. More operators have come into the market and building developers and contractors have begun to use thermography for quality control in new building and in renovation planning. In the year 2004 various organizations in building trade launched a pilot project to certificate building thermographers. The structure and the topics of the course were introduced in Thermosense 2005. By the end of the year 2005 the third course was completed. From the beginning of the procedure to the end of the third course about 40 persons have received a certificate. During the certification process, two guidelines have been published, as part of RT (Building Information) - files: instructions for ordering, for practical field work and for reporting of thermography survey in buildings. The guidelines also contain basics for interpretation. The interpretation is consistent with the other existing directions (building codes etc). At the turn of 2005 - 2006 a new book of building thermography was published. There is still lack of comprehensive as well as unambiguous rules for interpretation. In the paper we will present experiences on the courses, the main problems posed to the participants and findings during the last two - three years' field work. We will also introduce briefly the structure and content of the guidelines and an example how to use thermography as a tool of quality control in new building. The case studies are new one-family houses in a housing fair and exhibition area in the city of Oulu.

  8. "Eyeball test" of thermographic patterns for predicting a successful lateral infraclavicular block.

    Science.gov (United States)

    Andreasen, Asger M; Linnet, Karen E; Asghar, Semera; Rothe, Christian; Rosenstock, Charlotte V; Lange, Kai H W; Lundstrøm, Lars H

    2017-11-01

    Increased distal skin temperature can be used to predict the success of lateral infraclavicular (LIC) block. We hypothesized that an "eyeball test" of specific infrared thermographic patterns after LIC block could be used to determine block success. In this observational study, five observers trained in four distinct thermographic patterns independently evaluated thermographic images of the hands of 40 patients at baseline and at one-minute intervals for 30 min after a LIC block. Sensitivity, specificity, and predictive values of a positive and a negative test were estimated to evaluate the validity of specific thermographic patterns for predicting a successful block. Sensory and motor block of the musculocutaneous, radial, ulnar, and median nerves defined block success. Fleiss' kappa statistics of multiple interobserver agreements were used to evaluate reliability. As a diagnostic test, the defined specific thermographic patterns of the hand predicted a successful block with increasing accuracy over the 30-min observation period. Block success was predicted with a sensitivity of 92.4% (95% confidence interval [CI], 86.8 to 96.2) and with a specificity of 84.0% (95% CI, 70.3 to 92.4) at min 30. The Fleiss' kappa for the five observers was 0.87 (95% CI, 0.77 to 0.96). We conclude that visual evaluation by an eyeball test of specific thermographic patterns of the blocked hands may be useful as a valid and reliable diagnostic test for predicting a successful LIC block.

  9. Photoluminescence and absorption spectra of various common TL phosphors - interpretation of TL mechanisms

    International Nuclear Information System (INIS)

    Nagpal, J.S.

    1980-01-01

    Photoluminescence and absorption spectra of TL phosphors TLD-100, CaF 2 :Dy, CaSO 4 :Dy(0.05%wt), CaSO 4 :Tm(0.05%wt) and Mg 2 SiO 4 :Tb have been measured. The absorption spectra are typical of RE 2+ in rare earth doped irradiated phosphors. On heating RE 2+ yields RE 3+ and emission from the excited states of RE 3+ is observed. (author)

  10. Improvements in phosphors

    International Nuclear Information System (INIS)

    Rabatin, J.G.

    1981-01-01

    For X-ray image converter applications, especially when used in medical radiography, it is desirable to improve the speed and brightness of response for conversion of X-rays in phosphors. The rare earth oxyhalide phosphors coactivated with a combination of rare earth activators described in this patent are capable of exhibiting low afterglow with high ultraviolet emission. They have the general formula Lnsub(1-y-w)OX:Tbsub(y)Tmsub(w) where Ln is lanthanum or gadolinium, X is chlorine and/or bromine, y is from 0.0005 to 0.010 moles per mole and w is from 0.00005 to 0.005 moles per mole of the Lnsub(1-y-w)OX host. The method of preparation and characteristics of speed, afterglow and UV emission are described. (U.K.)

  11. Investigation of Luminescence Characteristics of Some Synthetic Nano phosphors and Possibility of Application in Mixed Field Radiation Detection

    International Nuclear Information System (INIS)

    Ahmed, N.Y.A.

    2013-01-01

    The work given in this thesis aimed at Fabrication of high quality nano phosphor particles for getting high sensitive thermoluminescence material to use as ionizing radiation dosimeter. Ca Sr S nano phosphor has been prepared by solid state diffusion reaction method. The prepared nano phosphor was then activated with proper addition of some rare earth elements (dysprosium and gadolinium) for the sake of improving its TL sensitivity. The doped Ca Sr S nano phosphor was then treated by different courses of heat annealing for dual sake and regeneration. High temperature and high gamma dose sensitization are also used to increase sensitivity of Ca Sr S doped. By this means the TL-intensity of treated samples proved about 24 times observed enhancement. The prepared Ca Sr S: Dy nano phosphor is very reliable as pure gamma dosimeter for various applications such as personal, environmental and clinical dosimetry.

  12. Fabrication and characterization of thin-film phosphor combinatorial libraries

    Science.gov (United States)

    Mordkovich, V. Z.; Jin, Zhengwu; Yamada, Y.; Fukumura, T.; Kawasaki, M.; Koinuma, H.

    2002-05-01

    The laser molecular beam epitaxy method was employed to fabricate thin-film combinatorial libraries of ZnO-based phosphors on different substrates. Fabrication of both pixel libraries, on the example of Fe-doped ZnO, and spread libraries, on the example of Eu-doped ZnO, has been demonstrated. Screening of the Fe-doped ZnO libraries led to the discovery of weak green cathodoluminescence with the maximum efficiency at the Fe content of 0.58 mol %. Screening of the Eu-doped ZnO libraries led to the discovery of unusual reddish-violet cathodoluminescence which is observed in a broad range of Eu concentration. No photoluminescence was registered in either system.

  13. A novel orange emissive phosphor SrWO4:Sm3+ for white light-emitting diodes

    International Nuclear Information System (INIS)

    Ju Zhenghua; Wei Ruiping; Ma Jingxin; Pang Chaoran; Liu Weisheng

    2010-01-01

    Research highlights: → A novel orange emissive phosphor SrWO 4 :Sm 3+ was firstly reported. → The optics properties of Sm 3+ -doped SrWO 4 phosphor were successfully discussed. → The temperature-dependent luminescence indicates the phosphor exhibits a small thermal-quenching property. → The phosphor is a potential candidate as orange-emitting component for white LED. - Abstract: A novel orange emissive phosphor, Sm 3+ -doped SrWO 4 , was synthesized by high temperature solid-state reaction in air atmosphere. The excitation spectra show that the phosphors can be efficiently excited by ultraviolet and near-ultraviolet light, the optimized concentration is 4 mol%. Three emission peaks locate at 562, 596 and 642 nm, corresponding to CIE chromaticity coordinates of (x = 0.54, y = 0.46), which indicates the orange light emitting. The decay curves are well fitted with triple-exponential decay models. The quantum yield of the Sr 0.96 Sm 0.04 WO 4 phosphor is about 70.65% under excitation of 377 nm. Furthermore, the temperature-dependent luminescence indicates the phosphor exhibits a small thermal-quenching property. So the phosphor is able to be applied to UV-LED chip-based white light-emitting diodes.

  14. Thermally stimulated properties in ZnSe:Tb and ZnSe:(Mn, Tb) phosphors

    Science.gov (United States)

    Mishra, A. K.; Mishra, S. K.; Pandey, S. P.; Lakshmi Mishra, Kshama

    2018-02-01

    Thermoluminescence studies were performed of ZnSe:Tb and ZnSe:(Mn, Tb) phosphors. A method of preparation for ZnSe phosphors doped with Tb and (Mn, Tb) has been discussed. The thermoluminescence (TL) properties of these phosphors have been studied from 100 to 370 K temperature after exciting by UV radiation (365 nm) at three uniform heating rates 0.4, 0.6 and 0.9 K/s. The trapping parameters like trap depth, lifetime of electrons and capture cross-section have also been determined using various methods.

  15. Laser discrimination by stimulated emission of a phosphor

    Science.gov (United States)

    Mathur, V. K.; Chakrabarti, K.

    1991-01-01

    A method for discriminating sources of UV, near infrared, and far infrared laser radiation was discovered. This technology is based on the use of a single magnesium sulfide phosphor doubly doped with rare earth ions, which is thermally/optically stimulated to generate colors correlatable to the incident laser radiation. The phosphor, after initial charging by visible light, exhibits green stimulated luminescence when exposed to a near infrared source (Nd: YAG laser). On exposure to far infrared sources (CO2 laser) the phosphor emission changes to orange color. A UV laser produces both an orange red as well as green color. A device using this phosphor is useful for detecting the laser and for discriminating between the near infrared, far infrared, and UV lasers. The technology is also capable of infrared laser diode beam profiling since the radiation source leaves an imprint on the phosphor that can be photographed. Continued development of the technology offers potential for discrimination between even smaller bandwidths within the infrared spectrum, a possible aid to communication or wavemixing devices that need to rapidly identify and process optical signals.

  16. Up-conversion routines of Er{sup 3+}–Yb{sup 3+} doped Y{sub 6}O{sub 5}F{sub 8} and YOF phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sangmoon, E-mail: spark@silla.ac.kr [Center for Green Fusion Technology and Department of Engineering in Energy & Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of); Yang, Wonseok; Park, Chu-Young; Noh, Minhee; Choi, Seulki [Center for Green Fusion Technology and Department of Engineering in Energy & Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of); Park, Dahye; Jang, Ho Seong; Cho, So-Hye [Center for Materials Architecturing, Institute of Multidisciplinary Convergence of Materials, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of)

    2015-11-15

    Highlights: • Single-phase optical materials of Y{sub 6}O{sub 5}F{sub 8}:Er and YOF:Er were prepared. • Effective spectral converting properties were observed in Y{sub 6}O{sub 5}F{sub 8}:Er,Yb. • 980 nm diode laser was irradiated for up-converting analysis. • A multi-photon process in the phosphors was investigated. - Abstract: Optical materials composed of a Y{sub 6(1−p−q)}Er{sub 6p}Yb{sub 6q}O{sub 5}F{sub 8} (p = 0.001–0.1, q = 0.005–0.1) solid solution with Y{sub 0.99}Er{sub 0.01}OF were prepared via a solid-state reaction using excess NH{sub 4}F flux at 950 °C for 30 min. X-ray diffraction patterns of Y{sub 6(1−p−q)}Er{sub 6p}Yb{sub 6q}O{sub 5}F{sub 8} and Y{sub 0.99}Er{sub 0.01}OF were compared upon altering the synthesis temperature and the molar ratio of the NH{sub 4}F flux to the Y{sup 3+} (Er{sup 3+}, Yb{sup 3+}) ions. The effective spectral-conversion properties of Er{sup 3+} and Er{sup 3+}–Yb{sup 3+} ions in Y{sub 6}O{sub 5}F{sub 8} phosphors were monitored during excitation with a 980 nm wavelength diode-laser. Selection of appropriate Er{sup 3+} and/or Yb{sup 3+} concentrations in the Y{sub 6}O{sub 5}F{sub 8} structure led to achievement of the desired up-conversion emission, from the green to the red regions of the spectra. Furthermore, the mechanism of up-conversion in the phosphors was described by an energy-level schematic. Up-conversion emission spectra and the dependence of the emission intensity on pump power (between 193 and 310 mW) in the Y{sub 6(0.995−q)}Er{sub 0.03}Yb{sub 6q}O{sub 5}F{sub 8} phosphors were also investigated.

  17. High-efficient, bicolor-emitting GdVO_4:Dy"3"+ phosphor under near ultraviolet excitation

    International Nuclear Information System (INIS)

    Lu, Jinjin; Zhou, Jia; Jia, Huayu; Tian, Yue

    2015-01-01

    Bicolor emitting GdVO_4:Dy"3"+ phosphor with short columniation-shape was prepared via a simple co-precipitation process. The optimal doping concentration for obtaining maximal luminescent intensity was confirmed to be 0.3 mol% and the electric dipole–dipole interaction is responsible for concentration quenching of Dy"3"+ emission in GdVO_4 phosphor. In order to evaluate the luminescent performance of as-prepared phosphor, the luminescent efficiency and color coordinates were studied. The results show that luminescent efficiency of this phosphor is very high under near UV excitation and twice times higher than commercial Y_2O_2S:Eu"3"+ phosphor. In addition, the color coordinates for optimal Dy"3"+ concentration are (0.339, 0.379), which are close to equal energy point. Therefore, the GdVO_4:Dy"3"+ phosphor may have potential application for solid state lighting.

  18. PRE AND POSTPRANDIAL THERMOGRAPHIC PROFILE OF GREEN IGUANAS (IGUANA IGUANA

    Directory of Open Access Journals (Sweden)

    Simona Rusu

    2016-11-01

    Full Text Available Abstract The body temperature of 10 clinically healthy green iguanas (Iguana iguana was measured using a thermographic camera (FLIR E6, Flir Systems Sweden before and after the food was offered. For each animal there were performed a total of 6 measurements (3 before feeding and 3 after the food was offered. The purpose of this experiment was to observe the thermographic pattern of the body before and after the feeding, since herbivore reptiles tend to bask after the feeding to increase the body temperature that will help them afterwards digest the food. The animals were housed in individual vivariums with every animal having a basking spot available. The pictures were taken outside the vivarium in an adjacent room. The animals were handled with gloves and transported in a cardboard box in order to avoid heat transfer between the handler and the iguana that would have produced thermal artefacts. Each individual was placed on a table on a styrofoam slate, again, to avoid the heat transfer between the table and the animal`s body. For each animal a total of 4 pictures were taken (up, front, left and right. The pictures were analysed with the FLIR Tools program that is provided by the manufacturer and 3 temperatures were taken into consideration (the head temperature, body temperature on the right side and body temperature on the left side. The temperatures were compared between them and with the temperature of the vivariums that consisted of the average between the temperature in 3 different spots (basking spot, the feeding bowl site and the coldest spot measured with an infrared thermometer GM300 (Benetech, China. The temperature of the body was dependent on the vivarium temperature and it was a significant temperature difference between the measurements before the feeding and after the feeding. Also we discovered a significant difference between the head temperature and the body temperature on the left side before the feeding that disappeared

  19. Thermographic and microscopic evaluation of LARS knee ligament tearing.

    Science.gov (United States)

    Pătraşcu, Jenel Marian; Amarandei, Mihaela; Kun, Karla Noemy; Borugă, Ovidiu; Totorean, Alina; Andor, Bogdan; Florescu, Sorin

    2014-01-01

    Damage to knee articular ligaments causes important functional problems and adversely affects particularly the stability of the knee joint. Several methods were developed in order to repair damage to the anterior cruciate ligament (ACL), which employ autografts, allografts, as well as synthetic ligaments. One such synthetic scaffold, the ligament advanced reinforcement system (LARS) synthetic ligament is made of non-absorbing polyethylene terephthalate fibers whose structure allow tissue ingrowths in the intra-articular part, improving the stability of the joint. The LARS ligament is nowadays widely used in modern knee surgery in the Europe, Canada, China or Japan. This paper evaluates LARS ligament from two perspectives. The first regards a study done by the Orthopedics Clinic II, Timisoara, Romania, which compared results obtained by employing two techniques of ACL repair - the Bone-Tendon-Bone (BTB) or LARS arthroscopic, intra-articular techniques. This study found that patients treated with the BTB technique presented with an IKDC score of 45.82±1.14 units preoperative, with increasing values in the first nine months after each implant post-surgical ligament restoration, reaching an average value of 75.92 ± 2.88 units postoperative. Patients treated with the LARS technique presented with an IKDC score of 43.64 ± 1.11 units preoperative, and a score of 77.32 ± 2.71 units postoperative. The second perspective describes the thermographic and microscopic analysis of an artificial knee ligament tearing or loosening. The objective of the study was to obtain information regarding the design of artificial ligaments in order to expand their lifespan and avoid complications such as recurring synovitis, osteoarthritis and trauma of the knee joint. Thermographic data has shown that tearing begins from the inside out, thus improving the inner design of the ligament would probably enhance its durability. An optical microscope was employed to obtain images of structural

  20. Thermographic measurements of high-speed metal cutting

    Science.gov (United States)

    Mueller, Bernhard; Renz, Ulrich

    2002-03-01

    Thermographic measurements of a high-speed cutting process have been performed with an infrared camera. To realize images without motion blur the integration times were reduced to a few microseconds. Since the high tool wear influences the measured temperatures a set-up has been realized which enables small cutting lengths. Only single images have been recorded because the process is too fast to acquire a sequence of images even with the frame rate of the very fast infrared camera which has been used. To expose the camera when the rotating tool is in the middle of the camera image an experimental set-up with a light barrier and a digital delay generator with a time resolution of 1 ns has been realized. This enables a very exact triggering of the camera at the desired position of the tool in the image. Since the cutting depth is between 0.1 and 0.2 mm a high spatial resolution was also necessary which was obtained by a special close-up lens allowing a resolution of app. 45 microns. The experimental set-up will be described and infrared images and evaluated temperatures of a titanium alloy and a carbon steel will be presented for cutting speeds up to 42 m/s.

  1. A Thermographic Measurement Approach to Assess Supercapacitor Electrical Performances

    Directory of Open Access Journals (Sweden)

    Stanislaw Galla

    2017-12-01

    Full Text Available This paper describes a proposal for the qualitative assessment of condition of supercapacitors based on the conducted thermographic measurements. The presented measurement stand was accompanied by the concept of methodology of performing tests. Necessary conditions, which were needed to minimize the influence of disturbing factors on the performance of thermal imaging measurements, were also indicated. Mentioned factors resulted from both: the hardware limitations and from the necessity to prepare samples. The algorithm that was used to determine the basic parameters for assessment has been presented. The article suggests to use additional factors that may facilitate the analysis of obtained results. Measuring the usefulness of the proposed methodology was tested on commercial samples of supercapacitors. All of the tests were taken in conjunction with the classical methods based on capacitance (C and equivalent series resistance (ESR measurements, which were also presented in the paper. Selected results presenting the observed changes occurring in both: basic parameters of supercapacitors and accompanying fluctuations of thermal fields, along with analysis, were shown. The observed limitations of the proposed assessment method and the suggestions for its development were also described.

  2. Automated system for crack detection using infrared thermograph

    International Nuclear Information System (INIS)

    Starman, Stanislav

    2009-01-01

    The objective of this study was the development of the automated system for crack detection on square steel bars used in the automotive industry for axle and shaft construction. The automated system for thermographic crack detection uses brief pulsed eddy currents to heat steel components under inspection. Cracks, if present, will disturb the current flow and so generate changes in the temperature profile in the crack area. These changes of temperature are visualized using an infrared camera. The image acquired by the infrared camera is evaluated through an image processing system. The advantages afforded by the system are its inspection time, its excellent flaw detection sensitivity and its ability to detect hidden, subsurface cracks. The automated system consists of four IR cameras (each side of steel bar is evaluated at a time), coil, high frequency generator and control place with computers. The system is a part of the inspection line where the subsurface and surface cracks are searched. If the crack is present, the cracked place is automatically marked. The components without cracks are then deposited apart from defective blocks. The system is fully automated and its ability is to evaluate four meter blocks within 20 seconds. This is the real reason for using this system in real industrial applications. (author)

  3. A study of mammographic and thermographic findings in breast diseases

    International Nuclear Information System (INIS)

    Cho, Won Sik; Jeon, Woo Ki; Kim, Jeong Sook; Han, Chang Yul

    1989-01-01

    The ideal diagnostic methods in breast diseases consist of the physical examination and complementary radiologic examination. In radiologic examination mammography is the most popular screening methods and the older simple complementary method is thermography which is efficient under the conditions of elevated skin temperature in inflammatory and malignant lesions. From Jan. 1st 1987 through Jan. 30th, 1988, 110 pts. with complaints of mammary problems were examined by mammography and thermography at Paik Hospital, Inje University. The authors selected and analyzed 97 cases had been pathologically proved through the operation and the fine needle aspiration biopsy. The results were as follows: 1. The most prevalent age group was 5th decade (40%) in cancer, 4th decade (47%) in mammary dysplasia and followed by fibroadenoma (63%) in 4th decade. 2. The mammographic and thermographic findings were compared between the mammary dysplasia and the infiltrating ductal cancer. In mammary dysplasia abnormal hot emissions were appeared in 9/44 (17%) correlated with atypical hyperchromatic cytoplasm relates to pre-malignant group. 3. We hope and expect the early detection of breast cancer through the follow-up study in pre-malignant group of mammary dysplasia

  4. Recovering uranium from phosphoric acid

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Wet-process phosphoric acid contains a significant amount of uranium. This uranium totals more than 1,500 tons/yr in current U.S. acid output--and projections put the uranium level at 8,000 tons/yr in the year 2000. Since the phosphoric acid is a major raw material for fertilizers, uranium finds its way into those products and is effectively lost as a resource, while adding to the amount of radioactive material that can contaminate the food chain. So, resource-conservation and environmental considerations both make recovery of the uranium from phosphoric acid desirable. This paper describes the newly developed process for recovering uranium from phosphoric acid by using solvent-extraction technique. After many extractants had been tested, the researchers eventually selected the combination of di (2-ethylhexyl) phosphoric acid (DEPA) and trioctylphosphine oxide (TOPO) as the most suitable. The flowscheme of the process is included

  5. Recent advances in rare earth doped alkali-alkaline earth borates for solid state lighting applications

    Science.gov (United States)

    Verma, Shefali; Verma, Kartikey; Kumar, Deepak; Chaudhary, Babulal; Som, Sudipta; Sharma, Vishal; Kumar, Vijay; Swart, Hendrik C.

    2018-04-01

    As a novel class of inorganic phosphor, the alkali-alkaline earth borate phosphors have gained huge attention due to their charming applications in solid-state lighting (SSL) and display devices. The current research drive shows that phosphors based on the alkali-alkaline earth borates have transformed the science and technology due to their high transparency over a broad spectral range, their flexibility in structure and durability for mechanical and high-laser applications. Recent advances in various aspects of rare-earth (RE) doped borate based phosphors and their utilizations in SSL and light emitting diodes are summarized in this review article. Moreover, the present status and upcoming scenario of RE-doped borate phosphors were reviewed in general along with the proper credential from the existing literature. It is believed that this review is a sole compilation of crucial information about the RE-doped borate phosphors in a single platform.

  6. Effect of synthesis methods on luminescence properties of LiCaPO{sub 4}:Ce phosphor for radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Palan, C.B., E-mail: chetupalan@rediffmail.com; Omanwar, S.K.

    2016-10-15

    The polycrystalline doped and un-doped LiCaPO{sub 4} phosphors were successfully prepared via solid state diffusion [SSD] and sol–gel [SG] methods. The sol–gel method was implied to decrease the processing time and heating temperature. The prepared un-doped and doped LiCaPO{sub 4} phosphors were characterized through X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Additionally photoluminescence (PL), thermoluminescence (TL) and optically stimulated luminescence (OSL) properties were studied. The XRD patterns of prepared LiCaPO{sub 4} and LiCaPO{sub 4}:Ce phosphors were well matched with the ICDD file. The average particles size of LiCaPO{sub 4} and LiCaPO{sub 4}:Ce phosphors were found to be in the range 2–10 μm by SSD method and 2-5 μm by SG method. The excitation spectra of LiCaPO{sub 4} and LiCaPO{sub 4}:Ce phosphors consist of broad band in the range 200–330 nm and maximum intensity was observed at 314 nm. Also emission spectra consist of broad band in range from 330–500 nm and maximum intensity was observed at 369 nm. With the increase of Ce{sup 3+} ions concentration, the emission spectra of LiCaPO{sub 4}:Ce{sup 3+} phosphors shifted to a longer wavelength. The prepared phosphors were showed excellent TL properties under β irradiation. The OSL sensitivity of the LiCaPO{sub 4}:Ce phosphor synthesized by the SSD method was the nearly same as compared with the OSL sensitivity of LiCaPO{sub 4}:Ce phosphor synthesized by the SG method.

  7. Integrated procedures and monitoring methodologies for thermographic investigations of architectural heritage: two applicative cases in Sicily, Italy

    International Nuclear Information System (INIS)

    Bianco, A.

    2013-01-01

    The paper explains some opportunities and limitations of thermographic investigations in terms of their capability to define the conservative conditions of architectural heritage and in terms of the historical recollection for a technical diagnosis. Different approaches are demonstrated in two case studies: the first integrates thermography with other investigative methods; the second combines thermographic monitoring with hygrothermal monitoring. (author)

  8. Photoluminescent properties of Sr2CeO4: Eu3+ and Sr2CeO4: Eu2+ phosphors suitable for near ultraviolet excitation

    International Nuclear Information System (INIS)

    Suresh, K.; Poornachandra Rao, N.V.; Murthy, K.V.R.

    2014-01-01

    Powder phosphors of 1 mol% Eu 3+ - and Eu 2+ -doped strontium cerium oxide (Sr 2 CeO 4 ) were synthesized by standard solid-state reaction method. Eu 3+ - and Eu 2+ -doped Sr 2 CeO 4 phosphors fired at 1100 ℃ for 2 h were analysed by X-ray diffraction (XRD) and photoluminescence (PL) techniques. The XRD patterns confirm that the obtained phosphors are a single phase of Sr 2 CeO 4 composed of orthorhombic structure. Room temperature PL excitation spectrum of air-heated Sr 2 CeO 4 : Eu phosphor has exhibited bands at 260, 280 and 350 nm. Whereas the excitation spectrum of Sr 2 CeO 4 : Eu phosphor heated under reducing (carbon) atmosphere exhibited single broadband range from 260 to 390 nm. The (PL) emission peaks of both the phosphors at 467 (blue), 537 (green) and 616 nm (red) generate white light under 260, 280 and 350 nm excitation wavelengths. The Commission International de l'Eclairage (CIE) colour coordinates conforms that these phosphors emitting white light. The results reveal that these phosphors are multifunctional phosphors which emit white light under these excitations that they could be used as white components for display and lamp devices and as well as possible good light-conversion phosphor LEDs under near-ultraviolet (nUV) chip. (author)

  9. X-ray absorption spectroscopy on phosphoric-salt pellets. Determination of the geometric and electronic structure of metal-oxide doped sodium-phosphate glasses; Roentgenabsorptionsspektroskopie an Phosphorsalzperlen. Bestimmung der geometrischen und elektronischen Struktur von metalloxid-dotierten Natriumphosphatglaesern

    Energy Technology Data Exchange (ETDEWEB)

    Brendebach, B.

    2004-02-01

    Sodium metaphosphate glasses doped with transition metal oxides show characteristic colors. X-ray absorption spectroscopy (XAS) investigations provide information whether the coloration stems from different electronic transitions or changes in the geometrical structure of the glasses. Even though the violet color of MnO{sub y}-doped glasses is considered as an evidence for Mn{sup 3+}-ions, Mn K-XAS reveals that the majority of the manganese ions are in the oxidation state +II and have a mixed coordination of four and six oxygen atoms, respectively. The oxygen coordination around the nickel ions in NiO-doped glasses with different metall oxide concentrations is always six. The change of color from citreous to auburn with increasing nickel oxide content is attributed to a systematic change in the bonding characteristic from mainly ionic-like to a small but significant contribution of covalent-like bonding. Analysis of higher coordination shells provides no indication of the formation of metal oxide clusters. (orig.)

  10. Mass prophylactic screening of the organized female populaton using the Thermograph-Computer System

    International Nuclear Information System (INIS)

    Vepkhvadze, R.Ya.; Khvedelidze, E.Sh.

    1984-01-01

    Organizational aspects of the Thermograph Computer System usage have been analyzed. It has been shown that results of thermodiagnosis completely coincide with clinical conclusion, but roentrenological method permits to reveal a disease only for 19 patients from 36 ones. It is possible to examine 120 women for the aim of early diagnosis of mammary gland diseases during the day operating hours with the use of the Thermograph Computer System. A movable thermodiagnostic room simultaneoUsly served as an inspection room to discover visual forms of tumor diseases including diseases of cervix uteri and may be used for mass preventive examination of the organized female population

  11. Treatment of Reflex sympathetic dystrophy with Bee venom -Using Digital Infrared Thermographic Imaging-

    Directory of Open Access Journals (Sweden)

    Myung-jang Lim

    2006-12-01

    Full Text Available Objectives : The purpose of this case is to report the patient with Reflex sympathetic dystrophy, who is improved by Bee venom. Method : We treated the patient with Bee venom who was suffering from Reflex sympathetic dystrophy, using Digital Infrared Thermographic Imaging and Verbal Numerical Rating Scale(VNRS to evaluate the therapeutic effects. We compared the temperature of the patient body before and after treatment. Result and Conclusion : We found that Bee venom had excellent outcome to relieve pain, atrophy and ankle joint ROM, and that Bee venom also had clinical effect on hypothermia on the Digital Infrared Thermographic Imaging.

  12. Application of SVM classifier in thermographic image classification for early detection of breast cancer

    Science.gov (United States)

    Oleszkiewicz, Witold; Cichosz, Paweł; Jagodziński, Dariusz; Matysiewicz, Mateusz; Neumann, Łukasz; Nowak, Robert M.; Okuniewski, Rafał

    2016-09-01

    This article presents the application of machine learning algorithms for early detection of breast cancer on the basis of thermographic images. Supervised learning model: Support vector machine (SVM) and Sequential Minimal Optimization algorithm (SMO) for the training of SVM classifier were implemented. The SVM classifier was included in a client-server application which enables to create a training set of examinations and to apply classifiers (including SVM) for the diagnosis and early detection of the breast cancer. The sensitivity and specificity of SVM classifier were calculated based on the thermographic images from studies. Furthermore, the heuristic method for SVM's parameters tuning was proposed.

  13. Infrared-thermographic screening of the activity and enantioselectivity of enzymes.

    Science.gov (United States)

    Reetz, M T; Hermes, M; Becker, M H

    2001-05-01

    The infrared radiation caused by the heat of reaction of an enantioselective enzyme-catalyzed transformation can be detected by modern photovoltaic infrared (IR)-thermographic cameras equipped with focal-plane array detectors. Specifically, in the lipase-catalyzed enantioselective acylation of racemic 1-phenylethanol, the (R)- and (S)-substrates are allowed to react separately in the wells of microtiter plates, the (R)-alcohol showing hot spots in the IR-thermographic images. Thus, highly enantioselective enzymes can be identified at kinetic resolution.

  14. Luminescence properties of CdSiO3:Mn2+ phosphor

    International Nuclear Information System (INIS)

    Lei Bingfu; Liu Yingliang; Ye Zeren; Shi Chunshan

    2004-01-01

    A novel long-lasting phosphor CdSiO 3 :Mn 2+ is reported in this paper. The Mn 2+ -doped CdSiO 3 phosphor emits orange light with CIE chromaticity coordinates x=0.5814 and y=0.4139 under 254 nm UV light excitation. In the emission spectrum of 1% Mn 2+ -doped CdSiO 3 phosphor, there is a broad emission band centered at 575 nm which can be attributed to the spin-forbidden transition of the d-orbital electron associated with the Mn 2+ ion. The phosphorescence can be seen by the naked eyes in the dark clearly even after the 254 nm UV irradiation have been removed for about 1 h. The mechanism of the origin of the long-lasting phosphorescence was discussed using the thermoluminescence curves

  15. Luminescence properties of Na2Sr2Al2PO4Cl9:Sm3+ phosphor

    Science.gov (United States)

    Tamboli, Sumedha; Shahare, D. I.; Dhoble, S. J.

    2018-04-01

    A series of Sm3+ ions doped Na2Sr2Al2PO4Cl9 phosphors were synthesized via solid state synthesis method. Photoluminescence (PL) emission spectra were obtained by keeping excitation wavelength at 406 nm. Emission spectra show three emission peaks at 563 nm, 595 nm and 644 nm. The CIE chromaticity diagram shows emission colour of the phosphor in the orange-red region of the visible spectrum, indicating that the phosphor may be useful in preparing orange light-emitting diodes. Na2Sr2Al2PO4Cl9:Sm3+ phosphors were irradiated by γ-rays from a 60Co source and β-rays from a 90Sr source. Their thermoluminescence (TL) glow curves were obtained by Nucleonix 1009I TL reader. TL Trapping parameters such as activation energy of trapped electrons and order of kinetics were obtained by using Chen's peak shape method, Glow curve fitting method and initial rise method.

  16. Structural and spectral properties of MgZnO2:Sm3+ phosphor

    Science.gov (United States)

    Rajput, Preasha; Sharma, Pallavi; Biswas, Pankaj; Kamni

    2018-05-01

    The samarium doped MgZnO2 phosphor was synthesized by the low-cost combustion method. The powder X-ray diffraction (XRD) analysis confirmed the crystallinity and phase purity of the phosphor. The lattice parameters were determined by indexing the diffraction peaks. The photoluminescence (PL) study revealed that the phosphor exhibited a broad excitation band in the UV region ranging between 200 to 350 nm. The 601 nm emission was ascribed to 4G5/2 to 6H7/2 transitions of the Sm3+ ion. The optical bandgap of MgZnO2:Sm3+ was obtained to be 3.56 eV. The phosphor can be projected as a useful material in X- and gamma-ray scintillators.

  17. Photoluminescence properties of Eu2+-activated Ca2Y2Si2O9 phosphor

    NARCIS (Netherlands)

    Zhang, Zhijun; Delsing, A.C.A.; Notten, P.H.L.; Zhao, Jingtai; Hintzen, H.T.J.M.

    2012-01-01

    Eu2+-activated Ca2Y2Si2O9 phosphors with different Eu2+ concentrations have been prepared by a solid-state reaction method at high temperature and their photoluminescence (PL) properties were investigated. Photoluminescence results show that Eu2+-doped Ca2Y2Si2O9 can be efficiently excited by

  18. Enhanced exciton emission from ZnO nano-phosphor induced by Yb3+ ions

    CSIR Research Space (South Africa)

    Kabongo, GL

    2014-01-01

    Full Text Available In this work, the sol–gel method was used to prepare Ytterbium (Yb(sup3+)) doped ZnO nano-phosphors with different concentrations of Yb(sup3+) ions. Their structural, morphological, photoluminescence, electronic states and the chemical composition...

  19. Synthesis and cathodoluminescent properties of Y2SiO5:Tb3+ phosphors prepared from uniform precursor

    International Nuclear Information System (INIS)

    Fan Deyong; Yang Sen; Wang Jieqiong; Zheng Aqun; Song Xiaoping; Yu Demei

    2012-01-01

    The luminescent properties of phosphors are sensitive to the size of phosphor particles. The commercial Y 2 SiO 5 :Tb 3+ phosphors usually show relatively larger particle size (5–10 μm) due to the irregular morphology of rare earth oxide precursor and thus degrade the luminescent properties. In this paper, we report the Y 2 SiO 5 :Tb 3+ phosphors synthesized from the uniform Tb-doped Y 2 O 3 precursor by a homogeneous precipitation method. Compared with the commercial phosphors, the obtained Y 2 SiO 5 :Tb 3+ phosphors manifest the uniform morphology with much smaller particles distributing from 0.8 μm to 1.9 μm. Consequently, the cathodoluminescent intensity under low excitation voltage (1–5 kV) was increased, demonstrating a strong green emission with a dominant wavelength of 545 nm. Our results indicate an effective way to develop the high-quality phosphors for field emission display. - Highlights: ► The Y 2 SiO 5 :Tb 3+ phosphors are synthesized by a homogeneous precipitation method. ► They manifest the uniform morphology with much smaller particles than commercial one. ► The corresponding cathodoluminescent intensity of green emission is greatly enhanced. ► Our results indicate an effective way to develop the high-quality phosphors for FED.

  20. Intense blue upconversion emission and intrinsic optical bistability in Tm3+/Yb3+/Zn2+ tridoped YVO4 phosphors

    Science.gov (United States)

    Yadav, Manglesh; Mondal, Manisha; Mukhopadhyay, Lakshmi; Rai, Vineet Kumar

    2018-04-01

    Tm3+/Yb3+/Zn2+:yttrium metavanadate (YVO4) phosphors prepared through chemical coprecipitation and the solid state reaction method have been structurally characterized by an x-ray diffraction (XRD) study. Photoluminescence study of the developed phosphors under ultraviolet (UV) and near infrared (NIR) excitation has been performed. The excitation spectrum of the tetragonal zircon type YVO4 phosphors corresponding to the emission at ˜476 nm exhibits a broad excitation peak in the 250-350 nm region, which is due to charge distribution in the {{{{VO}}}4}3- group. Under 980 nm CW diode laser excitation, enhancements of about ˜3000 times and ˜40 times have been observed for the blue band in the tridoped Tm3+Yb3+Zn2+:YVO4 phosphors compared to those of the Tm3+:YVO4 singly and Tm3+/Yb3+:YVO4 codoped phosphors, respectively. A downconversion (DC) emission study shows an enhancement of about ˜50 times for the blue band in the tridoped phosphors compared to that of the singly doped phosphors. Optical bistability (OB) behavior of the developed phosphors has been also investigated upon 980 nm excitation. The calculated Commission Internationale de l’Éclairage (CIE) color coordinates lie in the blue region with 96.5% color purity under 980 nm excitation, having a color temperature of ˜3400 K. Our observations show that the developed phosphors may be suitably used in dual mode luminescence spectroscopy, display devices, and UV LED chips.

  1. Phase transition and multicolor luminescence of Eu2+/Mn2+-activated Ca3(PO4)2 phosphors

    International Nuclear Information System (INIS)

    Li, Kai; Chen, Daqin; Xu, Ju; Zhang, Rui; Yu, Yunlong; Wang, Yuansheng

    2014-01-01

    Graphical abstract: We have synthesized Eu 2+ doped and Eu 2+ /Mn 2+ co-doped Ca 3 (PO 4 ) 2 phosphors. The emitting color varies from blue to green with increasing of Eu 2+ content for the Eu 2+ -doped phosphor, and the quantum yield of the 0.05Eu 2+ : Ca 2.95 (PO 4 ) 2 sample reaches 56.7%. Interestingly, Mn 2+ co-doping into Eu 2+ : Ca 3 (PO 4 ) 2 leads to its phase transition from orthorhombic to rhombohedral, and subsequently generates tunable multi-color luminescence from green to red via Eu 2+ → Mn 2+ energy transfer. - Highlights: • A series of novel Eu 2+ : Ca 3 (PO 4 ) 2 phosphors were successfully synthesized. • Phase transition of Ca 3 (PO 4 ) 2 from orthorhombic to rhombohedral occurred when Mn 2+ ions were doped. • The phosphors exhibited tunable multi-color luminescence. • The quantum yield of 0.05Eu 2+ : Ca 2.95 (PO 4 ) 2 phosphor can reach 56.7%. • The analyses of phosphors were carried out by many measurements. - Abstract: Intense blue-green-emitting Eu 2+ : Ca 3 (PO 4 ) 2 and tunable multicolor-emitting Eu 2+ /Mn 2+ : Ca 3 (PO 4 ) 2 phosphors are prepared via a solid-state reaction route. Eu 2+ -doped orthorhombic Ca 3 (PO 4 ) 2 phosphor exhibits a broad emission band in the wavelength range of 400–700 nm with a maximum quantum yield of 56.7%, and the emission peak red-shifts gradually from 479 to 520 nm with increase of Eu 2+ doping content. Broad excitation spectrum (250–420 nm) of Eu 2+ : Ca 3 (PO 4 ) 2 matches well with the near-ultraviolet LED chip, indicating its potential applications as tri-color phosphors in white LEDs. Interestingly, Mn 2+ co-doping into Eu 2+ : Ca 3 (PO 4 ) 2 leads to its phase transition from orthorhombic to rhombohedral, and subsequently generates tunable multi-color luminescence from green to red via Eu 2+ → Mn 2+ energy transfer, under 365 nm UV lamp excitation

  2. Uranium extraction from phosphoric acid

    International Nuclear Information System (INIS)

    Lounis, A.

    1983-05-01

    A study has been carried out for the extraction of uranium from phosphoric acid produced in Algeria. First of all, the Algerian phosphoric acid produced in Algeria by SONATRACH has been characterised. This study helped us to synthesize a phosphoric acid that enabled us to pass from laboratory tests to pilot scale tests. We have then examined extraction and stripping parameters: diluent, DZEPHA/TOPO ratio and oxidising agent. The laboratory experiments enabled us to set the optimum condition for the choice of diluent, extractant concentration, ratio of the synergic mixture, oxidant concentration, redox potential. The equilibrium isotherms lead to the determination of the number of theoretical stages for the uranium extraction and stripping of uranium, then the extraction from phosphoric acid has been verified on a pilot scale (using a mixer-settler)

  3. EPR and optical properties of Eu{sup 2+} and Mn{sup 2+} co-doped MgSrAl{sub 10}O{sub 17} blue–green light emitting powder phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Singh, N. [Department of Chemical Engineering, Konkuk University, Seoul 143-701 (Korea, Republic of); Singh, Vijay, E-mail: vijayjiin2006@yahoo.com [Department of Chemical Engineering, Konkuk University, Seoul 143-701 (Korea, Republic of); Sivaramaiah, G. [Department of Physics, Government College (M), Kadapa 516 004 (India); Rao, J.L. [Department of Physics, Sri Venkateswara University, Tirupati 517 502 (India); Singh, Pramod K. [Materials Research Laboratory, Sharda University, Greater Noida 201 310 (India); Pathak, M.S. [Department of Chemical Engineering, Konkuk University, Seoul 143-701 (Korea, Republic of); Dhoble, S.J. [Department of Physics, RTM Nagpur University, Nagpur 440 033 (India); Mohapatra, M. [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2016-10-15

    Strong blue–green light emitting MgSrAl{sub 10}O{sub 17}:Eu{sup 2+},Mn{sup 2+} phosphor was synthesized by a low-temperature initiated, self-propagating and gas producing combustion process in a very short time (<5 min). Structural characterization of the luminescent material was studied with X-ray diffraction analysis and energy-dispersive X-ray analysis. The absorption spectrum exhibits bands due to Eu{sup 2+} and Mn{sup 3+} ions. The excitation spectrum shows a peak at 337 nm. Upon excitation at 337 nm, the emission spectrum exhibits an intense band centered at 462 nm due to transitions from the 4f{sup 6}5d{sup 1} to the 4f{sup 7} configuration of the Eu{sup 2+} ions, whereas sharp peak at 513 nm attributed to {sup 4}T{sub 1}→{sup 6}A{sub 1} transition of Mn{sup 2+} ions. The X-band EPR spectra of MgSrAl{sub 10}O{sub 17}:Eu{sup 2+},Mn{sup 2+} showed the presence of Eu{sup 2+} and Mn{sup 2+} ions.

  4. Spectrum designation and effect of Al substitution on the luminescence of Cr{sup 3+} doped ZnGa{sub 2}O{sub 4} nano-sized phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Weiwei [Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Ministry of Education), School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Zhang Junying, E-mail: zjy@buaa.edu.c [Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Ministry of Education), School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Chen Ziyu; Wang Tianmin [Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Ministry of Education), School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Zheng Shukai [College of Electronic and Information Engineering, Hebei University, Baoding 071200 (China)

    2010-10-15

    Low-temperature photoluminescent spectra of ZnGa{sub 2}O{sub 4}:Cr{sup 3+} nano-sized phosphors calcined at different temperatures were reported. The fine structure of the emission spectra has been designated to Cr{sup 3+} ions in different sites including ideal octahedral, Zn-interstitial, Ga{sub ZN}{sup 4}-Zn{sub Ga}{sup 6} sites and Ga{sub 2}O{sub 3} impurity. The vibronic sidebands for both Stokes' and anti-Stokes' sides are related to the host lattice vibrations, which were confirmed by IR and Raman spectra. Al{sup 3+} is substituted in Ga{sup 3+} sites to form Zn(Ga{sub 1-y}Al{sub y}){sub 2}O{sub 4}:Cr{sub 0.01}{sup 3+} (0{<=}y{<=}0.5). The blue shift and luminescent intensity variations of the charge transfer band and 3d-3d transitions in the spectra caused by Al substitution were related to larger band gap and stronger crystal field, respectively. The calculated crystal-field parameters indicated that Al incorporation enhanced the crystal field strength and induced more trigonal distortion due to different radii of Al{sup 3+} and Ga{sup 3+}.

  5. Temperature dependence of structural and luminescence properties of Eu{sup 3+}-doped Y{sub 2}O{sub 3} red-emitting phosphor thin films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ali, A.G.; Dejene, B.F. [University of the Free State (Qwaqwa Campus), Department of Physics, Phuthaditjhaba (South Africa); Swart, H.C. [University of the Free State, Department of Physics, Bloemfontein (South Africa)

    2016-04-15

    Pulse laser deposition was used to obtain nanocrystalline red-emitting Y{sub 2}O{sub 3}:Eu{sup 3+} thin-film phosphors. X-ray diffraction measurements show that the un-annealed thin film was amorphous, while those annealed were crystalline. At lower annealing temperature of 600-700 C, cubic bixbyite Y{sub 2}O{sub 3}:Eu{sup 3+} was formed. As the annealing temperatures were increased to 800 C, hexagonal phase emerged. The average crystallite size of the film was 64 nm. Photoluminescence measurement indicates intense red emission around 612 nm due to the {sup 5}D{sub 0} → {sup 7}F{sub 2} transition. Scanning electron microscopy indicated that agglomerates of non-crystalline particles with spherical shapes were present for the un-annealed films. After annealing at high temperature, finer morphology was revealed. Atomic force microscopy further confirmed the formation of new morphology at the higher annealing temperatures. UV-Vis measurement indicated a band gap in the range of 4.6-4.8 eV. It was concluded that the annealing temperature played an important role in the luminescence intensity and crystallinity of these films. (orig.)

  6. Structural and luminescent study of TeO2-BaO-Bi2O3-Ag glass system doped with Eu3+ and Dy3+ for possible color-tunable phosphor application

    Science.gov (United States)

    Lewandowski, Tomasz; Seweryński, Cezary; Walas, Michalina; Łapiński, Marcin; Synak, Anna; Sadowski, Wojciech; Kościelska, Barbara

    2018-05-01

    Tellurite glass systems of 73TeO2-4BaO-3Bi2O3-1Ag:xEu2O3-(2-x)Dy2O3 (where x = 0.5, 1, 1.5, 2 in molar ratio) composition have been successfully synthesized. In order to acquire Ag nanoparticles, materials have been heat treated at 350 °C in the air atmosphere. Structural properties of obtained samples were evaluated with various techniques. X-Ray Diffraction (XRD) measurements indicated that obtained materials are amorphous in nature. UV-vis results presented transitions characteristic to Dy3+ and Eu3+ ions. Additionally, X-Ray Photoelectron Spectroscopy (XPS) analysis indicated the presence of silver in metallic form. Photoluminescence measurements shown influence of Ag nanoparticles on emission characteristics. Simultaneous emission of Dy3+ and Eu3+ has been observed when samples were excited with λexc = 390 nm. Change of the emission color induced by heat treatment has been observed and described in case of x = 1 glass series. According to CIE results emission color changes as Eu/Dy ratio and heat treatment time are changed. Emission shifts from reddish-orange to yellowish white color. Obtained photoluminescence results confirm that synthesized materials are good candidates for color tunable phosphors.

  7. Industrial radiography with phosphor screens

    International Nuclear Information System (INIS)

    Broadhead, P.

    1981-01-01

    An experimental system that comprises a film of low silver content and a pair of high resolution phosphor intensifying screens and a commercial industrial X-ray film of similar speed are compared for image quality. It is concluded that the use of phosphor screens offers an increase in image quality when the information is limited by the graininess or quantum mottle of a radiograph which is frequently the case in practical radiography. (author)

  8. Uranium extraction from phosphoric acid

    International Nuclear Information System (INIS)

    Araujo Figueiredo, C. de

    1984-01-01

    The recovery of uranium from phosphoric liquor by two extraction process is studied. First, uranium is reduced to tetravalent condition and is extracted by dioctypyrophosphoric acid. The re-extraction is made by concentrated phosphoric acid with an oxidizing agent. The re-extract is submitted to the second process and uranium is extracted by di-ethylhexilphosphoric acid and trioctylphosphine oxide. (M.A.C.) [pt

  9. Luminescence and luminescence quenching of highly efficient Y2Mo4O15:Eu3+ phosphors and ceramics

    OpenAIRE

    Janulevičius, Matas; Marmokas, Paulius; Misevičius, Martynas; Grigorjevaitė, Julija; Mikoliūnaitė, Lina; Šakirzanovas, Simas; Katelnikovas, Artūras

    2016-01-01

    A good LED phosphor must possess strong enough absorption, high quantum yields, colour purity, and quenching temperatures. Our synthesized Y2Mo4O15:Eu3+ phosphors possess all of these properties. Excitation of these materials with near-UV or blue radiation yields bright red emission and the colour coordinates are relatively stable upon temperature increase. Furthermore, samples doped with 50% Eu3+ showed quantum yields up to 85%, what is suitable for commercial application. Temperature depend...

  10. Surface and spectral studies of green emitting Sr{sub 3}B{sub 2}O{sub 6}:Tb{sup 3+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Neharika [School of Physics, Shri Mata Vaishno Devi University, Katra 182320, J& K (India); Kumar, Vinay, E-mail: vinaykumar@smvdu.ac.in [School of Physics, Shri Mata Vaishno Devi University, Katra 182320, J& K (India); Sharma, J.; Singh, Vivek K. [School of Physics, Shri Mata Vaishno Devi University, Katra 182320, J& K (India); Ntwaeaborwa, O.M.; Swart, H.C. [Department of Physics, University of the Free State, PO Box 339, Bloemfontein ZA9300 (South Africa)

    2016-01-15

    Highlights: • XPS technique has been used to study the surface composition of the phosphor. • The phosphor is synthesized by combustion method using urea as fuel. • Multipole–multipole interaction was found to play a key role for concentration quenching of Tb{sup 3+} doped Sr{sub 3}B{sub 2}O{sub 6} phosphor. - Abstract: In this paper, we report the synthesis of trivalent Tb{sup 3+} doped Sr{sub 3}B{sub 2}O{sub 6} phosphor by combustion method using urea as an organic fuel. The structure of the product has been verified by X-ray diffraction study which shows a rhombohedral phase with a space group of R-3c having lattice constants a = 9.064 Å, b = 9.064 Å, c = 12.611 Å. X-ray photoelectron spectroscopy has been used to study the elemental composition and electronic states of the Tb{sup 3+} doped Sr{sub 3}B{sub 2}O{sub 6} phosphor. Photoluminescence spectra showed that the phosphor emits in the greenish region (with the main peak at 544 nm) of color gamut under UV excitation. The diffuse reflectance spectra of the Sr{sub 3}B{sub 2}O{sub 6} phosphor were studied. Lifetime and band gap of the phosphors were calculated to be 2.55 ms and 5.25 ± 0.02 eV, respectively.

  11. Thermographic process monitoring in powderbed based additive manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Krauss, Harald, E-mail: harald.krauss@iwb.tum.de; Zaeh, Michael F. [AMLab, iwb Application Center Augsburg, Technische Universität München (Germany); Zeugner, Thomas [Augsburg University (Germany)

    2015-03-31

    on the other hand. These issues and proper key figures for thermographic monitoring of the Selective Laser Melting process are discussed in the paper. Even though microbolometric temperature measurement is limited to repetition rates in the Hz-regime and sub megapixel resolution, current results show the feasibility of process surveillance by thermography for a limited section of the building platform in a commercial system.

  12. Photoluminescent properties of Y2O3:Eu3+ phosphors prepared via urea precipitation in non-aqueous solution

    International Nuclear Information System (INIS)

    Sun, Y.; Qi, L.; Lee, M.; Lee, B.I.; Samuels, W.D.; Exarhos, G.J.

    2004-01-01

    Europium-doped yttrium oxide phosphors were obtained by firing precursors prepared by urea precipitation in ethanol and ethylenediamine. The precipitation in non-aqueous solution was carried out in an autoclave at 150 deg. C to allow the decomposition of urea. The photoluminescent intensities of the phosphors prepared in ethanol and ethylenediamine increased by about 30% compared to that of the phosphor prepared by the conventional urea homogeneous precipitation in aqueous solution. Amorphous carbonates and amorphous hydroxides/carbonates mixtures were identified as precursors from ethanol and ethylenediamine, respectively. The morphology and particle size were studied by SEM and dynamic laser scattering method

  13. Monolithic translucent BaMgAl10O17:Eu2+ phosphors for laser-driven solid state lighting

    Directory of Open Access Journals (Sweden)

    Clayton Cozzan

    2016-10-01

    Full Text Available With high power light emitting diodes and laser diodes being explored for white light generation and visible light communication, thermally robust encapsulation schemes for color-converting inorganic phosphors are essential. In the current work, the canonical blue-emitting phosphor, high purity Eu-doped BaMgAl10O17, has been prepared using microwave-assisted heating (25 min and densified into translucent ceramic phosphor monoliths using spark plasma sintering (30 min. The resulting translucent ceramic monoliths convert UV laser light to blue light with the same efficiency as the starting powder and provide superior thermal management in comparison with silicone encapsulation.

  14. Rare earth activated yttrium aluminate phosphors with modulated luminescence.

    Science.gov (United States)

    Muresan, L E; Popovici, E J; Perhaita, I; Indrea, E; Oro, J; Casan Pastor, N

    2016-06-01

    Yttrium aluminate (Y3 A5 O12 ) was doped with different rare earth ions (i.e. Gd(3+) , Ce(3+) , Eu(3+) and/or Tb(3+) ) in order to obtain phosphors (YAG:RE) with general formula,Y3-x-a Gdx REa Al5 O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho-structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic-Y3 Al5 O12 phase as major component along with monoclinic-Y4 Al2 O9 and orthorhombic-YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce(3+) from the 5d level to the ground state levels ((2) F5/2 , (2) F7/2 ). The emission intensity of Ce(3+) is enhanced in the presence of the Tb(3+) ions and is decreased in the presence of Eu(3+) ions due to some radiative or non-radiative processes that take place between activator ions. By varying the rare earth ions, the emission colour can be modulated from green to white and red. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  15. Diagnostic phosphors for photon beams at the ALS and APS

    International Nuclear Information System (INIS)

    Shu, Deming; Warwick, T.; Johnson, E.D.

    1991-01-01

    Some tests have been made of phosphors for photon beam diagnosis. Plasma sprayed coatings were checked for damage and decay during a period of several ampere-hours of irradiation from the NSLS Xray ring. Surface temperatures were measured and extrapolated to give an indication of the temperatures expected in more powerful photon beams. Based on our findings we have chosen plasma-sprayed coatings of Europium-doped Yttrium Oxide as the best candidate for use on masks and flags in ''white'' photon beams of the new facilities. 4 refs., 2 figs

  16. Luminescence and color center distributions in K3YB6O12:Ce3+ phosphor

    International Nuclear Information System (INIS)

    Yang, Li; Wan, Yingpeng; Weng, Honggen; Huang, Yanlin; Chen, Cuili; Seo, Hyo Jin

    2016-01-01

    Polycrystalline Ce 3+ -doped K 3 YB 6 O 12 (1–14 mol%) phosphors were prepared by facile chemical sol–gel synthesis. The phase formation of the phosphors was confirmed by x-ray powder diffraction (XRD) analysis. The photoluminescence excitation spectra (PLE), emission spectra (PL) and the luminescence decay curves were tested. Under the near-UV light, the phosphors present the emission from blue color to yellowish green due to the allowed 4 f  –5 d transitions of Ce 3+ ions. The absolute quantum efficiency (QE) of K 3 YB 6 O 12 :Ce 3+ can reach 53% under the excitation of near-UV light. The luminescence thermal quenching of the phosphor was investigated by the temperature-dependent spectra. The crystallographic site of Ce 3+ ions in the lattice was identified and discussed on the basis of luminescence characteristics and structural data. There is only one isolated Ce 3+ center occupying the Y(II) sites in the lightly doped samples presenting a typical doublet emission profile. While the Ce 3+ multi-centers could be created with the enhancement of the doping levels, which could induce the distinct red-shift of the spectra due to the dipole–dipole interactions. The result in this work could be useful for the further investigation of other rare earth ions in this host. (paper)

  17. Luminescence properties and energy transfer investigations of Sr_3Lu(PO_4)_3:Ce"3"+, Tb"3"+ phosphors

    International Nuclear Information System (INIS)

    Yang, Zaifa; Xu, Denghui; Sun, Jiayue; Du, Jiangnan; Gao, Xuedong

    2016-01-01

    Highlights: • A phosphor Sr_3Lu(PO_4)_3:Ce"3"+, Tb"3"+ for UV-based white LEDs was firstly synthesized successfully. • The phase structure and photoluminescence properties of samples were studied in detail. • The energy transfer process from Ce"3"+ to Tb"3"+ ions was illustrated in detail. • Sr_3Lu(PO_4)_3:Ce"3"+, Tb"3"+ phosphor has potential applications as an UV-convertible phosphor for white light emitting diodes. - Abstract: A series of Ce"3"+ or Tb"3"+ doped and Ce"3"+/Tb"3"+ co-doped Sr_3Lu(PO_4)_3 phosphors were prepared via the conventional high temperature solid-state reaction. The phase structure, photoluminescence and energy transfer properties of samples were studied in detail. The optimal proportion of Ce"3"+ single doping is 4 mol% with maximal fluorescence intensity. The Sr_3Lu(PO_4)_3:Ce"3"+, Tb"3"+ phosphor shows both a blue emission (428 nm) from Ce"3"+ and a yellowish-green emission (545 nm) from Tb"3"+ with considerable intensity under ultraviolet (UV) excitation (268 nm). The energy transfer from Ce"3"+ to Tb"3"+ ions takes place in the Sr_3Lu(PO_4)_3:Ce"3"+, Tb"3"+ phosphor on the basis of the analysis of the luminescence spectra. The energy transfer mechanism from Ce"3"+ to Tb"3"+ ions was proved to be dipole–dipole interaction. The energy transfer behaviors in Sr_3Lu(PO_4)_3:Ce"3"+, Tb"3"+ phosphor is also investigated by the lifetime measurement. The results show that this phosphor has potential applications for UV white-light LEDs.

  18. An experimental and theoretical study of new phosphors for full color field emission displays

    Science.gov (United States)

    Zhang, Fu-Li

    An in depth study is reported of the cathodoluminescent (CL) properties of three new highly efficiency blue phosphors for field emission display (FED) applications doped with fast activators. The superior performance of a new Eu-doped green SrGa2S4 will also be reported. This work addresses four main topics: (1) a detailed study of the dependence of the luminescent intensity on activator concentration, as a function of electron beam voltage and current density; (2) the optical properties of thew phosphors and the development of a CL efficiency characterization technique using a critical screen weight method, which can obtain maximum light output and improve measurement accuracy; (3) understanding the low voltage CL mechanism associated with nanocrystal size by developing a thin film and disk model based on transportation theory and experimental results; (4) Development of a comprehensive evaluation method of red, green, and blue (RGB) phosphors for full color displays by calculation of luminance ratios, required luminance, and measurements of spectra, efficiency and saturation behavior. For FEDs which combine the best properties of CRT and flat panel displays, the development of efficient phosphors at low voltages and high current densities is shown to be critical to meet the luminance and power requirement demands for portable displays. Of particular importance is the need for a good blue phosphor, and to understand the dependence of the CL efficiency on nanocrystal size, penetration depth, diffusion length and surface recombination rate. This has been obtained from the thin film and disk models and fits to experiment. Comparisons between full color phosphor sets show that the performance of a display can vary by over a factor of three depending on the choice of the RGB set. Other factors that are important for optimizing the performance of FED phosphors are reviewed.

  19. 21 CFR 182.1073 - Phosphoric acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Phosphoric acid. 182.1073 Section 182.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is generally...

  20. 21 CFR 582.1073 - Phosphoric acid.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Phosphoric acid. 582.1073 Section 582.1073 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1073 Phosphoric acid. (a) Product. Phosphoric acid. (b) Conditions of use. This substance is...

  1. Luminescent properties of UV excitable blue emitting phosphors MSr4(BO3)3:Ce3+ (M = Li and Na)

    International Nuclear Information System (INIS)

    Guo Chongfeng; Ding Xu; Seo, Hyo Jin; Ren Zhaoyu; Bai Jintao

    2011-01-01

    Research highlights: → Novel blue emitting phosphors borate MSr 4 (BO 3 ) 3 (M = Li or Na) were prepared first. → Luminescent properties of phosphors borate MSr 4 (BO 3 ) 3 (M = Li or Na) were investigated extensively as candidates of blue emitting phosphor used for UV excited LED. → The optimal concentrations of dopant Ce 3+ ions in compound MSr 4 (BO 3 ) 3 (M = Li or Na) were determined as 0.05 for Li and x = 0.09 for Na excited by UV light respectively. - Abstract: A series of Ce 3+ doped novel borate phosphors MSr 4 (BO 3 ) 3 (M = Li or Na) were successfully synthesized by traditional solid-state reaction. The crystal structures and the phase purities of samples were characterized by powder X-ray diffraction. The optimal concentrations of dopant Ce 3+ ions in compound MSr 4 (BO 3 ) 3 (M = Li or Na) were determined through the measurements of photoluminescence spectra of phosphors. Ce 3+ doped phosphors MSr 4 (BO 3 ) 3 (M = Li or Na) show strong broad band absorption in UV spectral region and bright blue emission under the excitation of 345 nm light. In addition, the temperature dependences of emission spectra of M 1+x Sr 4-2x Ce x (BO 3 ) 3 (M = Li or Na) phosphors with optimal composition x = 0.05 for Li and x = 0.09 for Na excited under 355 nm pulse laser were also investigated. The experimental results indicate that the M 1+x Sr 4-2x Ce x (BO 3 ) 3 (M = Li or Na) phosphors are promising blue emitting phosphors pumped by UV light.

  2. Simple preparation of LiF:Mg,Ti phosphor

    International Nuclear Information System (INIS)

    Moharil, S.V.; Shahare, D.I.; Upaded, S.V.; Deshmukh, B.T.

    1993-01-01

    LiF-TLD 100 is a low-impedance (Z eff = 8.2) tissue equivalent material which is widely used in thermoluminescence (TL) dosimetry of ionizing radiations and personnel monitoring. Mg and Ti have been found to be the major impurities which impart the Tl characteristics. Recipes for the preparation of this phosphor, have not been found to be satisfactory for routine manufacture; there have always been problems associated with reproducibility and even with batch homogeneity. One of the reasons for this is that most procedures start either from readily available LiF or by melting the synthesized LiF, or both. The background impurities in the starting LiF powder can mask the intentional impurities, particularly Ti which has to be doped in rather small concentrations (10 p.p.m.). Melting LiF can again be tricky, as the LiF melt is volatile and highly corrosive. In this letter we report the preparation of LiF: Mg, Ti. The impurities were incorporated during the synthesis of LiF. The phosphor was prepared by heat treatments in ambient air without melting the compound. The characteristics of the prepared phosphors were studied and compared with those of LiF-TLD 100. (author)

  3. Optical properties of highly n-doped germanium obtained by in situ doping and laser annealing

    International Nuclear Information System (INIS)

    Frigerio, J; Ballabio, A; Isella, G; Gallacher, K; Millar, R; Paul, D; Gilberti, V; Baldassarre, L; Ortolani, M; Milazzo, R; Napolitani, E; Maiolo, L; Minotti, A; Pecora, A; Bottegoni, F; Biagioni, P

    2017-01-01

    High n-type doping in germanium is essential for many electronic and optoelectronic applications especially for high performance Ohmic contacts, lasing and mid-infrared plasmonics. We report on the combination of in situ doping and excimer laser annealing to improve the activation of phosphorous in germanium. An activated n-doping concentration of 8.8  ×  10 19 cm −3 has been achieved starting from an incorporated phosphorous concentration of 1.1  ×  10 20 cm −3 . Infrared reflectivity data fitted with a multi-layer Drude model indicate good uniformity over a 350 nm thick layer. Photoluminescence demonstrates clear bandgap narrowing and an increased ratio of direct to indirect bandgap emission confirming the high doping densities achieved. (paper)

  4. Optical properties of highly n-doped germanium obtained by in situ doping and laser annealing

    Science.gov (United States)

    Frigerio, J.; Ballabio, A.; Gallacher, K.; Giliberti, V.; Baldassarre, L.; Millar, R.; Milazzo, R.; Maiolo, L.; Minotti, A.; Bottegoni, F.; Biagioni, P.; Paul, D.; Ortolani, M.; Pecora, A.; Napolitani, E.; Isella, G.

    2017-11-01

    High n-type doping in germanium is essential for many electronic and optoelectronic applications especially for high performance Ohmic contacts, lasing and mid-infrared plasmonics. We report on the combination of in situ doping and excimer laser annealing to improve the activation of phosphorous in germanium. An activated n-doping concentration of 8.8  ×  1019 cm-3 has been achieved starting from an incorporated phosphorous concentration of 1.1  ×  1020 cm-3. Infrared reflectivity data fitted with a multi-layer Drude model indicate good uniformity over a 350 nm thick layer. Photoluminescence demonstrates clear bandgap narrowing and an increased ratio of direct to indirect bandgap emission confirming the high doping densities achieved.

  5. Plasmatic and thermographic consequences of local acute irradiation; a qualitative and quantitative analysis in the pig

    International Nuclear Information System (INIS)

    Lefaix, J.L; Daburon, F.; Crechet, F.; Tricaud, Y.

    1987-04-01

    Acute phase reactant proteins associated with thermographic measurements and enzymatic activity assays in plasma were carried out on 39 pigs, following local exposure of the thigh to a collimated source of iridium 192 at doses ranging between 30 and 84 Gy (2 cm depth dose). The inflammatory response after irradiation, from day 1 to day 30 was accompanied by plasma protein changes associated with an elevation of local and general temperatures in irradiated animals. Degenerative processes in muscle led to an increase of plasmatic creatine kinase and lactate-dehydrogenase. Results were developed qualitatively (distribution pattern of proteins, thermographic measurements, enzymatic activities and clinical evolution of the lesions) and qualitatively (plasma level of creatine kinase versus applied radiation doses and pharmalogical treatments) [fr

  6. Thermographic Mobile Mapping of Urban Environment for Lighting and Energy Studies

    Directory of Open Access Journals (Sweden)

    Susana Lagüela López

    2014-12-01

    Full Text Available The generation of 3D models of buildings has been proved as a useful procedure for multiple applications related to energy, from energy rehabilitation management to design of heating systems, analysis of solar contribution to both heating and lighting of buildings. In a greater scale, 3D models of buildings can be used for the evaluation of heat islands, and the global thermal inertia of neighborhoods, which are essential knowledge for urban planning. This paper presents a complete methodology for the generation of 3D models of buildings at big-scale: neighborhoods, villages; including thermographic information as provider of information of the thermal behavior of the building elements and ensemble. The methodology involves sensor integration in a mobile unit for data acquisition, and data processing for the generation of the final thermographic 3D models of urban environment.

  7. Recovering uranium from phosphoric acid

    International Nuclear Information System (INIS)

    Abodishish, H.A.; Ritchey, R.W.

    1982-01-01

    Precipitation of Fe 3 HN 4 H 8 (PO 4 ) 6 is prevented in the second cycle extractor, in a two cycle uranium recovery process, by washing ammonia laden organic solvent stream, from the second cycle stripper, with first cycle raffinate iron stream containing phosphoric acid, prior to passing the solvent stream into the second cycle extractor. (author)

  8. Television-aided thermographic investigations in nuclear and solid state research

    International Nuclear Information System (INIS)

    Buettig, H.; Wollschlaeger, K.

    1983-01-01

    After a brief review of the physical and hardware fundamentals of televison-aided thermographic investigations, two practical examples of nuclear and solid state research work are presented. The problems discussed concern studies of the relative density distribution in beams of particles (ions, electrons, neutral atoms) or of visible radiation on the one hand, and the optimization of operating conditions in heavy-current implantations (ion implantation in Si at ion beam currents up to 60 μA) on the other hand

  9. Automatic recognition of thermographic examinations for early detection of breast cancer

    Science.gov (United States)

    Matysiewicz, Mateusz; Neumann, Łukasz; Nowak, Robert M.; Okuniewski, Rafał; Oleszkiewicz, Witold; Cichosz, Paweł; Jagodziński, Dariusz

    2016-09-01

    This article describes the processing and classification of thermographic examinations taken with device developed by Braster SA. The device records the surface temperature of the breast skin using the liquid crystal matrices. Images are analyzed with the use of machine learning algorithms. The result of classification is available after a few minutes and when it detects suspicious changes patient may be referred for detailed examinations.

  10. Luminescence properties of Ca2 Ga2 SiO7 :RE phosphors for UV white-light-emitting diodes.

    Science.gov (United States)

    Jiao, Mengmeng; Lv, Wenzhen; Lü, Wei; Zhao, Qi; Shao, Baiqi; You, Hongpeng

    2015-03-16

    A series of Eu(2+) -, Ce(3+) -, and Tb(3+) -doped Ca2 Ga2 SiO7 phosphors is synthesized by using a high-temperature solid-state reaction. The powder X-ray diffraction and structure refinement data indicate that our prepared phosphors are single phased and the phosphor crystalizes in a tetrahedral system with the ${P\\bar 42m}$ (113) space group. The Eu(2+) - and Ce(3+) -doped phosphors both have broad excitation bands, which match well with the UV light-emitting diodes chips. Under irradiation of λ=350 nm, Ca2 Ga2 SiO7 :Eu(2+) and Ca2 Ga2 SiO7 :Ce(3+) , Li(+) have green and blue emissions, respectively. Luminescence of Ca2 Ga2 SiO7 :Tb(3+) , Li(+) phosphor varies with the different Tb(3+) contents. The thermal stability and energy-migration mechanism of Ca2 Ga2 SiO7 :Eu(2+) are also studied. The investigation results indicate that the prepared Ca2 Ga2 SiO7 :Eu(2+) and Ca2 Ga2 SiO7 :Ce(3+) , Li(+) samples show potential as green and blue phosphors, respectively, for UV-excited white-light-emitting diodes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Synthesis and luminescence properties of SrMoO{sub 4}:RE{sup 3+} (RE = Eu or Tb) phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Shinho [Silla University, Busan (Korea, Republic of)

    2014-05-15

    SrMoO{sub 4}:RE{sup 3+} (RE = Eu or Tb) phosphors were synthesized with different concentrations of activator ions by using the conventional solid-state reaction method. The effects of the concentration of activator ions on the structural, morphological, and optical properties of strontium molybdate phosphors were investigated by using X-ray diffraction, scanning electron microscopy, and fluorescence spectrophotometry, respectively. XRD patterns revealed that all synthesized phosphors showed the tetragonal SrMoO{sub 4} structure, irrespective of the type and the concentration of activator ions. The crystallite size showed an overall increasing tendency with increasing concentration of activator ions. The emission spectra of Eu{sup 3+}-doped SrMoO{sub 4} phosphors under excitation at 295 nm exhibited one intense red band at 619 nm and five weak bands centered at 541, 561, 596, 657, and 704 nm, respectively. For the Tb{sup 3+}-doped SrMoO{sub 4} phosphors, a strong emission peak at 550 nm and two weak lines, 494 and 591 nm, were observed. The intensities of all the emission bands reached maxima when 0.05 mol of Tb{sup 3+} ions was used. The results suggest that the optimum concentrations for synthesizing highly-luminescent red and green phosphors are 0.01 mol and 0.05 mol, respectively.

  12. Luminescent properties and energy transfer in the green phosphors LaBSiO5:Tb3+, Ce3+.

    Science.gov (United States)

    Wang, Zhengliang; Cheng, Ping; He, Pei; Liu, Yong; Zhou, Yayun; Zhou, Qiang

    2015-09-01

    LaBSiO5 phosphors doped with Ce(3+) and Tb(3+) were synthesized using the conventional solid-state method at 1100 °C. The phase purity and luminescent properties of these phosphors are investigated. LaBSiO5:Tb(3+) phosphors show intense green emission, and LaBSiO5 phosphors doped with Ce(3+) show blue-violet emission under UV light excitation. LaBSiO5 phosphors co-doped with Ce(3+) and Tb(3+) exhibit blue-violet and green emission under excitation by UV light. The blue-violet emission is due to the 5d-4f transition of Ce(3+) and the green emission is ascribed to the (5) D4 → (7) F5 transition of Tb(3+). The spectral overlap between the excitation band of Tb(3+) and the emission band of Ce(3+) supports the occurrence of energy transfer from Ce(3+) to Tb(3+), and the energy transfer process was investigated. Copyright © 2014 John Wiley & Sons, Ltd.

  13. Luminescence property and emission enhancement of YbAlO3:Mn4+ red phosphor by Mg2+ or Li+ ions

    Science.gov (United States)

    Cao, Renping; Luo, Wenjie; Xu, Haidong; Luo, Zhiyang; Hu, Qianglin; Fu, Ting; Peng, Dedong

    2016-03-01

    YbAlO3:Mn4+, YbAlO3:Mn4+, Li+, and YbAlO3:Mn4+, Mg2+ phosphors are synthesized by high temperature solid-state reaction method in air. Their crystal structures and luminescence properties are investigated. Photoluminescence excitation (PLE) spectrum monitored at 677 nm contains broad PLE band with three PLE peaks located at ∼318, 395, and 470 nm within the range 220-600 nm. Emission spectra with excitation 318 and 470 nm exhibit three emission band peaks located at ∼645, 677, and 700 nm in the range of 610-800 nm and their corresponding chromaticity coordinates are about (x = 0.6942, y = 0.3057). The possible luminous mechanism of Mn4+ ion is analyzed by the simple energy level diagram of Mn4+ ion. The optimum Mn4+-doped concentration in YbAlO3:Mn4+ phosphor is about 0.4 mol% and the luminescence lifetime of YbAlO3:0.4%Mn4+ phosphor is ∼0.59 ms. Emission intensity of YbAlO3:0.4%Mn4+ phosphor can be enhanced ∼6 times after Mg2+ ion is co-doped and it is ∼2 times when Li+ ion is co-doped. The content in the paper is useful to research new Mn4+-doped luminescence materials and improve luminescence property of other Mn4+-doped phosphors.

  14. Application of strong phosphoric acid to radiochemistry

    International Nuclear Information System (INIS)

    Terada, Kikuo

    1977-01-01

    Not only inorganic and organic compounds but also natural substrances, such as accumulations in soil, are completely decomposed and distilled by heating with strong phosphoric acid for 30 to 50 minutes. As applications of strong phosphoric acid to radiochemistry, determination of uranium and boron by use of solubilization effect of this substance, titration of uranyl ion by use of sulfuric iron (II) contained in this substance, application to tracer experiment, and determination of radioactive ruthenium in environmental samples are reviewed. Strong phosphoric acid is also applied to activation analysis, for example, determination of N in pyrographite with iodate potassium-strong phosphoric acid method, separation of Os and Ru with sulfuric cerium (IV) - strong phosphoric acid method or potassium dechromate-strong phosphoric acid method, analysis of Se, As and Sb rocks and accumulations with ammonium bromide, sodium chloride and sodium bromide-strong phosphoric acid method. (Kanao, N.)

  15. Formation of rod type structures of CaSO4: Ce,P,Dy TLD phosphor using different synthesis routes

    International Nuclear Information System (INIS)

    Atone, M.S.; Wani, J.A.; Dhoble, S.J.

    2011-01-01

    Effect of Ce and P co-activation in CaSO 4 : Dy, standard TLD phosphor prepared by different synthesis root techniques and it's structural morphology is reported first time in this paper. We have already reported the sensitization of luminescence in CaSO 4 : Dy with phosphorous (P) and cerium (Ce) ions separately via acid distillation route. In the current investigation, we have doped these impurities (Ce, P, Dy) simultaneously in CaSO 4 host lattice. We have employed a well known chemical precipitation method and modified acid distillation method and have attempted to analyse the surface morphology resulted from these two synthesis routes. Chemical precipitation usually takes place at room temperature and in this way allows the reaction to take place silently. In case of acid distillation method we have reduced the synthesis temperature to 493K which is considerably less than 653K employed in previously reported literature. In case of precipitation method particle shape seems to be spherical and particle size is around one micro range or in the neighbourhood of nanorange. However, in the case of modified acid distillation method particles have shaped in to rod like structures and particle size again falls in the micro range. The photoluminescence intensity of the phosphor prepared by chemical precipitation method is weak as compared to the phosphor prepared by modified acid distillation method. Both the phosphors prepared by different methods have shown characteristic transitions of dopants. The emission spectra of prepared phosphors at 309 nm and 329 nm of Ce 3+ ions overlap well with excitation of Dy 3+ ions. Thermoluminescence (TL) property of both phosphors is again good though certain variation is observed in case of phosphor prepared by modified acid distillation method which shows rod like structure of phosphor. This variation in TL may be attributed to change in surface morphology (formation of rod type structure of particles) of the phosphor. (author)

  16. Synthesis and characterization of novel red emitting nanocrystal Gd6WO12:Eu3+ phosphors

    International Nuclear Information System (INIS)

    Tian Yue; Chen Baojiu; Hua Ruinian; Zhong Haiyang; Cheng Lihong; Sun Jiashi; Lu Weili; Wan Jing

    2009-01-01

    Novel nanosized Gd 6 WO 12 :Eu 3+ phosphors were synthesized via a co-precipitation reaction. The crystal structure and morphology of the phosphors were characterized by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). It was found that the resultant powders show a regular and sphere-like shape with average particle size of 60 nm. Intrinsic red emission originating from Eu 3+ was observed while excited at the W 6+ →O 2- and Eu 3+ →O 2- charge transfer bands or f-f absorption bands. The color coordinates of the phosphors were calculated to be x=0.625, y=0.375. The concentration dependence of the luminescence was studied, and optimum doping concentration for obtaining maximum emitting intensity was confirmed to be around 12 mol%. It was also found that the electric dipole-dipole interaction plays an important role for quenching luminescence of Eu 3+ .

  17. Study on preparation of orange-emitting phosphor Y3Mg2AlSi2O12: Ce3+ for wLED

    Directory of Open Access Journals (Sweden)

    Yan Shirun

    2017-12-01

    Full Text Available Ce3+-doped garnet-structured orange-emitting phosphor Y3Mg2AlSi2O12:Ce3+ was prepared by sol-gel combustion using urea as a fuel.Effects of the reduction temperature,Ce3+ doping concentration on the structure,morphology,and photoluminescence property of the as-prepared phosphor were investigated by X-ray diffraction(XRD,scaning electron microscope(SEM,photoluminescence spectroscopy and UV-Vis reflection spectroscopy.The crystallinities,morphologies,and photoluminescence properties of the phosphors prepared by sol-gel combustion and solid-state reaction were compared.The reasons causing different performance of the phosphors were discussed.

  18. Photoluminescence studies of organic phosphor coated diffusing surface using blue inorganic light-emitting diode as excitation source

    International Nuclear Information System (INIS)

    Singh, Gyanendra; Mehta, Dalip Singh

    2013-01-01

    We report the studies on photoluminescence (PL) of organic phosphor coated on a diffusing surface using a blue inorganic light-emitting diode (LED) array as an excitation source. The organic phosphor composite coated diffuser was used to scatter the directional blue light from the LED array. Some of the blue light is absorbed by the organic phosphor composite and the phosphor molecules are excited and re-emit light at longer wavelengths due to the PL process. The output light consists of scattered blue light plus phosphor generated broadband yellow light, thus making white light. The diffuser was made up of a plastic substrate coated with an organic composite of small molecule fluorescent material zinc(II)bis(8-hydroxyquinoline) (Znq 2 ) doped with different percentages of electro-phosphorescent metal complex iridium(III)bis(2-methyldibenzo-[f, h] quinoxaline) (acetylacetonate) ([Ir(MDQ) 2 (acac)]). By means of changing the concentration and the thickness of the phosphor composite material the colour coordinates of white light were achieved. The CIE coordinates and correlated colour temperature were calculated for various thicknesses and phosphor composite concentrations and the results are reported. (paper)

  19. Synthesis and luminescent features of NaCaPO4:Tb3+ green phosphor for near UV-based LEDs

    International Nuclear Information System (INIS)

    Ratnam, B.V.; Jayasimhadri, M.; Bhaskar Kumar, G.; Jang, Kiwan; Kim, S.S.; Lee, Y.I.; Lim, J.M.; Shin, D.S.; Song, T.K.

    2013-01-01

    Highlights: ► Successfully synthesized orthorhombic phase of NaCaPO 4 (NCP) phosphors ► Structural and Luminescent properties have been investigated. ► In the excitation spectrum, 7 F 6 → 5 G 6 transition at 370 nm exhibit highest intensity. ► CIE coordinates of Tb 3+ : NCP phosphor indicate green light emission in CIE diagram. ► Hence, Tb 3+ doped NaCaPO 4 is suitable for UV based pc-LEDs. -- Abstract: An efficient green emitting Tb 3+ doped NaCaPO 4 (NCP) phosphor was synthesized by using conventional solid-state reaction for solid-state lighting applications. X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), FT-IR, emission and excitation properties were extensively investigated for NCP phosphors. X-ray diffraction analysis confirmed the formation of NaCaPO 4 with orthorhombic structure. The excitation spectrum consists of strong 4f–4f transition at around 370 nm, which has higher intensity than the f–d transition. Emission spectra indicated that this phosphor can be efficiently excited by UV light in the range from 250 to 400 nm, and shows strong emission band centered at 547 nm. Analysis of the emission spectra with different Tb 3+ concentrations revealed that the optimum dopant concentration for these NCP phosphors is about 5 mol% of Tb 3+ . Diminishing of 5 D 3 level and increasing of 5 D 4 level emission intensity with the Tb 3+ concentration explained successfully. The emission color was analyzed and confirmed with the help of chromaticity coordinates and color temperature. The excellent luminescent properties of NaCaPO 4 :Tb 3+ phosphor makes it as a potential green phosphor upon near-UV LED excitation

  20. Radioluminescent nuclear batteries with different phosphor layers

    International Nuclear Information System (INIS)

    Hong, Liang; Tang, Xiao-Bin; Xu, Zhi-Heng; Liu, Yun-Peng; Chen, Da

    2014-01-01

    Highlights: • We present and test the electrical properties of the nuclear battery. • The best thickness range for ZnS:Cu phosphor layer is 12–14 mg cm −2 for 147 Pm radioisotope. • The best thickness range for Y 2 O 2 S:Eu phosphor layer is 17–21 mg cm −2147 Pm radioisotope. • The battery with ZnS:Cu phosphor layer can provide higher energy conversion efficiency. • The mechanism affecting the nuclear battery output performance is revealed. - Abstract: A radioluminescent nuclear battery based on the beta radioluminescence of phosphors is presented, and which consists of 147 Pm radioisotope, phosphor layers, and GaAs photovoltaic cell. ZnS:Cu and Y 2 O 2 S:Eu phosphor layers for various thickness were fabricated. To investigate the effect of phosphor layer parameters on the battery, the electrical properties were measured. Results indicate that the optimal thickness ranges for the ZnS:Cu and Y 2 O 2 S:Eu phosphor layers are 12 mg cm −2 to 14 mg cm −2 and 17 mg cm −2 to 21 mg cm −2 , respectively. ZnS:Cu phosphor layer exhibits higher fluorescence efficiency compared with the Y 2 O 2 S:Eu phosphor layer. Its spectrum properly matches the spectral response of GaAs photovoltaic cell. As a result, the battery with ZnS:Cu phosphor layer indicates higher energy conversion efficiency than that with Y 2 O 2 S:Eu phosphor layer. Additionally, the mechanism of the phosphor layer parameters that influence the output performance of the battery is discussed through the Monte Carlo method and transmissivity test

  1. Energy transfer between Pr3+ and Mn2+ in K2YZr(PO4)3: Pr, Mn phosphor

    International Nuclear Information System (INIS)

    Liang Wei; Wang Yuhua

    2011-01-01

    Research highlights: → Pr 3+ , Mn 2+ co-doped K 2 YZr(PO 4 ) 3 phosphor is a novel type of practical visible quantum cutting phosphor in promising application. → The optimal quantum efficiency (QE) of this co-doped system K 2 YZr(PO 4 ) 3 : Pr 3+ , Mn 2+ reached to 126.3%. → The Mn 2+6 A 1g → 4 E g - 4 A 1g transition was found to coincide well with the 1 S 0 → 1 I 6 transition of Pr 3+ . → The energy transfer from Pr 3+ to Mn 2+ was also observed, converting the first photon from the PCE of Pr 3+ into the red emission of Mn 2+ , and the QC process occurred in this Pr 3+ , Mn 2+ co-doped K 2 YZr(PO 4 ) 3 phosphor. - Abstract: Pr 3+ , Mn 2+ co-doped K 2 YZr(PO 4 ) 3 samples were prepared by solid-state reaction method and their photoluminescence (PL) properties were investigated in ultra-violet (UV) and vacuum ultra-violet (VUV) region. The results indicated that in Pr 3+ singly doped K 2 YZr(PO 4 ) 3 sample, the first-step transition ( 1 S 0 → 1 I 6 , 3 P J around 405 nm) of Pr 3+ is near the ultraviolet (UV) range, not useful for practical application. When Mn 2+ was doped as a co-activator ion, the energy of 1 S 0 → 1 I 6 , 3 P J transition can be transferred synchronously from Pr 3+ to Mn 2+ and then emit a visible photon. The optimal quantum efficiency (QE) of this co-doped system K 2 YZr(PO 4 ) 3 : Pr 3+ , Mn 2+ reached to 126.3%, suggesting a novel type of practical visible quantum cutting phosphor in promising application.

  2. Phosphorous loads evaluation from soil

    International Nuclear Information System (INIS)

    Mezzanotte, V.

    1996-01-01

    With reference to the well known difficulty of quantifying non point phosphorous loads, as well as to their growing relative importance where point source leads decrease, a literature review has been carried out concerning soil export coefficients. On such basis, the values which seem to be the most appropriate for Italy have been estimated for different land use categories. The main mechanisms determining non point phosphorous load generation and the factors affecting their importance are also described. In the end, criteria for estimating the importance of non point sources in a basin are suggested to be used for deciding whether a traditional, parametric assessment (inevitably involving a certain error) can be acceptable or experimental measures are needed

  3. Uranium extraction in phosphoric acid

    International Nuclear Information System (INIS)

    Araujo Figueiredo, C. de

    1984-01-01

    Uranium is recovered from the phosphoric liquor produced from the concentrate obtained from phosphorus-uraniferous mineral from Itataia mines (CE, Brazil). The proposed process consists of two extraction cycles. In the first one, uranium is reduced to its tetravalent state and then extracted by dioctylpyrophosphoric acid, diluted in Kerosene. Re-extraction is carried out with concentrated phosphoric acid containing an oxidising agent to convert uranium to its hexavalent state. This extract (from the first cycle) is submitted to the second cycle where uranium is extracted with DEPA-TOPO (di-2-hexylphosphoric acid/tri-n-octyl phosphine oxide) in Kerosene. The extract is then washed and uranium is backextracted and precipitated as commercial concentrate. The organic phase is recovered. Results from discontinuous tests were satisfactory, enabling to establish operational conditions for the performance of a continuous test in a micro-pilot plant. (Author) [pt

  4. Synthesis and photoluminescence characteristics of (Y,Gd)BO3:RE (RE = Eu(3+), Ce(3+), Dy(3+) and Tb(3+)) phosphors for blue chip and near-UV white LEDs.

    Science.gov (United States)

    Rangari, V V; Singh, V; Dhoble, S J

    2016-03-01

    A series of Eu(3+)-, Ce(3+)-, Dy(3+)- and Tb(3+)-doped (Y,Gd)BO3 phosphors was synthesized by a solid-state diffusion method. X-Ray diffraction confirmed their hexagonal structure and the scanning electron microscopy results showed crystalline particles. The excitation spectra revealed that (Y,Gd)BO3 phosphors doped with Eu(3+), Ce(3+), Dy(3+) and Tb(3+) are effectively excited with near UV-light of 395 nm/blue light, 364, 351 and 314 nm, respectively. Photoluminescence spectra of Eu(3+)-, Ce(3+)- and Tb(3+)/Dy(3+)-doped phosphor showed intense emission of reddish orange, blue and white light, respectively. The phosphor Y0.60Gd0.38BO3:Ce0.02 showed CIE 1931 color coordinates of (0.158, 0.031) and better color purity compared with commercially available blue BAM:Eu(2+) phosphor. The phosphor (Y,Gd)BO3 doped with Eu(3+), Dy(3+) and Tb(3+) showed CIE 1931 color coordinates of (0.667, 0.332), (0.251, 0.299) and (0.333, 0.391) respectively. Significant photoluminescence characteristics of the prepared phosphors indicate that they might serve as potential candidates for blue chip and near-UV white light-emitting diode applications. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Luminescent properties of (Y,Gd)BO3:Bi3+,RE3+ (RE=Eu, Tb) phosphor under VUV/UV excitation

    International Nuclear Information System (INIS)

    Zeng Xiaoqing; Im, Seoung-Jae; Jang, Sang-Hun; Kim, Young-Mo; Park, Hyoung-Bin; Son, Seung-Hyun; Hatanaka, Hidekazu; Kim, Gi-Young; Kim, Seul-Gi

    2006-01-01

    Bi 3+ - and RE 3+ -co-doped (Y,Gd)BO 3 phosphors were prepared and their luminescent properties under vacuum ultraviolet (VUV)/UV excitation were investigated. Strong red emission for (Y,Gd)BO 3 :Bi 3+ ,Eu 3+ and strong green emission for (Y,Gd)BO 3 :Bi 3+ ,Tb 3+ are observed under VUV excitation from 147 to 200 nm with a much broader excitation region than that of single Eu 3+ -doped or Tb 3+ -doped (Y,Gd)BO 3 phosphor. Strong emissions are also observed under UV excitation around 265 nm where as nearly no luminescence is observed for single Eu 3+ -doped or Tb 3+ -doped (Y,Gd)BO 3 . The luminescence enhancement of Bi 3+ - and RE 3+ -co-doped (Y,Gd)BO 3 phosphors is due to energy transfer from Bi 3+ ion to Eu 3+ or Tb 3+ ion not only in the VUV region but also in the UV region. Besides, host sensitization competition between Bi 3+ and Eu 3+ or Tb 3+ is also observed. The investigated phosphors may be preferable for devices with a VUV light 147-200 nm as an excitation source such as PDP or mercury-free fluorescent lamp

  6. Luminescence studies on phosphor screens

    International Nuclear Information System (INIS)

    Panayiotakis, G.; Nomikos, C.; Bakas, A.; Proimos, B.

    1994-01-01

    We report our results on x-ray phosphor screens prepared of some new materials focusing attention on their efficiency under fluoroscopy conditions, on optimization conditions and on comparisons among the various materials. All data are presented in absolute values. A theoretical model is presented, that takes into account the granular structure of the screens, permitting the explanation and prediction of the luminescence properties of the screens. (authors)

  7. Luminescence studies on phosphor screens

    Energy Technology Data Exchange (ETDEWEB)

    Panayiotakis, G; Nomikos, C; Bakas, A; Proimos, B [Medical Physics Department, University of Patras, 265 00 Patras, Greece (Greece)

    1994-12-31

    We report our results on x-ray phosphor screens prepared of some new materials focusing attention on their efficiency under fluoroscopy conditions, on optimization conditions and on comparisons among the various materials. All data are presented in absolute values. A theoretical model is presented, that takes into account the granular structure of the screens, permitting the explanation and prediction of the luminescence properties of the screens. (authors). 12 refs, 3 figs.

  8. Micro/nano phosphors for gamma, electron, fast and thermal neutron dosimetry: an overview

    International Nuclear Information System (INIS)

    Dhole, Sanjay D.

    2016-01-01

    In this talk an overview of the micro/nano phosphors, nuclear track in glass and Fricke dosimeter will be covered. Eu and Cu doped K_2Ca_2(SO_4)_3 by chemical co-precipitation, CaSO_4:Dy (micro by acid re-crystallization method and Al_2O_3:C by Thermal Plasma reactor method were synthesized and their photoluminescence (PL), Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) properties were characterized

  9. UVB emitting LiSrBO3 phosphor for phototherapy lamp

    Science.gov (United States)

    Kunghatkar, R. G.; Hemne, P. S.; Dhoble, S. J.

    2018-05-01

    LiSrBO3 doped Gadolinium have been synthesized by sol gel technique. The formation of host was confirmed by XRD techniques. The incorporation of Gd3+ was confirmed by photoluminescence (PL) characterization. The UVB emission is observed at 316 nm when UV excited by 274 nm. The second order emission are also observed in PL emission spectra at 612 nm and 627 nm. Energy band gap is found to be 5.81 eV by using Kubelka - Munk function. The UVB emission at 316 nm of Gd3+ doped materials are used as phototherapy lamp phosphor.

  10. Consumption of Pt anode in phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Kamiya, N.; Urata, K.; Motohira, N.; Ota, K. [Yokohama National University, Yokohama (Japan)

    1997-12-05

    Consumption of Pt anode was investigated in phosphoric acid of various concentration. In 30-70wt% phosphoric acid, Pt dissolved at the rate of 19{mu}gcm{sup -2}h{sup -1}. On the other hand, in 85 wt% phosphoric acid, the amount increased to 0.91 mgcm{sup -2}h{sup -1} which is ca. 180 and 1800 times as much as in 1M sulfuric acid and 1M alkaline solution, respectively. In the diluted phosphoric acid solution, the Pt surface was covered with Pt oxides during the electrolysis, which would prevent the surface from corrosion. However, in the concentrated phosphoric acid, no such oxide surface was observed. Concentrated phosphoric acid might form stable complex with Pt species, therefore the uncovered bare Pt surface is situated in the serious corrosion condition under the high overvoltage and Pt would dissolve into the solution directly instead of forming the Pt oxides. 11 refs., 9 figs., 1 tab.

  11. Combustion synthesis and photoluminescence in novel red emitting yttrium gadolinium pyrosilicate nanocrystalline phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Hedaoo, V.P., E-mail: vraikwar@rediffmail.com [Department of Physics, R. J. College, Ghatkopar, Mumbai, MS 400086 (India); Bhatkar, V.B. [Department of Physics, Shri Shivaji Science College, Amravati, MS 444602 (India); Omanwar, S.K. [Department of Physics, SGB Amravati University, Amravati, MS 444602 (India)

    2016-07-05

    Yttrium Gadolinium Pyrosilicate Y{sub 2-x}Gd{sub x}Si{sub 2}O{sub 7}:Eu{sup 3+} (x = 0.05, 0.10, 0.15) phosphor powder was prepared by facile and time efficient modified combustion method for the first time. The phosphor was characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence excitation (PLE) and emission (PL) spectroscopy and color chromaticity coordinates. XRD revealed the monoclinic crystal structure with space group P1¯. The crystallite size was calculated by Williamson-Hall (W–H) analysis. Nanoplates-like morphology was observed in FESEM analysis with size in the range 50–80 nm. TEM images confirmed the particle size and shape. Upon excitation by 254 nm UV light, the phosphor showed the characteristic red emission peaks at 589 nm and 613 nm corresponding to {sup 5}D{sub 0} → {sup 7}F{sub 1} and {sup 5}D{sub 0} → {sup 7}F{sub 2} transitions respectively. It was observed that the nanocrystalline phosphor Y{sub 2-x}Gd{sub x}Si{sub 2}O{sub 7}:Eu{sup 3+}can be tuned to emit orange to red color by adjusting the ratio Y/Gd. This phosphor thus can be a potential candidate as orange to red color emitting tunable nanocrystalline phosphor for optical devices. - Highlights: • A novel Yttrium Gadolinium Pyrosilicate doped with Eu{sup 3+} is reported. • Facile and time efficient modified combustion method is used. • The nanocrystalline structure was shown by X-ray diffraction, W–H analysis. • FESEM and TEM images confirmed the nanocrystalline structure. • The reported phosphor can be tuned from orange to red by varying Y/Gd ratio.

  12. Adjusting White OLEDs with Yellow Light Emission Phosphor Dye and Ultrathin NPB Layer Structure

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2013-01-01

    Full Text Available High efficiency white organic light emission devices were demonstrated with phosphor material dye bis[2-(4-tertbutylphenylbenzothiazolato-N,C2′]iridium (acetylacetonate and ultrathin layer structure. The ultra thin layer be composed of 4,4′-bis[N-1-naphthyl-N-phenyl-amino]biphenyl (NPB or 4,4′-N,N′-dicarbazole-biphenyl : NPB mixed layer with blue light emission. The emission spectra of devices could be adjusted by different phosphor doping concentrations and ultra thin layer structure. Warm white light emitting device could be obtained with 5 wt% doping concentration and power efficiency of 9.93 lm/W at 5 V. Pure white light with Commission Internationale de l'Eclairage (CIE coordinates of (0.33, 0.30 and external quantum efficiency of 4.49% could be achieved with ultra thin layer device structure and 3 wt% phosphor doped device.

  13. Phosphors for X-ray intensification screens

    International Nuclear Information System (INIS)

    Rebatin, J.G.

    1980-01-01

    An improved rare earth oxyhalide phosphor for x-ray intensification screens is described. The phosphors, of formula LnOX.T where Ln = La or Gd, X = Cl or Br and T = Tm or Tb, are mixed with a small amount of a trivalent antimony compound. The addition of antimony overcomes ageing due to attack by atmospheric moisture and renders the phosphor freeflowing so that dispersions can be readily made. Preferably the phosphor is washed with an aqueous solution of the antimony compound and the compound is the fluoride, chloride or butoxide, or potassium antimony tartrate. (U.K.)

  14. Interest and limits of microwaves thermographic measurements for the diagnosis and pronostic of local acute exposure in the pig

    International Nuclear Information System (INIS)

    Daburon, F.; Lefaix, J.L.; Remy, J.; Fayart, G.; Tricaud, Y.

    1985-01-01

    Microwaves thermographic measurements were carried out on 30 pigs following local exposure of the thigh by a collimated source of iridium 192 at doses ranging between 30 and 84 Gy (2 cm depth dose). Measurement and data processing methods were developed both qualitatively (thermographic images vs anatomo-clinical evolution of the lesions) and quantitatively (by means of indexes calculated from the rough thermographic data to evaluate the relations between the intensity of the local thermic reaction and the applied dose or dose rate). Beside the diagnostic value of the method, which accounts for the global radiological injuries better than the physical dose really distributed, its pronostic value -much more reliable- makes it possible to estimate the severity of the injuries and their later evolution very early (between 10 and 15 days) [fr

  15. Luminescence properties of phosphate phosphor Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fu [College of Science, Hebei North University, Zhangjiakou 075000 (China); Liu, Yufeng, E-mail: liuyufeng4@126.com [State Key Lab of Power Systems, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Tian, Xiaodong; Dong, Guoyi [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Yu, Quanmao [Institute of Functional Materials, Jiangxi University of Finance & Economics, Nanchang 330013 (China)

    2015-05-15

    A series of reddish orange-emitting phosphate phosphors Ba{sub 3}Y{sub 1−x}(PO{sub 4}){sub 3}:xSm{sup 3+}(0.01≤x≤0.20) were synthesized by solid-state reaction. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of as-synthesized phosphors. The optimized phosphors Ba{sub 3}Y{sub 0.95}(PO{sub 4}){sub 3}:0.05Sm{sup 3+} present several excitation bands from 300 to 500 nm, and exhibit intense reddish orange-emitting properties. The energy transfer type between Sm{sup 3+} ions was confirmed as d–d interaction by using Van Uitert model. The chromatic properties of the typical sample Ba{sub 3}Y(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphor have been found to have chromaticity coordinates of (0.583, 0.405), which are located in reddish orange region under the excitation of 401 nm. These results indicated that Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors have potential applications in the field of lighting and display due to their effective excitation in the near-ultraviolet range. - Graphical abstract: The color coordinates for 5 mol% Sm{sup 3+} doped Ba{sub 3}Y(PO{sub 4}){sub 3} phosphor were calculated to be (0.583, 0.405), which are located in reddish orange region under the excitation of 401 nm. The peaks of Ba{sub 3}Y{sub 0.95}(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphor with the highest emission intensity at 600 nm are broader than those of Y{sub 2}O{sub 3}:Eu{sup 3+} and Y{sub 2}O{sub 2}S:Eu{sup 3+} phosphors. All these characteristics suggest that Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors are suitable for near-UV (370–410 nm) excitation and can be applicable to near UV-based WLEDs. ▪ - Highlights: • Different concentration Sm{sup 3+}-doped Ba{sub 3}Y(PO{sub 4}){sub 3} phosphors were fabricated by solid state method. • The optimized phosphors present the several excitation bands from 300 to 500 nm. • The Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} shows bright reddish orange

  16. Temperature measurements on fast-rotating objects using a thermographic camera with an optomechanical image derotator

    Science.gov (United States)

    Altmann, Bettina; Pape, Christian; Reithmeier, Eduard

    2017-08-01

    Increasing requirements concerning the quality and lifetime of machine components in industrial and automotive applications require comprehensive investigations of the components in conditions close to the application. Irregularities in heating of mechanical parts reveal regions with increased loading of pressure, draft or friction. In the long run this leads to damage and total failure of the machine. Thermographic measurements of rotating objects, e.g., rolling bearings, brakes, and clutches provide an approach to investigate those defects. However, it is challenging to measure fast-rotating objects accurately. Currently one contact-free approach is performing stroboscopic measurements using an infrared sensor. The data acquisition is triggered so that the image is taken once per revolution. This leads to a huge loss of information on the majority of the movement and to motion blur. The objective of this research is showing the potential of using an optomechanical image derotator together with a thermographic camera. The derotator follows the rotation of the measurement object so that quasi-stationary thermal images during motion can be acquired by the infrared sensor. Unlike conventional derotators which use a glass prism to achieve this effect, the derotator within this work is equipped with a sophisticated reflector assembly. These reflectors are made of aluminum to transfer infrared radiation emitted by the rotating object. Because of the resulting stationary thermal image, the operation can be monitored continuously even for fast-rotating objects. The field of view can also be set to a small off-axis region of interest which then can be investigated with higher resolution or frame rate. To depict the potential of this approach, thermographic measurements on a rolling bearings in different operating states are presented.

  17. The effect of airflow on thermographically determined temperature of the distal forelimb of the horse.

    Science.gov (United States)

    Westermann, S; Stanek, C; Schramel, J P; Ion, A; Buchner, H H F

    2013-09-01

    Current literature suggests that thermographic imaging of horses should be performed in a draught-free room. However, studies on the effect of airflow on determined temperature have not been published. To investigate effects of airflow on thermographically determined temperature of horses' forelimbs; to assess the relationship of wind velocity, rectal temperature, ambient temperature and humidity. Thermographic images were obtained for the forelimbs of 6 horses in a draught-free room. Three replicates (R) with defined wind velocities (R1, 0.5-1.0 m/s; R2, 1.3-2.6 m/s; and R3, 3.0-4.0 m/s) were conducted. Each replicate consisted of a baseline image, a 15 min phase with the wind on and a 15 min phase with the wind off. We exposed only the right leg to airflow and determined the temperature by thermography with the wind on and wind off. Temperature differences between baseline and wind on, between wind on and wind off and between different wind velocities were analysed by a general linear model, Student's paired t test and ANOVA. After the onset of wind, the temperature on the right forelimb decreased within 1-3 min (by approximately 0.6°C at R1, 1.5°C at R2 and 2.1°C at R3). With the wind off, the temperature increased within 3 min (by approximately 1.2°C at R1, 1.7°C at R2 and 2.1°C at R3). With increasing wind velocity, the temperature differences between baseline and wind on and between wind on and wind off increased significantly. Barely noticeable wind velocities caused a decrease in thermographically determined temperatures of the forelimbs of the horse. Further research is required to assess the influence of airflow on other parts of the body and at different ambient temperatures, as well as the effect on horses with inflammatory lesions, especially of the distal limbs. It is essential for practitioners to perform thermography on horses in a draught-free environment in order to avoid false-positive or -negative diagnoses. © 2012 EVJ Ltd.

  18. A new promising phosphor, Na3La2(BO3)3:Ln (Ln=Eu, Tb)

    International Nuclear Information System (INIS)

    Li Zhihua; Zeng Jinghui; Zhang Guochun; Li Yadong

    2005-01-01

    We present an efficient way to search a host for ultraviolet (UV) phosphor from UV nonlinear optical (NLO) materials. With the guidance, Na 3 La 2 (BO 3 ) 3 (NLBO), as a promising NLO material with a broad transparency range and high damage threshold, was adopted as a host material for the first time. The lanthanide ions (Tb 3+ and Eu 3+ )-doped NLBO phosphors have been synthesized by solid-state reaction. Luminescent properties of the Ln-doped (Ln=Tb 3+ , Eu 3+ ) sodium lanthanum borate were investigated under UV ray excitation. The emission spectrum was employed to probe the local environments of Eu 3+ ions in NLBO crystal. For red phosphor, NLBO:Eu, the measured dominating emission peak was at 613 nm, which is attributed to 5 D - 7 F 2 transition of Eu 3+ . The luminescence indicates that the local symmetry of Eu 3+ in NLBO crystal lattice has no inversion center. Optimum Eu 3+ concentration of NLBO:Eu 3+ under UV excitation with 395 nm wavelength is about 30 mol%. The green phosphor, NLBO:Tb, showed bright green emission at 543 with 252 nm excited light. The measured concentration quenching curve demonstrated that the maximum concentration of Tb 3+ in NLBO was about 20%. The luminescence mechanism of Ln-doped NLBO (Tb 3+ and Eu 3+ ) was analyzed. The relative high quenching concentration was also discussed

  19. Silver lead borate glasses doped with europium ions for phosphors

    Indian Academy of Sciences (India)

    From the differential scanning calorimetry studies, the glass transition temperatures ( T g )have been investigated and their values are ranging from 449 to 458 ∘ C. The investigation of Fourier transformer infraredspectra shows the presence of boron atoms in both BO 3 and BO 4 units in the glass network. In addition, it was ...

  20. Effect of loading rate on creep of phosphorous doped copper

    Energy Technology Data Exchange (ETDEWEB)

    Andersson-Oestling, Henrik C.M.; Sandstroem, Rolf (Swerea KIMAB (Sweden))

    2011-12-15

    Creep testing of copper intended for nuclear waste disposal has been performed on continuous creep tests machines at a temperature of 75 deg C. The loading time has been varied from 1 hour to 6 months. The rupture strain including both loading and creep strains does not differ from traditional dead weight lever creep test rigs. The loading strain increases with increasing loading time, at the expense of the creep strain. The time dependence of the creep strain has been modelled taking athermal plastic deformation and creep into account. During loading the contribution to the strain from the athermal plastic deformation dominates until the stress is close to the constant load level. When the constant load has been reached there is no more athermal strain and all of the strain comes from creep

  1. Photoluminescence analysis of Ce3+:Zn2SiO4 & Li++ Ce3+:Zn2SiO4: phosphors by a sol-gel method

    Science.gov (United States)

    Babu, B. Chandra; Vandana, C. Sai; Guravamma, J.; Rudramadevi, B. Hemalatha; Buddhudu, S.

    2015-06-01

    Here, we report on the development and photoluminescence analysis of Zn2SiO4, Ce3+:Zn2SiO4 & Li+ + Ce3+: Zn2SiO4 novel powder phosphors prepared by a sol-gel technique. The total amount of Ce3+ ions was kept constant in this experiment at 0.05 mol% total doping. The excitation and emission spectra of undoped (Zn2SiO4) and Ce3+ doped Zn2SiO4 and 0.05 mol% Li+ co-doped samples have been investigated. Cerium doped Zn2SiO4 powder phosphors had broad blue emission corresponding to the 2D3/2→2FJ transition at 443nm. Stable green-yellow-red emission has been observed from Zn2SiO4 host matrix and also we have been observed the enhanced luminescence of Li+ co-doped Zn2SiO4:Ce3+. Excitation and emission spectra of these blue luminescent phosphors have been analyzed in evaluating their potential as luminescent screen coating phosphors.

  2. The High-Temperature Synthesis of the Nanoscaled White-Light Phosphors Applied in the White-Light LEDs

    Directory of Open Access Journals (Sweden)

    Hao-Ying Lu

    2015-01-01

    Full Text Available The white-light phosphors consisting of Dy3+ doped YPO4 and Dy3+ doped YP1-XVXO4 were prepared by the chemical coprecipitation method. After the 1200°C thermal treatment in the air atmosphere, the white-light phosphors with particle sizes around 90 nm can be obtained. In order to reduce the average particle size of phosphors, the alkaline washing method was applied to the original synthesis process, which reduces the particle sizes to 65 nm. From the PLE spectra, four absorption peaks locating at 325, 352, 366, and 390 nm can be observed in the YPO4-based phosphors. These peaks appear due to the following electron transitions: 6H15/2→4K15/2, 6H15/2→4M15/2+6P7/2, 6H15/2→4I11/2, and 6H15/2→4M19/2. Besides, the emission peaks of wavelengths 484 nm and 576 nm can be observed in the PL spectra. In order to obtain the white-light phosphors, the vanadium ions were applied to substitute the phosphorus ions to compose the YP1-XVXO4 phosphors. From the PL spectra, the strongest PL intensity can be obtained with 30% vanadium ions. As the concentration of vanadium ions increases to 40%, the phosphors with the CIE coordinates locating at the white-light area can be obtained.

  3. Mechanoluminescence, photoluminescence and thermoluminescence studies of SrZrO3:Ce phosphor

    Directory of Open Access Journals (Sweden)

    Neha Tiwari

    2015-01-01

    Full Text Available The present paper reports the synthesis and characterization, photoluminescence thermoluminescence and mechanoluminescence studies of Ce3+ doped SrZrO3 phosphors. The effects of variable concentration of Cerium on meachanoluminescence (ML and photoluminescence behavior were studied. The samples were prepared by combustion a synthesis technique which is suitable for less time taking techniques also for large scale production for phosphors. The starting material used for sample preparation are Sr(NO33, Zr(NO33 XH2O and Ce(NO33 6H2O and urea used as a fuel. The prepared sample was characterized by X-ray diffraction technique (XRD with variable concentration of Ce (0.05–0.5 mol%. There is no any phase change found with increase the concentration of Ce. Sample shows orthorhombic structure and the particle size calculated by Scherer's formula. The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM technique. Mechanoluminescence studies on SrZrO3phosphors doped with Ce and underwent an impulsive deformation with an impact of a piston for Mechanoluminescence (ML investigations. Temporal characteristics in order to investigate about the luminescence centre responsible for ML peak, increasing impact velocity causes more number of electrons will be ionized to reach to the conduction band so there will be more number of electrons available to be recombined at recombination or luminescence centre. In photoluminescence study PL emission spectra show the isolated peak position observed at 388 nm near UV region of spectrum due to 5d–4f transition of Ce3+ion.Thermoluminescence study shows doping of Ce3+ ions reduced the TL intensity TL glow curve shows the high fading and less stability when it doped with cerium. The activation energy high for the doped SrZrO3 phosphor means that the trapped electron is highly trapped in trap level. The present study gives the advance application for fracture

  4. The Preparation and Optical Properties of Novel LiLa(MoO42:Sm3+,Eu3+ Red Phosphor

    Directory of Open Access Journals (Sweden)

    Jiaxi Wang

    2018-02-01

    Full Text Available Novel LiLa1−x−y(MoO42:xSm3+,yEu3+ (in short: LL1−x−yM:xSm3+,yEu3+ double molybdate red phosphors were synthesized by a solid-state reaction at as low temperature as 610 °C. The optimal doping concentration of Sm3+ in LiLa1−x(MoO42:xSm3+ (LL1−xM:xSm3+ phosphor is x = 0.05 and higher concentrations lead to emission quenching by the electric dipole—electric dipole mechanism. In the samples co-doped with Eu3+ ions, the absorption spectrum in the near ultraviolet and blue regions became broader and stronger than these of the Sm3+ single-doped samples. The efficient energy transfer from Sm3+ to Eu3+ was found and the energy transfer efficiency was calculated. Under the excitation at 403 nm, the chromaticity coordinates of LL0.95−yM:0.05Sm3+,yEu3+ approach to the NTSC standard values (0.670, 0.330 continuously with increasing Eu3+ doping concentration. The phosphor exhibits high luminous efficiency under near UV or blue light excitation and remarkable thermal stability. At 150 °C, the integrated emission intensity of the Eu3+ remained 85% of the initial intensity at room temperature and the activation energy is calculated to be 0.254 eV. The addition of the LL0.83M:0.05Sm3+,0.12Eu3+ red phosphors can improve the color purity and reduce the correlated color temperature of WLED lamps. Hence, LL1−x−yM:xSm3+,yEu3+ is a promising WLED red phosphor.

  5. Relations between structure and material properties in earth alkaline silicate basing phosphors; Struktureigenschaftsbeziehungen in Erdalkalisilikat basierenden Leuchtstoffen

    Energy Technology Data Exchange (ETDEWEB)

    Hempel, Wolfgang

    2008-03-19

    This work is basing on the relation between structure and luminescence of Eu{sup 2+} doped Earth-Alkaline-Silicates. After an overview of Earth-Alkaline-Silicates silicates with an additional cation (Li{sup +}, Al{sup 3+}) and an additional anion (Cl{sup -}, N{sup 3-}) are examined in chapter 4 and 5. Basing on this data an relation between structural influence - like ion-radii, anion and coordination polyeder - and phosphor luminescence is set up. The ability of using as an industrial phosphor is made in the final chapter. (orig.)

  6. Methyl phosphate formation as a major degradation mode of direct methanol fuel cells with phosphoric acid based electrolytes

    DEFF Research Database (Denmark)

    Aili, David; Vassiliev, Anton; Jensen, Jens Oluf

    2015-01-01

    Phosphoric acid and phosphoric acid doped polymer membranes are widely used as electrolytes in hydrogen based fuel cells operating at elevated temperatures. Such electrolytes have been explored for direct oxidation of methanol to further increase the versatility of the systems, however......, with demonstrated lifetimes of only a few days to weeks. In this work the methyl phosphate formation from the acid and methanol is identified and proposed to be a major mechanism for the cell degradation. Proton conductivity and fuel cell durability tests validate the mechanism at high methanol contents....

  7. Red Emission of SrAl2O4:Mn4+ Phosphor for Warm White Light-Emitting Diodes

    Science.gov (United States)

    Chi, N. T. K.; Tuan, N. T.; Lien, N. T. K.; Nguyen, D. H.

    2018-05-01

    In this work, SrAl2O4:Mn4+ phosphor is prepared by co-precipitation. The phase structure, morphology, composition and luminescent performance of the phosphor are investigated in detail with x-ray diffraction, field emission scanning electron microscopy, steady-state photoluminescence (PL) spectra, and temperature-dependent PL measurements. The phosphor shows a strong red emission peak at ˜ 690 nm, which is due to the transition between electronic levels and the electric dipole transition 2Eg to 4A2g of Mn4+ ions located at the sites with D3d local symmetry. The sample doped with 0.04 mol.% Mn4+ exhibits intense red emission with high thermal stability and appropriate International Commission on Illumination (CIE) coordinates (x = 0.6959, y = 0.2737). It is also found that the phosphor absorption in an extended band from 250 nm to 500 nm has three peaks at 320 nm, 405 nm, and 470 nm, which match well with the emission band of ultraviolet (UV) lighting emission diode (LED) or blue LED chips. These results demonstrate that SrAl2O4:Mn4+ phosphor can play the role of activator in narrow red-emitting phosphor, which is potentially useful in UV (˜ 320 nm) or blue (˜ 460 nm) LED.

  8. Synthesis of Eu{sub x}Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z} green phosphor and its luminescent properties

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Jeong Ho; Won, Hyong Sik; Park, Youn-Gon; Kim, Sang Hyun; Song, Won Young; Suzuki, Hideo; Yoon, Chulsoo [Samsung Electro-Mechanics Co., LTD, Corporate R and D Institute, Suwon, Gyunggi-Do (Korea)

    2009-06-15

    Rare-earth-doped oxynitride or nitride compounds have been reported to be photoluminescent and may then serve as new phosphors because of their good thermal and chemical stabilities. In this work, Eu{sup 2+}-doped {beta}-SiAlON phosphor with a composition of Eu{sub x}Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z} (x=0.018,z=0.23) was prepared by gas-pressured solid state reaction. The crystallinity and particle morphology of the prepared phosphor were characterized. The Stokes shift and zero-phonon line were calculated mathematically and estimated from the spectral data. The temperature dependence of photoluminescence was measured from 25 to 250 C. The prepared Eu{sup 2+}-doped {beta}-SiAlON green phosphor showed superior thermal quenching property compared to silicate (SrBaSiO{sub 4}:Eu{sup 2+}) green phosphor. The white light-emitting diode (LED) back-lighting unit (BLU) using the prepared {beta}-SiAlON:Eu{sup 2+} green phosphor exhibited higher color gamut than a commercial silicate phosphor. (orig.)

  9. Thermographic method for evaluation of thermal influence of exterior surface colour of buildings

    Science.gov (United States)

    Wu, Yanpeng; Li, Deying; Jin, Rendong; Liu, Li; Bai, Jiabin; Feng, Jianming

    2008-12-01

    Architecture colour is an important part in urban designing. It directly affects the expressing and the thermal effect of exterior surface of buildings. It has proved that four factors affect the sign visibility, graphics, colour, lighting condition and age of the observers, and colour is the main aspect. The best method is to prevent the exterior space heating up in the first place, by reflecting heat away room the exterior surface.The colour of paint to coat building's exterior wall can have a huge impact on energy efficiency. While the suitable colour is essential to increasing the energy efficiency of paint colour during the warm summer months, those products also help paint colour efficiency and reduce heat loss from buildings during winter months making the interior more comfortable all year long. The article is based on analyzing the importance of architecture color design and existing urban colour design. The effect of external surface colour on the thermal behaviour of a building has been studied experimentally by Infrared Thermographic method in University of Science and technology Beijing insummer.The experimental results showed that different colour has quietly different thermal effect on the exterior surface of buildings. The thermal effect of carmine and fawn has nearly the same values. The main factor which is color express, give some suggest ting about urban color design. The investigation reveals that the use of suitable surface colour can dramatically reduce maximum the temperatures of the exterior wall. Keywords: architectural colour, thermal, thermographic

  10. Thermographic Imaging of the Superficial Temperature in Racing Greyhounds before and after the Race

    Directory of Open Access Journals (Sweden)

    Mari Vainionpää

    2012-01-01

    Full Text Available A total of 47 racing greyhounds were enrolled in this study on two race days (in July and September, resp. at a racetrack. Twelve of the dogs participated in the study on both days. Thermographic images were taken before and after each race. From the images, superficial temperature points of selected sites (tendo calcaneus, musculus gastrocnemius, musculus gracilis, and musculus biceps femoris portio caudalis were taken and used to investigate the differences in superficial temperatures before and after the race. The thermographic images were compared between the right and left legs of a dog, between the raced distances, and between the two race days. The theoretical heat capacity of a racing greyhound was calculated. With regard to all distances raced, the superficial temperatures measured from the musculus gastrocnemius were significantly higher after the race than at baseline. No significant differences were found between the left and right legs of a dog after completing any of the distances. Significant difference was found between the two race days. The heat loss mechanisms of racing greyhounds during the race through forced conduction, radiation, evaporation, and panting can be considered adequate when observing the calculated heat capacity of the dogs.

  11. Thermographic imaging of the superficial temperature in racing greyhounds before and after the race.

    Science.gov (United States)

    Vainionpää, Mari; Tienhaara, Esa-Pekka; Raekallio, Marja; Junnila, Jouni; Snellman, Marjatta; Vainio, Outi

    2012-01-01

    A total of 47 racing greyhounds were enrolled in this study on two race days (in July and September, resp.) at a racetrack. Twelve of the dogs participated in the study on both days. Thermographic images were taken before and after each race. From the images, superficial temperature points of selected sites (tendo calcaneus, musculus gastrocnemius, musculus gracilis, and musculus biceps femoris portio caudalis) were taken and used to investigate the differences in superficial temperatures before and after the race. The thermographic images were compared between the right and left legs of a dog, between the raced distances, and between the two race days. The theoretical heat capacity of a racing greyhound was calculated. With regard to all distances raced, the superficial temperatures measured from the musculus gastrocnemius were significantly higher after the race than at baseline. No significant differences were found between the left and right legs of a dog after completing any of the distances. Significant difference was found between the two race days. The heat loss mechanisms of racing greyhounds during the race through forced conduction, radiation, evaporation, and panting can be considered adequate when observing the calculated heat capacity of the dogs.

  12. Combustion synthesis of CaSc2O4:Ce3+ nano-phosphors in a closed system

    International Nuclear Information System (INIS)

    Peng Wenfang; Zou Shaoyu; Liu Guanxi; Xiao Quanlan; Zhang Rui; Xie Lijuan; Cao Liwei; Meng Jianxin; Liu Yingliang

    2011-01-01

    Highlights: → CaSc 2 O 4 :Ce 3+ nano-phosphors can be prepared by a single-step combustion method. → The ignition temperature is the lowest in the combustion synthesis of Ce 3+ /Eu 2+ doped phosphors. → The as-prepared nano-phosphors give a uniform particle size in the range of 15-20 nm and have highly dispersity and fluorescence intensity. → It is a convenient method for preparation of monodispersed oxide nano-phosphors, especially those being sensitive to air at high temperature. - Abstract: The CaSc 2 O 4 :Ce 3+ nano-phosphors were successfully prepared by a single-step combustion method at an ignition temperature as low as 200 deg. C in a closed autoclave using glycine as a fuel and PEG4000 as a dispersant. The samples were characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results revealed that CaSc 2 O 4 :Ce 3+ nano-phosphors can be conveniently prepared at an ignition temperature as low as 200 deg. C, which was much lower than that in the ordinary combustion methods. The optimized ignition temperature was 220 deg. C. The CaSc 2 O 4 :Ce 3+ nano-phosphors give a uniform particle size in the range of 15-20 nm. The low ignition temperature and the addition of PEG4000 dispersant play important roles in the formation of small sized nanoparticles. The as-prepared nano-phosphors were incompact aggregates, but highly dispersed nano-phosphors can be obtained after further ultrasonic treatment. The CaSc 2 O 4 :Ce 3+ nano-phosphors give satisfactory luminescence characteristic benefiting from the closed circumstance, in which cerium atoms can be isolated from the oxidizing atmosphere and non-fluorescent Ce 4+ ions can be ruled out. The present highly dispersed CaSc 2 O 4 :Ce 3+ nano-phosphors with efficient fluorescence are promising in the field of biological labeling, and the present low temperature combustion method is facile and convenient and can

  13. Blue to bluish-green tunable phosphor Sr2LiSiO4F:Ce3+,Tb3+ and efficient energy transfer for near-ultraviolet light-emitting diodes

    International Nuclear Information System (INIS)

    Xie, Mubiao; Zeng, Lihua; Ye, TingLi; Yang, Xi; Zhu, Xianmei; Peng, Siyun; Lei, Lei

    2014-01-01

    Ce 3+ and Tb 3+ activated Sr 2 LiSiO 4 F phosphors were prepared by a solid state reaction technique at high temperature, and their ultraviolet (UV)-visible spectroscopic properties were investigated. Under ultraviolet light excitation, Ce 3+ -doped Sr 2 LiSiO 4 F phosphors emit blue light (420 nm), while Tb 3+ -doped phosphors show yellowish green emission. Efficient energy transfer from Ce 3+ to Tb 3+ ions in co-doped samples was confirmed in terms of corresponding excitation and emission spectra. The energy transfer mechanism between Ce 3+ and Tb 3+ was discussed and demonstrated to be dipole–dipole interaction in Sr 2 LiSiO 4 F:Ce 3+ ,Tb 3+ phosphors. Due to energy transfer from Ce 3+ to Tb 3+ , Ce 3+ and Tb 3+ co-doped Sr 2 LiSiO 4 F phosphors show intense absorption in near-UV region, and present tunable emission from blue to bluish green under 360 nm light excitation. The results indicate that these phosphors can be considered as candidates for white LEDs pumped by n-UV chips. (paper)

  14. Novel UV-emitting single crystalline film phosphors grown by LPE method

    International Nuclear Information System (INIS)

    Zorenko, Y.; Gorbenko, V.; Savchyn, V.; Voznyak, T.; Nikl, M.; Mares, J.A.; Winnacker, A.

    2010-01-01

    This work reports the development of new types of UV-emitting phosphors based on single crystalline films (SCF) of aluminum garnet and perovskite compounds grown by the liquid phase epitaxy method. We consider peculiarities of the growth and the luminescent and scintillation properties of the following four types of UV SCF phosphors: i) Ce-doped SCF of Y-Lu-Al-perovskites with the Ce 3+ emission in the 300-450 nm range of the decay time of 16-17 ns; ii) Pr-doped SCF of Y-Lu-Al garnets and perovskites with the Pr 3+ emission in the 300-400 nm and 235-330 nm ranges with the decay time of 13-19 and 7-8 ns, respectively; iii) La 3+ or Sc 3+ doped SCF of Y-Lu-Al-garnets, emitting in the 280-400 nm range due to formation of the La Y,Lu , Sc Y,Lu and Sc Al centers with decay time of the order of several hundreds of nanoseconds; iv) Bi 3+ doped SCF of garnets with Bi 3+ emission in 275-350 nm with decay time of about 1.9 μs.

  15. Enhancing the performance of Ce:YAG phosphor-in-silica-glass by controlling interface reaction

    International Nuclear Information System (INIS)

    Zhou, Beiying; Luo, Wei; Liu, Sheng; Gu, Shijia; Lu, Mengchen; Zhang, Yan; Fan, Yuchi; Jiang, Wan; Wang, Lianjun

    2017-01-01

    Dispersing the Ce"3"+ doped yttrium aluminum garnet (Ce:YAG) phosphor in the glass matrix has been widely investigated to replace conventional organic resin or silicone packaging. However, the reaction layer formed between commercial phosphors and glass matrix severely degrades the optical performance of Ce:YAG phosphor in silica glass (PiSG) materials. This paper demonstrates an ultra-fast method for preparing high performance PiSG materials. Instead of traditional melting process, the highly transparent PiSG samples can be rapidly fabricated from mixtures of commercial Ce:YAG phosphor and mesoporous SiO_2 (SBA-15) powders using spark plasma sintering (SPS) at relatively low temperature (1000 °C) within short time (10 min). Owing to the inhibition of the deleterious interface reactions between Ce:YAG phosphor and silica glass matrix, the phosphor has been perfectly preserved, and the internal relative quantum yield of the PiSG sample reaches as high as 93.5% when excited at 455 nm, which is the highest efficiency in current research. Furthermore, combining the PiSG sample, we successfully fabricate a light-emitting diode (LED) module exhibiting a superior performance with luminous efficacy of 127.9 lm/W, correlated color temperature of 5877 K and color rendering index of 69 at the operating current of 120 mA. This work on the high performance LED modules provides not only a new approach to fabricate the functional glass-based materials that is sensitive to the high temperature, but also a possibility to extend the lifetime and improve the optical performances of the glass based LEDs.

  16. Frequency upconversion fluorescence studies of Er{sup 3+}/Yb{sup 3+}-codoped KNbO{sub 3} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnaiah, R. [Department of Electronic Materials Engineering, Silla University, Busan 617-736 (Korea, Republic of); Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Kim, Dong Woo [Department of Electronic Materials Engineering, Silla University, Busan 617-736 (Korea, Republic of); Yi, Soung Soo, E-mail: ssyi@silla.ac.k [Department of Electronic Materials Engineering, Silla University, Busan 617-736 (Korea, Republic of); Kim, Kwang Duk; Kim, Sung Hoon [Department of Engineering in Energy and Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of); Jang, Kiwan; Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Jeong, Jung Hyun [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2009-05-29

    Different concentrations of Er{sup 3+} and Yb{sup 3+} ions-doped potassium niobate (K{sub 0.9}NbO{sub 3}:Yb{sub (x)}Er{sub (0.1-x)} for x = 0, 0.01, 0.05, 0.09 and 0.1) polycrystalline powder phosphors were prepared by the conventional solid state reaction method and were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Energy transfer and upconversion fluorescence properties of the Yb{sup 3+} and Er{sup 3+}-codoped phosphors have been discussed. The XRD data has shown mono-phase for pure KNbO{sub 3} while the doped samples represented additional phase formation. The SEM micrographs represented the rectangular crystal growth habit for the KNbO{sub 3} phosphors when doped with 0.1 mol of Er{sup 3+} ions. An intense green emission at 557 nm along with a red emission at 674 nm was observed when the doped samples were excited with 975 nm IR radiation. The upconversion mechanism has been discussed based on the excited state absorption and energy transfer mechanisms.

  17. Rainbow Emission from an Atomic Transition in Doped Quantum Dots.

    Science.gov (United States)

    Hazarika, Abhijit; Pandey, Anshu; Sarma, D D

    2014-07-03

    Although semiconductor quantum dots are promising materials for displays and lighting due to their tunable emissions, these materials also suffer from the serious disadvantage of self-absorption of emitted light. The reabsorption of emitted light is a serious loss mechanism in practical situations because most phosphors exhibit subunity quantum yields. Manganese-based phosphors that also exhibit high stability and quantum efficiency do not suffer from this problem but in turn lack emission tunability, seriously affecting their practical utility. Here, we present a class of manganese-doped quantum dot materials, where strain is used to tune the wavelength of the dopant emission, extending the otherwise limited emission tunability over the yellow-orange range for manganese ions to almost the entire visible spectrum covering all colors from blue to red. These new materials thus combine the advantages of both quantum dots and conventional doped phosphors, thereby opening new possibilities for a wide range of applications in the future.

  18. Synthesis and luminescence properties of ZnAl{sub 2}O{sub 4}:RE{sup 3+} (RE = Eu, Sm) phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Jin; Cho, Shin Ho [Silla University, Busan (Korea, Republic of)

    2014-01-15

    ZnAl{sub 2}O{sub 4}:RE{sup 3+} (RE = Eu or Sm) phosphor powders were synthesized with different concentrations of activator ions by using the conventional solid-state reaction method. The effects of the concentration of activator ions on the structural, morphological, and luminescent properties of zinc aluminate phosphors were investigated. The X-ray diffraction patterns revealed that the phosphors synthesized with different concentrations of activator ions showed mixed phases of ZnAl{sub 2}O{sub 4}, ZnO, and Al{sub 2}O{sub 3}. The crystallite size was estimated using the Scherrer formula, and the maximum size was obtained for 0.20 mol of Eu{sup 3+} ions. The emission spectra of of Eu{sup 3+}-doped ZnAl{sub 2}O{sub 4} phosphors under excitation at 303 nm exhibited one intense green band at approximately 520 nm and three weak bands centered at 590, 621, and 701 nm, respectively. The intensity of all the emission bands reached a maximum for 0.05 mol of Eu{sup 3+} ions. For the Sm{sup 3+}-doped ZnAl{sub 2}O{sub 4} phosphors, a broad emission band peak at 526 nm and several weak lines in the range 470 - 700 nm were observed. The results suggest that the luminescent intensity of the phosphors can be enhanced by controlling the amount of activator ions incorporated into the host lattice.

  19. Enhanced luminescence in Mg{sup 2+} codoped CaTiO{sub 3}:Eu{sup 3+} phosphor prepared by solid state reaction

    Energy Technology Data Exchange (ETDEWEB)

    Vandana, C. Sai; Rudramadevi, B. Hemalatha [Department of Physics, Sri Venkateswara University, Tirupati-517 502 (India)

    2016-05-23

    CaTiO{sub 3} phosphors doped with Eu{sup 3+} and codoped with Mg{sup 2+} were prepared by Solid State Reaction method. The powders were characterized by X-ray diffraction, SEM with EDS, Raman scattering, and photoluminescence spectroscopy. The Crystalline phase and vibrational modes of the phosphors were studied using XRD pattern and Raman Spectrum respectively. The morphological studies of the phosphor samples were carried out using SEM analysis. From PL spectra we have observed two prominent red emission peaks around at 595 nm ({sup 5}D{sub 0}→{sup 7}F{sub 1}), 619 nm ({sup 5}D{sub 0}→{sup 7}F{sub 2}) with the excitation of 399 nm for Eu{sup 3+} doped CaTiO{sub 3} powders. The PL intensity of CaTiO{sub 3}:Eu{sup 3+} phosphor is enhanced significantly on codoping with Mg{sup 2+}. The observed enhanced emissions are due to energy transfer from Mg{sup 2+} to Eu{sup 3+}, which is due to radiative recombination. Eu{sup 3+} doped phosphors are well known to be promising materials for electroluminescent devices, optical amplifiers, and lasers.

  20. Luminescence properties of NaY(WO{sub 4}){sub 2}:Sm{sup 3+}, Eu{sup 3+} phosphors prepared by molten salt method

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ting; Meng, Qingyu, E-mail: qingyumeng163@163.com; Sun, Wenjun

    2016-02-15

    Sm{sup 3+} singly doped NaY(WO{sub 4}){sub 2} and Sm{sup 3+}, Eu{sup 3+} co-doped NaY(WO{sub 4}){sub 2} phosphors have been synthesized by molten salt method. The crystal structure and morphology were characterized by means of X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). In Sm{sup 3+} singly doped NaY(WO{sub 4}){sub 2} phosphors, the suitable doping concentration was proved. In Sm{sup 3+}, Eu{sup 3+} co-doped NaY(WO{sub 4}){sub 2} phosphors, the energy transfer from Sm{sup 3+} to Eu{sup 3+} is confirmed by the luminescent spectra. A strong absorption line at 405 nm can be generated from {sup 6}H{sub 5/2}-{sup 4}K{sub 11/2} ({sup 4}F{sub 7/2}) transition of Sm{sup 3+} in Sm{sup 3+}, Eu{sup 3+} co-doped NaY(WO{sub 4}){sub 2} phosphors, which is suitable for the emission of the near-ultraviolet light-emitting diodes. The energy transfer efficiency, energy transfer rate and average distance between Sm{sup 3+} and Eu{sup 3+} in the NaY(WO{sub 4}){sub 2}:Sm{sup 3+}, Eu{sup 3+} phosphors have been calculated based on the fluorescent dynamic analysis. Finally, the energy transfer mechanism between Sm{sup 3+} and Eu{sup 3+} is confirmed, the energy transfer occurs between {sup 4}G{sub 5/2} state of Sm{sup 3+} ions and {sup 5}D{sub 0} state rather than {sup 5}D{sub 1} state of Eu{sup 3+} ions.

  1. Pretreatment of industrial phosphoric acid by Algerian filter-aids

    International Nuclear Information System (INIS)

    Mellah, A.; Setti, Louisa; Chegrouche, Salah

    1993-01-01

    The present work involves the filtration of industrial phosphoric acid by different filter-aids such as kieselguhr, celite and bleaching clay. The retention of substances contained in wet phosphoric acid was determined using the three filter-aids. Thus, the phosphoric acid, obtained by filtration on kieselguhr has the same specifications as technical phosphoric acid produced by Rhone-Poulenc (France) as standard

  2. Method of purifying phosphoric acid after solvent extraction

    International Nuclear Information System (INIS)

    Kouloheris, A.P.; Lefever, J.A.

    1979-01-01

    A method of purifying phosphoric acid after solvent extraction is described. The phosphoric acid is contacted with a sorbent which sorbs or takes up the residual amount of organic carrier and the phosphoric acid separated from the organic carrier-laden sorbent. The method is especially suitable for removing residual organic carrier from phosphoric acid after solvent extraction uranium recovery. (author)

  3. 46 CFR 151.50-23 - Phosphoric acid.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Phosphoric acid. 151.50-23 Section 151.50-23 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-23 Phosphoric acid. (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions of...

  4. Phosphorous-Containing Polymers for Regenerative Medicine

    Science.gov (United States)

    Watson, Brendan M.; Kasper, F. Kurtis; Mikos, Antonios G.

    2014-01-01

    Disease and injury have resulted in a large, unmet need for functional tissue replacements. Polymeric scaffolds can be used to deliver cells and bioactive signals to address this need for regenerating damaged tissue. Phosphorous-containing polymers have been implemented to improve and accelerate the formation of native tissue both by mimicking the native role of phosphorous groups in the body and by attachment of other bioactive molecules. This manuscript reviews the synthesis, properties, and performance of phosphorous-containing polymers that can be useful in regenerative medicine applications. PMID:24565855

  5. Effect of Annealing Time of YAG:Ce3+ Phosphor on White Light Chromaticity Values

    Science.gov (United States)

    Abd, Husnen R.; Hassan, Z.; Ahmed, Naser M.; Almessiere, Munirah Abdullah; Omar, A. F.; Alsultany, Forat H.; Sabah, Fayroz A.; Osman, Ummu Shuhada

    2018-02-01

    Yttrium and aluminium nitrate phosphors doped with cerium nitrate and mixed with urea (fuel) are prepared by using microwave-induced combustion synthesis according to the formula Y(3-0.06)Al5O12:0.06Ce3+ (YAG:Ce3+) to produce white light emitting diodes by conversion from blue indium gallium nitride-light emitting diode chips. The sintering time with fixed temperature (1050°C) for phosphor powder was optimized and found to be 5 h. The crystallinity, structure, chemical composition, luminescent properties with varying currents densities and chromaticity were characterized by x-ray diffraction, field emission-scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, photoluminescence emission, electroluminescence and standard CIE 1931 chromaticity diagram, respectively. The energy levels of Ce3+ in YAG were discussed based on its absorption and excitation spectra. The results show that the obtained YAG:Ce3+ phosphor sintered for 5 h has good crystallinity with pure phase, low agglomerate with spherical shaped particles and strong yellow emission, offering cool-white LED with tuneable correlated color temperature and a good color rendering index compared to those prepared by sintering for 2 h and as-prepared phosphor powders.

  6. Preparation and luminescence properties of Ca3(VO4)2: Eu3+, Sm3+ phosphor for light-emitting diodes

    International Nuclear Information System (INIS)

    Huang Jiaping; Li Qiuxia; Chen Donghua

    2010-01-01

    Rare-earth ions co-activated red phosphors Ca 3 (VO 4 ) 2 : Eu 3+ , Sm 3+ were synthesized by modified solid-state reactions. The samples were characterized by X-ray powder diffractometer (XRD), energy-dispersive X-ray spectrometer (EDS), transmission electron microscopy (TEM) and luminescence spectrometer (LS). The results showed that the Eu-Sm system exhibits higher emission intensity than those of the Eu single-doped system and Sm separate-doped system under blue light. Samarium (III) ions are effective in broadening and strengthening absorptions around 467 nm. Furthermore, they exhibit enhanced luminescence emission. Luminescent measurements showed that the phosphors can be efficiently excited by ultraviolet (UV) to visible region, emitting a red light with a peak wavelength of 616 nm. The material has potential application as a phosphor for light-emitting diodes (LEDs).

  7. Synthesis and characterization of novel Na15 (SO4 )5 F4 Cl:Ce3+ halosulfate phosphors.

    Science.gov (United States)

    Bhake, A M; Nair, Govind B; Zade, G D; Dhoble, S J

    2016-12-01

    A series of Na 15 (SO 4 ) 5 F 4 Cl phosphors doped with Ce 3+ ions was prepared using the wet chemical method. X-Ray diffraction studies were used to determine their phase formation and purity. Fourier transform infrared spectroscopy effectively identified the chemical bonds present in the molecule. The photoluminescence properties of the as-prepared phosphors were investigated and the Ce 3+ ions in these hosts were found to give broadband emission in the UV range. For the thermoluminescence study, phosphors were irradiated with a 5 Gy dose of γ-rays from a 60 Co source. Chen's half-width method was employed to calculate the trapping parameters from the thermoluminescence glow curve. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  8. Sol-Gel Synthesis and Luminescence of Green Light Emitting Phosphors Zn2SiO4/Mn2+

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Mn2+ doped Zn2SiO4 phosphors were synthesized by sol-gel method, and the influence of zinc source, Mn2+ dopant concentration and annealing temperature were investigated. Results show that zinc nitrate based precursor with strong green emission intensities is better than zinc acetate based precursor. The intensity of green light emission reaches a peak at 254 nm when the Mn2+ dopant concentration is about 5%( molar percentage). Structural details of the phosphors were examined through X-ray diffractometry, thermogravimetric and differential thermal analysis. The result indicates that they are both rhombohedral structures, which remain amorphous below 700 ℃and crystallize completely around 1 000℃. The luminescent properties of Zn2SiO4/Mn2+ phosphors were characterized by excitation and emission spectra.

  9. Improvements in x-ray image converters and phosphors

    International Nuclear Information System (INIS)

    Rabatin, J.G.

    1981-01-01

    Improvements to an X-ray image converter comprising crystals of rare earth phosphor admixtures are described. The phosphor admixtures utilize thulium-activated lanthanum and/or gadolinium oxyhalide phosphor material to increase the relative speed and resolution of an X-ray image compared with conventional rare earth phosphors. Examples of various radiographic screens containing one or more of the phosphor materials are given. (U.K.)

  10. Host-Sensitized and Tunable Luminescence of GdNbO4:Ln3+ (Ln3+ = Eu3+/Tb3+/Tm3+) Nanocrystalline Phosphors with Abundant Color.

    Science.gov (United States)

    Liu, Xiaoming; Chen, Chen; Li, Shuailong; Dai, Yuhua; Guo, Huiqin; Tang, Xinghua; Xie, Yu; Yan, Liushui

    2016-10-17

    Up to now, GdNbO 4 has always been regarded as an essentially inert material in the visible region with excitation of UV light and electron beams. Nevertheless, here we demonstrate a new recreating blue emission of GdNbO 4 nanocrystalline phosphors with a quantum efficiency of 41.6% and host sensitized luminescence in GdNbO 4 :Ln 3+ (Ln 3+ = Eu 3+ /Tb 3+ /Tm 3+ ) nanocrystalline phosphors with abundant color in response to UV light and electron beams. The GdNbO 4 and GdNbO 4 :Ln 3+ (Ln 3+ = Eu 3+ /Tb 3+ /Tm 3+ ) nanocrystalline phosphors were synthesized by a Pechini-type sol-gel process. With excitation of UV light and low-voltage electron beams, the obtained GdNbO 4 nanocrystalline phosphor presents a strong blue luminescence from 280 to 650 nm centered around 440 nm, and the GdNbO 4 :Ln 3+ nanocrystalline phosphors show both host emission and respective emission lines derived from the characterize f-f transitions of the doping Eu 3+ , Tb 3+ , and Tm 3+ ions. The luminescence color of GdNbO 4 :Ln 3+ nanocrystalline phosphors can be tuned from blue to green, red, blue-green, orange, pinkish, white, etc. by varying the doping species, concentration, and relative ratio of the codoping rare earth ions in GdNbO 4 host lattice. A single-phase white-light-emission has been realized in Eu 3+ /Tb 3+ /Tm 3+ triply doped GdNbO 4 nanocrystalline phosphors. The luminescence properties and mechanisms of GdNbO 4 and GdNbO 4 :Ln 3+ (Ln 3+ = Eu 3+ /Tb 3+ /Tm 3+ ) are updated.

  11. Characteristics of the Panasonic UD-802 phosphors

    International Nuclear Information System (INIS)

    Ben-Shachar, B.; Catchen, G.L.; Hoffman, J.M.

    1989-01-01

    Several basic dosimetric characteristics of Li 2 B 4 O 7 :Cu and CaSO 4 :Tm phosphors in Panasonic UD-802 dosemeters were measured. The TL dose response linearity was determined over the useful range of personnel and environmental dosimetry (0.005 - 10 mGy), and the minimum measurable doses were calculated. The intrinsic ultraviolet (UV) radiation sensitivity of both phosphors was checked before and after γ irradiation for the purpose of re-assessing high doses. The results indicate that Li 2 B 4 O 7 :Cu is UV sensitive and, therefore, re-assessment is not applicable. Although the CaSO 4 :Tm phosphor exhibited UV sensitivity after γ irradiation, the results were not consistent with those reported earlier and more study is required. The fading of both phosphors was evaluated in Panasonic UD-801 dosemeters for periods up to 90 days. (author)

  12. Phosphate Phosphors for Solid-State Lighting

    CERN Document Server

    Shinde, Kartik N; Swart, H C; Park, Kyeongsoon

    2012-01-01

    The idea for this book arose out of the realization that, although excellent surveys and a phosphor handbook are available, there is no single source covering the area of phosphate based phosphors especially for lamp industry. Moreover, as this field gets only limited attention in most general books on luminescence, there is a clear need for a book in which attention is specifically directed toward this rapidly growing field of solid state lighting and its many applications. This book is aimed at providing a sound introduction to the synthesis and optical characterization of phosphate phosphor for undergraduate and graduate students as well as teachers and researchers. The book provides guidance through the multidisciplinary field of solid state lighting specially phosphate phosphors for beginners, scientists and engineers from universities, research organizations, and especially industry. In order to make it useful for a wide audience, both fundamentals and applications are discussed, together.

  13. Electrolyte Additives for Phosphoric Acid Fuel Cells

    DEFF Research Database (Denmark)

    Gang, Xiao; Hjuler, H.A.; Olsen, C.A.

    1993-01-01

    , as a fuel-cell performance with the modified electrolytes. Specific conductivity measurements of some of the modified phosphoric acid electrolytes are reported. At a given temperature, the conductivity of the C4F9SO3K-modified electrolyte decreases with an increasing amount of the additive; the conductivity...... of the remains at the same value as the conductivity of the pure phosphoric acid. At a given composition, the conductivity of any modified electrolyte increases with temperature. We conclude that the improved cell performance for modified electrolytes is not due to any increase in conductivity.......Electrochemical characteristics of a series of modified phosphoric acid electrolytes containing fluorinated car on compounds and silicone fluids as additives are presented. When used in phosphoric acid fuel cells, the modified electrolytes improve the performance due to the enhanced oxygen...

  14. Blue–green afterglow of BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Bao-gai [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); Ma, Qing-lan [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); School of Electronics and Information, Nantong University, Jiangsu 226019 (China); Xiong, Rui [School of Physics and Technology, Wuhan University, Hubei 430072 (China); Li, Xiazhang [Analysis and Testing Center, Changzhou University, Jiangsu 213164 (China); Huang, Yuan Ming, E-mail: dongshanisland@126.com [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China)

    2016-03-15

    Highlights: • Afterglow can be achieved when Eu{sup 2+} is absent in the DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. • The afterglow of DyAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors is discernible to naked eyes for minutes. • Dy{sup 3+} introduced trap centers are believed to be responsible for the afterglow. - Abstract: Dy{sup 3+} doped barium aluminate (BaAl{sub 2}O{sub 4}:Dy{sup 3+}) phosphors were prepared via the sol–gel combustion route at the ignition temperature of 600 °C. The phosphors were characterized with X-ray diffractometry, scanning electron microscopy, transmission electron microscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Regardless of the absence of Eu{sup 2+} luminescent centers, broadband blue–green afterglow with its peak at about 490 nm was recorded in the BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. The decay profile of the blue–green afterglow can be best fitted into a two-component exponential function with the two lifetime decay constants to be 8.81 and 45.25 s, respectively. The observation of blue–green afterglow from BaAl{sub 2}O{sub 4}:Dy{sup 3+} in the absence of Eu{sup 2+} provides unique opportunity in unveiling the afterglow mechanisms of rare-earth doped alkaline-metal aluminates. Possible mechanisms on the blue–green afterglow in BaAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors are discussed in terms of the Dy{sup 3+} ions introduced trap centers as well as luminescent centers in the crystal lattice.

  15. Using thermographic cameras to investigate eye temperature and clinical severity in depression

    Science.gov (United States)

    Maller, Jerome J.; George, Shefin Sam; Viswanathan, Rekha Puzhavakkathumadom; Fitzgerald, Paul B.; Junor, Paul

    2016-02-01

    Previous studies suggest that altered corneal temperature may be a feature of schizophrenia, but the association between major depressive disorder (MDD) and corneal temperature has yet to be assessed. The aim of this study is to investigate whether eye temperature is different among MDD patients than among healthy individuals. We used a thermographic camera to measure and compare the temperature profile across the corneas of 16 patients with MDD and 16 age- and sex-matched healthy subjects. We found that the average corneal temperature between the two groups did not differ statistically, although clinical severity correlated positively with right corneal temperature. Corneal temperature may be an indicator of clinical severity in psychiatric disorders, including depression.

  16. Thermographic Non-Destructive Evaluation for Natural Fiber-Reinforced Composite Laminates

    Directory of Open Access Journals (Sweden)

    Hai Zhang

    2018-02-01

    Full Text Available Natural fibers, including mineral and plant fibers, are increasingly used for polymer composite materials due to their low environmental impact. In this paper, thermographic non-destructive inspection techniques were used to evaluate and characterize basalt, jute/hemp and bagasse fibers composite panels. Different defects were analyzed in terms of impact damage, delaminations and resin abnormalities. Of particular interest, homogeneous particleboards of sugarcane bagasse, a new plant fiber material, were studied. Pulsed phase thermography and principal component thermography were used as the post-processing methods. In addition, ultrasonic C-scan and continuous wave terahertz imaging were also carried out on the mineral fiber laminates for comparative purposes. Finally, an analytical comparison of different methods was given.

  17. White light emission and effect of annealing on the Ho3+–Yb3+ codoped BaCa2Al8O15 phosphor

    International Nuclear Information System (INIS)

    Kumari, Astha; Rai, Vineet Kumar

    2015-01-01

    Graphical abstract: The upconversion emission spectra of the Ho 3+ /Yb 3+ doped/codoped BaCa 2 Al 8 O 15 phosphors with different doping concentrations of Ho 3+ /Yb 3+ ions along with UC emission spectrum of the white light emitting phosphor annealed at 800 °C. - Highlights: • BaCa 2 Al 8 O 15 phosphors codoped with Ho 3+ –Yb 3+ have been prepared by combustion method. • Phosphor annealed at 800 °C, illuminate an intense white light upon NIR excitation. • The sample annealed at higher temperatures emits in the pure green region. • The colour emitted persists in the white region even at high pump power density. • Developed phosphor is suitable for making upconverters and WLEDs. - Abstract: The BaCa 2 Al 8 O 15 (BCAO) phosphors codoped with suitable Ho 3+ –Yb 3+ dopant concentration prepared by combustion method illuminate an intense white light upon near infrared diode laser excitation. The structural analysis of the phosphors and the detection of impurity contents have been performed by using the X-Ray Diffraction, FESEM and FTIR analysis. The purity of white light emitted from the sample has been confirmed by the CIE chromaticity diagram. Also, the white light emitted from the sample persists with the variation of pump power density. The phosphors emit upconversion (UC) emission bands in the blue, green and red region (three primary colours required for white light emission) along with one more band in the near infrared region of the electromagnetic spectrum. On annealing the white light emitting sample at higher temperatures, the sample starts to emit green colour and also the intensity of green and red UC emission bands get enhanced largely.

  18. Use of thermographic imaging in clinical diagnosis of small animal: preliminary notes

    Directory of Open Access Journals (Sweden)

    Veronica Redaelli

    2014-06-01

    Full Text Available INTRODUCTION. The authors, after a description of the physics of infrared thermographic technique (IRT, analyze the reading of images and the main applications in the veterinary field, compared to the existing literature on the subject and to their experimental researches. IRT lends itself to countless applications in biology, thanks to its characteristics of versatility, lack of invasiveness and high sensitivity. Probably the major limitation to its application in the animal lies in the ease of use and in its extreme sensitivity. MATERIALS AND METHODS. From September 2009 to October 2010, the experimental investigation with the thermo camera took into consideration 110 animals (92 dogs and 18 cats, without any selection criteria. All patients were brought to the Faculty of Veterinary Medicine in Milan University by the owner, to be examined by a specialist, or to undergo one of the following diagnostic procedures: X-rays, computed tomography, or ultrasound examinations; finally some patients were brought in for surgical procedures. With the consent of the owner, 1 to 10 thermographic images were recorded from each clinical case. Results. In this first experimental investigation, thermography has shown a high sensitivity (100%, but a low specificity (44%. This figure excludes the use of thermal imaging technology to replace other imaging techniques such as radiography, computed tomography and magnetic resonance imaging. Furthermore, it does not show any ability to recognize the etiology of the disease, but only the thermal alteration, and this is restricting its use. However, this experimental study has demonstrated that thermography can be used in veterinary medicine, and specifically in dogs and cats. It is hoped that in the field of targeted diseases this technique will become an important tool for diagnostic purposes by using working protocols validated and repeatable.

  19. Radioisotopic and thermographic imaging of the lower limbs oedema - comparison diagnostic techniques

    International Nuclear Information System (INIS)

    Stepien, A.; Pawlus, J.; Nowak, E.; Kulka, J.; Gielzycki, J.; Kraft, O.

    2005-01-01

    In this paper, authors achieved comparison between lymphoscintigraphy and thermography in patients with limbs oedema. It allow to determinate current role of lymphoscintigraphy and verify useful of thermography in limbs oedema diagnosis. Analysis included 60 patients with the lower limbs oedema. Each patients Doppler duplex scan and thermographic study was performed. Additionally, 10 patients were classified to the lymphoscintigraphy. Thermography: In studies camera ThermaCAM S60 (FLIR SYSTEM) were used. Infrared radiation detector was 320 x 240 uncooled microbolometers with thermal resolution - 0.08 o C (for 30 o C). Lymphoscintigraphy: Each patient received subcutaneous, in the second web space, Nanosis (schering) labeled 99m Tc. Dynamic data acquisition has been started immediately after injection the radiotracer to the both extremities using digital gamma camera X Ring (Mediso). Static study of whole body was performed after 1.5 hour. Thermal disorders were observed in 58 patients. On the base ultrasound and clinical examinations 10 patients were classified to lymphoscintigraphy. In this group in 5 cases traits lymphatic insufficient were observed. Thermographic study in group of patients with scintigraphic disorders was showed regional hypothermia, with small regions of hypothermia in tissues included oedema. Lymphoscintigraphy is a useful and indispensable tool in oedema diagnosis. In patients with insufficient of lymphatic system, thermography comparison to lymphoscintigraphy, in clinical diagnosis did not influence on the future diagnosis and therapeutics proceedings. Regional hyperthermic disorders in patients with limbs oedema, who had negative results of examinations (Doppler duplex scan and lymphoscintigraphy), could indicate on inflammatory complications. In cases of venous insufficient thermography allow to visualize specific venous disorders. (author)

  20. Fluorescent lighting with aluminum nitride phosphors

    Science.gov (United States)

    Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Srivastava, Alok M.

    2016-05-10

    A fluorescent lamp includes a glass envelope; at least two electrodes connected to the glass envelope; mercury vapor and an inert gas within the glass envelope; and a phosphor within the glass envelope, wherein the phosphor blend includes aluminum nitride. The phosphor may be a wurtzite (hexagonal) crystalline structure Al.sub.(1-x)M.sub.xN phosphor, where M may be drawn from beryllium, magnesium, calcium, strontium, barium, zinc, scandium, yttrium, lanthanum, cerium, praseodymium, europium, gadolinium, terbium, ytterbium, bismuth, manganese, silicon, germanium, tin, boron, or gallium is synthesized to include dopants to control its luminescence under ultraviolet excitation. The disclosed Al.sub.(1-x)M.sub.xN:Mn phosphor provides bright orange-red emission, comparable in efficiency and spectrum to that of the standard orange-red phosphor used in fluorescent lighting, Y.sub.2O.sub.3:Eu. Furthermore, it offers excellent lumen maintenance in a fluorescent lamp, and does not utilize "critical rare earths," minimizing sensitivity to fluctuating market prices for the rare earth elements.

  1. Luminescence and luminescence quenching of highly efficient Y2Mo4O15:Eu(3+) phosphors and ceramics.

    Science.gov (United States)

    Janulevicius, Matas; Marmokas, Paulius; Misevicius, Martynas; Grigorjevaite, Julija; Mikoliunaite, Lina; Sakirzanovas, Simas; Katelnikovas, Arturas

    2016-05-16

    A good LED phosphor must possess strong enough absorption, high quantum yields, colour purity, and quenching temperatures. Our synthesized Y2Mo4O15:Eu(3+) phosphors possess all of these properties. Excitation of these materials with near-UV or blue radiation yields bright red emission and the colour coordinates are relatively stable upon temperature increase. Furthermore, samples doped with 50% Eu(3+) showed quantum yields up to 85%, what is suitable for commercial application. Temperature dependent emission spectra revealed that heavily Eu(3+) doped phosphors possess stable emission up to 400 K and lose half of the efficiency only at 515 K. In addition, ceramic disks of Y2Mo4O15:75%Eu(3+) phosphor with thickness of 0.71 and 0.98 mm were prepared and it turned out that they efficiently convert radiation of 375 and 400 nm LEDs to the red light, whereas combination with 455 nm LED yields purple colour.

  2. Luminescence and luminescence quenching of highly efficient Y2Mo4O15:Eu3+ phosphors and ceramics

    Science.gov (United States)

    Janulevicius, Matas; Marmokas, Paulius; Misevicius, Martynas; Grigorjevaite, Julija; Mikoliunaite, Lina; Sakirzanovas, Simas; Katelnikovas, Arturas

    2016-01-01

    A good LED phosphor must possess strong enough absorption, high quantum yields, colour purity, and quenching temperatures. Our synthesized Y2Mo4O15:Eu3+ phosphors possess all of these properties. Excitation of these materials with near-UV or blue radiation yields bright red emission and the colour coordinates are relatively stable upon temperature increase. Furthermore, samples doped with 50% Eu3+ showed quantum yields up to 85%, what is suitable for commercial application. Temperature dependent emission spectra revealed that heavily Eu3+ doped phosphors possess stable emission up to 400 K and lose half of the efficiency only at 515 K. In addition, ceramic disks of Y2Mo4O15:75%Eu3+ phosphor with thickness of 0.71 and 0.98 mm were prepared and it turned out that they efficiently convert radiation of 375 and 400 nm LEDs to the red light, whereas combination with 455 nm LED yields purple colour. PMID:27180941

  3. Study on luminescence and thermal stability of blue-emitting Sr_5(PO_4)_3F: Eu"2"+phosphor for application in InGaN-based LEDs

    International Nuclear Information System (INIS)

    Liu, Jie; Zhang, Zhi-Ming; Wu, Zhan-Chao; Wang, Fang-Fang; Li, Zhen-Jiang

    2017-01-01

    Highlights: • A blue phosphor Sr_5(PO_4)_3F: Eu"2"+ was prepared at low temperature of 800 °C. • The broad excitation band of the phosphor matches well with NUV LED chips. • The phosphor shows high color purity and good color stability. • A bright blue-emitting LED was fabricated with this phosphor on an InGaN chip. - Abstract: A series of blue-emitting phosphors Sr_5(PO_4)_3F: Eu"2"+ were synthesized by traditional high temperature solid-state reaction method. The micro-morphology and photoluminescence properties of the phosphors were investigated. The Sr_5(PO_4)_3F: Eu"2"+ phosphors exhibit broad excitation spectra ranging from 250 to 420 nm, and an intense asymmetric blue emission band peaking at 435 nm. Two different Eu"2"+ emission centers in Sr_5(PO_4)_3F: Eu"2"+ phosphors were confirmed via their fluorescence properties. The concentration quenching mechanism, fluorescence lifetime and thermal stability of Sr_5(PO_4)_3F: Eu"2"+ phosphors were studied in detail. The thermal stability can be improved obviously by anion substitution. The CIE chromaticity coordinates of Sr_5(PO_4)_3F: Eu"2"+ phosphors with different Eu"2"+-doped concentrations were calculated. A blue light-emitting diode was fabricated by combination of a 370 nm InGaN chip and the prepared phosphor Sr_5(PO_4)_3F: Eu"2"+. The present work suggests that Sr_5(PO_4)_3F: Eu"2"+ is a potential phosphor applied in InGaN-based LEDs.

  4. Study on luminescence and thermal stability of blue-emitting Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+}phosphor for application in InGaN-based LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie; Zhang, Zhi-Ming [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Wu, Zhan-Chao, E-mail: wuzhan_chao@163.com [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Wang, Fang-Fang [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Li, Zhen-Jiang, E-mail: zjli126@126.com [State Key Laboratory Base of Eco-chemical Engineering, College of Sino-German Science and Technology, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, Shandong (China)

    2017-07-15

    Highlights: • A blue phosphor Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} was prepared at low temperature of 800 °C. • The broad excitation band of the phosphor matches well with NUV LED chips. • The phosphor shows high color purity and good color stability. • A bright blue-emitting LED was fabricated with this phosphor on an InGaN chip. - Abstract: A series of blue-emitting phosphors Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} were synthesized by traditional high temperature solid-state reaction method. The micro-morphology and photoluminescence properties of the phosphors were investigated. The Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors exhibit broad excitation spectra ranging from 250 to 420 nm, and an intense asymmetric blue emission band peaking at 435 nm. Two different Eu{sup 2+} emission centers in Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors were confirmed via their fluorescence properties. The concentration quenching mechanism, fluorescence lifetime and thermal stability of Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors were studied in detail. The thermal stability can be improved obviously by anion substitution. The CIE chromaticity coordinates of Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors with different Eu{sup 2+}-doped concentrations were calculated. A blue light-emitting diode was fabricated by combination of a 370 nm InGaN chip and the prepared phosphor Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+}. The present work suggests that Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} is a potential phosphor applied in InGaN-based LEDs.

  5. Luminescence Studies on Lamp Phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Nagpal, J.S.; Godbole, S.V.; Varadharajan, G.; Page, A.G

    1998-07-01

    Photoluminescence and thermoluminescence of cerium magnesium aluminate CeMgAl{sub 11}O{sub 17}(Eu,Tb) and calcium halophosphate Ca{sub 5}(PO{sub 4}){sub 3}(F,Cl):Mn,Sb, two fluorescent materials currently in use for the commercial production of lamps in India, have been studied for possible applications in radiation and ultraviolet dosimetry. Cerium magnesium aluminate is highly sensitive to the visible spectral region. It has a linear response to 254 nm UV radiation over a wide range. Its UV sensitivity is significantly higher as compared to that of other known phosphors; however, its UV response is rate-dependent and may not play a significant role in UV dosimetry. Photoluminescence of CeMg aluminate is characteristic of Eu{sup 2+} and Tb{sup 3+} dopants, whereas the thermoluminescence emission of the UV irradiated powder at room temperature is dominated by Eu{sup 2+} dopant. Calcium halophosphate is insensitive to room lights, has a linear gamma response over 0.2-10{sup 2} Gy and may be useful in the case of radiation accidents. (author)

  6. Luminescence Studies on Lamp Phosphors

    International Nuclear Information System (INIS)

    Nagpal, J.S.; Godbole, S.V.; Varadharajan, G.; Page, A.G.

    1998-01-01

    Photoluminescence and thermoluminescence of cerium magnesium aluminate CeMgAl 11 O 17 (Eu,Tb) and calcium halophosphate Ca 5 (PO 4 ) 3 (F,Cl):Mn,Sb, two fluorescent materials currently in use for the commercial production of lamps in India, have been studied for possible applications in radiation and ultraviolet dosimetry. Cerium magnesium aluminate is highly sensitive to the visible spectral region. It has a linear response to 254 nm UV radiation over a wide range. Its UV sensitivity is significantly higher as compared to that of other known phosphors; however, its UV response is rate-dependent and may not play a significant role in UV dosimetry. Photoluminescence of CeMg aluminate is characteristic of Eu 2+ and Tb 3+ dopants, whereas the thermoluminescence emission of the UV irradiated powder at room temperature is dominated by Eu 2+ dopant. Calcium halophosphate is insensitive to room lights, has a linear gamma response over 0.2-10 2 Gy and may be useful in the case of radiation accidents. (author)

  7. MULTI-PHOTON PHOSPHOR FEASIBILITY RESEARCH

    Energy Technology Data Exchange (ETDEWEB)

    R. Graham; W. Chow

    2003-05-01

    Development of multi-photon phosphor materials for discharge lamps represents a goal that would achieve up to a doubling of discharge (fluorescent) lamp efficacy. This report reviews the existing literature on multi-photon phosphors, identifies obstacles in developing such phosphors, and recommends directions for future research to address these obstacles. To critically examine issues involved in developing a multi-photon phosphor, the project brought together a team of experts from universities, national laboratories, and an industrial lamp manufacturer. Results and findings are organized into three categories: (1) Multi-Photon Systems and Processes, (2) Chemistry and Materials Issues, and (3) Concepts and Models. Multi-Photon Systems and Processes: This category focuses on how to use our current understanding of multi-photon phosphor systems to design new phosphor systems for application in fluorescent lamps. The quickest way to develop multi-photon lamp phosphors lies in finding sensitizer ions for Gd{sup 3+} and identifying activator ions to red shift the blue emission from Pr{sup 3+} due to the {sup 1}S{sub 0} {yields} {sup 1}I{sub 6} transition associated with the first cascading step. Success in either of these developments would lead to more efficient fluorescent lamps. Chemistry and Materials Issues: The most promising multi-photon phosphors are found in fluoride hosts. However, stability of fluorides in environments typically found in fluorescent lamps needs to be greatly improved. Experimental investigation of fluorides in actual lamp environments needs to be undertaken while working on oxide and oxyfluoride alternative systems for backup. Concepts and Models: Successful design of a multi-photon phosphor system based on cascading transitions of Gd{sup 3+} and Pr{sup 3+} depends critically on how the former can be sensitized and the latter can sensitize an activator ion. Methods to predict energy level diagrams and Judd-Ofelt parameters of multi

  8. Facile preparation and formation mechanism of Sr2Si5N8:Eu2+ red-emitting phosphors

    Science.gov (United States)

    Wang, Yang; Wang, Yunli; Wang, Ming; Shao, Yiran; Zhu, Yingchun

    2018-05-01

    The red-emitting Sr2Si5N8:Eu2+ phosphors have been synthesized in a new facile process using (oxy)nitride precursors by inductive calcination under N2 atmosphere at ordinary pressure. Different from the prevailing methods, lower cost raw materials, simpler pretreatment, without harsh conditions and a shorter reaction time are achieved. It was found that red-emitting Sr2Si5N8:Eu2+ phosphors were synthesized with high crystallinity and purity after 1 h inductive calcination. The formation mechanism was characterized by XRD, SEM, TEM and Fluorescence microscopy. It was demonstrated that a hexagonal mesophase of Sr-doped α-Si3N4 was primarily formed in the reaction process, which transformed into the final product of the orthorhombic Sr2Si5N8:Eu2+ phosphors. During the reaction process, the color of the samples transforms from greenish-yellow to orange and eventually to red. The as-prepared phosphors have a wide excitation in the range of 250 ∼ 570 nm which matches blue light chips and give a red-light emission peaking at 610 nm. The results indicate a promising prospect for a simple, efficient and inexpensive way to prepare Sr2Si5N8:Eu2+ phosphors for blue/UV-based warm-white LEDs and other fluorescent applications.

  9. Synthesis and thermoluminescence characterization of Na6Mg(SO4)4:RE (RE = Ce, Tb) phosphors

    International Nuclear Information System (INIS)

    Kore, Bhushan P.; Dhoble, N.S.; Dhoble, S.J.

    2014-01-01

    Thermoluminescence (TL) properties of sulfate-based phosphors activated by different rare earths have received tremendous attention to the field of radiation dosimetry. Those TL materials based on CaSO 4 have been widely applied for medical and environmental dosimetry. Taking this fact into account we have synthesized Na 6 Mg(SO 4 ) 4 doped with Ce and Tb by wet chemical method. The prepared phosphor was characterized by XRD, FTIR, photoluminescence (PL) and thermoluminescence. For TL study, the phosphor is irradiated with γ-rays from 60 Co source. For studying luminescence properties, the prepared phosphor was annealed at different temperatures and effects of these annealing temperatures on Na 6 Mg(SO 4 ) 4 samples are investigated and quantified. The changes in the glow curve and PL emission spectrum are also investigated as a function of annealing temperature and the annealing temperature was optimized. For calculation of trapping parameters various methods such as peak shape (PS) method, initial rise (IR) method, various heating rate (VHR) method, and computerized glow curve deconvolution (CGCD) are employed. - Highlights: • Na 6 Mg(SO 4 ) 4 phosphor was successfully prepared by wet chemical method. • Effect of annealing temperatures on PL and TL properties has been studied. • Different trap analysis methods were used for calculating the trapping parameters. • Effect of these methods on activation energies were investigated in detail

  10. Photoluminescence and thermoluminescence characterization of Eu3+- and Dy3+ -activated Ca3(PO4)2 phosphor

    International Nuclear Information System (INIS)

    Nagpure, I.M.; Saha, Subhajit; Dhoble, S.J.

    2009-01-01

    Rare-earth-doped polycrystalline Ca 3 (PO 4 ) 2 :Eu, Ca 3 (PO 4 ) 2 :Dy and Ca 3 (PO 4 ) 2 :Eu,Dy phosphors prepared by a modified solid-state synthesis has been studied for its X-ray diffraction, thermoluminescence (TL) and photoluminescence (PL) characteristics. The PL emission spectra of the phosphor suggest the presence of Eu 3+ ion in Ca 3 (PO 4 ) 2 :Eu and Dy 3+ ion in Ca 3 (PO 4 ) 2 :Dy lattice sites. The TL glow curve of the Ca 3 (PO 4 ) 2 :Eu compounds has a simple structure with a prominent peak at 228 deg. C, while Ca 3 (PO 4 ) 2 :Dy peaking at 146 and 230 deg. C. TL sensitivity of phosphors are compared with CaSO 4 : Dy and found 1.52 and 1.20 times less in Ca 3 (PO 4 ) 2 :Eu and Ca 3 (PO 4 ) 2 :Dy phosphors, respectively. The Ca 3 (PO 4 ) 2 :Eu,Dy phosphors shows switching behavior under two different excitation wavelengths and enhancement in PL intensity of Dy 3+ ions were reported. The paper discusses the photoluminescence and thermoluminescence behavior of Eu 3+ and Dy 3+ ion in Ca 3 (PO 4 ) 2 hosts, it may be applicable to solid-state lighting as well as thermoluminescence dosimetry applications.

  11. Energy transfer from Pr3+ to Gd3+ ions in BaB8O13 phosphor for phototherapy lamps

    Science.gov (United States)

    Tamboli, Sumedha; Nair, Govind B.; Dhoble, S. J.; Burghate, D. K.

    2018-04-01

    A series of BaB8O13 phosphors doped with different concentrations of Gd3+ ions and co-doped with Pr3+ ions were synthesized by solid state synthesis method. X-ray powder diffraction (XRD) analysis confirmed the formation of the compound in a crystalline and homogeneous form. Scanning Electron Microscopy (SEM) was performed to study the surface morphology of the compound and Fourier Transform Infrared (FT-IR) spectroscopy measurements determined the nature of bonding between elements of the compounds. The photoluminescence (PL) excitation spectra of BaB8O13:Gd3+ phosphor showed excitation peaks at 246 nm, 252 nm and 274 nm. The prominent emission peak was observed at 313 nm which is in narrow band ultraviolet B (NB-UVB) range. Energy transfer was achieved by co-doping Pr3+ ions with Gd3+ ions. PL decay time was also measured for BaB8O13: Gd3+, Pr3+ phosphor. Emission at 313 nm can be used for the treatment of skin diseases.

  12. KCa4(BO33:Ln3+ (Ln = Dy, Eu, Tb phosphors for near UV excited white–light–emitting diodes

    Directory of Open Access Journals (Sweden)

    Allu Amarnath Reddy

    2013-02-01

    Full Text Available A series of doped KCa4(BO33:Ln3+ (Ln: Dy, Eu and Tb compositions were synthesized by solid–state reaction method and their photoluminescent properties were systematically investigated to ascertain their suitability for application in white light emitting diodes. The X–ray diffraction (XRD and nuclear magnetic resonance (MAS–NMR data indicates that Ln3+–ions are successfully occupied the non–centrosymmetric Ca2+ sites, in the orthorhombic crystalline phase of KCa4(BO33 having space group Ama2, without affecting the boron chemical environment. The present phosphor systems could be efficiently excitable at the broad UV wavelength region, from 250 to 350 nm, compatible to the most commonly available UV light–emitting diode (LED chips. Photoluminescence studies revealed optimal near white–light emission for KCa4(BO33 with 5 wt.% Dy3+ doping, while warm white–light (CIE; X = 0.353, Y = 0.369 is obtained at 1wt.% Dy3+ ion concentration. The principle of energy transfer between Eu3+ and Tb3+ also demonstrates the potential white–light from KCa4(BO33:Eu3+,Tb3+ phosphor. Whereas, single Tb3+ and Eu3+–doped systems showed bright green (Tb3+ and red (Eu3+ emissions, respectively. Having structural flexibility along with remarkable chemical/thermal stability and suitable quantum efficiency these phosphors can be promising candidates as white–light–emitter for near UV LEDs.

  13. Light emission efficiency and imaging properties of YAP:Ce granular phosphor screens

    International Nuclear Information System (INIS)

    Kalivas, N.; Valais, I.; Nikolopoulos, D.; Konstantinidis, A.; Cavouras, D.; Kandarakis, I.; Gaitanis, A.; Nomicos, C.D.; Panayiotakis, G.

    2007-01-01

    Phosphor materials are used in medical imaging combined with radiographic film or other photodetectors. Cerium (Ce 3+ ) -doped scintillators are of particular interest for medical imaging, because of their very fast response. YAP:Ce scintillator-based image detectors have already been evaluated in single-crystal form and under conditions of positron emission tomography and synchrotron or γ-ray irradiation. Furthermore, YAP:Ce phosphor has been evaluated in conjunction with radiographic films. The present work reports experimental and theoretical data concerning the light output absolute luminescence efficiency (AE) of the YAP:Ce screens under irradiation conditions employed in medical X-ray projection imaging (i.e., in diagnostic radiology). projection imaging (i.e., in diagnostic radiology). YAP:Ce phosphor screens with surface densities ranging between 53 and 110 mg/cm 2 were prepared by sedimentation on fused silica substrates in our laboratory. The resulted surface density of the screens was determined by dividing the phosphor mass deposited on the screen surface with the area of the surface. Additionally this work addresses the imaging performance of YAP:Ce by estimation of the detective quantum efficiency (DQE), i.e., the square of the signal to noise ratio transfer. Absolute efficiency was found to decrease with X-ray tube voltage for for YAP:Ce phosphor. The highest experimental efficiency was obtained for the 53.7 mg/cm 2 and 88.0 mg/cm 2 YAP:Ce screens. The highest DQE value was found for the 88.0 mg/cm 2 screen irradiated at 60 kVp. (orig.)

  14. Thermographic observation of the divertor target plates in the stellarators W7-AS and W7-X

    International Nuclear Information System (INIS)

    Hildebrandt, D.; Gadelmeier, F.; Grigull, P.; McCormick, K.; Naujoks, D.; Suender, D.

    2003-01-01

    Thermography is applied on the stellarator W7-AS to monitor the thermal load of the recently installed divertor targets. A three dimensional numerical code was developed to evaluate power fluxes arriving at the targets from the measured temporal evolution of the surface temperature distribution. Values of the thermal conductivity of the used CFC-target material for all three directions are required for this evaluation and determined by observing the propagation of controlled heat pulses applied by an infrared laser. The evaluation of the thermographic measurements during plasma operation shows characteristic spatial and temporal features of the arrived heat fluxes. Significant features in high density regimes like plasma detachment from the divertor target plates or strongly enhanced localised plasma radiation (MARFE) has been observed by the installed infrared cameras. The implications of these observations for the thermographic system for W7-X are shortly addressed

  15. Phosphor blends for high-CRI fluorescent lamps

    Science.gov (United States)

    Setlur, Anant Achyut [Niskayuna, NY; Srivastava, Alok Mani [Niskayuna, NY; Comanzo, Holly Ann [Niskayuna, NY; Manivannan, Venkatesan [Clifton Park, NY; Beers, William Winder [Chesterland, OH; Toth, Katalin [Pomaz, HU; Balazs, Laszlo D [Budapest, HU

    2008-06-24

    A phosphor blend comprises at least two phosphors each selected from one of the groups of phosphors that absorb UV electromagnetic radiation and emit in a region of visible light. The phosphor blend can be applied to a discharge gas radiation source to produce light sources having high color rendering index. A phosphor blend is advantageously includes the phosphor (Tb,Y,LuLa,Gd).sub.x(Al,Ga).sub.yO.sub.12:Ce.sup.3+, wherein x is in the range from about 2.8 to and including 3 and y is in the range from about 4 to and including 5.

  16. Airplane dopes and doping

    Science.gov (United States)

    Smith, W H

    1919-01-01

    Cellulose acetate and cellulose nitrate are the important constituents of airplane dopes in use at the present time, but planes were treated with other materials in the experimental stages of flying. The above compounds belong to the class of colloids and are of value because they produce a shrinking action on the fabric when drying out of solution, rendering it drum tight. Other colloids possessing the same property have been proposed and tried. In the first stages of the development of dope, however, shrinkage was not considered. The fabric was treated merely to render it waterproof. The first airplanes constructed were covered with cotton fabric stretched as tightly as possible over the winds, fuselage, etc., and flying was possible only in fine weather. The necessity of an airplane which would fly under all weather conditions at once became apparent. Then followed experiments with rubberized fabrics, fabrics treated with glue rendered insoluble by formaldehyde or bichromate, fabrics treated with drying and nondrying oils, shellac, casein, etc. It was found that fabrics treated as above lost their tension in damp weather, and the oil from the motor penetrated the proofing material and weakened the fabric. For the most part the film of material lacked durability. Cellulose nitrate lacquers, however were found to be more satisfactory under varying weather conditions, added less weight to the planes, and were easily applied. On the other hand, they were highly inflammable, and oil from the motor penetrated the film of cellulose nitrate, causing the tension of the fabric to be relaxed.

  17. Fabrication of silica glass containing yellow oxynitride phosphor by the sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Segawa, Hiroyo; Yoshimizu, Hisato; Hirosaki, Naoto; Inoue, Satoru, E-mail: SEGAWA.Hiroyo@nims.go.jp [National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2011-06-15

    We have prepared silica glass by the sol-gel method and studied its ability to disperse the Ca-{alpha}-SiAlON:Eu{sup 2+} phosphor for application in white light emitting diodes (LEDs). The emission color generated by irradiating doped glass with a blue LED at 450 nm depended on the concentration of SiAlON and the glass thickness, resulting in nearly white light. The luminescence efficiency of 1-mm-thick glass depended on the SiAlON concentration, and was highest at 4 wt% SiAlON.

  18. Thermographic skin temperature measurement compared with cold sensation in predicting the efficacy and distribution of epidural anesthesia.

    Science.gov (United States)

    Bruins, Arnoud A; Kistemaker, Kay R J; Boom, Annemieke; Klaessens, John H G M; Verdaasdonk, Rudolf M; Boer, Christa

    2018-04-01

    Due to the high rates of epidural failure (3-32%), novel techniques are required to objectively assess the successfulness of an epidural block. In this study we therefore investigated whether thermographic temperature measurements have a higher predictive value for a successful epidural block when compared to the cold sensation test as gold standard. Epidural anesthesia was induced in 61 patients undergoing elective abdominal, thoracic or orthopedic surgery. A thermographic picture was recorded at 5, 10 and 15 min following epidural anesthesia induction. After 15 min a cold sensation test was performed. Epidural anesthesia is associated with a decrease in skin temperature. Thermography predicts a successful epidural block with a sensitivity of 54% and a PPV of 92% and a specificity of 67% and a NPV of 17%. The cold sensation test shows a higher sensitivity and PPV than thermography (97 and 93%), but a lower specificity and NPV than thermography (25 and 50%). Thermographic temperature measurements can be used as an additional and objective method for the assessment of the effectiveness of an epidural block next to the cold sensation test, but have a low sensitivity and negative predictive value. The local decrease in temperature as observed in our study during epidural anesthesia is mainly attributed to a core-to-peripheral redistribution of body heat and vasodilation.

  19. Energy transfer in M₅(PO₄)₃  F:Eu²⁺,Ce³⁺ (M = Ca and Ba) phosphors.

    Science.gov (United States)

    Shinde, K N; Dhoble, S J

    2014-08-01

    M5(PO4)3F:Eu(2+) (M = Ca and Ba) co-doped with Ce(3+) phosphors were successfully prepared by the combustion synthesis method. The introduction of co-dopant (Ce(3+)) into the host enhanced the luminescent intensity of the M5(PO4)3F:Eu(2+) (M = Ca and Ba) efficiently. Previously, we have reported the synthesis and photoluminescence properties of same phosphors. The aim of this article is to report energy transfer mechanism between Ce(3+) ➔Eu(2+) ions in M5(PO4)3F:Eu(2+) (M = Ca and Ba) phosphors, where Ce(3+) ions act as sensitizers and Eu(2+) ions act as activators. The M5(PO4)3F:Eu(2+) (M = Ca and Ba) co-doped with Ce(3+) phosphor exhibits great potential for use in white ultraviolet (UV) light-emitting diode applications to serve as a single-phased phosphor that can be pumped with near-UV or UV light-emitting diodes. Copyright © 2013 John Wiley & Sons, Ltd.

  20. Synthesis, characterization and luminescent properties of mixed phase bismuth molybdate-doped with Eu3+ ions

    Science.gov (United States)

    Wang, Liyong; Guo, Xiaoqing; Cai, Xiaomeng; Song, Qingwei; Han, Yuanyuan; Jia, Guang

    2018-02-01

    Red phosphors of Eu3+-doped bismuth molybdate (BMO) are prepared by a low temperature hydrothermal method assisting with Phenol Formaldehyde resin (PFr), and characterized by X-ray diffraction (XRD) patterns, Fourier transform infrared-spectroscopy (FT-IR), thermogravimetric analyzer (TGA), differential thermal analyzer (DTA), and photoluminescence (PL) spectroscopy. PL properties influence factors including molar ratio of Bi3+ and Mo3+ ions, PFr dosage and dopants concentration are discussed in detail. The results show that BMO can act as a useful host for Eu3+ ions doping, and energy transferring from Bi3+ to Eu3+ achieved efficiently, the BMO phosphors displayed intense red color emission under ultraviolet light excitation.

  1. Novel tunable green-red-emitting oxynitride phosphors co-activated with Ce3+, Tb3+, and Eu3+: photoluminescence and energy transfer.

    Science.gov (United States)

    Huo, Jiansheng; Dong, Langping; Lü, Wei; Shao, Baiqi; You, Hongpeng

    2017-07-14

    A series of novel Ce 3+ , Tb 3+ and Eu 3+ ion doped Y 4 SiAlO 8 N-based oxynitride phosphors were synthesized by the solid-state method and characterized by X-ray powder diffraction, scanning electron microscopy, photoluminescence, lifetimes and thermo-luminescence. The excitation of the Ce 3+ /Tb 3+ co-doped and Ce 3+ /Tb 3+ /Eu 3+ tri-doped phosphor with near-UV radiation results in strong linear Tb 3+ green and Eu 3+ red emission. The occurrence of Ce 3+ -Tb 3+ and Ce 3+ -Tb 3+ -Eu 3+ energy transfer processes is responsible for the bright green or red luminescence. The Tb 3+ ion acting as an energy transfer bridge can alleviate MMCT quenching between the Ce 3+ -Eu 3+ ion pairs. The lifetime measurements demonstrated that the energy-transfer mechanisms of Ce 3+ → Tb 3+ and Tb 3+ → Eu 3+ are dipole-quadrupole and quadrupole-quadrupole interactions, respectively. The temperature dependent luminescence measurements showed that as-prepared green/red phosphors have good thermal stability against temperature quenching. The obtained results indicate that these phosphors might serve as promising candidates for n-UV LEDs.

  2. A Strategy for Synthesizing CaZnOS:Eu{sup 2+} Phosphor and Comparison of Optical Properties with CaS:Eu{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Zhongxian; Rong, Chunying; Zhou, Wenli; Zhang, Jilin; Li, Chengzhi; Yu, Liping; Liu, Shubin; Lian, Shixun, E-mail: shixunlian@gmail.com

    2014-01-15

    Graphical abstract: Pure-phase CaZnOS:Eu{sup 2+},Ce{sup 3+}phosphor with good chemical and thermal stability can be synthesized by co-doping with Ce{sup 3+} as deoxidizer rather than reduction atmosphere. The broad bluish-green excitation and broad red emission show it is a better phosphor than CaS:Eu{sup 2+} for white LED and for sunlight harvesting of plants. -- Highlights: • Pure-phase phosphor CaZnOS:Eu{sup 2+} was synthesized by co-doping with Ce{sup 3+} as deoxidizer. • Energy transfer mechanism from Ce{sup 3+} to Eu{sup 2+} in CaZnOS host is proposed. • CaZnOS:Eu{sup 2+}, Ce{sup 3+} phosphor has good chemical and thermal stability performance. • The similarities and differences between CaZnOS:Eu{sup 2+} and CaS:Eu{sup 2+} were analyzed. • The green excitation and red emission show superior solar harvesting for plants. -- Abstract: The red-emitting phosphor CaZnOS:Eu{sup 2+} was synthesized from CaCO{sub 3}, ZnS, Eu{sub 2}O{sub 3} and CeCl{sub 3} by controlling the sintering condition. It was found that Ce{sup 3+} ions can play a role of reductant to contribute to the formation of Eu{sup 2+} in CaZnOS matrix under inert protective atmosphere. While the gas flow changed to H{sub 2}/N{sub 2}, the product turned to CaS easily. XRD, photoluminescence spectra, UV–vis and IR absorption spectra were evaluated to investigate the origin of the distinctions of the optical properties and stabilities between the two divalent europium ions doped phosphors CaZnOS:Eu{sup 2+} and CaS:Eu{sup 2+}. The similarities and differences between them were analyzed.

  3. White light quality of phosphor converted light-emitting diodes: A phosphor materials perspective of view

    International Nuclear Information System (INIS)

    Sommer, Christian; Hartmann, Paul; Pachler, Peter; Hoschopf, Hans; Wenzl, Franz P.

    2012-01-01

    Highlights: ► We discuss the impact of the optical properties of a phosphor for colour temperature constancy in solid state lighting. ► Quantitative evaluation of permissible variations of the optical properties for batch-to-batch reproducibility. ► Quantitative evaluation of permissible variations of the optical properties upon temperature increase. ► Quantitative evaluation of permissible variations of the optical properties upon materials degradation. - Abstract: For a systematic approach to improve the white light quality of phosphor converted LEDs and to fulfil the demands for colour temperature reproducibility and constancy, it is imperative to understand how variations of the extinction coefficient and the quantum efficiency of the phosphor particles as well as variations of the excitation wavelength of the blue LED die affect the correlated colour temperature of the white LED source. Based on optical ray tracing of a phosphor converted white LED package we deduce permissible values for the variation of a given extinction coefficient and a given quantum efficiency of a phosphor material in order to maintain acceptable colour variations. These quantitative valuations of the required constancy of the optical properties of the phosphors will in particular provide some benchmarks for the synthesis of improved phosphor materials aiming at solid state lighting applications.

  4. Avaluation of the adaptability of dairy goats with help of thermographic precision in the semiarid brazilian

    Directory of Open Access Journals (Sweden)

    Elisângela Maria Nunes da Silva

    2014-06-01

    Full Text Available ABSTRACT. Silva E.M.N., Souza B.B., Silva G.A., Alcântara M.D.B., Cunha M.G.G. & Marques B.A.A. [Avaluation of the adaptability of dairy goats with help of thermographic precision in the semiarid brazilian.] Avaliação da adaptabilidade de caprinos leiteiros com auxílio da precisão termográfica no semiárido brasileiro. Revista Brasileira de Medicina Veterinaria, 36(2:231-237, 2014. Programa de Pós-Graduação em Medicina Veterinária, Universidade Federal de Campina Grande, Rodovia Patos-Teixeira, Km 01, Jatobá, Patos, PB 58708-110, Brasil. E-mail: elisangelamns@yahoo.com.br The present study aimed to evaluate the adaptability of dairy goats with help of thermographic precision in the semiarid brazilian. Thirty-six female goats were used in the study, mean age 2.5 years old and mean weight of 45 kg, all of them pure-bred, lactating and not pregnant, distributed in a completely randomized design, in a factorial outline 2 x 2; two genotypes (Anglo Nubian and Alpine vs two shifts (morning and afternoon with 18 repetitions. Analysis of variance showed that the shift had significant effect (P0.05. Also, there was no significant interaction between breed and shift. Regarding the parameters: respiratory rate (RR and surface temperature of the muzzle of cinnamon there was significant effect of breed and shift and significant interaction between breed and shift (P<0.05. Positive correlations between physiological parameters and room temperature and negative correlation between thermal gradients and more parameters. The Anglo Nubian breed had become more adapted to the semi-arid environmental conditions representing a good alternative for breeding programs. The Alpine breed increased respiratory effort required to dissipate heat and maintain homeothermy, proving to be more demanding regarding system creation and management in the semi-arid climatic conditions.

  5. Thermographic inspection of bond defects in Fiber Reinforced Polymer applied to masonry structures

    Science.gov (United States)

    Masini, N.; Aiello, M. A.; Capozzoli, L.; Vasanelli, E.

    2012-04-01

    Nowadays, externally bonded Fiber Reinforced Polymers (FRP) are extensively used for strengthening and repairing masonry and reinforced concrete existing structures; they have had a rapid spread in the area of rehabilitation for their many advantages over other conventional repair systems, such as lightweight, excellent corrosion and fatigue resistance, high strength, etc. FRP systems applied to masonry or concrete structures are typically installed using a wet-layup technique.The method is susceptible to cause flaws or defects in the bond between the FRP system and the substrate, which may reduce the effectiveness of the reinforcing systems and the correct transfer of load from the structure to the composite. Thus it is of primary importance to detect the presence of defects and to quantify their extension in order to eventually provide correct repair measurements. The IR thermography has been cited by the several guidelines as a good mean to qualitatively evaluate the presence of installation defects and to monitor the reinforcing system with time.The method is non-destructive and does not require contact with the composite or other means except air to detect the reinforcement. Some works in the literature have been published on this topic. Most of the researches aim at using the IR thermography technique to characterize quantitatively the defects in terms of depth, extension and type in order to have an experimental database on defect typology to evaluate the long term performances of the reinforcing system. Nevertheless, most of the works in the literature concerns with FRP applied to concrete structures without considering the case of masonry structures. In the present research artificial bond defects between FRP and the masonry substrate have been reproduced in laboratory and the IR multi temporal thermography technique has been used to detect them. Thermographic analysis has been carried out on two wall samples having limited dimensions (100 x 70 cm) both

  6. Ge{sup 4+}, Eu{sup 3+}-codoped Y{sub 2}SiO{sub 5} as a novel red phosphor for white LED applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan; Dong, Yuanyuan [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Wei, Bo [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu 215500 (China); Xu, Jiayue

    2017-05-15

    The phosphors Y{sub 2}SiO{sub 5}: Ge{sup 4+}, Eu{sup 3+} were synthesized by solid state reaction method assisted by flux, and have been characterized by X-ray powder diffraction and fluorescence spectrometer. The results showed that the phosphors can be effectively excited by near-UV (394 nm), and the major peak is located at 611 nm ascribed to the electric-dipole {sup 5}D{sub 0} → {sup 7}F{sub 2} transition of Eu{sup 3+}, the critical quenching concentration of Eu{sup 3+} in the phosphor is determined to be 15 mol% and the critical transfer distance is calculated as 8.90 Aa. Co-doping Y{sub 2}SiO{sub 5}: Eu{sup 3+} with Ge{sup 4+} helps to improve the luminescence intensity and color purity. The red emission of the phosphor under 394 nm excitation shows a good chromaticity index (0.652, 0.347) compared to commercial red phosphors Y{sub 2}O{sub 2}S: Eu{sup 3+} (0.631, 0.350). The quantum efficiency of the Y{sub 2}Si{sub 0.97}O{sub 5}: 0.03Ge{sup 4+}, 0.15Eu{sup 3+}phosphor under 394 nm excitation is estimated to be 45.24%. It can be concluded that efficient red light emitting diodes were fabricated using Ge{sup 4+}, Eu{sup 3+} co-doped phosphor based on near ultraviolet(NUV) excited LED lights. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. The Preparation and Optical Properties of Novel LiLa(MoO4)2:Sm3+,Eu3+ Red Phosphor

    Science.gov (United States)

    Luo, Li; Huang, Baoyu; He, Jingqi; Zhang, Wei; Zhao, Weiren; Wang, Jianqing

    2018-01-01

    Novel LiLa1−x−y(MoO4)2:xSm3+,yEu3+ (in short: LL1−x−yM:xSm3+,yEu3+) double molybdate red phosphors were synthesized by a solid-state reaction at as low temperature as 610 °C. The optimal doping concentration of Sm3+ in LiLa1−x(MoO4)2:xSm3+ (LL1−xM:xSm3+) phosphor is x = 0.05 and higher concentrations lead to emission quenching by the electric dipole—electric dipole mechanism. In the samples co-doped with Eu3+ ions, the absorption spectrum in the near ultraviolet and blue regions became broader and stronger than these of the Sm3+ single-doped samples. The efficient energy transfer from Sm3+ to Eu3+ was found and the energy transfer efficiency was calculated. Under the excitation at 403 nm, the chromaticity coordinates of LL0.95−yM:0.05Sm3+,yEu3+ approach to the NTSC standard values (0.670, 0.330) continuously with increasing Eu3+ doping concentration. The phosphor exhibits high luminous efficiency under near UV or blue light excitation and remarkable thermal stability. At 150 °C, the integrated emission intensity of the Eu3+ remained 85% of the initial intensity at room temperature and the activation energy is calculated to be 0.254 eV. The addition of the LL0.83M:0.05Sm3+,0.12Eu3+ red phosphors can improve the color purity and reduce the correlated color temperature of WLED lamps. Hence, LL1−x−yM:xSm3+,yEu3+ is a promising WLED red phosphor. PMID:29443910

  8. Ca8NaY(PO4)6F2:Eu2+,Mn2+: a potential color-tunable phosphor for white LEDs applications

    International Nuclear Information System (INIS)

    Fen, Zhang; Wanjun, Tang

    2015-01-01

    Eu 2+ - and/or Mn 2+ -activated Ca 8 NaY(PO 4 ) 6 F 2 phosphors have been prepared via a combustion-assisted synthesis route. The powder X-ray diffraction measurement revealed that Ca 8 NaY(PO 4 ) 6 F 2 crystallized in a hexagonal crystal system with the space group P6 3 /m (176). The photoluminescence spectrum of the Eu 2+ single-doped phosphor shows a broad blue emission band peaking at 451 nm under the excitation of UV irradiation. The Eu 2+ -/Mn 2+ -codoped phosphors show a blue emission band and an orange emission band, and the corresponding CIE coordinates intuitively indicate the tunable colors from blue to yellow area. The energy transfer from the Eu 2+ to Mn 2+ ions is demonstrated to be a quadrupole-quadrupole mechanism in terms of the experimental results and analysis of PL spectra and decay curves of the phosphors. The developed phosphors can be efficiently excited in the UV region and exhibit a tunable white-light emission, making them attractive as single-component white-light-emitting conversion phosphors for UV-based white LEDs. (orig.)

  9. Optimization of synthesis technique and luminescent properties in Eu{sup 3+}-activated NaCaPO{sub 4} phosphor for solid state lighting applications

    Energy Technology Data Exchange (ETDEWEB)

    Ratnam, B.V. [Department of Physics, Changwon National University, Changwon 51140 (Korea, Republic of); Sahu, Mukesh K.; Vishwakarma, Amit K.; Jha, Kaushal [Luminescent Materials Research Lab (LMRL), Department of Applied Physics, Delhi Technological University, Delhi 110042 (India); Woo, Hyun-Joo [Department of Physics, Changwon National University, Changwon 51140 (Korea, Republic of); Jang, Kiwan, E-mail: kwjang@changwon.ac.kr [Department of Physics, Changwon National University, Changwon 51140 (Korea, Republic of); Jayasimhadri, M., E-mail: jayaphysics@yahoo.com [Luminescent Materials Research Lab (LMRL), Department of Applied Physics, Delhi Technological University, Delhi 110042 (India)

    2017-05-15

    Europium activated NaCaPO{sub 4} phosphor has been synthesized by various synthesis techniques such as solid-state reaction (SSR), molten salt synthesis (MSS) and sol-gel combustion (SGC) method to optimize the synthesis procedure. The comparative investigations of structural and luminescent properties have been studied to know the best synthesis method. The XRD patterns and Rietveld refinement analysis of the synthesized phosphors confirmed the single phase orthorhombic structure of NaCaPO{sub 4}. Excitation spectra indicate the strong absorption in near ultraviolet (n-UV) region and the emission spectra exhibit strong emission band at 595 nm corresponds to {sup 5}D{sub 0}→{sup 7}F{sub 1} transition under n-UV (λ{sub ex}=392 nm) excitation. The SGC route synthesized phosphor exhibit intense emission than that of the SSR and MSS method. Therefore, the effect of dopant (Eu{sup 3+}) concentration on the emission intensity and concentration quenching mechanism has been discussed in detail for the Eu{sup 3+} doped NaCaPO{sub 4} phosphor synthesized by SGC method. The CIE chromaticity coordinates have been calculated for the phosphors synthesized by SSR, MSS and SGC methods to reveal the emitting color and also to know the utility of this phosphor for white LEDs.

  10. Synthesis and luminescence enhancement of CaTiO{sub 3}:Bi{sup 3+} yellow phosphor by codoping Al{sup 3+}/B{sup 3+} ions

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Renping, E-mail: jxcrp@163.com; Fu, Ting; Xu, Haidong; Luo, Wenjie; Peng, Dedong; Chen, Zhiquan; Fu, Jingwei

    2016-07-25

    CaTiO{sub 3}:Bi{sup 3+} and CaTiO{sub 3}:Bi{sup 3+}, Al{sup 3+}/B{sup 3+} phosphors are synthesized by solid-state reaction method in air. With excitation 272 and 320 nm, broad PL band peaking at 555 nm with full width at half maximum ∼200 nm is observed in the range of 400–800 nm due to the {sup 3}P{sub 1,0} → {sup 1}S{sub 0} transitions of Bi{sup 3+} ion. PLE spectrum monitored at 555 nm contains two PLE band peaking at ∼272 and 320 nm within the range 230–420 nm owing to metal-to-metal charge-transfer and {sup 1}S{sub 0} → {sup 3}P{sub 1} transition of Bi{sup 3+} ion, respectively. The optimal Bi{sup 3+} doping concentration in CaTiO{sub 3}:Bi{sup 3+} phosphor is about 0.5 mol%. Luminescence properties of CaTiO{sub 3}:Bi{sup 3+} phosphor may be improved obviously by co-doping Al{sup 3+}/B{sup 3+} ions, and its emission intensity can be enhanced 13–15 times after Al{sup 3+} ion is co-doped. Luminous mechanism of CaTiO{sub 3}:Bi{sup 3+} phosphor is analyzed by energy level diagram of Bi{sup 3+} ion. Decay curve and time-resolved spectra confirm that only a single type of Bi{sup 3+} luminescence center exists in CaTiO{sub 3}:Bi{sup 3+} phosphor. - Graphical abstract: PL spectra of CaTiO{sub 3}:Bi{sup 3+} and CaTiO{sub 3}:Bi{sup 3+}, Al{sup 3+}/B{sup 3+} phosphors and the corresponding pictures under 365 nm UV lamp. - Highlights: • CaTiO{sub 3}:Bi{sup 3+} and CaTiO{sub 3}:Bi{sup 3+}, Al{sup 3+}/B{sup 3+} phosphors are synthesized by solid-state reaction in air. • Broadband emission with FWHM ∼200 nm is observed within the range 400–800 nm. • Luminescence properties of CaTiO{sub 3}:Bi{sup 3+} phosphor can be improved by codoping Al{sup 3+}/B{sup 3+} ions. • PL intensity of CaTiO{sub 3}:Bi{sup 3+} phosphor can be enhanced 13–15 times after Al{sup 3+} ion is codoped.

  11. A novel high color purity blue-emitting phosphor: CaBi{sub 2}B{sub 2}O{sub 7}:Tm{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiangong, E-mail: lijiangong01@gmail.com [Department of Electronic Science and Engineering, Huanghuai University, Zhumadian 463000 (China); Yan, Huifang [Department of Foreign Languages and Literature, Huanghuai University, Zhumadian 463000 (China); Yan, Fengmei [Department of Chemistry and Chemical Engineering, Huanghuai University, Zhumadian 463000 (China)

    2016-07-15

    Graphical abstract: - Highlights: • A series of Tm{sup 3+}-doped CaBi{sub 2}B{sub 2}O{sub 7} blue-emitting phosphors were prepared. • The optimum doping content of Tm{sup 3+} ions was found. • The critical distance and concentration quenching mechanism was discussed. • The color purity of as prepared sample was analyzed and compared. - Abstract: A series of Tm{sup 3+}-doped CaBi{sub 2−x}B{sub 2}O{sub 7}:xTm{sup 3+} (0.02 ≤ x ≤ 0.12) blue-emitting phosphors with high color purity were prepared by solid-state reaction method. The crystal structure and luminescence properties of the as-prepared phosphors were studied. This phosphor shows a satisfactory blue performance (peak at 453 nm) due to the {sup 1}D{sub 2} → {sup 3}F{sub 4} transition of Tm{sup 3+} excited by 357 nm light. Investigation of Tm{sup 3+} content dependent emission spectra indicates that x = 0.04 is the optimum doping content of Tm{sup 3+} ions in the CaBi{sub 2}B{sub 2}O{sub 7} host. The critical distance and the concentration quenching mechanism were also investigated. In particular, the color purity of as prepared sample was analyzed and the result shows that the color purity of CaBi{sub 2}B{sub 2}O{sub 7}:Tm{sup 3+} is higher than the commercial blue phosphor BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} (BAM:Eu{sup 2+}) and the latest reported Tm{sup 3+} doped blue phosphors. The present work suggests that the CaBi{sub 2}B{sub 2}O{sub 7}:Tm{sup 3+} phosphor is a potential blue-emitting candidate for the application in the near-UV WLEDs.

  12. Combustion synthesis of CaSc{sub 2}O{sub 4}:Ce{sup 3+} nano-phosphors in a closed system

    Energy Technology Data Exchange (ETDEWEB)

    Peng Wenfang; Zou Shaoyu; Liu Guanxi; Xiao Quanlan; Zhang Rui; Xie Lijuan; Cao Liwei [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Meng Jianxin, E-mail: tmjx@jnu.edu.cn [Institute of Nano-Chemistry, Jinan University, Guangzhou 510632 (China); Liu Yingliang [Institute of Nano-Chemistry, Jinan University, Guangzhou 510632 (China)

    2011-06-09

    Highlights: > CaSc{sub 2}O{sub 4}:Ce{sup 3+} nano-phosphors can be prepared by a single-step combustion method. > The ignition temperature is the lowest in the combustion synthesis of Ce{sup 3+}/Eu{sup 2+} doped phosphors. > The as-prepared nano-phosphors give a uniform particle size in the range of 15-20 nm and have highly dispersity and fluorescence intensity. > It is a convenient method for preparation of monodispersed oxide nano-phosphors, especially those being sensitive to air at high temperature. - Abstract: The CaSc{sub 2}O{sub 4}:Ce{sup 3+} nano-phosphors were successfully prepared by a single-step combustion method at an ignition temperature as low as 200 deg. C in a closed autoclave using glycine as a fuel and PEG4000 as a dispersant. The samples were characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results revealed that CaSc{sub 2}O{sub 4}:Ce{sup 3+} nano-phosphors can be conveniently prepared at an ignition temperature as low as 200 deg. C, which was much lower than that in the ordinary combustion methods. The optimized ignition temperature was 220 deg. C. The CaSc{sub 2}O{sub 4}:Ce{sup 3+} nano-phosphors give a uniform particle size in the range of 15-20 nm. The low ignition temperature and the addition of PEG4000 dispersant play important roles in the formation of small sized nanoparticles. The as-prepared nano-phosphors were incompact aggregates, but highly dispersed nano-phosphors can be obtained after further ultrasonic treatment. The CaSc{sub 2}O{sub 4}:Ce{sup 3+} nano-phosphors give satisfactory luminescence characteristic benefiting from the closed circumstance, in which cerium atoms can be isolated from the oxidizing atmosphere and non-fluorescent Ce{sup 4+} ions can be ruled out. The present highly dispersed CaSc{sub 2}O{sub 4}:Ce{sup 3+} nano-phosphors with efficient fluorescence are promising in the field of biological labeling

  13. Tunable luminescence properties and efficient energy transfer in Eu2+, Tb3+ co-doped NaBaPO4

    Directory of Open Access Journals (Sweden)

    Qiuhong Zhang

    2014-01-01

    Full Text Available Eu2 + and Tb3+ singly doped and co-doped NaBaPO4 phosphors were synthesized by solid state reaction. The structure character, photoluminescence properties and the lifetime were investigated. The emission spectra of NaBaPO4:Eu2+, Tb3+, Na+ phosphor show both broad blue emission band and sharp green emission peaks. The energy transfer mechanism from Eu2+ to Tb3+ in NaBaPO4 host was discussed. The excitation spectra of NaBaPO4: Eu2+, Tb3+, Na+ phosphor show broad excitation band in the 250–400 nm range, which was in agreement with the near-ultraviolet (n-UV chip. The hue of the NaBaPO4: Eu2+, Tb3+, Na+ phosphors could be appropriately tuned by adjusting the contents of activators.

  14. Automatic thermographic scanning with the creation of 3D panoramic views of buildings

    Science.gov (United States)

    Ferrarini, G.; Cadelano, G.; Bortolin, A.

    2016-05-01

    Infrared thermography is widely applied to the inspection of building, enabling the identification of thermal anomalies due to the presence of hidden structures, air leakages, and moisture. One of the main advantages of this technique is the possibility to acquire rapidly a temperature map of a surface. However, due to the actual low-resolution of thermal camera and the necessity of scanning surfaces with different orientation, during a building survey it is necessary to take multiple images. In this work a device based on quantitative infrared thermography, called aIRview, has been applied during building surveys to automatically acquire thermograms with a camera mounted on a robotized pan tilt unit. The goal is to perform a first rapid survey of the building that could give useful information for the successive quantitative thermal investigations. For each data acquisition, the instrument covers a rotational field of view of 360° around the vertical axis and up to 180° around the horizontal one. The obtained images have been processed in order to create a full equirectangular projection of the ambient. For this reason the images have been integrated into a web visualization tool, working with web panorama viewers such as Google Street View, creating a webpage where it is possible to have a three dimensional virtual visit of the building. The thermographic data are embedded with the visual imaging and with other sensor data, facilitating the understanding of the physical phenomena underlying the temperature distribution.

  15. Establishing Differences in Thermographic Patterns between the Various Complications in Diabetic Foot Disease

    Directory of Open Access Journals (Sweden)

    Alfred Gatt

    2018-01-01

    Full Text Available Aim. To evaluate the potential of thermography as an assessment tool for the detection of foot complications by understanding the variations in temperature that occur in type 2 diabetes mellitus (DM. Methods. Participants were categorized according to a medical examination, ankle brachial index, doppler waveform analysis, and 10-gram monofilament testing into five groups: healthy adult, DM with no complications, DM with peripheral neuropathy, DM with neuroischaemia, and DM with peripheral arterial disease (PAD groups. Thermographic imaging of the toes and forefeet was performed. Results. 43 neuroischaemic feet, 41 neuropathic feet, 58 PAD feet, 21 DM feet without complications, and 126 healthy feet were analyzed. The temperatures of the feet and toes were significantly higher in the complications group when compared to the healthy adult and DM healthy groups. The higher the temperatures of the foot in DM, the higher the probability that it is affected by neuropathy, neuroischaemia, or PAD. Conclusions. Significant differences in mean temperatures exist between participants who were healthy and those with DM with no known complications when compared to participants with neuroischaemia, neuropathy, or PAD. As foot temperature rises, so does the probability of the presence of complications of neuropathy, neuroischaemia, or peripheral arterial disease.

  16. Analysis of grease contamination influence on the internal radial clearance of ball bearings by thermographic inspection

    Directory of Open Access Journals (Sweden)

    Mišković Žarko Z.

    2016-01-01

    Full Text Available One of the most important factors influencing ball bearings service life is its