Neutron activation analysis for study of distribution patterns of organo-halogen pollutants in apple

International Nuclear Information System (INIS)

Zhang Hong; Luo Jialing; Sun Huibin; Chai Zhifang; Chinese Academy of Sciences, Beijing

2007-01-01

The distribution characteristics of organo-halogens in apple and their sources were studied by neutron activation analysis combined with statistical analysis. The results indicated that concentrations of organo-halogens in apple were in the order of organo-chlorine >> organo-bromine > organo-iodine, and concentrations of the organo-chlorine in four parts of apple were in the order of seed >> peel >> endocarp ≥ pulp. Also, the organo-chlorine, -bromine and-iodine in apple were found to have different sources. The latter two were mainly from naturally synthetic products by plant itself, while the former was mainly from anthropogenic pollutants. (authors)

Recovering of uranium from phosphoric acid produced by the wet process

International Nuclear Information System (INIS)

Barreiro, A.J.; Lyon, W.L.; Holleman, R.A.; Randell, C.C.

1977-01-01

Process for recovering uranium as from an aqueous solution of phosphoric acid arising from a wet process, with a scrubbing agent essentially composed of a hydrocarbon whose boiling point is situated between 150 0 C and 300 0 C, which reacts with the contaminents formed in the sludge in the phosphoric acid, in an efficient enough quantity to wash the contamination products forming the phosphoric acid sludge, give a sludge phase and a purified phosphoric acid phase, after which the sludge phase is extracted [fr

Synthesis of 5-organo-, 9-organo-, and 9,11-diorgano-nido-7,8-dicarbaundecaborate salts by a cross-combination reaction

International Nuclear Information System (INIS)

Zakharkin, L.I.; Ol'shevskaya, V.A.; Petrovskij, P.V.

2000-01-01

It has been shown for the first time that salts of 5-iodine and 9,11-diiodine-nido-7,8-dicarbaundecaborates, containing iodine atoms near polyhedron pentagonal surface boron atoms, enter cross-combination reaction with magnesium organic compounds during catalysis by palladium complexes with formation of 5-organo-, 9-organo-, and 9,11-diorgano-nido-7,8-dicarbaundecaborate salts [ru

Removal of lead and phosphate ions from aqueous solutions by organo-smectite.

Science.gov (United States)

Bajda, Tomasz; Szala, Barbara; Solecka, Urszula

2015-01-01

Smectite has been modified using hexadecyltrimethyl ammonium bromide in an amount of double cationic exchange capacity. This alteration makes it possible to use organo-smectite as a sorbent to remove anionic forms. The experiment consisted of the interchangeable sorption of phosphate(V) and lead(II) by organo-smectite. Research was carried out with varying pH (2-5) and various concentrations (0.1-5 mmol/L). Organo-smectite with previously adsorbed lead ions removed more phosphate than the untreated organo-smectite. Experimental data show that lead is more likely to absorb on the organo-smectite than on the organo-smectite with previously adsorbed phosphate ions. It follows that the most effective use of the organo-smectite is through the sorption of first - Pb cations and then PO4 anions. With an increasing concentration of Pb(II) or P(V), the sorption efficiency increases. The maximum sorption efficiency of lead and phosphate ions is observed at pH 5. This enables the removal of harmful lead and phosphorus compounds from waste water and immobilizes them on the sorbent's surface. The alternating reactions of lead and phosphorus ions result in the crystallization of brompyromorphite Pb5(PO4)3Br.

Oxycarbonitride phosphors and light emitting devices using the same

Science.gov (United States)

Li, Yuanqiang; Romanelli, Michael Dennis; Tian, Yongchi

2013-10-08

Disclosed herein is a novel family of oxycarbidonitride phosphor compositions and light emitting devices incorporating the same. Within the sextant system of M--Al--Si--O--N--C--Ln and quintuplet system of M--Si--O--N--C--Ln (M=alkaline earth element, Ln=rare earth element), the phosphors are composed of either one single crystalline phase or two crystalline phases with high chemical and thermal stability. In certain embodiments, the disclosed phosphor of silicon oxycarbidonitrides emits green light at wavelength between 530-550 nm. In further embodiments, the disclosed phosphor compositions emit blue-green to yellow light in a wavelength range of 450-650 nm under near-UV and blue light excitation.

Adsorption and desorption of cadmium by synthetic and natural organo-clay complexes

International Nuclear Information System (INIS)

Levy, R.; Francis, C.W.; Oak Ridge National Lab., Tenn.

1976-01-01

Tracer levels of 109 Cd were used to study the adsorption and desorption of Cd by synthetic and natural organo-clay complexes. Synthetic organo-clay complexes were made by adsorbing humic acid extracted from soil to various forms of 3 ) 2 showed that Cd was adsorbed more tenaciously to the sesquioxides than organo-clay fractions

Organo-axial volvulus of the small intestine: radiological case report and consideration for its mechanism.

Science.gov (United States)

Ishiguro, Toshitaka; Hiyama, Takashi; Nasu, Katsuhiro; Akashi, Yoshimasa; Minami, Manabu

2017-07-01

Gastrointestinal volvulus is mainly classified into two subtypes, mesentero-axial volvulus and organo-axial volvulus. The detailed imaging findings of organo-axial volvulus of the small intestine have never been reported as far as we know. In this article, we report a case of organo-axial volvulus of the small intestine, focusing on the computed tomography (CT) findings. An 80-year-old man was radiologically diagnosed as having organo-axial volvulus of the terminal ileum and it was confirmed by open surgery without adhesion or any other anatomical abnormalities. CT showed two specific findings, split-bowel sign and rotating-C sign, which we think reflect pathophysiologic features of organo-axial volvulus. We think the pathogenic mechanism of organo-axial volvulus can be explained by the convergence of the reversed-rotational twist following the formation of a twisted but non-obstructive circular loop, even if there is no adhesion. Radiologists should be aware that organo-axial volvulus can occur even in the small intestine, and in the case of small bowel obstruction with single transition point, the two pathophysiologic signs mentioned above must be looked for to diagnose the possibility of organo-axial volvulus.

Activated phosphors having matrices of yttrium-transition metal compound

International Nuclear Information System (INIS)

De Kalb, E.L.; Fassel, V.A.

1975-01-01

A method is described for preparing a phosphor composition containing a lanthanide activator element with a host matrix having a transition element as a major component. The host matrix is composed of certain rare earth phosphates or vanadates such as YPO 4 with a portion of the rare earth replaced with one or more of the transition elements. On x-ray or other electromagnetic excitation, trace lanthanide impurities or additives within the phosphor are spectrometrically determined from their characteristic luminescence

Ligeti: Ricercare per organo / M. K.

Index Scriptorium Estoniae

M. K.

1991-01-01

Uuest heliplaadist "Ligeti: Ricercare per organo, Vivier, Les Communiantes, Cavana, Jodl; Scelsi: In nomine Lucis; Lennot: Livre d'Orgue-extrait; Richer: Orgue 88; Pärt: Pari intervallo, Pierre Bousseau (Orgel)" (AD:1990). Adda/TIS CD 581 240 (WD:59'45") DDD

40 CFR 721.5330 - Nickel salt of an organo compound containing nitrogen.

Science.gov (United States)

2010-07-01

... containing nitrogen. 721.5330 Section 721.5330 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5330 Nickel salt of an organo compound containing nitrogen. (a) Chemical... as nickel salt of an organo compound containing nitrogen (PMN P-92-686) is subject to reporting under...

Study on the relationship between uranium and phosphor in deposit No.60

International Nuclear Information System (INIS)

Zhang Wanliang

1997-01-01

The deposit No.60 is a large uranium-phosphor one located at the eastern margin of the volcanic basin No.65, and controlled by the stratigraphic horizon of the middle-lower part of the third member of the Ehuling Formation composed of volcaniclastic and terrigeneous classic rocks. Uranium and phosphor were preliminarily concentrated together during the formation of ore-hosting layer, and then reactivated, transported and reprecipitated together under the action of tectonothermal process, leading to the concentration of uranium in cellophane in the adsorption state. Uranium and phosphor are closely associated with the correlation coefficient of up to 0.8-0.9

NMR as a tool for kinetic studies: application to the assessment of organo tin reactivity

Energy Technology Data Exchange (ETDEWEB)

Fouquet, E.; Roulet, T. [Bordeaux-1 Univ., 33 - Talence (France); Pianet, I. [Bordeaux-1 Univ., 33 -Talence (France) CNRS, Centre d`Etudes Structurales et d`Analyse des Molecules Organiques; Willem, R. [Brussels University (VUB), Brussels (Belgium)

1998-02-01

There is a growing interest for the research of an answer to the environmental problems related to the industrial use of tetra organo tins. An interesting alternative would be to develop the chemistry of mono organo tins because of their lower toxicity and of the easy removal of ``inorganic`` tin side products. In this work, halogen exchange rates are measured for various mono organo tins with NMR techniques (EXSY spectra and 1 D {sup 119} Sn NMR), and an exchange mechanism is proposed. A correlation between kinetic data and the reactivity of the mono organo tins is then exemplified with radical allylic transfer and palladium catalyzed coupling reactions. (authors) 14 refs.

Organo-Selenium Coatings Inhibit Gram-Negative and Gram-Positive Bacterial Attachment to Ophthalmic Scleral Buckle Material.

Science.gov (United States)

Tran, Phat; Arnett, Avery; Jarvis, Courtney; Mosley, Thomas; Tran, Khien; Hanes, Rob; Webster, Dan; Mitchell, Kelly; Dominguez, Leo; Hamood, Abdul; Reid, Ted W

2017-09-01

Biofilm formation is a problem for solid and sponge-type scleral buckles. This can lead to complications that require removal of the buckle, and result in vision loss due to related ocular morbidity, primarily infection, or recurrent retinal detachment. We investigate the ability of a covalent organo-selenium coating to inhibit biofilm formation on a scleral buckle. Sponge and solid Labtican brand scleral buckles were coated with organo-selenium coupled to a silyation reagent. Staphylococcus aureus biofilm formation was monitored by a standard colony-forming unit assay and the confocal laser scanning microscopy, while Pseudomonas aeruginosa biofilm formation was examined by scanning electron microscopy. Stability studies were done, by soaking in phosphate buffer saline (PBS) at room temperature for 2 months. Toxicity against human corneal epithelial cell was examined by growing the cells in the presence of organo-selenium-coated scleral buckles. The organo-selenium coating inhibited biofilm formation by gram-negative and gram-positive bacteria. The buckle coatings also were shown to be fully active after soaking in PBS for 2 months. The organo-selenium coatings had no effect on the viability of human corneal epithelial cells. Organo-selenium can be used to covalently coat a scleral buckle, which is stable and inhibits biofilm formation for gram-negative and gram-positive bacteria. The organo-selenium buckle coating was stable and nontoxic to cell culture. This technology provides a means to inhibit bacterial attachment to devices attached to the eye, without damage to ocular cells.

Technological applications of organo-montmorillonites in the removal of pyrimethanil from water: adsorption/desorption and flocculation studies.

Science.gov (United States)

Flores, Federico M; Undabeytia, Tomas; Morillo, Esmeralda; Torres Sánchez, Rosa M

2017-06-01

Pyrimethanil (2-aniline-4, 6-dimethylpyrimidine, PRM) is used in fruit packing plants to control fungal infections and diseases. The effluents greatly polluted with this fungicide, as a point source contamination, need to be technologically treated for their regeneration before they reach water bodies. This work evaluates the use of organo-montmorillonites, synthetized in our laboratory, for their application in adsorption and coagulation/flocculation processes for the removal of PRM from water. The adsorption-desorption performance of PRM in a raw montmorillonite (Mt) and several organo-montmorillonites (organo-Mt) obtained by different amounts and types of exchanged surfactants (octadecyltrimethylammonium (ODTMA) and didodecyldimethylammonium (DDAB) bromides and benzyltrimethylammonium chloride (BTMA)) was studied. The PRM adsorption on raw Mt was assigned mainly to an interlayer occupancy, while hydrophobic interactions between PRM and the surfactants in the exchanged samples increased PRM adsorption, which was correlated with the surfactant loading. PRM desorption showed irreversible behavior in raw Mt, which changed to reversible for organo-Mt samples, and was also correlated with the increase of surfactant loading.Two of the organo-Mt with high surfactant loading (twice the CEC) were assayed for the removal of commercial PRM in coagulation/flocculation tests, and their performance was compared to that of the native clay (Mt). The use of the organo-Mt produced flocculation at a very low ratio (0.5 g L -1 ), whereas no flocculation was observed with Mt. These results proved the feasibility of the use of organo-Mt for the treatment of wastewater contaminated with PRM using a low organo-Mt/liquid ratio.

Determination of iodide, iodate and organo-iodine in waters with a new total organic iodine measurement approach.

Science.gov (United States)

Gong, Tingting; Zhang, Xiangru

2013-11-01

The dissolved iodine species that dominate aquatic systems are iodide, iodate and organo-iodine. These species may undergo transformation to one another and thus affect the formation of iodinated disinfection byproducts during disinfection of drinking waters or wastewater effluents. In this study, a fast, sensitive and accurate method for determining these iodine species in waters was developed by derivatizing iodide and iodate to organic iodine and measuring organic iodine with a total organic iodine (TOI) measurement approach. Within this method, organo-iodine was determined directly by TOI measurement; iodide was oxidized by monochloramine to hypoiodous acid and then hypoiodous acid reacted with phenol to form organic iodine, which was determined by TOI measurement; iodate was reduced by ascorbic acid to iodide and then determined as iodide. The quantitation limit of organo-iodine or sum of organo-iodine and iodide or sum of organo-iodine, iodide and iodate was 5 μg/L as I for a 40 mL water sample (or 2.5 μg/L as I for an 80 mL water sample, or 1.25 μg/L as I for a 160 mL water sample). This method was successfully applied to the determination of iodide, iodate and organo-iodine in a variety of water samples, including tap water, seawater, urine and wastewater. The recoveries of iodide, iodate and organo-iodine were 91-109%, 90-108% and 91-108%, respectively. The concentrations and distributions of iodine species in different water samples were obtained and compared. Copyright © 2013 Elsevier Ltd. All rights reserved.

Thermal degradation of organo-soluble polyimides

Institute of Scientific and Technical Information of China (English)

黄俐研; 史燚; 金熹高

1999-01-01

The thermal degradation behavior of two organo-soluble polyimides was investigated by high resolution pyrolysis-gas chromatography/mass spectrometry. The pyrolyzates of the polymers at various temperatures were identified and characterized quantitatively. The relationship between the polymer structure and pyrolyzate distribution was discussed. The kinetic parameters of the thermal degradation were calculated based on thermogravimetric measurements. Finally, the thermal degradation mechanism for the polymers was suggested.

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)

Direct uranium extraction from dihydrate and hemi-dihydrate wet process phosphoric acids by liquid emulsion membrane

International Nuclear Information System (INIS)

El-Hazek, N.T.; El Sayed, M.S.

2003-01-01

A new liquid emulsion membrane (LEM) process for uranium extraction from either dihydrate 28-30% P 2 O 5 (DH) or hemi-dihydrate 42-45% P 2 O 5 (HDH) wet process phosphoric acid is proposed. In this process, the organic component of the LEM is composed of a synergistic mixture of 0.1M di-2-ethyl hexyl phosphoric acid (DEHPA) and 0.025M trioctyl phosphine oxide (TOPO) with 4% Span 80. The internal or the strip acid phase is composed of 0.5M citric acid. The prepared LEM was proved to be stable in 42-45% P 2 O 5 acid concentration range and can, therefore, be applied to the phosphoric acid produced by the hemi-dihydrate process. After breakdown of the loaded emulsion, the uranyl citrate in the internal strip phase is separated by adding methanol followed by its calcination to the orange oxide. Most of the reagents used are recycled. The proposed process is characterized by simplicity, practically closed operation cycle in addition to lower capital and operating costs. (author)

Variáveis relacionadas à estabilidade de complexos organo-minerais em solos tropicais e subtropicais brasileiros Selected soil-variables related to the stability of organo-minerals complexes in tropical and subtropical brazilian soils

Directory of Open Access Journals (Sweden)

Alberto Vasconcellos Inda Junior

2007-10-01

Full Text Available A estabilidade de complexos organo-minerais é uma característica importante quanto à química e física de solos tropicais e subtropicais. O objetivo deste estudo foi identificar variáveis relacionadas à estabilidade de complexos organo-minerais, avaliada pela energia de ultra-som necessária para a dispersão total do solo em partículas primárias, em seis solos das regiões Sul e Centro-Oeste do Brasil com textura e mineralogia distintas. A energia de ultra-som necessária para dispersão total dos solos variou de 239 a 2.389J mL-1, sendo diretamente relacionada aos teores de carbono orgânico (R²=0,799, PThe stability of organo-mineral complexes is an important characteristic related to the soil chemistry and physics of tropical and subtropical soils. This study was aimed at identifing the variables related to the stability of organo-mineral complexes, evaluated by ultrasonic energy necessary to complete soil dispersion, of six soils from South and West-Center regions of Brazil with distint texture and mineralogy. The ultrasonic energy to complete soil dispersion varied from 239 a 2389J mL-1, and was positively related to the soil organic carbon concentrations (R²=0.799, P<0.05. The clay mineralogy had an important role to the stability of organo-mineral complexes, which were related to the content of low cristalinity iron oxides (R²=0.586, P<0.10, but did not had relationship with the total pedogenic iron oxides. The qualitative analysis of the clay mineralogy, by X-ray diffraction, evidenced that gibbsite and goethite are the main clay minerals related to the stability of organo-mineral complexes, reinforcing the importance of these minerals on the physical protection and coloidal stability of the soil organic matter in the tropical and subtropical soils.

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...

NATO Advanced Study Institute on Fundamental and Technological Aspects of Organo-f-Element Chemistry

CERN Document Server

Fragalà, Ignazio

1985-01-01

The past decade has seen a dramatic acceleration of activity and interest in phenomena surrounding lanthanide and actinide organo­ metallic compounds. Around the world, active research in organo-f­ element synthesis, chemistry, catalysis, crystallography, and quantum chemistry is in progress. This activity has spanned a remarkably wide range of disciplines, from synthetic/mechanistic inorganic and organic chemistry to radiochemistry, catalytic chemistry, spectroscopy (vibra­ tional, optical, magnetic resonance, photoelectron, Mossbauer), X-ray and neutron diffraction structural analysis, as well as to crystal field and molecular orbital theoretical studies at the interface of chemistry and physics. These investigations have been motivated both by fundamental and applied goals. The evidence that f-element organo­ metallic compounds have unique chemical and physical properties which cannot be duplicated by organometallic compounds of d-block elements has suggested many new areas of endeavor and application....

Organo-Zintl-based superatoms: [Ge9(CHO)3] and [Ge9(CHO)

Science.gov (United States)

Reddy, G. Naaresh; Jena, Puru; Giri, Santanab

2017-10-01

A systematic study, based on density functional theory and different hybrid functionals for exchange-correlation potential, shows that the electron affinities of organo-zintl clusters [Ge9(R)n] [R = CHO; n = 1, 3] are close to that of chlorine (3.6 eV) and iodine (3.0 eV). A detailed study of the molecular orbitals of these complexes, when compared to those of Al13-, Cl- and I-, confirm that they behave as superatoms, mimicking the chemistry of halogens. This study expands the scope of superatoms by including a new class of pseudo-halogens based on ligated organo-Zintl ions.

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...

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.

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.)

In situ characterization of organo-modified and unmodified montmorillonite aqueous suspensions by UV-visible spectroscopy.

Science.gov (United States)

Alin, Jonas; Rubino, Maria; Auras, Rafael

2015-10-15

UV-visible (UV-Vis) spectroscopy (Tyndall spectra) was applied and tested for its ability to measure organo-modified and unmodified montmorillonite (MMT) clays in aqueous suspensions. A full factorial design of experiments was used to study the influence of pH, NaCl and clay concentrations on the average particle size of the clay agglomerates. The methodology was evaluated by observing results that were consistent with previous research about the unmodified clay's behavior in aqueous suspensions. The results from this evaluation corresponded to accepted theories about the unmodified clay's behavior, indicating that the methodology is precise enough to distinguish the effects of the studied factors on these clay suspensions. The effect of clay concentration was related to the amount of ions per clay particle for the unmodified clay, but was not significant for the organo-modified MMT. The average particle size of the organo-modified MMT in suspension was significantly larger than that of the unmodified clay. Size of the organo-modified MMT agglomerates in suspension decreased in the presence of NaCl and at both high and low pH; this behavior was opposite to that of the unmodified clay. These results demonstrate that the UV-Vis methodology is well-suited for characterizing clay particle size in aqueous suspensions. The technique also is simple, rapid, and low-cost. Copyright © 2015 Elsevier Inc. All rights reserved.

Innovative Uses of Organo-philic Clays for Remediation of Soils, Sediments and Groundwater

International Nuclear Information System (INIS)

Bullock, A.M.

2009-01-01

PCBs and similar low-solubility organic compounds continue to offer significant challenges in terrestrial and sediment remediation applications. While selective media such as granular activated carbon (GAC) have proven to be successful at absorbing soluble organics, these media may have reduced performance due to blinding in the presence of high molecular weight organic matter. An alternative technology addresses this problem with a clay-based adsorption media, which effectively and efficiently stabilizes low-solubility organic matter. Organoclay TM reactive media utilizes granular sodium bentonite, which has been chemically modified to attract organic matter without absorbing water. The unique platelet structure of bentonite clays provides tremendous surface area and the capacity of the media to absorb over 60 percent of its own weight in organic matter. Because of these properties, organo-clays allow for several cost-effective in-situ remediation techniques, such as: - Flow-through filtration for removal of organic matter from aqueous solutions. Organo-clay can be utilized as a fixed-bed media in a column operation. This specialty media offers a high efficient alternative to Granular Activated Carbon (GAC) when applied as a flow through media to remove oil, PCB and other low soluble organic contaminates from water. - Placement in a Reactive Core Mat TM . Organo-clay may be encapsulated into carrier textiles which are adhered together to create a thin reactive layer with high strength and even distribution of the reactive media. This type of delivery mechanism can be successfully applied in a sub aqueous or terrestrial environment for sediment capping applications - Permeable reactive barriers. Organo-clay can deliver high sorption capacity, high efficiency, and excellent hydraulic conductivity as a passive reactive media in these applications. (authors)

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.

Miscellaneous Lasing Actions in Organo-Lead Halide Perovskite Films.

Science.gov (United States)

Duan, Zonghui; Wang, Shuai; Yi, Ningbo; Gu, Zhiyuan; Gao, Yisheng; Song, Qinghai; Xiao, Shumin

2017-06-21

Lasing actions in organo-lead halide perovskite films have been heavily studied in the past few years. However, due to the disordered nature of synthesized perovskite films, the lasing actions are usually understood as random lasers that are formed by multiple scattering. Herein, we demonstrate the miscellaneous lasing actions in organo-lead halide perovskite films. In addition to the random lasers, we show that a single or a few perovskite microparticles can generate laser emissions with their internal resonances instead of multiple scattering among them. We experimentally observed and numerically confirmed whispering gallery (WG)-like microlasers in polygon shaped and other deformed microparticles. Meanwhile, owing to the nature of total internal reflection and the novel shape of the nanoparticle, the size of the perovskite WG laser can be significantly decreased to a few hundred nanometers. Thus, wavelength-scale lead halide perovskite lasers were realized for the first time. All of these laser behaviors are complementary to typical random lasers in perovskite film and will help the understanding of lasing actions in complex lead halide perovskite systems.

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

Sorptive fractionation of organic matter and formation of organo-hydroxy-aluminum complexes during litter biodegradation in the presence of gibbsite

Science.gov (United States)

Heckman, K.; Grandy, A. S.; Gao, X.; Keiluweit, M.; Wickings, K.; Carpenter, K.; Chorover, J.; Rasmussen, C.

2013-11-01

Solid and aqueous phase Al species are recognized to affect organic matter (OM) stabilization in forest soils. However, little is known about the dynamics of formation, composition and dissolution of organo-Al hydroxide complexes in microbially-active soil systems, where plant litter is subject to microbial decomposition in close proximity to mineral weathering reactions. We incubated gibbsite-quartz mineral mixtures in the presence of forest floor material inoculated with a native microbial consortium for periods of 5, 60 and 154 days. At each time step, samples were density separated into light (2.0 g cm-3) fractions. The light fraction was mainly comprised of particulate organic matter, while the intermediate and heavy density fractions contained moderate and large amounts of Al-minerals, respectively. Multi-method interrogation of the fractions indicated the intermediate and heavy fractions differed both in mineral structure and organic compound composition. X-ray diffraction analysis and SEM/EDS of the mineral component of the intermediate fractions indicated some alteration of the original gibbsite structure into less crystalline Al hydroxide and possibly proto-imogolite species, whereas alteration of the gibbsite structure was not evident in the heavy fraction. DRIFT, Py-GC/MS and STXM/NEXAFS results all showed that intermediate fractions were composed mostly of lignin-derived compounds, phenolics, and polysaccharides. Heavy fraction organics were dominated by polysaccharides, and were enriched in proteins, N-bearing compounds, and lipids. The source of organics appeared to differ between the intermediate and heavy fractions. Heavy fractions were enriched in 13C with lower C/N ratios relative to intermediate fractions, suggesting a microbial origin. The observed differential fractionation of organics among hydroxy-Al mineral types suggests that microbial activity superimposed with abiotic mineral-surface-mediated fractionation leads to strong density

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

Corrosion resistance of cement brick on an organo-mineral base in a hydrogen sulfide medium

Energy Technology Data Exchange (ETDEWEB)

Potapov, A G; Belousov, G A; Pustovalov, V I; Skorikov, B M

1981-01-01

Results are presented of strength tests of cement brick made of different types of cement as a function of the composition of the mixing liquid and storage conditions. It is established that cement brick made of cement on a cinder base mixed in hydrogen sulfide water possesses the highest corrosive resistance to hydrogen sulfide attack. A marked increase in corrosion resistance is observed in cement brick on an organo-mineral base. Results of industrial tests of organo-mineral grouting mortar in a hydrogen sulfide medium are demonstrated.

Studies on the luminescence properties of CaZrO3:Eu3+ phosphors prepared by the solid state reaction method

Directory of Open Access Journals (Sweden)

Ishwar Prasad Sahu

2017-03-01

Full Text Available CaZrO3:xEu3+ (x = 1.0, 2.0, 3.0, 4.0, and 5.0 mol% phosphors were successfully prepared by a solid state reaction method. The crystal structure of sintered phosphors was hexagonal phase with space group of Pm-3m. The near ultra-violet (NUV excitation, emission spectra of the CaZrO3:xEu3+ phosphors were composed of sharp line emission associated with the transitions from the excited states 5D0 to the ground state 7Fj (j = 0, 1, 2, 3, 4 of Eu3+. The results indicated that CaZrO3:xEu3+ might become an important orange-red phosphor candidate for use in white light emitting diodes (WLEDs with near-UV LED chips. The mechanoluminescence (ML intensity increases linearly with increasing impact velocity of the moving piston, suggesting that the sintered phosphors can also be useful as a stress sensor.

Silver-organo-complex ink with high conductivity and inkjet stability

KAUST Repository

Vaseem, Mohammad

2017-06-22

A robust formulation of silver-organo-complex (SOC) ink and method of making same are provided. In an aspect, the complexing molecules act as reducing agents. The silver loaded ink can be printed and sintered on a wide range of substrates with uniform surface morphology and excellent adhesion.

Silver-organo-complex ink with high conductivity and inkjet stability

KAUST Repository

Vaseem, Mohammad; McKerricher, Garret; Shamim, Atif

2017-01-01

A robust formulation of silver-organo-complex (SOC) ink and method of making same are provided. In an aspect, the complexing molecules act as reducing agents. The silver loaded ink can be printed and sintered on a wide range of substrates with uniform surface morphology and excellent adhesion.

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.

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.)

Preparation and properties of organo(acetylacetonato)antimony(V) compounds

NARCIS (Netherlands)

Meinema, H.A.; Noltes, J.G.

Organo(acetylacetonato)antimony(V) compounds of the types R2SbCl2Acac, R4SbAcac, PhSbCl3Acac and Cl4SbAcac have been synthesized. The compounds are monomeric in solution. IR and PMR data of these compounds, which contain a chelated Acac ligand have been discussed. Ph2SbCl2Acac shows abnormal

Studies on the Luminescence Properties of CaZrO3:Eu3+ Phosphors Prepared by the Solid State Reaction Method

OpenAIRE

Sahu, Ishwar Prasad; Bisen, D.P.; Tamrakar, R.K.; Murthy, K.V.R.; Mohapatra, M.

2017-01-01

CaZrO3:xEu3+ (x = 1.0, 2.0, 3.0, 4.0, and 5.0 mol%) phosphors were successfully prepared by a solid state reaction method. The crystal structure of sintered phosphors was hexagonal phase with space group of Pm-3m. The near ultra-violet (NUV) excitation, emission spectra of the CaZrO3:xEu3+ phosphors were composed of sharp line emission associated with the transitions from the excited states 5D0 to the ground state 7Fj (j = 0, 1, 2, 3, 4) of Eu3+. The results indicated that CaZrO3:xEu3+ might ...

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

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.

Sorptive fractionation of organic matter and formation of organo-hydroxy-aluminum complexes during litter biodegradation in the presence of gibbsite

Science.gov (United States)

K. Heckman; A.S. Grandy; X. Gao; M. Keiluweit; K. Wickings; K. Carpenter; J. Chorover; C. Rasmussen

2013-01-01

Solid and aqueous phase Al species are recognized to affect organic matter (OM) stabilization in forest soils. However, little is known about the dynamics of formation, composition and dissolution of organo-Al hydroxide complexes in microbially-active soil systems, where plant litter is subject to microbial decomposition in close proximity to mineral weathering...

Organo-bridged silsesquioxane titanates for heterogeneous catalytic epoxidation with aqueous hydrogen peroxide

NARCIS (Netherlands)

Wang, Y.M.; Magusin, P.C.M.M.; Santen, van R.A.; Abbenhuis, H.C.L.

2007-01-01

Organo-bridged silsesquioxane titanates for heterogeneous catalytic epoxidation with aqueous hydrogen peroxide were synthesized through the acid-catalyzed hydrolysis and co-condensation of organotrialkoxysilane monomers and a,¿-bis(trialkoxysilyl) alkane cross-linkers in ethanol–water solution, with

VOLATILE ORGANO-METALLOIDS IN BIO-SOLID MATERIALS: ANALYSIS BY VACUUM DISTILLATION-GC/MS

Science.gov (United States)

An analytical method based on vacuum distillation-gas chromatography-mass spectrometry (VD-GC-MS)was developed for determining volatile organo-metalloid contaminants in bio-solid materials. Methodperformance was evaluated for dimethylselenide (DMSe), dimethyldisel...

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)

Crystallization of paraffins, formation of organo gels and flow in pipelines; Cristalizacao de parafinas, formacao de organogeis e escoamento em oleodutos

Energy Technology Data Exchange (ETDEWEB)

Vaz, Juliana Correia Bergallo; Mohamed, Rahoma Sadeg; Oliveira, Marcelo Ganzarolli de [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)]. E-mails: jcbvaz8@hotmail.com; mohamed@feq.unicamp.br; mgo@iqm.unicamp.br

2003-06-01

In this work, polarized light microscopy , differential scan calorimetry, X-ray diffraction and viscosimetry were used to investigate the phase behavior of binary and tertiary mixtures of the paraffins C10 , C21 , C25 , C28 , C32 ,C36 and C40. Phase transition temperatures for the binary mixtures C28/C40 , C21/C40 , C28/C32 and C21/C25 were obtained using DSC measurements. The formation of organogels in C10/C21, C10/C28, C10/C36, C10/C40, C10/C21/C28, C10/C21/C40 and C10/C28/C40 mixtures was confirmed using other techniques. The evidence of the formation of organo gels systems allows phase diagrams to be interpreted from a new perspective that takes into account the important role of these systems in the transportation of oil in pipelines and its implications in the retention of large amounts of oil in the gel structure. The results obtained suggest that all paraffins mixtures, considered in this work, are potentially capable of forming organo gels at a given temperature and composition, except those that form solid solutions. A very important characteristic of organo gels is that they do not form under shear rate. Therefore, a turbulent oil flow would make it more difficult to form paraffinic organo gels. On the other hand, once they have been formed, organo gels do not get unstructured under shear and constant oscillation and with the increase of temperature, which could make it difficult for oil to flow . Thus, the characterization of the formation of these organo gels can provide new information to solve technological problems of oil flow. (author)

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.

Stabilization of heavy metals in soil using two organo-bentonites.

Science.gov (United States)

Yu, Kai; Xu, Jian; Jiang, Xiaohong; Liu, Cun; McCall, Wesley; Lu, Jinlong

2017-10-01

Stabilization of Cu, Zn, Cd, Hg, Cr and As in soil using tetramethylammonium (TMA) and dodecyltrimethylammonium (DTMA) modified bentonites (T-Bents and D-Bents) as amendments was investigated. Toxicity characteristic leaching procedure (TCLP) was used to quantify the metal mobility after soil treatment. The structural parameters of modified bentonites, including the BET surface area, basal spacing and zeta potential were obtained as a function of the TMA and DTMA loading at 40, 80, 120, 160 and 200% of the bentonite's cation exchange capacity, respectively. The results indicated that the characteristics of the organo-bentonites fundamentally varied depending on the species and concentration of modifiers loaded on bentonite. T-Bents and D-Bents manifested distinct immobilization effectiveness towards various metals. In association with the organo-bentonite characteristics, the main interactive mechanisms for Cu, Zn and Cd proceeded via cation exchange, Hg proceeded via physical adsorption and partitioning, Cr and As proceeded via specific adsorption and electrostatic attraction, respectively. This study provided operational and mechanistic basis for optimizing the organic clay synthesis and selecting as the appropriate amendment for remediation of heavy metal contaminated soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Organo chlorine pesticides (OCPs) contaminants in sediments from Karachi harbour, Pakistan

International Nuclear Information System (INIS)

Khan, N.; Khan, S.H.; Amjad, S.; Muller, J.; Nizamani, S.; Bhanger, M.I.

2010-01-01

Mangrove swamps, inter tidal mud flats and creeks of backwaters represent main feature of Karachi harbour area. Karachi harbour sediment is under continuous influence of untreated industrial effluents and domestic waste discharged into the Harbour area via Lyari River. Sediment samples from sixteen locations were collected to evaluate the levels of contamination of organo chlorine pesticides (OCPs) in Karachi harbour and adjoining areas. It has been observed that residual concentrations of various organo chlorine pesticides were considerably higher in the semi-enclosed area of the upper Harbour in the vicinity of the discharge point of Lyari River. The residue of DDT mainly its metabolites (DDE and DDD) were widely distributed and have been detected in most of the sediment samples in relatively higher concentrations as compared to other OCPs. The higher levels of the DDTs would attribute to low tidal flushing of the area. The high proportion of pp'-DDE in the most sediment sampled (41-95%) suggested old inputs of DDTs in the environment. Ratio of sigma DDT and DDT was in the range of 0.04 - 0.24 at all locations which also reflects that the discharges of DDT were negligible in the Harbour area. This may be due to the restrictions being implemented on the use of DDTs and Pakistan has also switched over to natural pest control or using safer formulas. The data obtained during the study showed that concentration levels of other pesticides such as HCHs, HCB and Cyclodienes in the sediment were generally lower than the threshold levels known to harm wildlife by OCPs. The results clearly indicate that elevated concentration of organo chlorine pesticides (OCPs) in the marine sediment of Karachi harbour and adjoining area was localized and much lower than the concentrations reported from neighbouring and regional countries which suggests/confirms that the present use of pesticide in Pakistan is environmentally safe. (author)

Dependency of Nanodiamond Particle Size and Outermost-Surface Composition on Organo-Modification: Evaluation by Formation of Organized Molecular Films and Nanohybridization with Organic Polymers.

Science.gov (United States)

Tasaki, Taira; Guo, Yifei; Meng, Qi; Mamun, Muhammad Abdullah Al; Kasahara, Yusuke; Akasaka, Shuichi; Fujimori, Atsuhiro

2017-04-26

The formation behavior of organized organo-modified nanodiamond films and polymer nanocomposites has been investigated using nanodiamonds of several different particle sizes and outermost-surface compositions. The nanodiamond particle sizes used in this study were 3 and 5 nm, and the outermost surface contained -OH and/or -COOH groups. The nanodiamond was organo-modified to prepare -OH 2 + cations and -COO - anions on the outermost surface by carboxylic anion of fatty acid and long-chain phosphonium cation, respectively. The surface of nanodiamond is known to be covered with a nanolayer of adsorbed water, which was exploited here for the organo-modification of nanodiamond with long-chain fatty acids via adsorption, leading to nanodispersions of nanodiamond in general organic solvents as a mimic of solvency. Particle multilayers were then formed via the Langmuir-Blodgett technique and subjected to fine structural analysis. The organo-modification enabled integration and multilayer formation of inorganic nanoparticles due to enhancement of the van der Waals interactions between the chains. Therefore, "encounters" between the organo-modifying chain and the inorganic particles led to solubilization of the inorganic particles and enhanced interactions between the particles; this can be regarded as imparting a new functionality to the organic molecules. Nanocomposites with a transparent crystalline polymer were fabricated by nanodispersing the nanodiamond into the polymer matrix, which was achievable due to the organo-modification. The resulting transparent nanocomposites displayed enhanced degrees of crystallization and improved crystallization temperatures, compared with the neat polymer, due to a nucleation effect.

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.

Phosphor investigation in the production of Syrian phosphoric acid using Nuclear Magnetic Resonance

International Nuclear Information System (INIS)

Al-Hassanieh, O.; Al-Hameish, M.

2009-06-01

Nuclear magnetic resonance spectroscopy (NMR) was applied in this work to the industrial process of extraction of uranium from phosphoric acid and to the process of the purification of the phosphoric acid for food proposes. The structural changes of used extraction materials and the organic content of the final product was studied. 13 C , 1 H and 32 P-spectra of all material during the process were recorded. The spectra of the three used extraction materials Bis(2-ethylhexyl Phosphoric Acid)) DEHPA, TriOctyl Phosphine Oxide (TOPO) (C 8 H 1 7) 3 P=O and TriButyl Phosphate (TBP) (C 4 H 9 O) 3 P=O show a partial degradation during the process. The final product ( Phosphoric acid for Food proposes) doesn't contain any organic solvents or extraction material. (author)

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

Synthesis and characterization of functional copolymer/organo-silicate nanoarchitectures through interlamellar complex-radical (coterpolymerization

Directory of Open Access Journals (Sweden)

2008-09-01

Full Text Available The functional copolymers, having a combination of rigid/flexible linkages and an ability of complex-formation with interlayered surface of organo-silicate, and their nanocomposites have been synthesized by interlamellar complex-radical (coterpolymerization of intercalated monomer complexes of maleic anhydride (MA and itaconic acid (IA with dimethyl dodecylamine surface modified montmorillonite (organo-MMT (MA…DMDA-MMT and IA…DMDA-MMT n-butyl methacrylate (BMA and/or BMA/styrene monomer mixtures. The results of nanocomposite structure–composition– property relationship studies indicate that interlamellar complex-formation between anhydride/acid units and surface alkyl amine and rigid/flexible linkage balance in polymer chains are important factors providing the effective intercalation/ exfoliation of the polymer chains into the silicate galleries, the formation of nanostructural hybrids with higher thermal stability, dynamic mechanical behaviour and well dispersed morphology.

Effects of sawdust and organo mineral fertilizer and their residual effect on the yield of maize on degrades soil

International Nuclear Information System (INIS)

Dania, S.O.; Fagbola, O.; Isitekhale, H.H.E.

2012-01-01

Conventional mineral fertilizer alone cannot sustain arable crop production in soil which top layer has been eroded hence it is necessary to employ the application of organic base fertilizer. A greenhouse experiment was conducted to investigate the effects of sawdust, organo mineral fertilizer and their residual effects on the growth and yield of maize. Organo mineral fertilizer is the combination of organic manure and mineral fertilizer. Simulated degraded soil was used and the experimental design was a 2 x 2 x 3 factorial in a completely randomized design with three replicates. The factors investigated were: two levels of organo mineral fertilizer (with and without), two levels of soil amendment (with and without sawdust) and three levels of application methods. The methods of organo mineral fertilizer used were ring, subsurface and mixed methods. The amendment of soil to sawdust was ratio 1:1 by volume. The growth and yield of maize was significantly (p = 0.05) higher in non-amended soil with OMF under different application methods compared to soil amended with sawdust with or without OMF application. Ring method of application of OMF in non-amended soil significantly increased the growth and yield of maize compared to other methods of OMF application. The residual effect of OMF and sawdust on the growth and yield of maize was significantly higher in non-amended soil with OMF under different application methods compared to soil amended with sawdust. Addition of sawdust to soil does not improve the growth and yield of maize with or without OMF and under different application methods. Organo mineral fertilizer using ring and subsurface application methods has a beneficial effect in improving the growth and yield of maize in degraded soil where the top layer has been eroded. (author)

Effects of sawdust and organo mineral fertilizer and their residual effect on the yield of maize on degraded soil

International Nuclear Information System (INIS)

Dania, S.O.; Fagbola, O.

2012-01-01

Conventional mineral fertilizer alone cannot sustain arable crop production in soil which top layer has been eroded hence it is necessary to employ the application of organic base fertilizer. A greenhouse experiment was conducted to investigate the effects of sawdust, organo mineral fertilizer and their residual effects on the growth and yield of maize. Organo mineral fertilizer is the combination of organic manure and mineral fertilizer. Simulated degraded soil was used and the experimental design was a 2 x 2 x 3 factorial in a completely randomized design with three replicates. The factors investigated were: two levels of organo mineral fertilizer (with and without), two levels of soil amendment (with and without sawdust) and three levels of application methods. The methods of organo mineral fertilizer used were ring, subsurface and mixed methods. The amendment of soil to sawdust was ratio 1: 1 by volume. The growth and yield of maize was significantly (p = 0.05) higher in non-amended soil with OMF under different application methods compared to soil amended with sawdust with or without OMF application. Ring method of application of OMF in non-amended soil significantly increased the growth and yield of maize compared to other methods of OMF application. The residual effect of OMF and sawdust on the growth and yield of maize was significantly higher in non-amended soil with OMF under different application methods compared to soil amended with sawdust. Addition of sawdust to soil does not improve the growth and yield of maize with or without OMF and under different application methods. Organo mineral fertilizer using ring and subsurface application methods has a beneficial effect in improving the growth and yield of maize in degraded soil where the top layer has been eroded. (author)

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.

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

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.

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

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...

Tuning the diurnal natural daylight with phosphor converted white LED – Advent of new phosphor blend composition

International Nuclear Information System (INIS)

Kim, Yoon Hwa; Arunkumar, Paulraj; Park, Seung Hyok; Yoon, Ho Shin; Im, Won Bin

2015-01-01

Highlights: • Designed phosphor blend that mimics diurnal daylight for health benefits. • Developed new phosphor blend composition that mimics natural sunlight under near UV. • The phosphor blend also exhibits high CRI (≥90) under blue LED excitation. • Fabricated WLED exhibited ∼91% spectral resemblance with daylight at 4500 K. • While ∼39.2% spectral resemblance were observed for YAG:Ce 3+ at 4500 K. - Abstract: We demonstrate the feasibility of developing phosphor converted white LED (pc-WLED) that mimics diurnal natural daylight with the newly designed phosphor blend in the color temperature (CCT) 2700–6000 K for health benefits. Natural daylight (sunlight) spectrum possesses broad emission in the visible region and closely approximates black body radiator, with color rendition index (CRI) of 100 under wide CCT (2500–6500 K). Current white light LEDs although are efficient and durable, they are not broad enough compared to daylight. We report new phosphor blend based on Sr 3 MgSi 2 O 8 :Eu 2+ blue phosphor with broad emission and high CRI ≥ 96 under both near UV and blue excitation. The fabricated WLED has exhibited ∼91% spectral resemblance with natural daylight compared to 39.2% for YAG:Ce 3+ white LED at 4500 K. The developed phosphor blend tunes the spectrum in wider CCT and would be a prospective candidate for full spectrum daylight WLED

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.)

Solvent extraction of Zn and metals in Zn ores by nonphosphorous solvents

International Nuclear Information System (INIS)

Auchapt, J.M.; Tostain, Jacqueline.

1975-07-01

This bibliography follows a first work on Zn solvent extraction by organo-phosphorous compounds. The other solvents used in Zn extraction, are studied: oxygenated nonphosphorous solvents (ketones, alcohols, carboxylic acids, sulfonates), nitrogenous solvents and hydrocarbons [fr

A new synthetic methodology for the preparation of biocompatible and organo-soluble barbituric- and thiobarbituric acid based chitosan derivatives for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Shahzad, Sohail [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Shahzadi, Lubna [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Mahmood, Nasir [Department of Allied Health Sciences and Chemical Pathology, Department of Human Genetics and Molecular Biology, University of Health Sciences, Lahore (Pakistan); Siddiqi, Saadat Anwar [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Rauf, Abdul [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Manzoor, Faisal; Chaudhry, Aqif Anwar [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Rehman, Ihtesham ur [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Materials Science and Engineering, The Kroto Research Institute, The University of Sheffield, North Campus, Broad Lane, Sheffield, S3 7HQ (United Kingdom); Yar, Muhammad, E-mail: drmyar@ciitlahore.edu.pk [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan)

2016-09-01

Chitosan's poor solubility especially in organic solvents limits its use with other organo-soluble polymers; however such combinations are highly required to tailor their properties for specific biomedical applications. This paper describes the development of a new synthetic methodology for the synthesis of organo-soluble chitosan derivatives. These derivatives were synthesized from chitosan (CS), triethyl orthoformate and barbituric or thiobarbituric acid in the presence of 2-butannol. The chemical interactions and new functional motifs in the synthesized CS derivatives were evaluated by FTIR, DSC/TGA, UV/VIS, XRD and {sup 1}H NMR spectroscopy. A cytotoxicity investigation for these materials was performed by cell culture method using VERO cell line and all the synthesized derivatives were found to be non-toxic. The solubility analysis showed that these derivatives were readily soluble in organic solvents including DMSO and DMF. Their potential to use with organo-soluble commercially available polymers was exploited by electrospinning; the synthesized derivatives in combination with polycaprolactone delivered nanofibrous membranes. - Highlights: • Development of a new synthetic methodology • Synthesis of organo-soluble chitosan (CS) derivatives • VERO cells proliferation • Nanofibrous membranes from the synthesized chitosan derivatives and polycaprolactone.

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...

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...

An open aperture z-scan study of Sr2CeO4 blue phosphor

International Nuclear Information System (INIS)

Seema, R.; Sandeep, C.S. Suchand; Philip, Reji; Kalarikkal, Nandakumar

2011-01-01

Highlights: → Sr 2 CeO 4 blue phosphor has been prepared by a solid state reaction method. → The XRD study confirms that the structure of the system is orthorhombic. → The TEM reveals that Sr 2 CeO 4 is composed of elongated spherical structures of length ∼0.2-0.6 μm. → The FFT of TEM, XRD peaks and the JCPDS values are compared, from which the Sr 2 CeO 4 phase is reconfirmed. → A z-scan measurement gives the effective two-photon absorption coefficient to be 3.9 x 10 -11 m/W. - Abstract: Sr 2 CeO 4 blue phosphor has been prepared by the solid-state reaction method. The X-ray diffraction (XRD) study confirms the structure of the system to be orthorhombic. High resolution electron transmission microscopy reveals that Sr 2 CeO 4 prepared by the solid state reaction method is composed of elongated spherical structures of length ∼0.2-0.6 μm and width ∼90-150 nm. The excitation spectrum shows a broad band which peaks at 275 nm. The emission spectrum shows a broad band which peaks at 467 nm when excited at 275 nm. The emission band is assigned to the energy transfer between the molecular orbital of the ligand and charge transfer (CT) state of the Ce 4+ ion. The Commission International de l'Eclairage (CIE) co-ordinates are x = 0.15, and y = 0.23. The nonlinear absorption behavior of Sr 2 CeO 4 has been investigated using the open aperture z-scan technique. The calculated effective two-photon absorption coefficient shows that the Sr 2 CeO 4 blue phosphor is a promising optical limiting material.

Effect of surfactant alkyl chain length on the dispersion, and thermal and dynamic mechanical properties of LDPE/organo-LDH composites

Directory of Open Access Journals (Sweden)

2011-05-01

Full Text Available Low density polyethylene/layered double hydroxide (LDH composites were prepared via melt compounding using different kinds of organo-LDHs and polyethylene-grafted maleic anhydride as the compatibilizer. The organo-LDHs were successfully prepared by converting a commercial MgAl-carbonate LDH into a MgAl-nitrate LDH, which was later modified by anion exchange with linear and branched sodium alkyl sulfates having different alkyl chain lengths (nc = 6, 12 and 20. It was observed that, depending on the size of the surfactant alkyl chain, different degrees of polymer chain intercalation were achieved, which is a function of the interlayer distance of the organo-LDHs, of the packing level of the alkyl chains, and of the different interaction levels between the surfactant and the polymer chains. In particular, when the number of carbon atoms of the surfactant alkyl chain is larger than 12, the intercalation of polymer chains in the interlayer space and depression of the formation of large aggregates of organo-LDH platelets are favored. A remarkable improvement of the thermal-oxidative degradation was evidenced for all of the composites; whereas only a slight increase of the crystallization temperature and no significant changes of both melting temperature and degree of crystallinity were achieved. By thermodynamic mechanical analysis, it was evidenced that a softening of the matrix is may be due to the plasticizing effect of the surfactant.

Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles

International Nuclear Information System (INIS)

Wu, Pingxiao; Li, Shuzhen; Ju, Liting; Zhu, Nengwu; Wu, Jinhua; Li, Ping; Dang, Zhi

2012-01-01

Highlights: ► Organo-montmorillonite supported iron nanoparticles were found to be more efficient in the removal of Cr(VI) than unsupported iron nanoparticles. ► The iron nanoparticles were accommodated by the sectional structure of the clay minerals which were helpful to protect the nanoparticles from aggregating. ► XPS and XANES provided some direct information about the reduction mechanisms. ► The structure of the supported iron nanoparticles was stable in the reaction with Cr(VI). - Abstract: Iron nanoparticles exhibit greater reactivity than micro-sized Fe 0 , and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe 0 was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III).

Tuning the diurnal natural daylight with phosphor converted white LED – Advent of new phosphor blend composition

Energy Technology Data Exchange (ETDEWEB)

Kim, Yoon Hwa [School of Materials Science and Engineering, Chonnam National University, 300, Yongbong-dong, Buk-gu, Gwangju 500-757 (Korea, Republic of); Research Institute, Force4 Corp., Daechon-dong, Buk-gu, Gwangju 500-470 (Korea, Republic of); Arunkumar, Paulraj [School of Materials Science and Engineering, Chonnam National University, 300, Yongbong-dong, Buk-gu, Gwangju 500-757 (Korea, Republic of); Park, Seung Hyok; Yoon, Ho Shin [Research Institute, Force4 Corp., Daechon-dong, Buk-gu, Gwangju 500-470 (Korea, Republic of); Im, Won Bin, E-mail: imwonbin@jnu.ac.kr [School of Materials Science and Engineering, Chonnam National University, 300, Yongbong-dong, Buk-gu, Gwangju 500-757 (Korea, Republic of)

2015-03-15

Highlights: • Designed phosphor blend that mimics diurnal daylight for health benefits. • Developed new phosphor blend composition that mimics natural sunlight under near UV. • The phosphor blend also exhibits high CRI (≥90) under blue LED excitation. • Fabricated WLED exhibited ∼91% spectral resemblance with daylight at 4500 K. • While ∼39.2% spectral resemblance were observed for YAG:Ce{sup 3+} at 4500 K. - Abstract: We demonstrate the feasibility of developing phosphor converted white LED (pc-WLED) that mimics diurnal natural daylight with the newly designed phosphor blend in the color temperature (CCT) 2700–6000 K for health benefits. Natural daylight (sunlight) spectrum possesses broad emission in the visible region and closely approximates black body radiator, with color rendition index (CRI) of 100 under wide CCT (2500–6500 K). Current white light LEDs although are efficient and durable, they are not broad enough compared to daylight. We report new phosphor blend based on Sr{sub 3}MgSi{sub 2}O{sub 8}:Eu{sup 2+} blue phosphor with broad emission and high CRI ≥ 96 under both near UV and blue excitation. The fabricated WLED has exhibited ∼91% spectral resemblance with natural daylight compared to 39.2% for YAG:Ce{sup 3+} white LED at 4500 K. The developed phosphor blend tunes the spectrum in wider CCT and would be a prospective candidate for full spectrum daylight WLED.

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.

Diffusion, sorption, and retardation processes of anions in bentonite and organo-bentonites for multibarrier systems

Science.gov (United States)

Schampera, Birgit; Dultz, Stefan

2013-04-01

The low permeability, high cation exchange capacity (CEC) and plasticity of bentonites favor their use in multibarrier systems of waste deposits [1]. Bentonites have a high CEC but their ability to sorb anions is very low. There is, however, need for retardation of anions and organic pollutants in many applications. Bentonites, modified with certain organic cations, have the capacity to sorb anions and non-polar organic compounds in addition to cations. Investigations on organically modified clays address a wide variety of applications including immobilization of pollutants in contaminated soils, waste water treatment and in situ placement for the protection of ground water [2]. Many experiments on anion and cation sorption of organo-clays were conducted in the batch mode which does not reflect solid-liquid ratios and material densities in barrier systems. Diffusion experiments on compacted clays allow the evaluation of transport processes and sorption of pollutants at conditions relevant for repositories. For organo-clays only few diffusion studies are published e.g. [3] measured the diffusion of tritium and [4] the diffusion of H2O in bentonite and organo-bentonites. The organic cation hexadecylpyridinium (HDPy) was added to Wyoming bentonite (MX-80) in amounts corresponding to 2-400 % of the CEC. The uptake of organic cations was determined by the C-content, XRD and IR-spectroscopy. Wettability was analyzed by the contact angle. Physical, chemical and mineralogical properties of clays were characterized. Diffusion experiments were carried out in situ in a cell attached to the ATR-unit of a FTIR-spectrometer. For H2O-diffusion the compacted organo-clays are saturated first with D2O, afterwards H2O is supplied to the surface at the top of the clay platelet. Anion-diffusion was conducted with NO3--solution instead of H2O only having characteristic IR band positions at 1350 cm-1. Three different concentrations (0.25M, 0.5M and 1M) were used. Additional batch

MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES: PESTICIDES ON RUTILE AND ORGANO-RUTILE SURFACES

Science.gov (United States)

Non-bonded interactions between model pesticides and organo-mineral surfaces have been studied using molecular mechanical conformational calculations and molecular dynamics simulations. The minimum energy conformations and relative binding energies for the interaction of atrazine...

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.)

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.

X-ray intensifying screens

International Nuclear Information System (INIS)

Bossomaier, T.R.J.; Sangway, P.C.

1979-01-01

It is claimed that stabilization of X-ray intensifying screens against discolouration and hydrolysis of lanthanum or gadolinium oxyhalide phosphors can be achieved by incorporating into the phosphor/binder formulation a compound containing free epoxy groups. Suitable epoxy compounds include gamma glycidoxy trimethoxy silane and dimethyl di(m-glycidoxy methylphenyl) methane. The oxyhalide may be activated by Tb, Tm or Yb and may be mixed with other phosphors. Plasticisers and organo-tin stabilisers for the formulation are given. Many binders are specified, preferably these should not react with the free epoxy groups. (UK)

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)

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.)

Enantioselective organo-photocatalysis mediated by atropisomeric thiourea derivatives.

Science.gov (United States)

Vallavoju, Nandini; Selvakumar, Sermadurai; Jockusch, Steffen; Sibi, Mukund P; Sivaguru, Jayaraman

2014-05-26

Can photocatalysis be performed without electron or energy transfer? To address this, organo-photocatalysts that are based on atropisomeric thioureas and display lower excited-state energies than the reactive substrates have been developed. These photocatalysts were found to be efficient in promoting the [2+2] photocycloaddition of 4-alkenyl-substituted coumarins, which led to the corresponding products with high enantioselectivity (77-96% ee) at low catalyst loading (1-10 mol%). The photocatalytic cycle proceeds by energy sharing via the formation of both static and dynamic complexes (exciplex formation), which is aided by hydrogen bonding. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Persistent luminescence and thermoluminescence of UV/VIS -irradiated SrAl2O4: Eu2+, Dy3+ phosphor

International Nuclear Information System (INIS)

Pereyda-Pierre, C.; Meléndrez, R.; García, R.; Pedroza-Montero, M.; Barboza-Flores, M.

2011-01-01

The persistent luminescence and thermoluminescence properties of SrAl 2 O 4 : Eu 2+ , Dy 3+ phosphors excited with UV–VIS light in the 200–500 nm region were investigated. The thermoluminescence glow curve was found to be composed of peaks around 70, 125 and 245 °C. The persistent luminescence and thermoluminescence excitation spectra exhibited a broad band around 300–500 nm centered at 400 and 420 nm respectively. A linear behavior of the integrated thermoluminescence intensity and persistent luminescence versus irradiation time was found for the first 60 s. The charge detrapping from the 70 °C trapping levels was the major contributor to the observed persistent luminescence at room temperature. The SrAl 2 O 4 : Eu 2+ , Dy 3+ phosphors have suitable properties to be applied as storage and persistent luminescence UV–VIS irradiation dose phosphor. -- Highlights: ► SrAl 2 O 4 :Eu 2+ , Dy 3+ persistent luminescence and thermoluminescence was measured. ► The phosphor was irradiated with UV–VIS photons in the 200–500 nm wavelength range. ► SrAl 2 O 4 :Eu 2+ , Dy 3+ behaves adequately as persistent and storage UV–VIS dosimeter. ► The persistent luminescence dosimetry does not require heat or light stimulation.

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.

The Influence of Phosphor and Binder Chemistry on the Aging Characteristics of Remote Phosphor Products

Energy Technology Data Exchange (ETDEWEB)

Davis, Lynn; Yaga, Robert; Lamvik, Michael; Mills, Karmann; Fletcher, B.

2017-06-30

The influence of phosphor and binder layer chemistries on the lumen maintenance and color stability of remote phosphor disks were examined using wet high-temperature operational lifetime testing (WHTOL). As part of the experimental matrix, two different correlated color temperature (CCT) values, 2700 K and 5000 K, were studied and each had a different binder chemistry. The 2700 K samples used a urethane binder whereas the 5000 K samples used an acrylate binder. Experimental conditions were chosen to enable study of the binder and phosphor chemistries and to minimize photo-oxidation of the polycarbonate substrate. Under the more severe WHTOL conditions of 85°C and 85% relative humidity (RH), absorption in the binder layer significantly reduced luminous flux and produced a blue color shift. The milder WHTOL conditions of 75°C and 75% RH, resulted in chemical changes in the binder layer that may alter its index of refraction. As a result, lumen maintenance remained high, but a slight yellow shift was found. The aging of remote phosphor products provides insights into the impact of materials on the performance of phosphors in an LED lighting system.

Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wu, Pingxiao, E-mail: pppxwu@scut.edu.cn [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Li, Shuzhen [School of Chemical and Environmental Engineering, Wuyi University, Jiangmen, Guangdong Province 529020 (China); Ju, Liting [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Zhu, Nengwu [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006 (China); The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions (China); Wu, Jinhua; Li, Ping [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Dang, Zhi [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006 (China); The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions (China)

2012-06-15

Highlights: Black-Right-Pointing-Pointer Organo-montmorillonite supported iron nanoparticles were found to be more efficient in the removal of Cr(VI) than unsupported iron nanoparticles. Black-Right-Pointing-Pointer The iron nanoparticles were accommodated by the sectional structure of the clay minerals which were helpful to protect the nanoparticles from aggregating. Black-Right-Pointing-Pointer XPS and XANES provided some direct information about the reduction mechanisms. Black-Right-Pointing-Pointer The structure of the supported iron nanoparticles was stable in the reaction with Cr(VI). - Abstract: Iron nanoparticles exhibit greater reactivity than micro-sized Fe{sup 0}, and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe{sup 0} was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III).

Highly Efficient Broadband Yellow Phosphor Based on Zero-Dimensional Tin Mixed-Halide Perovskite.

Science.gov (United States)

Zhou, Chenkun; Tian, Yu; Yuan, Zhao; Lin, Haoran; Chen, Banghao; Clark, Ronald; Dilbeck, Tristan; Zhou, Yan; Hurley, Joseph; Neu, Jennifer; Besara, Tiglet; Siegrist, Theo; Djurovich, Peter; Ma, Biwu

2017-12-27

Organic-inorganic hybrid metal halide perovskites have emerged as a highly promising class of light emitters, which can be used as phosphors for optically pumped white light-emitting diodes (WLEDs). By controlling the structural dimensionality, metal halide perovskites can exhibit tunable narrow and broadband emissions from the free-exciton and self-trapped excited states, respectively. Here, we report a highly efficient broadband yellow light emitter based on zero-dimensional tin mixed-halide perovskite (C 4 N 2 H 14 Br) 4 SnBr x I 6-x (x = 3). This rare-earth-free ionically bonded crystalline material possesses a perfect host-dopant structure, in which the light-emitting metal halide species (SnBr x I 6-x 4- , x = 3) are completely isolated from each other and embedded in the wide band gap organic matrix composed of C 4 N 2 H 14 Br - . The strongly Stokes-shifted broadband yellow emission that peaked at 582 nm from this phosphor, which is a result of excited state structural reorganization, has an extremely large full width at half-maximum of 126 nm and a high photoluminescence quantum efficiency of ∼85% at room temperature. UV-pumped WLEDs fabricated using this yellow emitter together with a commercial europium-doped barium magnesium aluminate blue phosphor (BaMgAl 10 O 17 :Eu 2+ ) can exhibit high color rendering indexes of up to 85.

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.

Process for recovering a uranium containing concentrate and purified phosphoric acid from a wet process phosphoric acid containing uranium

International Nuclear Information System (INIS)

Weterings, C.A.M.; Janssen, J.A.

1985-01-01

A process is claimed for recovering from a wet process phosphoric acid which contains uranium, a uranium containing concentrate and a purified phosphoric acid. The wet process phosphoric acid is treated with a precipitant in the presence of a reducing agent and an aliphatic ketone

Process for recovering a uranium containing concentrate and purified phosphoric acid from a wet process phosphoric acid containing uranium

Energy Technology Data Exchange (ETDEWEB)

Weterings, C.A.M.; Janssen, J.A.

1985-04-30

A process is claimed for recovering from a wet process phosphoric acid which contains uranium, a uranium containing concentrate and a purified phosphoric acid. The wet process phosphoric acid is treated with a precipitant in the presence of a reducing agent and an aliphatic ketone.

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)

Novel organo soluble poly imides and polyimide nano composites based on 1,4-bis(4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, via BAOB-modified organo clay

International Nuclear Information System (INIS)

Mansoori, Y.; Darvishi, K.

2014-01-01

New, thermally stable poly imides (PI) containing a 1,3,4-oxadiazole ring in the polymer backbone based on 1,4-bis((4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, were synthesized. The prepared polymers were soluble in polar and aprotic solvents. The obtained results reveal that within the prepared polymers, polyimide which has been obtained from BAOB and 4,4-oxy diphthalic dianhydride, ODPA, has the most improved thermal properties. In the next part, thermally stable organophilic clay was obtained via cation exchange reaction between sodium montmorillonite (Na-MMT) and the hydrochloride salt of BAOB. Then, a series of PI/clay nano composite materials (PCNs) were synthesized from the in situ polymerization reaction of BAOB and ODPA via thermal imidization, BAOB-MMT was used as the filler at different concentrations. Intercalation of polymer chains within the organo clay galleries was confirmed by W XRD. The glass transition temperature is increased with respect to pristine PI for PCNs 1-3 wt %. At high clay loadings, the aggregation of organo clay particles results in a decrease in T g . In the Sem images of the pure polymer too many micro-cracks were observed in the background, while surface homogeneity of PCN 1 wt % is increased and micro-cracks are reduced. (Author)

Novel organo soluble poly imides and polyimide nano composites based on 1,4-bis(4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, via BAOB-modified organo clay

Energy Technology Data Exchange (ETDEWEB)

Mansoori, Y.; Darvishi, K., E-mail: ya_mansoori@yahoo.com [University of Mohaghegh Ardabili, Faculty of Science, Department of Applied Chemistry, Daneshgah, Ardabil (Iran, Islamic Republic of)

2014-10-01

New, thermally stable poly imides (PI) containing a 1,3,4-oxadiazole ring in the polymer backbone based on 1,4-bis((4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, were synthesized. The prepared polymers were soluble in polar and aprotic solvents. The obtained results reveal that within the prepared polymers, polyimide which has been obtained from BAOB and 4,4-oxy diphthalic dianhydride, ODPA, has the most improved thermal properties. In the next part, thermally stable organophilic clay was obtained via cation exchange reaction between sodium montmorillonite (Na-MMT) and the hydrochloride salt of BAOB. Then, a series of PI/clay nano composite materials (PCNs) were synthesized from the in situ polymerization reaction of BAOB and ODPA via thermal imidization, BAOB-MMT was used as the filler at different concentrations. Intercalation of polymer chains within the organo clay galleries was confirmed by W XRD. The glass transition temperature is increased with respect to pristine PI for PCNs 1-3 wt %. At high clay loadings, the aggregation of organo clay particles results in a decrease in T{sub g}. In the Sem images of the pure polymer too many micro-cracks were observed in the background, while surface homogeneity of PCN 1 wt % is increased and micro-cracks are reduced. (Author)

La aplicación de abono organo-mineral: una alternativa para la producción de maíz (Zea mays L., en suelos pardos con carbonatos.

Directory of Open Access Journals (Sweden)

Ignacio Corrales Garriga

2013-04-01

Full Text Available RESUMEN Durante tres años se condujo un experimento en áreas del Instituto de Investigaciones de Viandas Tropicales (INIVIT de Camagüey, empleando diferentes abonos organo-mineral, con el objetivo de conocer su influencia en el rendimiento del maíz (Zea maiz, L, sobre un suelo Pardo Sialítico Mullido Carbonatado de pH ligeramente ácido, bajo contenido de P2O5 y medio de K2O y materia orgánica. Para las mezclas organo-mineral se emplearon como abonos orgánicos el estiércol vacuno y la cachaza y como fertilizantes minerales, el superfosfato triple y el cloruro de potasio. El organo-mineral se aplicó en el momento de la siembra a una dosis de 745 kg ha1 de acuerdo a cada tratamiento, los que fueron replicados 4 veces en un diseño de bloques al azar. Se midió el rendimiento y sus componentes y se tomaron muestras de suelo para conocer la variación de sus propiedades. Los datos fueron evaluados por un análisis de varianza de clasificación doble y se aplicó la prueba de rango múltiple de Duncan para un nivel de significación del 5 %. Los resultados muestran que el empleo de los abonos organo-minerales favorece el rendimiento, reducen los fertilizantes químicos a emplear y mejoran las propiedades del suelo. ORGANO-MINERAL FERTILIZER APPLICATION: AN ALTERNATIVE FOR PRODUCTION OF CORN (Zea mays L., IN SIALYTIC BROWN CARBONATED SOIL. ABSTRACT. For three years, an experiment was conducted in areas of the Research Institute (INIVIT Camaguey , using different organo- mineral fertilizers , in order to study its influence on the performance of maize ( Zea mays , L on a Fluffy Sialytic Brown Carbonated soil slightly acidic pH , low P2O5 and K2O and medium organic matter. For organo- mineral mixtures were used as organic fertilizers and cow manure and cachaza and mineral fertilizer, triple superphosphate and potassium chloride. The organo- mineral was applied at the time of planting at a dose of 745 kg ha1 according to each treatment, which

White light-emitting diodes (LEDs) using (oxy)nitride phosphors

International Nuclear Information System (INIS)

Xie, R-J; Hirosaki, N; Sakuma, K; Kimura, N

2008-01-01

(Oxy)nitride phosphors have attracted great attention recently because they are promising luminescent materials for phosphor-converted white light-emitting diodes (LEDs). This paper reports the luminescent properties of (oxy)nitride phosphors in the system of M-Si-Al-O-N (M = Li, Ca or Sr), and optical properties of white LEDs using a GaN-based blue LED and (oxy)nitride phosphors. The phosphors show high conversion efficiency of blue light, suitable emission colours and small thermal quenching. The bichromatic white LEDs exhibit high luminous efficacy (∼55 lm W -1 ) and the multi-phosphor converted white LEDs show high colour rendering index (Ra 82-95). The results indicate that (oxy)nitride phosphors demonstrate their superior suitability to use as down-conversion luminescent materials in white LEDs

Enabling Lambertian-Like Warm White Organic Light-Emitting Diodes with a Yellow Phosphor Embedded Flexible Film

Directory of Open Access Journals (Sweden)

Cheng-Chang Chen

2014-01-01

Full Text Available We demonstrate in this report a new constructive method of fabricating white organic light-emitting devices (OLEDs with a flexible plastic film embedded with yellow phosphor. The flexible film is composed of polydimethylsiloxane (PDMS and fabricated by using spin coating followed by peeling technology. From the results, the resultant electroluminescent spectrum shows the white OLED to have chromatic coordinates of 0.38 and 0.54 and correlated color temperature of 4200 K. The warm white OLED exhibits the yield of 10.3 cd/A and the luminous power efficiency of 5.4 lm/W at a luminance of 1000 cd/m2. A desirable Lambertian-like far-field pattern is detected from the white OLEDs with the yellow phosphor containing PDMS film. This method is simple, reproducible, and cost-effective, proving to be a highly feasible approach to realize white OLED.

[Change traits of phosphorous consumption structure in China and their effects on environmental phosphorous loads].

Science.gov (United States)

Ma, Dun-Chao; Hu, Shan-Ying; Chen, Ding-Jiang; Li, You-Run

2012-04-01

Substance flow analysis was used to construct a model to analyze change traits of China's phosphorous (P) consumption structure from 1980 to 2008 and their influences on environmental phosphorous loads, then the correlation between several socioeconomic factors and phosphorous consumption pollution was investigated. It is found that phosphorous nutrient inputs of urban life and rural life on a per capita level climbed to 1.20 kg x a(-1) and 0.99 kg x a(-1) from 0.83 kg x a(-1) and 0.75 kg x a(-1) respectively, but phosphorous recycling ratios of urban life fell to 15.6% from 62.6%. P inputs of animal husbandry and planting also kept increasing, but the recycling ratio of the former decreased from 67.5% to 40.5%, meanwhile much P input of the latter was left in agricultural soil. Correlation coefficients were all above 0.90, indicating that population, urbanization level, development levels of planting and animal husbandry were important incentives for P consumption pollution in China. Environmental Kuznets curve showed that China still stayed in the early development stage, promoting economic growth at an expense of environmental quality. This study demonstrates that China's P consumption system is being transformed into a linear and open structure, and that P nutrient loss and environmental P loads increase continually.

Re-processing CRT phosphors for mercury-free applications

International Nuclear Information System (INIS)

Dexpert-Ghys, Jeannette; Regnier, Sophie; Canac, Sophie; Beaudette, Tristan; Guillot, Philippe; Caillier, Bruno; Mauricot, Robert; Navarro, Julien; Sekhri, Salem

2009-01-01

This study is part of an operation in the framework of treatment and revalorization of IEEE (Informatics, Electronics and related) wastes. It aims to recover the active phosphors in cathode ray tubes (CRTs) and to re-cycle these powders by appropriate treatments as phosphors for mercury-free applications such as plasma display panels, flat lamps, advertising and lighting. The studied waste comes from a large panel of CRTs from any supplier. Several thermo-chemical treatments have been investigated. The removal of zinc sulfide-based phosphors and the recovery of a red phosphor Y 2 O 3 :Eu 3+ has been achieved by one (basic attack) route. The photoluminescence efficiency under VUV excitation of the obtained powders is at most 30% that of a commercial phosphor. The second route (acid attack) appears less promising. It has been established that silicate-based impurities could prevent isolating the yttrium based phosphor.

Re-processing CRT phosphors for mercury-free applications

Energy Technology Data Exchange (ETDEWEB)

Dexpert-Ghys, Jeannette, E-mail: jdexpert@cemes.f [CEMES, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse cedex 4 (France); Regnier, Sophie; Canac, Sophie [ICAM, 75 avenue de Grande Bretagne, 31300 Toulouse (France); Beaudette, Tristan; Guillot, Philippe; Caillier, Bruno [DPHE, Universite Jean Francois Champollion, place de Verdun, 81012 Albi cedex 9 (France); Mauricot, Robert; Navarro, Julien [CEMES, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse cedex 4 (France); Sekhri, Salem [ENVOI, Cheminement Glueck, 31100 Toulouse (France)

2009-12-15

This study is part of an operation in the framework of treatment and revalorization of IEEE (Informatics, Electronics and related) wastes. It aims to recover the active phosphors in cathode ray tubes (CRTs) and to re-cycle these powders by appropriate treatments as phosphors for mercury-free applications such as plasma display panels, flat lamps, advertising and lighting. The studied waste comes from a large panel of CRTs from any supplier. Several thermo-chemical treatments have been investigated. The removal of zinc sulfide-based phosphors and the recovery of a red phosphor Y{sub 2}O{sub 3}:Eu{sup 3+} has been achieved by one (basic attack) route. The photoluminescence efficiency under VUV excitation of the obtained powders is at most 30% that of a commercial phosphor. The second route (acid attack) appears less promising. It has been established that silicate-based impurities could prevent isolating the yttrium based phosphor.

Modeling granular phosphor screens by Monte Carlo methods

International Nuclear Information System (INIS)

Liaparinos, Panagiotis F.; Kandarakis, Ioannis S.; Cavouras, Dionisis A.; Delis, Harry B.; Panayiotakis, George S.

2006-01-01

The intrinsic phosphor properties are of significant importance for the performance of phosphor screens used in medical imaging systems. In previous analytical-theoretical and Monte Carlo studies on granular phosphor materials, values of optical properties, and light interaction cross sections were found by fitting to experimental data. These values were then employed for the assessment of phosphor screen imaging performance. However, it was found that, depending on the experimental technique and fitting methodology, the optical parameters of a specific phosphor material varied within a wide range of values, i.e., variations of light scattering with respect to light absorption coefficients were often observed for the same phosphor material. In this study, x-ray and light transport within granular phosphor materials was studied by developing a computational model using Monte Carlo methods. The model was based on the intrinsic physical characteristics of the phosphor. Input values required to feed the model can be easily obtained from tabulated data. The complex refractive index was introduced and microscopic probabilities for light interactions were produced, using Mie scattering theory. Model validation was carried out by comparing model results on x-ray and light parameters (x-ray absorption, statistical fluctuations in the x-ray to light conversion process, number of emitted light photons, output light spatial distribution) with previous published experimental data on Gd 2 O 2 S:Tb phosphor material (Kodak Min-R screen). Results showed the dependence of the modulation transfer function (MTF) on phosphor grain size and material packing density. It was predicted that granular Gd 2 O 2 S:Tb screens of high packing density and small grain size may exhibit considerably better resolution and light emission properties than the conventional Gd 2 O 2 S:Tb screens, under similar conditions (x-ray incident energy, screen thickness)

Uranium recovery from wet-process phosphoric acid

International Nuclear Information System (INIS)

McCullough, J.F.; Phillips, J.F. Jr.; Tate, L.R.

1979-01-01

A method of recovering uranium from wet-process phosphoric acid is claimed where the acid is treated with a mixture of an ammonium salt or ammonia, a reducing agent, and then a miscible solvent. Solids are separated from the phosphoric acid liquid phase. The solid consists of a mixture of metal phosphates and uranium. It is washed free of adhering phosphoric acid with fresh miscible solvent. The solid is dried and dissolved in acid whereupon uranium is recovered from the solution. Miscible solvent and water are distilled away from the phosphoric acid. The distillate is rectified and water discarded. All miscible solvent is recovered for recycle. 5 claims

Effect of Solvent-Assisted Nanoscaled Organo-Gels on Morphology and Performance of Organic Solar Cells

DEFF Research Database (Denmark)

Zuo, Li-Jian; Hu, Xiao-Lian; Ye, Tao

2012-01-01

with that of the organo-gels in solution. Through this knowledge, we eventually achieve controlled morphology and optimized organic solar cells (OSCs) performance. Our results present a significant step forward for understanding the self-assembly behavior of conjugated polymers, control of their morphology...... and optimization of OSC performance....

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

Preparation of high purification and food grade phosphoric acid from technical grade phosphoric acid by liquid-liquid detraction method

International Nuclear Information System (INIS)

Alimoradi, M.; Borji, F.; Kishani, A.

2002-01-01

Pay attention to increasing consumption of high purification and food grade phosphoric acid in various industries and food industries and on in on hand and lack of preparation between production and distribution of this products its purification is so vital. In this article of liquid-liquid extraction method with normal hexane-mixture of ammonia and acetone-diisopropyl alcohol and normal butanol solvents and these determination of distribution coefficient each one with ph-me try titration we can evaluate effectiveness and sufficiency each one. Because of proper coefficient distribution and its local production of normal butanol solvent and low price is the best solvent. To phosphoric acid modifying coefficient distribution for extraction of phosphoric acid we can add a little value sulfuric acid to the mixture and to remove flouride impurity we add a little Na 2 O. After extraction stage extracted phosphoric acid in the normal strips by evaluating with distilled water and then by passing the carbon active bed and following passes of cationic resine column and concentrated with vacuum distillation. Conclusion of this article is produce of phosphoric acid 85% w/w and food grade from impure phosphoric acid 52% w/w with technical grade

Poly(organo phosphazene) nanoparticles surface modified with poly(ethylene oxide).

Science.gov (United States)

Vandorpe, J; Schacht, E; Stolnik, S; Garnett, M C; Davies, M C; Illum, L; Davis, S S

1996-10-05

The use of biodegradable derivatives of poly(organo phosphazenes) for the preparation of nanoparticles and their surface modification with the novel poly(ethylene oxide) derivative of poly(organo phosphazene) has been assessed using a range of in vitro characterization methods. The nanoparticles were produced by the precipitation solvent evaporation method from the derivative co-substituted with phenylalanine and glycine ethyl ester side groups. A reduction in particle size to less than 200 nm was achieved by an increase in pH of the preparation medium. The formation (and colloidal stability) of these nanoparticles seems to be controlled by two opposite effects: attractive hydrophobic interactions between phenylalanine ester groups and electrostatic repulsions arising from the carboxyl groups formed due to (partial) hydrolysis of the ester bond(s) at the high pH of the preparation medium. The poly[(glycine ethyl ester)phosphazene] derivative containing 5000-Da poly(ethylene oxide) as 5% of the side groups was used for the surface modification of nanoparticles. Adsorbed onto the particles, the polymer produced a thick coating layer of approximately 35 nm. The coated nanoparticles exhibited reduced surface negative potential and improved colloidal stability toward electrolyte-induced flocculation, relative to the uncoated system. However, the steric stabilization provided was less effective than that of a Poloxamine 908 coating. This difference in effectiveness of the steric stabilization might indicate that, although both the stabilizing polymers possess a 5000-Da poly(ethylene oxide) moiety, there is a difference in the arrangements of these poly(ethylene oxide) chains at the particle surface. (c) 1996 John Wiley & Sons, Inc.

Correlation between the structure and infra-red absorption characteristics of mono-deuterated compounds: contribution to the study of organo-magnesium compounds

International Nuclear Information System (INIS)

Paillous, A.

1965-10-01

The high sensitivity of the ν (C-D) vibration to the variations brought about by the substitution of the carbon attached to the deuterium is shown in the case of organic or organo-metallic mono-deuterated molecules. In particular, syntheses of various mono-deuterated organo-magnesium compounds have been carried out; results are given concerning an infra-red spectrometric examination of these compounds in the range 2100 - 2250 cm -1 . The results show the existence of only one type of deuterated carbon, which suggests that the same carbanion is involved in various ionic associations for the different magnesium-containing compounds. (authors) [fr

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

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

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.

X-ray investigation of phosphors for black-white television

International Nuclear Information System (INIS)

Lazowy, B.

1975-01-01

The investigations of phosphors made by means of the powder diffraction method are presented. The diffraction patterns has been obtained by means of the DRON-1 diffractometer, using the Ksub(α) copper radiation and a nickel filter. Reflex intensity was estimated, indexing was made and lattice constants for particular structure types were calculated. The objects of the investigations were the phosphors from various firms of white luminescence and home phosphors of white, blue and yellow luminescence. On the base of the results it was found that all investigated phosphors of yellow luminescence belonged to the hexagonal system. These phosphors, depending on baking conditions, have structure of regular symmetry. The phosphors of white luminescence are a mixture of hexagonal and regular phase and any changes in elementary cell sizes were not observed. All phosphors of white luminescence have analogous structure, positions of all reflexes are identical, negligible differences in their intensities occur only, which proves somewhat different arrangement of atoms in mixed crystals. (author)

Phylogenetic or environmental control on the organo-chemical composition of Sphagnum mosses?

Science.gov (United States)

Limpens, Juul; Nilsson, Mats

2014-05-01

Decomposition of organic material is one of the key processes that determines the size of the soil-feedback to global warming, but it is also a process surrounded with one of the largest uncertainties, making understanding its mechanistic drivers of crucial importance. In organic soils decomposition is closely determined by the organo-chemical composition of the litter entering the soil. But what, in turn drives the organo-chemical composition? Is it an emergent feature of the environment the species producing the litter grow in, or is it an evolutionary trait that can be tracked through the species' phylogeny? We set out to answer this question for one of the most import peat-forming plants on earth: the genus Sphagnum. We sampled 18 Sphagnum species, about equally distributed over 6 sites spanning a wide range of environmental conditions: most species were collected at multiple sites. For all species we characterised the chemical composition, focussing on three functional chemistry groups: (i) mineral elements, (ii) carbohydrate polymers (iii) non-carbohydrate polymers (aromatic and aliphatic compounds) . For each group of compounds we used multivariate statistical techniques to derive the degree of variation explained by environment: (site, position within site) and phylogeny (sections within genus Sphagnum). We found that the variation in mineral element concentrations was mostly explained by environment, with the biggest differences in the concentrations of basic cat-ions calcium and magnesium. In contrast, the variation in carbohydrates was mostly explained by phylogeny, with clear associations between sections and monosaccharides. The monosaccharide rhamnose was associated with species from the Acutifolia section known for their poor degradability, whereas xylose and galactose were closely associated with degradable species from the Cuspidata section. The composition non-carbohydrate polymers took an intermediate position: both environment and phylogeny

Pretreatment of phosphoric acid for uranium recovery by the wet phosphoric acid process

International Nuclear Information System (INIS)

Chern, S.L.P.; Chen, Y.C.L.; Chang, S.S.H.; Kuo, T.S.; Ting, G.C.M.

1980-01-01

The proposal deals with reprocessing of phosphoric acid arising from uranium separation according to the wet phosphoric acid process and being intended for recycling. In detail, the sludge will be removed by means of an inclined separating device containing corrugated plates, then the organic impurities are washed out with kerosene in suitable facilities, and the crude phase remaining in the settling tank will be separated from the kerosene in a separating centrifuge. The method has only got low cost of installation. (UWI) [de

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)

Organo-layered double hydroxides composite thin films deposited by laser techniques

Energy Technology Data Exchange (ETDEWEB)

Birjega, R. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Vlad, A., E-mail: angela.vlad@gmail.com [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Matei, A.; Dumitru, M.; Stokker-Cheregi, F.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Zavoianu, R. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest 030018 (Romania); Raditoiu, V.; Corobea, M.C. [National R.& D. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021 Bucharest (Romania)

2016-06-30

Highlights: • PLD and MAPLE was successfully used to produce organo-layered double hydroxides. • The organic anions (dodecyl sulfate-DS) were intercalated in co-precipitation step. • Zn2.5Al-LDH (Zn/Al = 2.5) and Zn2.5Al-DS thin films obtained in this work could be suitable for further applications as hydrophobic surfaces. - Abstract: We used laser techniques to create hydrophobic thin films of layered double hydroxides (LDHs) and organo-modified LDHs. A LDH based on Zn-Al with Zn{sup 2+}/Al{sup 3+} ratio of 2.5 was used as host material, while dodecyl sulfate (DS), which is an organic surfactant, acted as guest material. Pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) were employed for the growth of the films. The organic anions were intercalated in co-precipitation step. The powders were subsequently used either as materials for MAPLE, or they were pressed and used as targets for PLD. The surface topography of the thin films was investigated by atomic force microscopy (AFM), the crystallographic structure of the powders and films was checked by X-ray diffraction. FTIR spectroscopy was used to evidence DS interlayer intercalation, both for powders and the derived films. Contact angle measurements were performed in order to establish the wettability properties of the as-prepared thin films, in view of functionalization applications as hydrophobic surfaces, owing to the effect of DS intercalation.

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.

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

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

Tm3+ activated lanthanum phosphate: a blue PDP phosphor

International Nuclear Information System (INIS)

Rao, R.P.

2005-01-01

Plasma display panels (PDPs) are gaining attention due to their high performance and scalability as a medium for large format TVs. The performance and life of a PDP strongly depends upon the nature of phosphors. Currently, Eu 2+ activated barium magnesium aluminate (BAM) is being used as a blue component. Because of its low life, efforts are being made to explore new blue emitting phosphors. One of the alternatives to BAM is Tm 3+ activated lanthanum phosphate (LPTM) phosphor. LPTM phosphor samples are prepared by a solid-state as well as sol-gel process in presence of flux. The phosphor of the present investigation, having uniform and spherical shape particles in the range of 0.1-2 μm, is appropriate for thin phosphor screens required for PDP applications. It exhibits a narrow band emission in the blue region, peaking at 452 nm and also a number of narrow bands in the UV region when excited by 147 and 173 nm radiation from a xenon gas mixture. Various possible transitions responsible for UV and visible emission from Tm 3+ ion are presented. These phosphors also exhibit good color saturation and better stability when excited with VUV radiation. To achieve higher brightness, they are blended with other UV excited blue emitting phosphors such as BAM. Results related to morphology, excitation, after glow decay, emission and degradation of these phosphors in the powder form as well as in plasma display panels are presented and discussed

Chromium(VI) sorption efficiency of acid-activated banana peel over organo-montmorillonite in aqueous solutions.

Science.gov (United States)

Ashraf, Anam; Bibi, Irshad; Niazi, Nabeel Khan; Ok, Yong Sik; Murtaza, Ghulam; Shahid, Muhammad; Kunhikrishnan, Anitha; Li, Dongwei; Mahmood, Tariq

2017-07-03

In the present study, we examined sorption of chromate (Cr(VI)) to acid-activated banana peel (AABP) and organo-montmorillonite (O-mont) as a function of pH, initial Cr(VI) concentration at a sorbent dose of 4 g L -1 and at 20 ± 1°C in aqueous solutions. In sorption edge experiments, maximum Cr(VI) removal was obtained at pH 3 after 2 hours by AABP and O-mont (88% and 69%). Sorption isotherm data showed that the sorption capacity of AABP was higher than O-mont (15.1 vs. 6.67 mg g -1 , respectively, at pH 4). Freundlich and Langmuir models provided the best fits to describe Cr(VI) sorption onto AABP (R 2 = 0.97) and O-mont (R 2 = 0.96). Fourier transform infrared spectroscopy elucidated that for AABP mainly the -OH, -COOH, -NH 2 , and for O-mont intercalated amines and -OH surface functional groups were involved in Cr(VI) sorption. The scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDX) analyses, although partly, indicate that the (wt. %) proportion of cations (e.g., Ca, Mg) in AABP decreased after Cr(VI) sorption. This may be due to ion exchange of chromite (Cr(III)) (produced from Cr(VI) reduction) with cationic elements in AABP. Also, Cr(VI) desorption (using phosphate solution) from AABP was lower (29%) than that from O-mont (51%) up to the third regeneration cycle. This bench scale comparative study highlights that the utilization of widely available and low-cost acid-activated biomaterials has a greater potential than organo-clays for Cr(VI) removal in aqueous media. However, future studies are warranted to precisely delineate different mechanisms of Cr(VI) sorption/reduction by acid-activated biomaterials and organo-clays.

Method of recovering phosphoric acid type decontaminating electrolytes by electrodeposition

International Nuclear Information System (INIS)

Sasaki, Takashi; Wada, Koichi; Kobayashi, Toshio.

1985-01-01

Purpose: To recoving phosphoric acid type highly concentrated decontaminating liquid used for the electrolytic decontamination of contaminated equipments, components, etc in nuclear power plants or the like through electrodeposition by diaphragm electrolysis. Method: Before supplying phosphoric acid decontaminating liquid at high concentration used in the electrolytic decontaminating step to an electrodeposition recovering tank, phosphoric acid in the decontaminating electrolyte is extracted with solvents and decomposed liquid extracts (electrolyte reduced with the phosphoric acid component) are supplied to the cathode chamber of the electrodeposition recovering tank, where phosphoric acid is back-extracted with water from the solvents after extraction of phosphoric acid. Then, the back-extracted liquids (aqueous phosphoric acid solution scarcely containing metal ions) are sent to the anode chamber of the electrodeposition recovering tank. Metal ions in the liquid are captured by electrodeposition in the cathode chamber, as well as phosphoric acid in the liquids is concentrated to the initial concentration of the electrolyte in the anode chamber for reuse as the decontaminating electrolyte. As the phosphoric acid extracting agent used in the electrodeposition recovering step for the decontaminating electrolyte, water-insoluble and non-combustible tributyl phosphate (TBP) is most effective. (Horiuchi, T.)

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

White-electroluminescent device with horizontally patterned blue/yellow phosphor-layer structure

International Nuclear Information System (INIS)

Won Park, Boo; Sik Choi, Nam; Won Park, Kwang; Mo Son, So; Kim, Jong Su; Kyun Shon, Pong

2007-01-01

White-electroluminescent (EL) devices with stripe-patterned and square-patterned phosphor-layer structures are fabricated through a screen printing method: electrode/BaTiO 3 insulator layer/patterned blue ZnS:Cu, Cl and yellow ZnS:Cu, Mn phosphor layer/ITO PET substrate. The luminous intensities of EL devices with stripe-patterned and square-patterned phosphor-layer structures are 33% and 23% higher than a conventional device with the phosphor-layer structure without any patterns using the phosphor blend. It can be explained in terms of the absorption of the emitted blue light of blue phosphor layer by the yellow-emitting phosphor layer. The EL device of our patterned phosphor-layer structure gives the possibility to enhance the luminance

Photoluminescence of phosphors for PDP with VUV excitation

International Nuclear Information System (INIS)

Lu, H.-C.; Chen, H.-K.; Tseng, T.-Y.; Kuo, W.-L.; Alam, M.S.; Cheng, B.-M.

2005-01-01

In a plasma display panel (PDP) He-Xe or Ne-Xe gaseous mixtures are subjected to electric discharge between two glass panels, so to generate VUV light. Red, green and blue phosphors absorb this VUV radiation and re-radiate the energy as visible light to produce the colors that appear on the screen. The phosphor plays an important role in the working of a PDP. To improve the efficiency of phosphors, we have established a photoluminescence end station coupled to the beam line of a synchrotron to study the luminescence of PDP phosphors. This luminescence is analyzed with a 0.32 m monochromator having maximum resolution 0.04 nm, and is monitored with a photomultiplier tube operated in a photon-counting mode. Preliminary data demonstrate the powerful performance of this end-station for studying PDP phosphors

Organo-Functionalization of Silicon Nanocrystals Synthesized by Inductively Coupled Plasma Chemical Vapor Deposition

Energy Technology Data Exchange (ETDEWEB)

Lee, Don-Sung; Choe, Dong-Hoe; Jeong, Hyun-Dam [Chonnam National University, Gwangju (Korea, Republic of); Yoo, Seung-Wan; Kim, Jung-Hyung [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

2016-05-15

Octadecyl-terminated silicon nanocrystals (ODE-Si NCs) are obtained via a surface-initiated thermal hydrosilylation reaction on hydride-terminated Si NCs (H-Si NCs). Pristine Si NCs were synthesized at the gram scale by using inductively coupled plasma chemical vapor deposition (ICP-CVD) . The H-Si NCs were produced through a chemical etching process with hydrofluoric acid (HF), ethanol (EtOH), and distilled water (d-H{sub 2}O). The results obtained from X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) indicate that the synthesized Si NCs obtained via ICP-CVD have diamond cubic-structured silicon with a grain size of 10 nm and a densely packed Si NC array consisting of individual NCs. Organo-functionalized Si NCs, i.e., ODE-Si NCs, are well soluble in organic solvent whereas pristine Si NCs synthesized through ICP-CVD are not. The surface chemistry of the ODE-Si NCs was confirmed via Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy ({sup 1}H-NMR), and field emission transmission electron microscopy (FE-TEM). Thereby, these newly synthesized and scalable organo-functionalized Si NCs are applicable as raw materials for practical use in devices by tuning the surface chemistry with various capping molecules.

μOrgano: A Lego®-Like Plug & Play System for Modular Multi-Organ-Chips.

Directory of Open Access Journals (Sweden)

Peter Loskill

Full Text Available Human organ-on-a-chip systems for drug screening have evolved as feasible alternatives to animal models, which are unreliable, expensive, and at times erroneous. While chips featuring single organs can be of great use for both pharmaceutical testing and basic organ-level studies, the huge potential of the organ-on-a-chip technology is revealed by connecting multiple organs on one chip to create a single integrated system for sophisticated fundamental biological studies and devising therapies for disease. Furthermore, since most organ-on-a-chip systems require special protocols with organ-specific media for the differentiation and maturation of the tissues, multi-organ systems will need to be temporally customizable and flexible in terms of the time point of connection of the individual organ units. We present a customizable Lego®-like plug & play system, μOrgano, which enables initial individual culture of single organ-on-a-chip systems and subsequent connection to create integrated multi-organ microphysiological systems. As a proof of concept, the μOrgano system was used to connect multiple heart chips in series with excellent cell viability and spontaneously physiological beat rates.

μOrgano: A Lego®-Like Plug & Play System for Modular Multi-Organ-Chips.

Science.gov (United States)

Loskill, Peter; Marcus, Sivan G; Mathur, Anurag; Reese, Willie Mae; Healy, Kevin E

2015-01-01

Human organ-on-a-chip systems for drug screening have evolved as feasible alternatives to animal models, which are unreliable, expensive, and at times erroneous. While chips featuring single organs can be of great use for both pharmaceutical testing and basic organ-level studies, the huge potential of the organ-on-a-chip technology is revealed by connecting multiple organs on one chip to create a single integrated system for sophisticated fundamental biological studies and devising therapies for disease. Furthermore, since most organ-on-a-chip systems require special protocols with organ-specific media for the differentiation and maturation of the tissues, multi-organ systems will need to be temporally customizable and flexible in terms of the time point of connection of the individual organ units. We present a customizable Lego®-like plug & play system, μOrgano, which enables initial individual culture of single organ-on-a-chip systems and subsequent connection to create integrated multi-organ microphysiological systems. As a proof of concept, the μOrgano system was used to connect multiple heart chips in series with excellent cell viability and spontaneously physiological beat rates.

High Extraction Phosphors for Solid State Lighting

Energy Technology Data Exchange (ETDEWEB)

Summers, Chris [Phosphortech Corporation, Kennesaw, GA (United States); Menkara, Hisham [Phosphortech Corporation, Kennesaw, GA (United States); Wagner, Brent [Phosphortech Corporation, Kennesaw, GA (United States)

2011-09-01

We have developed high-index, high efficiency bulk luminescent materials and novel nano-sized phosphors for improved solid-state white LED lamps. These advances can potentially contribute to reducing the loss in luminous efficiencies due to scattering, re-absorption, and thermal quenching. The bulk and nanostructured luminescent materials investigated are index matched to GaN and have broad and size-tunable absorption bands, size and impurity tuned emission bands, size-driven elimination of scattering effects, and a separation between absorption and emission bands. These innovations were accomplished through the use of novel synthesis techniques suitable for high volume production for LED lamp applications. The program produced a full-color set of high quantum yield phosphors with high chemical stability. In the bulk phosphor study, the ZnSeS:Cu,Ag phosphor was optimized to achieve >91% efficiency using erbium (Er) and other activators as sensitizers. Detailed analysis of temperature quenching effects on a large number of ZnSeS:Cu,Ag,X and strontium- and calcium-thiogallate phosphors lead to a breakthrough in the understanding of the anti-quenching behavior and a physical bandgap model was developed of this phenomena. In a follow up to this study, optimized phosphor blends for high efficiency and color performance were developed and demonstrated a 2-component phosphor system with good white chromaticity, color temperature, and high color rendering. By extending the protocols of quantum dot synthesis, large nanocrystals, greater than 20 nm in diameter were synthesized and exhibited bulk-like behavior and blue light absorption. The optimization of ZnSe:Mn nanophosphors achieved ~85% QE The limitations of core-shell nanocrystal systems were addressed by investigating alternative deltadoped structures. To address the manufacturability of these systems, a one-pot manufacturing protocol was developed for ZnSe:Mn nanophosphors. To enhance the stability of these material

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...

Process for winning uranium from wet process phosphoric acid

International Nuclear Information System (INIS)

1980-01-01

A process is described for winning uranium from wet process phosphoric acid by means of liquid-liquid extraction with organic phosphoric acid esters. The process is optimised by keeping the sulphate percentage in the phosphoric acid below 2% by weight, and preferably below 0.6% by weight, as compared to P 2 O 5 in the phosphoric acid. This is achieved by adding an excess of Ba and/or Ca carbonate or sulfide solution and filtering off the formed calcium and/or barium sulphate precipitates. Solid KClO 3 is then added to the filtrate to oxidise U 4+ to U 6+ . The normal extraction procedure using organic phosphoric esters as extraction liquid, can then be applied. (Th.P.)

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)

Phosphate phosphors for solid-state lighting

Energy Technology Data Exchange (ETDEWEB)

Shinde, Kartik N. [N.S. Science and Arts College, Bhadrawati (India). Dept. of Physics; Swart, H.C. [University of the Orange Free State, Bloemfontein (South Africa). Dept. of Physics; Dhoble, S.J. [R.T.M. Nagpur Univ. (India). Dept. of Physics; Park, Kyeongsoon [Sejong Univ., Seoul (Korea, Republic of). Faculty of Nanotechnology and Advanced Materials Engineering

2012-07-01

Essential information for students in researchers working towards new and more efficient solid-state lighting. Comprehensive survey based on the authors' long experience. Useful both for teaching and reference. 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.

A SrBPO5: Eu2+ phosphor for neutron imaging

International Nuclear Information System (INIS)

Sakasai, K.; Katagiri, M.; Toh, K.; Nakamura, T.

2001-01-01

A SrBPO 5 : Eu 2+ phosphor material has been investigated for neutron imaging. This phosphor showed photostimulated luminescence (PSL) by illumination of 635 nm laser light after X-ray irradiation. The spectral characteristics of the phosphor were similar to those of BaFBr: Eu 2+ , which is a commonly used phosphor of imaging plates. In addition, we found that this phosphor also showed PSL for neutron irradiation. It comes from the fact that it contains atomic boron in base matrix. Therefore, this phosphor can be used for neutron imaging without adding neutron sensitive materials such as Gd in commercially available neutron imaging plates. The PSL intensity and the neutron detection will be increased by using enriched boron instead of natural boron. (author)

Encapsulation of strontium aluminate phosphors to enhance water resistance and luminescence

International Nuclear Information System (INIS)

Zhu Yong; Zeng Jianghua; Li Wenyu; Xu Li; Guan Qiu; Liu Yingliang

2009-01-01

Strontium aluminate SrAl 2 O 4 :Eu 2+ ,Dy 3+ phosphors are chemically unstable against water or even moisture. To enhance the water resistance of the phosphors, an encapsulation was performed by direct surface reactions with phosphoric acid (H 3 PO 4 ). The morphology, surface structure, surface element composition, water resistance, luminescence, and photoacoustic spectrum of the phosphors before and after encapsulation were discussed. Experimental results showed that phosphors were perfectly encapsulated by amorphous layers in nanoscale and crystalline layers in microscale under different conditions. The water resistance of phosphors was greatly enhanced by the two types of layer. More importantly, the amorphous layers enhanced the luminescence of phosphors markedly. The possible mechanism for the enhancements was also proposed.

Photocatalytic effects for the TiO2-coated phosphor materials

International Nuclear Information System (INIS)

Yoon, Jin-Ho; Jung, Sang-Chul; Kim, Jung-Sik

2011-01-01

Research highlights: → The photocatalytic behavior of the coupling of TiO 2 with phosphorescent materials. → The photobleaching of an MB aqueous solution under visible light irradiation. → The ALD TiO 2 -coated phosphor composite showed much higher photocatalytic reactivity. → The light emitted from the phosphors contributed to the photo-generation. - Abstract: This study investigated the photocatalytic behavior of the coupling of TiO 2 with phosphorescent materials. A TiO 2 thin film was deposited on CaAl 2 O 4 :Eu 2+ ,Nd 3+ phosphor particles by using atomic layer deposition (ALD), and its photocatalytic reaction was investigated by the photobleaching of an aqueous solution of methylene-blue (MB) under visible light irradiation. To clarify the mechanism of the TiO 2 -phosphorescent materials, two different samples of TiO 2 -coated phosphor and TiO 2 -Al 2 O 3 -coated phosphor particles were prepared. The photocatalytic mechanisms of the ALD TiO 2 -coated phosphor powders were different from those of the pure TiO 2 and TiO 2 -Al 2 O 3 -coated phosphor. The absorbance in a solution of the ALD TiO 2 -coated phosphor decreased much faster than that of pure TiO 2 under visible irradiation. In addition, the ALD TiO 2 -coated phosphor showed moderately higher photocatalytic degradation of MB solution than the TiO 2 -Al 2 O 3 -coated phosphor did. The TiO 2 -coated phosphorescent materials were characterized by transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and X-ray photon spectroscopy (XPS).

Water- and organo-dispersible gold nanoparticles supported by using ammonium salts of hyperbranched polystyrene: preparation and catalysis.

Science.gov (United States)

Gao, Lei; Nishikata, Takashi; Kojima, Keisuke; Chikama, Katsumi; Nagashima, Hideo

2013-12-01

Gold nanoparticles (1 nm in size) stabilized by ammonium salts of hyperbranched polystyrene are prepared. Selection of the R groups provides access to both water- and organo-dispersible gold nanoparticles. The resulting gold nanoparticles are subjected to studies on catalysis in solution, which include reduction of 4-nitrophenol with sodium borohydride, aerobic oxidation of alcohols, and homocoupling of phenylboronic acid. In the reduction of 4-nitrophenol, the catalytic activity is clearly dependent on the size of the gold nanoparticles. For the aerobic oxidation of alcohols, two types of biphasic oxidation are achieved: one is the catalyst dispersing in the aqueous phase, whereas the other is in the organic phase. The catalysts are reusable more than four times without loss of the catalytic activity. Selective synthesis of biphenyl is achieved by the homocoupling of phenylboronic acid catalyzed by organo-dispersible gold nanoparticles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of the synergic effect of some neutral organophosphoric compounds on the extraction of uranium from phosphoric acid solutions by D1-(2-Ethyl Hexyl) phosphoric acid

International Nuclear Information System (INIS)

Stas, J.; Khorfan, S.; Koudsi, Y.

1998-05-01

The extraction of uranium (VI) from pure phosphoric acid media by D2EHPA/Kerosene has been studied. The mechanism of the extraction was found as follows: The logarithm of the equilibrium constant of the extraction (LogKex) was found (3.06), (3.32), (3.24), (3.3) for the following phosphoric acid concentrations respectively (1), (2), (3), (4) Mol/1, and the enthalpy change DELTA H was found (-100.68 kj/mol). (-76 kj/mol) for (1), (2) mol/1 phosphoric acid concentrations. The synergic effect of TOPO, TBP, and TBPI with DEHPA have been studied during the extraction of uranium from pure phosphoric acid and Syrian commercial phosphoric acid. The synergic effect increases as follows: TBP< TBPI<< TOPO (In pure phosphoric acid), TBPI approx TBP<< TOPO (In Syrian commercial phosphoric acid). The difficulty of extracting uranium (VI) from Syrian commercial phosphoric acid in comparison with pure phosphoric acid is due to the presence of several impurities capable of complexing uranium, and a small amounts of solid and organic matters, all these are factors which reduce the distribution coefficient of uranium. (Author)

A survey of phosphors novel for thermography

Energy Technology Data Exchange (ETDEWEB)

Bruebach, J., E-mail: bruebach@ekt.tu-darmstadt.d [Fachgebiet Reaktive Stroemungen und Messtechnik, Center of Smart Interfaces Technische Universitaet Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany); Kissel, T. [Fachgebiet Reaktive Stroemungen und Messtechnik, Center of Smart Interfaces Technische Universitaet Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany); Frotscher, M. [Eduard-Zintl-Institut fuer Anorganische und Physikalische Chemie, Technische Universitaet Darmstadt, Petersenstrasse 18, 64287 Darmstadt (Germany); Euler, M. [Fachgebiet Reaktive Stroemungen und Messtechnik, Center of Smart Interfaces Technische Universitaet Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany); Albert, B. [Eduard-Zintl-Institut fuer Anorganische und Physikalische Chemie, Technische Universitaet Darmstadt, Petersenstrasse 18, 64287 Darmstadt (Germany); Dreizler, A. [Fachgebiet Reaktive Stroemungen und Messtechnik, Center of Smart Interfaces Technische Universitaet Darmstadt, Petersenstrasse 32, 64287 Darmstadt (Germany)

2011-04-15

With regard to phosphor thermometry, seven luminescent ceramic materials were synthesised and characterised, namely CaMoO{sub 4}:Eu{sup 3+}, CaTiO{sub 3}:Pr{sup 3+}, LaPO{sub 4}:Eu{sup 3+}, LaVO{sub 4}:Eu{sup 3+}, LiAl{sub 5}O{sub 8}:Fe{sup 3+}, TiMg{sub 2}O{sub 4}:Mn{sup 4+} and ZnGa{sub 2}O{sub 4}:Mn{sup 2+}. In this context, emission spectra and temperature lifetime characteristics are presented. Thus, a survey of phosphors novel for thermography is given in order to encourage further studies and more detailed characterisations of the respective materials. - Research Highlights: Seven phosphor materials novel for thermometry were synthesised. These materials were characterised diffractometrically as well as concerning their emission spectra and lifetime temperature characteristics. The number of phosphor materials characterised for thermometry purposes was extended by seven materials.

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)

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.)

Angle-resolved photoluminescence spectrum of a uniform phosphor layer

Science.gov (United States)

Fujieda, Ichiro; Ohta, Masamichi

2017-10-01

A photoluminescence spectrum depends on an emission angle due to self-absorption in a phosphor material. Assuming isotropic initial emission and Lambert-Beer's law, we have derived simple expressions for the angle-resolved spectra emerging from the top and bottom surfaces of a uniform phosphor layer. The transmittance of an excitation light through the phosphor layer can be regarded as a design parameter. For a strongly-absorbing phosphor layer, the forward flux is less intense and more red-shifted than the backward flux. The red-shift is enhanced as the emission direction deviates away from the plane normal. When we increase the transmittance, the backward flux decreases monotonically. The forward flux peaks at a certain transmittance value. The two fluxes become similar to each other for a weakly-absorbing phosphor layer. We have observed these behaviors in experiment. In a practical application, self-absorption decreases the efficiency of conversion and results in angle-dependent variations in chromaticity coordinates. A patterned phosphor layer with a secondary optical element such as a remote reflector alleviates these problems.

Crosslinked Hexafluoropropylidene Polybenzimidazole Membranes with Chloromethyl Polysulfone for Fuel Cell Applications

DEFF Research Database (Denmark)

Yang, Jingshuai; Li, Qingfeng; Cleemann, Lars Nilausen

2013-01-01

Hexafluoropropylidene polybenzimidazole (F6PBI) was synthesized with excellent chemical stability and improved solubility. When doped with phosphoric acid, however, the F6PBI membranes showed plastic deformation at elevated temperatures. Further efforts were made to covalently crosslink F6PBI...... membranes with chloromethyl polysulfone as a polymeric crosslinker. Comparing with linear F6PBI and mPBI membranes, the polymer crosslinked F6PBI membranes exhibited little organo solubility, excellent stability towards the radical oxidation, high resistance to swelling in concentrated phosphoric acid...... with the linear F6PBI and mPBI membranes....

Purification of Effluent from the Groundwood Production by Organo-zeolite

Directory of Open Access Journals (Sweden)

Anić-Vučinić, A.

2008-11-01

Fig. 1B the pertaining zeta potentials of the samples are shown. HDTMA cations were essentially quantitatively taken up by the clinoptilolite tuff up to loading level of L = 0.204 mmol g-1-(Fig. 1A. The results of the zeta potential measurements show that the negative surface charge changed to positive after modification with surfactant solutions (Fig. 1B. HDTMA cations form a stable organophilic coating on the clinoptilolite surface, and above surfactant loading level of 0.110 mmol g-1(isoelectric point, a second layer of HDTMA+ cations reverses the surface charge into positive. The optimal mass concentration of coagulant AlCl3·6H2O for the tested wastewater is γ = 0.8 g dm-1(Figs. 2A and 2B. Zeta potential of the solution above sediment received by coagulation with AlCl3·6H2O of mass concentration γ= 0.8 g dm-3 is ζ= -3.92 mV. The efficiency of removing the turbidity (Table 1 and COD is η = 67 % (from 799 to 263 NTU and 54% (from 13 200 to 6 040 mg dm-3. The efficiency of removing solved organic carbon and colour is significantlylesser: 22.7% (from 3010 to 2322 mg dm-3 and η = 33.0 % (from 681 to 457 Pt Co. By processing the solutions received after coagulation with AlCl3·6H2O of mass concentration of 0.8 g dm-3, with natural tuff and organo-zeolites whose loading are: 0.074; 0.123; 0.164 and 0.204 mmol g-1 HDTMA, TOC was decreased from γ=2322 mg dm-3 to the following: γ=2042, 1976, 1945, 1907 and 1821 mg dm-3 and was sorbed: q = 28.0; 34.6; 37.7; 41.5; and 50.1 mg g-1 TOC (Fig. 3A. Using the sample of organo-zeolite with loading of 0.204 mmol g-1 HDTMA, the efficiency of removing the organic carbon was improved from η= 22.7 % to 40.0 %. The efficiency of discolouring the tested solutions also increases with the change of the surface charge of organo-zeolites from negative to positive(Fig. 3B. The efficiency of removing the colour by using the natural tuff was improved from η= 33.0 % to η = 40.0 %, and by using the organo-zeolite with loading of L = 0

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....

Preconcentration of gold ions from water samples by modified organo-nanoclay sorbent prior to flame atomic absorption spectrometry determination

Energy Technology Data Exchange (ETDEWEB)

Afzali, Daryoush, E-mail: daryoush_afzali@yahoo.com [Nanochemistry Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman (Iran, Islamic Republic of); Mostafavi, Ali [Chemistry Department, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Mirzaei, Mohammad [Nanochemistry Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman (Iran, Islamic Republic of); Chemistry Department, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

2010-09-15

In this work, the applicability of modified organo nanoclay as a new and easy prepared solid sorbent for the preconcentration of trace amounts of Au(III) ion from water samples is studied. The organo nanoclay was modified with 5-(4'-dimethylamino benzyliden)-rhodanine and used as a sorbent for separation of Au(III) ions. The sorption of gold ions was quantitative in the pH range of 2.0-6.0. Quantitative desorption occurred with 6.0 mL of 1.0 mol L{sup -1} Na{sub 2}S{sub 2}O{sub 3}. The amount of eluted Au(III) was measured using flame atomic absorption spectrometry. In the initial solution the linear dynamic range was in the range of 0.45 ng mL{sup -1} to 10.0 {mu}g mL{sup -1}, the detection limit was 0.1 ng mL{sup -1} and the preconcentration factor was 105. Also, the relative standard deviation was {+-}2.3% (n = 8 and C = 2.0 {mu}g mL{sup -1}) and the maximum capacity of the sorbent was 3.9 mg of Au(III) per gram of modified organo nanoclay. The influences of the experimental parameters including sample pH, eluent volume and eluent type, sample volume, and interference of some ions on the recoveries of the gold ion were investigated. The proposed method was applied for preconcentration and determination of gold in different samples.

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.

Sorption of radioiodine in organo-clays and -soils

International Nuclear Information System (INIS)

Bors, J.

1990-01-01

In the framework of investigations on the sorption of radioiodine to natural and artificially altered soil components, a number of clay minerals and natural soils were treated with quaternary alkylammonium ions to replace the exchangeable metal cations. With help of batch experiments the resulting organo-clays were tested with respect to their sorption capability of radioiodine quantified by the distribution ratio (R D -value). Treatment of bentonite, vermiculite and cretaceous clay as well as of samples from natural horizons of chernozem soil with hexadecylpyridinium (HDPY + ) and benzethonium (BE + ) exhibited sorptions rates and amounts, which are several orders of magnitude higher than those of the respective untreated samples. Moderate increases of the R D -values were found after cation exchange with hexadecyltrimethylammonium (HDTMA + ), while the applications of trimethylphenylammonium (TMPA + ) and tetramethylammonium (TMA + ) were ineffective. Considerable sorption of radioiodine was observed with the commercially available Bentone. (orig.)

My Career: Composer

Science.gov (United States)

Morganelli, Patrick

2013-01-01

In this article, the author talks about his career as a composer and offers some advice for aspiring composers. The author works as a composer in the movie industry, creating music that supports a film's story. Other composers work on television shows, and some do both television and film. The composer uses music to tell the audience what kind of…

Photoluminescence properties of aeschynite-type LaNbTiO6:RE3+ (RE = Tb, Dy, Ho) down-converting phosphors.

Science.gov (United States)

Ma, Qian; Lu, Mengkai; Yang, Ping; Zhang, Aiyu; Cao, Yongqiang

2014-06-01

In this study, a series of LaNbTiO6:RE(3+) (RE = Tb, Dy, Ho) down-converting phosphors were synthesized using a modified sol-gel combustion method, and their photoluminescence (PL) properties were investigated as a function of activator concentration and annealing temperature. The resultant particles were characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy, UV/Vis diffuse reflectance spectroscopy and PL spectra. The highly crystalline LaNbTiO6:RE(3+) (RE = Tb, Dy, Ho) phosphors with an average size of 200-300 nm obtained at 1100°C have an orthorhombic aeschynite-type structure and exhibit the highest luminescent intensity in our study range. The emission spectra of LaNbTiO6:RE(3+) (RE = Tb, Dy, Ho) phosphors under excitations at UV/blue sources are mainly composed of characteristic peaks arising from the f-f transitions of RE(3+), including 489 nm ((5) D4 → (7) F6) and 545 nm ((5) D4 → (7) F5) for Tb(3+), 476 and 482 nm ((4) F9/2 → (6) H15/2) and 571 nm ((4) F9/2 → (6) H13/2) for Dy(3+), and 545 nm ((5) F4 + (5) S2 → (5) I8) for Ho(3+), respectively. The luminescent mechanisms were further investigated. It can be expected that these phosphors are of intense interest and potential importance for many optical applications. Copyright © 2013 John Wiley & Sons, Ltd.

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.

Structural and lithological conditioning of the large karst systems of the Sierra de los Organos, Pinar del Rio, Cuba; Condicionantes estructurales y litologicas de los grandes sistemas karsticos de la Sierra de los Organos, Pinar del Rio, Cuba

Energy Technology Data Exchange (ETDEWEB)

Diaz Guanche, C.; Ramirez Hernandez, R.; Farfan Gonzalez, H.; Estevez Cruz, E.; Ordaz Hernandez, A.; Aldana Vilas, C.

2016-07-01

he karst, a complex phenomenon, is governed by a number of variables which dictate its genesis and evolution. Among these variables tectonic settings and lithology play the main role. In Cuba, approximately 65% of the territory is occupied by karst. The Sierra de los Organos, part of Cordillera de Guaniguanico, has some of the largest karstic systems in the country. With the aim of demonstrating the relationship between the spatial and morphological development of the underground karstic systems and the geological structure and lithology of the area, several structural and morphological measurements and field observations have been made. These measurements and observations allowing us to conclude that the karstic processes take place mainly in massive, relatively homogeneous and very thick limestone in the Sierra de los Organos. Moreover, these rocks are characterized by both low porosity and a high degree of fracturing. These karstic forms are also conditioned by the existence of various fracturing systems with general NE-SW and NW-SE orientations. Interception of these fracturing systems provides, as expected, areas with the largest volumes of karstic cavities. (Author)

Sorption of radioiodine in organo-clays and -soils

Energy Technology Data Exchange (ETDEWEB)

Bors, J. (Niedersaechsisches Inst. fuer Radiooekologie, Hannover (Germany, F.R.))

1990-01-01

In the framework of investigations on the sorption of radioiodine to natural and artificially altered soil components, a number of clay minerals and natural soils were treated with quaternary alkylammonium ions to replace the exchangeable metal cations. With help of batch experiments the resulting organo-clays were tested with respect to their sorption capability of radioiodine quantified by the distribution ratio (R{sub D}-value). Treatment of bentonite, vermiculite and cretaceous clay as well as of samples from natural horizons of chernozem soil with hexadecylpyridinium (HDPY{sup +}) and benzethonium (BE{sup +}) exhibited sorptions rates and amounts, which are several orders of magnitude higher than those of the respective untreated samples. Moderate increases of the R{sub D}-values were found after cation exchange with hexadecyltrimethylammonium (HDTMA{sup +}), while the applications of trimethylphenylammonium (TMPA{sup +}) and tetramethylammonium (TMA{sup +}) were ineffective. Considerable sorption of radioiodine was observed with the commercially available Bentone. (orig.).

The quality study of recycled glass phosphor waste for LED

Science.gov (United States)

Tsai, Chun-Chin; Chen, Guan-Hao; Yue, Cheng-Feng; Chen, Cin-Fu; Cheng, Wood-Hi

2017-02-01

To study the feasibility and quality of recycled glass phosphor waste for LED packaging, the experiments were conducted to compare optical characteristics between fresh color conversion layer and that made of recycled waste. The fresh color conversion layer was fabricated through sintering pristine mixture of Y.A.G. powder [yellow phosphor (Y3AlO12 : Ce3+). Those recycled waste glass phosphor re-melted to form Secondary Molten Glass Phosphor (S.M.G.P.). The experiments on such low melting temperature glass results showed that transmission rates of S.M.G.P. are 9% higher than those of first-sintered glass phosphor, corresponding to 1.25% greater average bubble size and 36% more bubble coverage area in S.M.G.P. In the recent years, high power LED modules and laser projectors have been requiring higher thermal stability by using glass phosphor materials for light mixing. Nevertheless, phosphor and related materials are too expensive to expand their markets. It seems a right trend and research goal that recycling such waste of high thermal stability and quality materials could be preferably one of feasible cost-down solutions. This technical approach could bring out brighter future for solid lighting and light source module industries.

Teaching Composing with an Identity as a Teacher-Composer

Science.gov (United States)

Francis, Jennie

2012-01-01

I enjoy composing and feel able to write songs that I like and which feel significant to me. This has not always been the case and the change had nothing to do with my school education or my degree. Composing at secondary school did not move beyond Bach and Handel pastiche. I did not take any composing courses during my degree. What did influence…

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.

Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

Science.gov (United States)

Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

2009-01-01

Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

High temperature thermometric phosphors for use in a temperature sensor

Science.gov (United States)

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

1998-01-01

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.

Raman Spectra of Luminescent Graphene Oxide (GO-Phosphor Hybrid Nanoscrolls

Directory of Open Access Journals (Sweden)

Janardhanan. R. Rani

2015-12-01

Full Text Available Graphene oxide (GO-phosphor hybrid nanoscrolls were synthesized using a simple chemical method. The GO-phosphor ratio was varied to find the optimum ratio for enhanced optical characteristics of the hybrid. A scanning electron microscope analysis revealed that synthesized GO scrolls achieved a length of over 20 μm with interior cavities. The GO-phosphor hybrid is extensively analyzed using Raman spectroscopy, suggesting that various Raman combination modes are activated with the appearance of a low-frequency radial breathing-like mode (RBLM of the type observed in carbon nanotubes. All of the synthesized GO-phosphor hybrids exhibit an intense luminescent emission around 540 nm along with a broad emission at approximately 400 nm, with the intensity ratio varying with the GO-phosphor ratio. The photoluminescence emissions were gauged using Commission Internationale d'Eclairage (CIE coordinates and at an optimum ratio. The coordinates shift to the white region of the color spectra. Our study suggests that the GO-phosphor hybrid nanoscrolls are suitable candidates for light-emitting applications.

On the feasibility of infrared phosphors in super-slow particle searches

International Nuclear Information System (INIS)

Hagstrom, R.; Rugari, A.D.

1984-01-01

This chapter proposes that super-slow projectiles will produce ionization signals in media with narrow bandgaps. A specific choice of narrow bandgap phosphors is recommended which would be economically suitable for use as detectors. Topics considered include the possibilities for practical detectors, a description of detectors based on narrow bandgap phosphors, the experimental determination of relevant properties of narrow bandgap phosphors, and the observation of ionizing particles using narrow bandgap phosphors. It is determined that the temperature dependence of the glow of the phosphors is strong enough that a reduction of operating temperature by about 60 C could be sufficient to produce the desired signal to background ratio

Recuperation of uranium from phosphoric acid

International Nuclear Information System (INIS)

Cordero, G.; Jodra, L.G.; Otero, J.L.; Josa, J.M.

1977-01-01

The Spanish capacity for phosphoric acid production is 500.000 t P 2 O 5 /yr. This acid has an average concentration of 365 g U 3 O 8 / t P 2 O 5 . Therefore about 180 t U 3 O 8 /yr are dissolved. In 1969, the Junta de Energia Nuclear (JEN) developed, in bench scale, a solvent extraction process to recover the uranium from the phosphoric acid. The solvent used was a synergistic mixture of D2EHPA and TOPO. The results were very promising with good recovery and very high quality for the uranium concentrate. Later, the J.E.N. continued the studies in a pilot plant scale. For this purpose, was built an experimental facility in Huelva; it can treat about 7 cu. m/day of brown acid. Fosforico Espanol, S.A. (FESA) collaborated in the studies and agreed to setting up these installations in their factory. They also provided fresh phosphoric acid for the tests. In this pilot plant we studied the following stages: a) Clarification and conditioning of the phosphoric acid; b) Uranium extraction followed by stripping in a reducing medium; c) Purification by extraction and washing; d) Obtention of the concentrate by stripping with ammonia and CO 2 gas, followed by crystallization of the ammonium uranyl tricarbonate (AUT); and e) Calcination of the concentrate to decompose the AUT to uranium oxides. The results confirmed the laboratory test data. Recuperation levels were between 85 and 90%. The AUT calcined at 550 0 C. gave a product with 96-98% U 3 O 8 . In view of the pilot plant results we have prepared a black book for an industrial plant to treat about 3700 cu. m/day of phosphoric acid. At the present time the financial aspects of this installation are being studied [es

Process for recovering yttrium and lanthanides from wet-process phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Janssen, J.A.; Weterings, C.A.

1983-06-28

Process for recovering yttrium and lanthanides from wet-process phosphoric acid by adding a flocculant to the phosphoric acid, separating out the resultant precipitate and then recovering yttrium and lanthanides from the precipitate. Uranium is recovered from the remaining phosphoric acid.

Development of BaSO4:Eu thermoluminescence phosphor

International Nuclear Information System (INIS)

Madhusoodanan, U.; Jose, M.T.; Lakshmanan, A.R.

1999-01-01

A highly sensitive thermoluminescence (TL) phosphor based on BaSO 4 :Eu was developed following the coprecipitation technique and firing in argon atmosphere at 1123 K. Photoluminescence studies confirm that firing in argon atmosphere instead of air increased the incorporation of Eu ions in 2+ valence state. At low γ-ray doses, its TL sensitivity is nearly 2 to 3 times higher than that of CaSO 4 :Dy phosphor. The other salient features of this BaSO 4 :Eu TL phosphor are a constant glow curve shape and a nearly linear γ-ray dose response

Counter current extraction of phosphoric acid: Food grade acid production

International Nuclear Information System (INIS)

Shlewit, H.; AlIbrahim, M.

2009-01-01

Extraction, scrubbing and stripping of phosphoric acid from the Syrian wet-phosphoric acid was carried out using Micro-pilot plant of mixer settler type of 8 l/h capacity. Tributyl phosphate (TBP)/di-isopropyl ether (DIPE) in kerosene was used as extractant. Extraction and stripping equilibrium curves were evaluated. The number of extraction and stripping stages to achieve the convenient and feasible yield was determined. Detailed flow sheet was suggested for the proposed continuous process. Data obtained include useful information for the design of phosphoric acid extraction plant. The produced phosphoric acid was characterized using different analytical techniques. (author)

Point defect engineering strategies to retard phosphorous diffusion in germanium

KAUST Repository

Tahini, H. A.; Chroneos, Alexander I.; Grimes, Robin W.; Schwingenschlö gl, Udo; Bracht, Hartmut A.

2013-01-01

The diffusion of phosphorous in germanium is very fast, requiring point defect engineering strategies to retard it in support of technological application. Density functional theory corroborated with hybrid density functional calculations are used to investigate the influence of the isovalent codopants tin and hafnium in the migration of phosphorous via the vacancy-mediated diffusion process. The migration energy barriers for phosphorous are increased significantly in the presence of oversized isovalent codopants. Therefore, it is proposed that tin and in particular hafnium codoping are efficient point defect engineering strategies to retard phosphorous migration. © the Owner Societies 2013.

Phosphor Scanner For Imaging X-Ray Diffraction

Science.gov (United States)

Carter, Daniel C.; Hecht, Diana L.; Witherow, William K.

1992-01-01

Improved optoelectronic scanning apparatus generates digitized image of x-ray image recorded in phosphor. Scanning fiber-optic probe supplies laser light stimulating luminescence in areas of phosphor exposed to x rays. Luminescence passes through probe and fiber to integrating sphere and photomultiplier. Sensitivity and resolution exceed previously available scanners. Intended for use in x-ray crystallography, medical radiography, and molecular biology.

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

Purification of di-nonyl phenyl phosphoric acid (DNPPA) for synergistic extraction of uranium from strong phosphoric acid

International Nuclear Information System (INIS)

Singh, D.K.; Vijayalakshmi, R.; Singh, H.; Sharma, J.N.; Ruhela, R.

2009-01-01

Di-nonyl phenyl phosphoric acid (DNPPA) obtained from various synthesis methods is always associated with impurities such as mono-nonyl phenyl phosphoric acid and nonyl phenol which need to be separated for its effective use in the extraction of uranium from strong phosphoric acid. Two methods of purification namely liquid-solid separation method using neodymium salt and liquid-liquid separation method using methylene glycol have been described. In the liquid solid separation method the purity of DNPPA obtained was about 95% with less than 1.0% monoester, however it heavily suffers in the recovery aspect which is of the order of 50-60%. The methylene glycol treatment method, results in high purity and recovery of the product. Purity obtained was about 95.0% diester and less than 0.5% monoester and recovery was more than 90%. Analysis of DNPPA was done by potentiometric titration method using autotitrator. (author)

The Impact of Organo-Mineral Complexation on Mineral Weathering in the Soil Zone under Unsaturated Conditions

Science.gov (United States)

Michael, H. A.; Tan, F.; Yoo, K.; Imhoff, P. T.

2017-12-01

While organo-mineral complexes can protect organic matter (OM) from biodegradation, their impact on soil mineral weathering is not clear. Previous bench-scale experiments that focused on specific OM and minerals showed that the adsorption of OM to mineral surfaces accelerates the dissolution of some minerals. However, the impact of natural organo-mineral complexes on mineral dissolution under unsaturated conditions is not well known. In this study, soil samples prepared from an undisturbed forest site were used to determine mineral weathering rates under differing conditions of OM sorption to minerals. Two types of soil samples were generated: 1) soil with OM (C horizon soil from 84-100cm depth), and 2) soil without OM (the same soil as in 1) but with OM removed by heating to 350°for 24 h). Soil samples were column-packed and subjected to intermittent infiltration and drainage to mimic natural rainfall events. Each soil sample type was run in duplicate. The unsaturated condition was created by applying gas pressure to the column, and the unsaturated chemical weathering rates during each cycle were calculated from the effluent concentrations. During a single cycle, when applying the same gas pressure, soils with OM retained more moisture than OM-removed media, indicating increased water retention capacity under the impact of OM. This is consistent with the water retention data measured by evaporation experiments (HYPROP) and the dew point method (WP4C Potential Meter). Correspondingly, silicon (Si) denudation rates indicated that dissolution of silicate minerals was 2-4 times higher in OM soils, suggesting that organo-mineral complexes accelerate mineral dissolution under unsaturated conditions. When combining data from all cycles, the results showed that Si denudation rates were positively related to soil water content: denundation rate increased with increasing water content. Therefore, natural mineral chemical weathering under unsaturated conditions, while

Self-adaptive phosphor coating technology for wafer-level scale chip packaging

International Nuclear Information System (INIS)

Zhou Linsong; Rao Haibo; Wang Wei; Wan Xianlong; Liao Junyuan; Wang Xuemei; Zhou Da; Lei Qiaolin

2013-01-01

A new self-adaptive phosphor coating technology has been successfully developed, which adopted a slurry method combined with a self-exposure process. A phosphor suspension in the water-soluble photoresist was applied and exposed to LED blue light itself and developed to form a conformal phosphor coating with self-adaptability to the angular distribution of intensity of blue light and better-performing spatial color uniformity. The self-adaptive phosphor coating technology had been successfully adopted in the wafer surface to realize a wafer-level scale phosphor conformal coating. The first-stage experiments show satisfying results and give an adequate demonstration of the flexibility of self-adaptive coating technology on application of WLSCP. (semiconductor devices)

Effects of Graphene Monolayer Coating on the Optical Performance of Remote Phosphors

Science.gov (United States)

Yazdan Mehr, M.; Volgbert, S.; van Driel, W. D.; Zhang, G. Q.

2017-10-01

A graphene monolayer has been successfully coated on one side of a bisphenol-A-polycarbonate (BPA-PC) plate, used as a substrate for remote phosphor applications in light-emitting diode (LED)-based products. Using a photoresist transferring method, graphene sheet has been coated on BPA-PC plates. The results show that this graphene monolayer significantly improves the lifetime and performance of LEDs mainly by protecting them against external degradation factors such as moisture and oxygen. Also, LED-based products composed of graphene-coated BPA-PC plates exhibit longer stability with comparatively less loss of luminous efficiency. This method has great potential to significantly improve the reliability of not only LED-based products but also many other microelectronics packaging and components, in which moisture and oxygen are the key causes of failures.

Uptake and distribution of organo-iodine in deep-sea corals.

Science.gov (United States)

Prouty, Nancy G; Roark, E Brendan; Mohon, Leslye M; Chang, Ching-Chih

2018-07-01

Understanding iodine concentration, transport, and bioavailability is essential in evaluating iodine's impact to the environment and its effectiveness as an environmental biogeotracer. While iodine and its radionuclides have proven to be important tracers in geologic and biologic studies, little is known about transport of this element to the deep sea and subsequent uptake in deep-sea coral habitats. Results presented here on deep-sea black coral iodine speciation and iodine isotope variability provides key information on iodine behavior in natural and anthropogenic environments, and its geochemical pathway in the Gulf of Mexico. Organo-iodine is the dominant iodine species in the black corals, demonstrating that binding of iodine to organic matter plays an important role in the transport and transfer of iodine to the deep-sea corals. The identification of growth bands captured in high-resolution scanning electron images (SEM) with synchronous peaks in iodine variability suggest that riverine delivery of terrestrial-derived organo-iodine is the most plausible explanation to account for annual periodicity in the deep-sea coral geochemistry. Whereas previous studies have suggested the presence of annual growth rings in deep-sea corals, this present study provides a mechanism to explain the formation of annual growth bands. Furthermore, deep-sea coral ages based on iodine peak counts agree well with those ages derived from radiocarbon ( 14 C) measurements. These results hold promise for developing chronologies independent of 14 C dating, which is an essential component in constraining reservoir ages and using radiocarbon as a tracer of ocean circulation. Furthermore, the presence of enriched 129 I/ 127 I ratios during the most recent period of skeleton growth is linked to nuclear weapons testing during the 1960s. The sensitivity of the coral skeleton to record changes in surface water 129 I composition provides further evidence that iodine composition and isotope

Uptake and distribution of organo-iodine in deep-sea corals

Science.gov (United States)

Prouty, Nancy G.; Roark, E. Brendan; Mohon, Leslye M.; Chang, Ching-Chih

2018-01-01

Understanding iodine concentration, transport, and bioavailability is essential in evaluating iodine's impact to the environment and its effectiveness as an environmental biogeotracer. While iodine and its radionuclides have proven to be important tracers in geologic and biologic studies, little is known about transport of this element to the deep sea and subsequent uptake in deep-sea coral habitats. Results presented here on deep-sea black coral iodine speciation and iodine isotope variability provides key information on iodine behavior in natural and anthropogenic environments, and its geochemical pathway in the Gulf of Mexico. Organo-iodine is the dominant iodine species in the black corals, demonstrating that binding of iodine to organic matter plays an important role in the transport and transfer of iodine to the deep-sea corals. The identification of growth bands captured in high-resolution scanning electron images (SEM) with synchronous peaks in iodine variability suggest that riverine delivery of terrestrial-derived organo-iodine is the most plausible explanation to account for annual periodicity in the deep-sea coral geochemistry. Whereas previous studies have suggested the presence of annual growth rings in deep-sea corals, this present study provides a mechanism to explain the formation of annual growth bands. Furthermore, deep-sea coral ages based on iodine peak counts agree well with those ages derived from radiocarbon (14C) measurements. These results hold promise for developing chronologies independent of 14C dating, which is an essential component in constraining reservoir ages and using radiocarbon as a tracer of ocean circulation. Furthermore, the presence of enriched 129I/127I ratios during the most recent period of skeleton growth is linked to nuclear weapons testing during the 1960s. The sensitivity of the coral skeleton to record changes in surface water 129I composition provides further evidence that iodine composition and isotope

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

Thermoluminescence of calcium-based phosphors

International Nuclear Information System (INIS)

Sunta, C.M.

1985-01-01

The paper reviews the thermoluminescence (TL) properties of calcium fluoride, calcium sulphate and calcium carbonate phosphors. In the case of the calcium fluoride mineral phosphor the main emitter of TL is the cerium impurity. Based on the TL emission spectra, two types of Ce 3+ centres can be easily distinguished; those associated with O 2- compensating ion and those which have either no local compensators or are associated with F - interstitial ions at the adjacent vacant body centre position. The spectra undergo remarkable changes at high doses. Such changes are associated with the probabilities of charge trapping at different types of traps and also with the probabilities of recombination at different types of luminescent centres. Some of the traps and recombination centres are spatially associated while others are distributed randomly. In calcium carbonate mineral, Mn 2+ is invariably the emitting impurity. Mn 2+ can be used as an efficient dopant for TL emission in all the three calcium based TL phosphors. A co-dopant like Ce 3+ intensifies the luminescence yield from Mn 2+ . Models of different types of electron and hole trapping centres are given. (author)

Synthesis of Cu/TiO{sub 2}/organo-attapulgite fiber nanocomposite and its photocatalytic activity for degradation of acetone in air

Energy Technology Data Exchange (ETDEWEB)

Zhang, Gaoke, E-mail: gkzhang@whut.edu.cn; Wang, He; Guo, Sheng; Wang, Junting; Liu, Jin

2016-01-30

Graphical abstract: - Highlights: • A novel Cu/TiO{sub 2}/organo-attapulgite fiber nanocomposite was synthesized successfully. • Micro-mesopore nanocomposite structure was in favor of the degradation of acetone. • CTAB modification improved the adsorption capability of the catalyst. • The photocatalytic degradation mechanism of the acetone by the catalyst was studied. - Abstract: The Cu/TiO{sub 2}/organo-attapulgite fiber (CTOA) nanocomposite was synthesized by a facile method and was used for photocatalytic degradation of acetone in air under UV light irradiation. The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), transmission electron microscopy (TEM), UV–vis diffuse reflectance spectrum (UV–vis DRS), inductively coupled plasma (ICP) spectrometry and N{sub 2} adsorption–desorption measurement. The results showed that the structure of organo-attapulgite (OAT) had no obvious change as compared to unmodified attapulgite (AT) and the attapulgite fibers in the OAT were well-dispersed. Both micropores and mesopores exist in the CTOA catalyst. The CTOA catalysts prepared at the Cu/TiO{sub 2} molar ratio of 0.003 shows an excellent photocatalytic activity for the degradation of acetone in air. The synergistic effect of Cu species and cetyltrimethylammonium bromide modification can be responsible for the enhanced photocatalytic activity of the CTOA catalyst. The mechanism of the photocatalytic degradation of acetone by the CTOA catalyst was discussed.

The effect of organo-clay on the dielectric properties of silicone rubber

International Nuclear Information System (INIS)

Razzaghi-Kashani, M; Gharavi, N; Javadi, S

2008-01-01

Dielectric elastomers are highly deformable and fast response smart materials capable of actuation under electric fields. Among commercially available dielectric elastomers, silicone rubber can be compounded with different fillers in order to modify its electrical and mechanical properties. To study the effect of organically modified montmorillonite (OMMT) on the dielectric properties of silicone rubber, OMMT was added to this rubber at two levels, 2% and 5%, using two methods, low-shear and high-shear mixing. Composites were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The XRD patterns showed different crystallite structures for silicate platelets in the rubber matrix as a result of the two different mixing methods. In low-shear mixing, the ordered crystallite structure of the clay remains almost unchanged, whereas in high-shear mixing it loses its ordered structure, leading to the disappearance of the diffraction peaks. SEM and AFM micrographs depicted better dispersion and more uniform distribution of the organo-clay under high-shear mixing compared to those obtained by low-shear mixing. The tensile properties also confirmed the different degree of dispersion of the nano-clay resulting from the two different methods of mixing. The dielectric properties of the composites were measured under AC electric fields, and the results were compared with reference silicone rubbers with no OMMT. It was shown that the order of organo-clay layers in the less dispersed structure of the clay imparts an additional ionic polarization and higher dielectric permittivity compared to the case where the clay layers are more dispersed and lost their order. The storage and loss dielectric constants of base silicone rubber increase when it is compounded with OMMT

Discovery of a Red-Emitting Li3RbGe8O18:Mn4+ Phosphor in the Alkali-Germanate System: Structural Determination and Electronic Calculations.

Science.gov (United States)

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

2016-10-17

A solid-state combinatorial chemistry approach, which used the A-Ge-O (A = Li, K, Rb) system doped with a small amount of Mn 4+ as an activator, was adopted in a search for novel red-emitting phosphors. The A site may have been composed of either a single alkali metal ion or of a combination of them. This approach led to the discovery of a novel phosphor in the above system with the chemical formula Li 3 RbGe 8 O 18 :Mn 4+ . The crystal structure of this novel phosphor was solved via direct methods, and subsequent Rietveld refinement revealed a trigonal structure in the P3̅1m space group. The discovered phosphor is believed to be novel in the sense that neither the crystal structure nor the chemical formula matches any of the prototype structures available in the crystallographic information database (ICDD or ICSD). The measured photoluminescence intensity that peaked at a wavelength of 667 nm was found to be much higher than the best intensity obtained among all the existing A 2 Ge 4 O 9 (A = Li, K, Rb) compounds in the alkali-germanate system. An ab initio calculation based on density function theory (DFT) was conducted to verify the crystal structure model and compare the calculated value of the optical band gap with the experimental results. The optical band gap obtained from diffuse reflectance measurement (5.26 eV) and DFT calculation (4.64 eV) results were in very good agreement. The emission wavelength of this phosphor that exists in the deep red region of the electromagnetic spectrum may be very useful for increasing the color gamut of LED-based display devices such as ultrahigh-definition television (UHDTV) as per the ITU-R BT.2020-2 recommendations and also for down-converter phosphors that are used in solar-cell applications.

Comparison between mixed and spatially separated remote phosphor fabricated via a screen-printing process

Science.gov (United States)

Kim, Byung-Ho; Hwang, Jonghee; Lee, Young Jin; Kim, Jin-Ho; Jeon, Dae-Woo; Lee, Mi Jai

2016-08-01

We developed a fabrication method for remote phosphor by a screen-printing process, using green phosphor, red phosphor, and thermally stable glass frit. The glass frit was introduced for long-term stability. The optical properties of the remote phosphor were observed via an integrating sphere; the photoluminescence spectrum dramatically changed on incorporating a minor amount of the red phosphor. These unique optical properties were elucidated using four factors: phosphor ratio, scattering induced by packing density, light intensity per unit volume, and reabsorption. The thermal stability of the remote phosphor was investigated at 500°C, demonstrating its outstanding thermal properties.

Luminescent properties of phosphor converted LED using an orange-emitting Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor

Energy Technology Data Exchange (ETDEWEB)

Song, Hee Jo; Yim, Dong Kyun [Department of Materials Science and Engineering, College of Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Cho, In-Sun [Department of Mechanical Engineering, Stanford University, CA 94305 (United States); Roh, Hee-Suk; Kim, Ju Seong [Department of Materials Science and Engineering, College of Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Kim, Dong-Wan, E-mail: dwkim@ajou.ac.kr [Department of Materials Science and Engineering, Ajou University, Woncheon-dong, San 5, Yeongtong-gu, Suwon 443-749 (Korea, Republic of); Hong, Kug Sun, E-mail: kshongss@plaza.snu.ac.kr [Department of Materials Science and Engineering, College of Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

2012-12-15

Graphical abstract: Display Omitted Highlights: ► Phase-pure Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} powders were synthesized by a solid state reaction process. ► The optimum emission intensity was observed at the Eu{sup 2+} ion concentration of 0.006. ► The dipole–dipole interaction was the major concentration quenching mechanism. ► The pc-LED coated with Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} had higher CRI than commercial red phosphor. -- Abstract: A series of orange-emitting Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphors were synthesized by a conventional solid-state reaction method. The as-prepared phosphors were characterized by X-ray powder diffraction (XRD), fluorescence spectroscopy, and spectroradiometry. XRD showed that all prepared samples exhibited a monoclinic Rb{sub 2}CaP{sub 2}O{sub 7} phase. Fluorescence spectroscopy showed that the photoluminescence efficiency of Rb{sub 2}Ca{sub 1−x}P{sub 2}O{sub 7}:Eu{sub x}{sup 2+} phosphors increased with increasing Eu{sup 2+} concentration until x = 0.006, then decreased at higher concentrations, due to a concentration quenching effect. The thermal activation energy was also measured to be 0.40 eV. Furthermore, a phosphor-converted LED (pc-LED) coated with Rb{sub 2}Ca{sub 0.994}P{sub 2}O{sub 7}:Eu{sub 0.006}{sup 2+} was fabricated, which exhibited bright orange emission under a forward bias, from 200 to 300 mA. The color rendering index (CRI) of pc-LED coated with Rb{sub 2}Ca{sub 0.994}P{sub 2}O{sub 7}:Eu{sub 0.006}{sup 2+} was higher than the CRI of pc-LED coated with commercial red phosphor, due to the broad emission band of Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor. In applying with three-band pc-LEDs, moreover, white pc-LED using Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor had a higher CRI, than using commercial phosphor. These results indicated that Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor could be a good candidate for a near-UV based w-LED.

Synthesis of novel Dy3+ activated phosphate phosphors for NUV excited LED

International Nuclear Information System (INIS)

Shinde, K.N.; Dhoble, S.J.; Kumar, Animesh

2011-01-01

The new trivalent dysprosium activated X 6 AlP 5 O 20 (where X=Sr, Ba, Ca and Mg) phosphors were prepared by the combustion method. The prepared phosphors are characterized by XRD, photoluminescence and SEM techniques. Excited by 350 nm near-ultraviolet (NUV) light, the phosphors show an efficient blue and yellow band emissions, which originates from the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+ ion, respectively. The excitation spectra of the phosphors are broadband extending from 340 to 400 nm, which are characteristics of NUV excited LED. The effect of the Dy 3+ concentration on the luminescence properties of X 6 AlP 5 O 20 :Dy 3+ (where X=Sr, Ba, Ca and Mg) phosphors is studied. Ca 6 AlP 5 O 20 phosphors show strong PL emission intensity around 25 times more as compared to Ba 6 AlP 5 O 20 , Sr 6 AlP 5 O 20 and Mg 6 AlP 5 O 20 phosphors. The investigated prepared phosphors are suitable for a NUV excited LED. - Research highlights: → Novel Dy 3+ activated X 6 AlP 5 O 20 (where X=Sr,Ba,Ca and Mg) phosphors were prepared by combustion method which is very low cost and time saving synthesis method. → The excitation spectra of the phosphors are broad band extending from 340 nm to 400 nm, which is characteristics of NUV excited LED. → PL emission spectra show two emissions (485 and 573 nm) and X 6 AlP 5 O 20 :Dy 3+ 0.5 mol% (where X=Sr,Ba,Ca and Mg) phosphors shows strongest PL emission intensity. → SEM analysis indicates that phosphor particles have irregular shape, porous morphology and less than 3-4 μm in size, which is suitable for the solid state lighting (coating purpose).

Blue emitting KSCN:xCe phosphor for solid state lighting

Energy Technology Data Exchange (ETDEWEB)

Chikte, Devayani, E-mail: devi.awade@gmail.com [G.N. Khalsa College, Matunga, Mumbai 400019 (India); Omanwar, S.K. [Department of Physics, S.G.B. Amravati University, Amravati (India); Moharil, S.V. [Department of Physics, R.T.M. Nagpur University, Nagpur 440010 (India)

2014-01-15

The intense blue emitting phosphor KSCN:xCe (x=0.005, 0.01, 0.02, 0.04) is synthesized by a simple, time saving, economical method of re-crystallization through aqueous solution at 353 K. Photoluminescence measurements showed that the said phosphor exhibits emission with good intensity peaking at 450 nm corresponding to d→f transitions of Ce{sup 3+} ion. The excitation spectra monitored at 450 nm shows small peak at 282 nm and broad intense excitation band peaking at 350 nm. The latter lies in near ultraviolet (350–410 nm) emission of UV LED. The phosphor KSCN:0.02Ce{sup 3+} shows CIE 1931 color coordinates as (0.1484, 0.0602) whereas the commercial blue phosphor BAM:Eu{sup 2+} shows the color co-ordinates as (0.1417, 0.1072), respectively, indicating better color purity for KSCN: 0.02Ce{sup 3+} compared to the BAM:Eu{sup 2+} phosphor. The color coordinates of KSCN: 0.02Ce{sup 3+} phosphor (0.1484, 0.0602) are nearer to the color coordinate for blue color suggested by the color systems EBUPAL/SECAM, sRGB Blue as well as Adobe blue(0.15, 0.06). -- Highlights: • Novel phosphor KSCN:xCe prepared for the first time. • Method is simple, time saving, economical, easy to handle. • Intense, blue, Characteristic Ce{sup 3+} emission at 450 nm. • nUV excitation, suitable for solid state lighting.

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)

Light Converting Inorganic Phosphors for White Light-Emitting Diodes

Directory of Open Access Journals (Sweden)

Chiao-Wen Yeh

2010-03-01

Full Text Available White light-emitting diodes (WLEDs have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV LEDs and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED or polymer light-emitting diode (PLED, have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450-480 nm and nUV (380-400 nm LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+ is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

Light Converting Inorganic Phosphors for White Light-Emitting Diodes

Science.gov (United States)

Chen, Lei; Lin, Chun-Che; Yeh, Chiao-Wen; Liu, Ru-Shi

2010-01-01

White light-emitting diodes (WLEDs) have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV) LEDs) and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED) or polymer light-emitting diode (PLED), have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450−480 nm) and nUV (380−400 nm) LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+) is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

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.

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.

A novel red-emitting phosphor for white light-emitting diodes

International Nuclear Information System (INIS)

Ren, Fuqiang; Chen, Donghua

2010-01-01

A novel red-emitting phosphor of Eu 3+ -activated molybdate was prepared at 850 o C by a modified solid-state reaction. Photoluminescence (PL) results showed that the phosphor can be efficiently excited by UV-visible light from 350 to 550 nm, and exhibited bright red emission at 614 nm. XPS are taken to investigate the structure and compositions of this material. The crystallization and particle sizes of the phosphor have been investigated by using powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM images show that the grain size of the phosphor is about 30 nm which is in full agreement with the theoretical calculation data from the XRD patterns.

Comparative studies on the corrosion protection effect of DBSA-doped polyaniline prepared from in situ emulsion polymerization in the presence of hydrophilic Na+-MMT and organophilic organo-MMT clay platelets

International Nuclear Information System (INIS)

Chang, K.-C.; Lai, M.-C.; Peng, C.-W.; Chen, Y.-T.; Yeh, J.-M.; Lin, C.-L.; Yang, J.-C.

2006-01-01

A series of polyaniline (PANI)/Na + -montmorillonite (MMT) clay and PANI/organo-MMT nanocomposite materials have been successfully prepared by in situ emulsion polymerization in the presence of inorganic nanolayers of hydrophilic Na + -MMT clay or organophilic organo-MMT clay with DBSA and KPS as surfactant and initiator, respectively. The as-synthesized Na + -PCN and organo-PCN materials were characterized and compared by Fourier transformation infrared (FTIR) spectroscopy, wide-angle powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Na + -PCN materials in the form of coatings with low loading of Na + -MMT clay (e.g., 3 wt.%, CLAN3) on cold-rolled steel (CRS) were found much superior in corrosion protection over those of organo-PCN materials with same clay loading based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and impedance spectroscopy in 5 wt.% aqueous NaCl electrolyte. The molecular weights of PANI extracted from PCN materials and neat PANI were determined by gel permeation chromatography (GPC) with NMP as eluant. Effects of material composition on the gas permeability, optical properties and electrical conductivity of neat PANI and a series of PCN materials, in the form of free-standing film, solution and powder-pressed pellet, were also studied by gas permeability analyzer (GPA), ultraviolet-vis spectra and four-point probe technique, respectively

Separation of rare earths from solutions of phosphoric acid

International Nuclear Information System (INIS)

Jones, E.A.

1977-01-01

Rare earths are separated from 6M phosphoric acid by adsorption onto cation resin BIORAD AG50W-X8. The phosphoric acid is then washed from the column, and the rare earths are eluted with 4M hydrochloric acid

Surface-Plasmon-Enhanced Emissions of Phosphors with Au Nanoparticles Embedded in ITO

Energy Technology Data Exchange (ETDEWEB)

Kim, Ja-Yeon [Korea Photonics Technology Institute (KOPTI), Gwangju (Korea, Republic of); Oh, Seung Jong; Park, Hyun-Sun; Kim, Min-Woo; Cho, Yoo-Hyun; Kwon, Min-Ki [Chosun University, Gwangju (Korea, Republic of)

2017-03-15

Au nanoparticles were embedded in a transparent conducting layer of indium tin oxide in order to evaluate the feasibility of applying a surface-plasmon (SP)-enhanced phosphor to light-emitting diodes (LEDs). The efficiency of the phosphor was improved by energy matching between the phosphor and the SP of the Au nanoparticles. After the density of the Au nanoparticles and the thickness of the spacer layer had been optimized, the efficiency of a green phosphor was improved by 64% compared to that of an isolated green phosphor. This work provides a way to fabricate high-efficiency LEDs with high color-rendering indices and wide color gamuts in white LEDs.

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.

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

Composing and Arranging Careers

Science.gov (United States)

Schwartz, Elliott; And Others

1977-01-01

With the inspiration, the originality, the skill and craftsmanship, the business acumen, the patience, and the luck, it's possible to become a classical composer, pop/rock/country composer, jingle composer, or educational composer. Describes these careers. (Editor/RK)

Luminescence properties of Sr{sub 3-x-3y/2}M{sub x}Ce{sub y}AlO{sub 4}F (M=Ca, Ba, 0{<=}x{<=}0.9, 0.001{<=}y{<=}0.05) phosphors

Energy Technology Data Exchange (ETDEWEB)

Choi, Hye-Min [Department of Engineering in Energy and Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of); Park, Sangmoon, E-mail: spark@silla.ac.kr [Department of Engineering in Energy and Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of)

2012-09-15

Luminescent materials composed of Sr{sub 3-x-3y/2}M{sub x}Ce{sub y}AlO{sub 4}F (M=Ca, Ba, 0{<=}x{<=}0.9, 0.001{<=}y{<=}0.05) were prepared by the solid-state reaction method. X-ray diffraction (XRD) patterns of the obtained oxyfluorides are exhibited for indexing peak positions. Dynamic excitation and emission spectra of the Ce{sup 3+}-activated oxyfluoride phosphors are clearly monitored. The critical emission quenching as a function of Ce{sup 3+} contents in Sr{sub 2.5-3y/2}M{sub 0.5}Ce{sub y}AlO{sub 4}F phosphors is revealed at quite low concentrations of the activator. CIE coordinates of blue and green Sr{sub 2.5-3y/2}M{sub 0.5}Ce{sub y}AlO{sub 4}F phosphors are clearly measured. The relative quantum efficiency of Sr{sub 2.4985}Ca{sub 0.5}Ce{sub 0.005}AlO{sub 4}F based on the integrated emission is determined. The Sr{sub 3-x-3y/2}M{sub x}Ce{sub y}AlO{sub 4}F phosphors excited near 410 nm light could be prominent phosphors in applications of NUV-LED. - Highlights: Black-Right-Pointing-Pointer Blue and green emitting oxyfluoride phosphors are excitated near 410 nm Black-Right-Pointing-Pointer Ce{sup 3+}-activated oxyfluoride phosphors are quite effective to prepare white light for near-UV LED applications. Black-Right-Pointing-Pointer Gradual substitution of Ce{sup 3+} content in the oxyfluoride hosts changes CIE values.

Analysis of phosphoric ore bacterial and eucaryal microbial diversity ...

African Journals Online (AJOL)

These findings provided new opportunities into phosphoric ore microbiology that could be useful in biological system removing waste gases generated from the phosphoric industry. Keywords: Microbial community, bacteria, archaea, eucarya, mining residue. African Journal of Biotechnology, Vol 13(30) 3023-3029 ...

Photoluminescence and phosphorescence properties of Sr1-xZn2-y(PO4)2:Eux2+,Mny2+ phosphor for UV-based white-LEDs

International Nuclear Information System (INIS)

Jeong, Junho; Jayasimhadri, M.; Sueb Lee, Ho; Jang, Kiwan; Soo Yi, Soung; Hyun Jeong, Jung; Kim, Changdae

2009-01-01

Sr 1-x Zn 2-y (PO 4 ) 2 :Eu x 2+ ,Mn y 2+ (SZP: Eu x 2+ ,Mn y 2+ ) phosphors (x=0, 0.01 and y=0, 0.01) were prepared by using a stoichiometric solid-state reaction method and their photoluminescence and phosphorescence decay properties were investigated. The emission spectrum of SrZn 2 (PO 4 ) 2 :Eu 0.01 2+ , Mn 0.01 2+ measured under 400 nm excitation was composed of the violettish blue and the emerald green emissioins centered at 421 and 547 nm, respectively. The excitation wavelength of the emission peak at 547 nm was about 421 nm in the excitation spectrum of SZP:Mn 0.01 2+ . Since, this value is equal to the transition energy of Eu 2+ , the energy transfer from Eu 2+ to Mn 2+ in SZP:Eu 0.01 2+ ,Mn 0.01 2+ phosphor has been demonstrated. The CIE chromaticity coordinates of SZP:Eu 0.01 2+ ,Mn 0.01 2+ phosphor were (0.330, 0.328) under the excitation wavelength 375 nm at room temperature. The phosphorescence from SZP:Eu 0.01 2+ ,Mn 0.01 2+ could be seen by naked eyes for few seconds and it has persisted for about 4.4 h while monitoring by using a PMT spectrometer. Therefore, SZP:Eu x 2+ ,Mn y 2+ phosphor may be a potential candidate for the UV-based white light-emitting diodes (LEDs).

Intravascular imaging with a storage phosphor detector

Energy Technology Data Exchange (ETDEWEB)

Shikhaliev, Polad M; Petrek, Peter; Matthews, Kenneth L II; Fritz, Shannon G [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA (United States); Bujenovic, L Steven [PET Imaging Center, Our Lady of the Lake Medical Center, Baton Rouge, LA (United States); Xu Tong, E-mail: pshikhal@lsu.ed [Department of Physics, Carleton University, Ottawa (Canada)

2010-05-21

The aim of this study is to develop and test an intravascular positron imaging system based on a storage phosphor detector for imaging and detecting vulnerable plaques of human coronary arteries. The radiotracer F18-FDG accumulates in vulnerable plaques with inflammation of the overlying cap. The vulnerable plaques can, therefore, be imaged by recording positrons emitted from F18-FDG with a detector inserted into the artery. A prototype intravascular detector was constructed based on storage phosphor. The detector uses a flexible storage phosphor tube with 55 mm length, 2 mm diameter and 0.28 mm wall thickness. The intravascular detector is guided into the vessel using x-ray fluoroscopy and the accumulated x-ray signal must be erased prior to positron imaging. For this purpose, a light diffuser, 0.9 mm in diameter and 55 mm in length, was inserted into the detector tube. The light diffuser was connected to a laser source through a 2 m long optical fiber. The diffuser redirected the 0.38 W laser light to the inner surface of the phosphor detector to erase it. A heart phantom with 300 cm{sup 3} volume and three coronary arteries with 3.2 mm diameter and with several plaques was constructed. FDG solution with 0.5 {mu}Ci cm{sup -3} activity concentration was filled in the heart and coronary arteries. The detector was inserted in a coronary artery and the signal from the plaques and surrounding background activity was recorded for 2 min. Then the phosphor detector was extracted and read out using a storage phosphor reader. The light diffuser erased the signal resulting from fluoroscopic exposure to level below that encountered during positron imaging. Vulnerable plaques with area activities higher than 1.2 nCi mm{sup -2} were visualized by the detector. This activity is a factor of 10-20 lower than that expected in human vulnerable plaques. The detector was able to image the internal surface of the coronary vessels with 50 mm length and 360{sup 0} circumference. Spatial

Output blue light evaluation for phosphor based smart white LED wafer level packages.

Science.gov (United States)

Kolahdouz, Zahra; Rostamian, Ali; Kolahdouz, Mohammadreza; Ma, Teng; van Zeijl, Henk; Zhang, Kouchi

2016-02-22

This study presents a blue light detector for evaluating the output light of phosphor based white LED package. It is composed of a silicon stripe-shaped photodiode designed and implemented in a 2 μm BiCMOS process which can be used for wafer level integration of different passive and active devices all in just 5 lithography steps. The final device shows a high selectivity to blue light. The maximum responsivity at 480 nm is matched with the target blue LED illumination. The designed structure have better responsivity compared to simple photodiode structure due to reducing the effect of dead layer formation close to the surface because of implantation. It has also a two-fold increase in the responsivity and quantum efficiency compared to previously similar published sensors.

Development of BaSO sub 4 :Eu thermoluminescence phosphor

CERN Document Server

Madhusoodanan, U; Lakshmanan, A R

1999-01-01

A highly sensitive thermoluminescence (TL) phosphor based on BaSO sub 4 :Eu was developed following the coprecipitation technique and firing in argon atmosphere at 1123 K. Photoluminescence studies confirm that firing in argon atmosphere instead of air increased the incorporation of Eu ions in 2+ valence state. At low gamma-ray doses, its TL sensitivity is nearly 2 to 3 times higher than that of CaSO sub 4 :Dy phosphor. The other salient features of this BaSO sub 4 :Eu TL phosphor are a constant glow curve shape and a nearly linear gamma-ray dose response.

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.

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.

Preparation of red phosphor (Y, Gd)BO3:Eu by soft chemistry methods

International Nuclear Information System (INIS)

Cui Xiangzhong; Zhuang Weidong; Yu Zhijian; Xia Tian; Huang Xiaowei; Li Hongwei

2008-01-01

The three soft chemistry methods were employed to prepare the red phosphor (Y, Gd)BO 3 :Eu, such as coprecipitation-combustion method, salt assisted combustion method and emulsion method. The main factors affecting particle size, particle distribution and luminescent properties of the product were investigated in detail, and as a result, the preparation processes were optimized. The phosphors were characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), transmission electronic microscope (TEM) and vacuum ultraviolet (VUV) spectra. Results reveal that phosphors with different morphology, small particle size and high luminescence intensity could be obtained by soft chemistry methods. The difference between the luminescence properties of phosphors in this work and commercial rare earth borate phosphor is discussed. The phosphor with grain shape and high luminescence intensity could be prepared by coprecipitation-combustion method, nanophosphor could be prepared by salt assisted combustion method, and spherical phosphor with a narrow size distribution could be obtained by using emulsion method

World wide IFC phosphoric acid fuel cell implementation

Energy Technology Data Exchange (ETDEWEB)

King, J.M. Jr

1996-04-01

International Fuel Cells, a subsidary of United technologies Corporation, is engaged in research and development of all types of fuel cell technologies and currently manufactures alkaline fuel cell power plants for the U.S. manned space flight program and natural gas fueled stationary power plants using phosphoric acid fuel cells. This paper describes the phosphoric acid fuel cell power plants.

Towards zero discharge by integrated effluent treatment approach

International Nuclear Information System (INIS)

Rath, Ashish Kumar; Pattnaik, Sambhu Prasad; Pati, Ganeswar; Saha, Sushant; Viswanath, Kowtha

2014-01-01

Heavy Water Plant, Talcher houses two Organo-phosphorus Solvent Production Plants namely, 60 MTPY TBP Plant engaged in the production of Tri-n-Butyl Phosphate and Versatile Solvent Production Plant (VSPP) capable of producing various Organo Phosphorus Solvents namely, 100 MTPY D2EHPA (Di-2-Ethyl Hexyl Phosphoric Acid), or 40 MTPY TAPO (Tri-Alkyl Phosphine Oxide) or TOPO (Tri-n-Octyl Phosphine Oxide) or DNPPA (Di-Nonyl Phenyl Phosphoric Acid). These solvents have important application for separation duties in front and back end of nuclear fuel cycle and also in conventional hydrometallurgy for separation metals like Ni, Cu, Zn, Co etc., both of these plants are first of their kind in India designed by the Heavy Water Board, Mumbai with R and D inputs from BARC. The two plants employ esterification (1) process between PCl 3 / and a suitable oxo-alcohol followed by hydrolysis, neutralization and product purification. The second and third steps find large usage of Water, which eventually surface as liquid effluent. All the gaseous emissions from plants, mostly HCl gas are traded off for Saline Water as liquid effluent by scrubbing the same with Sodium Hydroxide Solution

Initiation in the study of uranium recovery from the phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Anchondo Adalid, J M

1974-01-01

The loss of considerable amounts of uranium in the Mexican phosphoric acid industry makes it important to study economic methods of recovery; the studies can serve as a basis for the construction and operation of a pilot plant as a normal preliminary to larger-scale projects. Routine experimental techniques for solvent extraction were employed. Extraction efficiencies of the order of 90-95% were obtained using 0.09-0.18M solutions of a mixture of phosphoric octyl esters applied to 4 and 6M solutions of phosphoric acid (reagent grade) containing uranium in concentrations of 0.05-0.50g of U/sub 3/O/sub 8/ per litre of acid. The conclusion was reached that phosphoric octyl esters can be used for recovering uranium in satisfactory quantities from phosphoric acid solutions by means of solvent extraction, and that the uranium can be separated from the solvent by the established procedures.

Initiation in the study of uranium recovery from the phosphoric acid

International Nuclear Information System (INIS)

Anchondo Adalid, J.M.

1974-01-01

The loss of considerable amounts of uranium in the Mexican phosphoric acid industry makes it important to study economic methods of recovery; the studies can serve as a basis for the construction and operation of a pilot plant as a normal preliminary to larger-scale projects. Routine experimental techniques for solvent extraction were employed. Extraction efficiencies of the order of 90-95% were obtained using 0.09-0.18M solutions of a mixture of phosphoric octyl esters applied to 4 and 6M solutions of phosphoric acid (reagent grade) containing uranium in concentrations of 0.05-0.50g of U 3 O 8 per litre of acid. The conclusion was reached that phosphoric octyl esters can be used for recovering uranium in satisfactory quantities from phosphoric acid solutions by means of solvent extraction, and that the uranium can be separated from the solvent by the established procedures. (author)

Method for the recovery of uranium from a concentrate using pure phosphoric acid

International Nuclear Information System (INIS)

1980-01-01

Procedure for the recovery of an uranium bearing concentrate and pure phosphoric acid from a wet process phosphoric acid from the treatment fluid with a precipitation means in conjunction with an organic diluent, the thus formed precipitate to separate and from the remaining mixture of phosphoric acid and diluent the phosphoric acid to extract, characterised in that one applies an inorganic fluorine compound. (G.C.)

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.

Influence of iron redox cycling on organo-mineral associations in arctic tundra soils

Science.gov (United States)

Herndon, E.; AlBashaireh, A.; Duroe, K.; Singer, D. M.

2016-12-01

Geochemical interactions between soil organic matter and minerals influence decomposition in many environments but remain poorly understood in arctic tundra systems. In tundra soils that are periodically to persistently saturated, the accumulation of iron oxyhydroxides and organo-iron precipitates at redox interfaces may inhibit decomposition by binding organic molecules and protecting them from microbial degradation. Here, we couple synchrotron-source spectroscopic techniques with chemical sequential extractions and physical density fractionations to evaluate the spatial distribution and speciation of Fe-bearing phases and associated organic matter in organic and mineral horizons of the seasonally thawed active layer in tundra soils from northern Alaska. Mineral-associated organic matter comprised 63 ± 9% of soil organic carbon stored in the active layer of ice wedge polygons. Ferrous iron produced in anoxic mineral horizons diffused upwards and precipitated as poorly-crystalline oxyhydroxides and organic-bound Fe(III) in the organic horizons. Ferrihydrite and goethite were present as coatings on mineral grains and plant debris and in aggregates with clays and particulate organic matter. Organic matter released through acid-dissolution of iron oxides may represent a small pool of readily-degradable organic molecules temporarily stabilized by sorption to iron oxyhydroxide surfaces, while larger quantities of particulate organic carbon and humic-like substances may be physically protected from decomposition by Fe-oxide coatings and aggregation. We conclude that formation of poorly-crystalline and crystalline iron oxides at redox interfaces contributes to mineral protection of organic matter through sorption, aggregation, and co-precipitation reactions. Further study of organo-mineral associations is necessary to determine the net impact of mineral-stabilization on carbon storage in rapidly warming arctic ecosystems.

Printed organo-functionalized graphene for biosensing applications.

Science.gov (United States)

Wisitsoraat, A; Mensing, J Ph; Karuwan, C; Sriprachuabwong, C; Jaruwongrungsee, K; Phokharatkul, D; Daniels, T M; Liewhiran, C; Tuantranont, A

2017-01-15

Graphene is a highly promising material for biosensors due to its excellent physical and chemical properties which facilitate electron transfer between the active locales of enzymes or other biomaterials and a transducer surface. Printing technology has recently emerged as a low-cost and practical method for fabrication of flexible and disposable electronics devices. The combination of these technologies is promising for the production and commercialization of low cost sensors. In this review, recent developments in organo-functionalized graphene and printed biosensor technologies are comprehensively covered. Firstly, various methods for printing graphene-based fluids on different substrates are discussed. Secondly, different graphene-based ink materials and preparation methods are described. Lastly, biosensing performances of printed or printable graphene-based electrochemical and field effect transistor sensors for some important analytes are elaborated. The reported printed graphene based sensors exhibit promising properties with good reliability suitable for commercial applications. Among most reports, only a few printed graphene-based biosensors including screen-printed oxidase-functionalized graphene biosensor have been demonstrated. The technology is still at early stage but rapidly growing and will earn great attention in the near future due to increasing demand of low-cost and disposable biosensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of organo clay on curing, mechanical and dielectric properties of NR/SBR blends

Science.gov (United States)

Ravikumar, K.; Joseph, Reji; Ravichandran, K.

2018-04-01

Natural rubber (NR) and styrene butadiene rubber (SBR) based elastomeric blends reinforced with organically modified Sodium bentonite clay were prepared by two roll mills. Vulcanization parameters such as minimum and maximum torque values scorch and cure times are measured by Oscillating Disc Rheometer. Mechanical properties such as Tensile strength, modulus at 100%, 200% and 300% elongation and elongation at break and Hardness were measured by Universal testing machine and Durometer Shore A hardness meter respectively. Dielectric properties such as dielectric constant (ε’), dissipation factor (tanδ) and volume resistivity (ρv) were measured at room temperature. The curing studies show that torque values are increasing in NR/SBR blends by increase NR content. The scorch and optimum cure time in NR/SBR blends reinforced organo modified clay was found through increase in the SBR content. This may be due to better processing safety of the NR/SBR blends reinforced with organo modified clay. Mechanical properties show that addition of SBR in blends, tensile strength, elongation modulus increases, but 100% modulus slightly increases and no change was observed in Hardness. Dielectric studies show that dielectric constant of NR and SBR rubbers are almost same, it may due to their non-polar nature. But addition of SBR in NR/SBR blend, dielectric constant gradually increases and maximum value observed at 50/50 ratio. But no considerable change was observed in dissipation factor. Frequency dependant resistivity shows that volume resistivity was not changed with respect to frequency up to 3.5 kHz and beyond that the frequency dependence resistivity was found.

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.

TL dosimetric characterization of gamma irradiated SrSO{sub 4}:Eu phosphors

Energy Technology Data Exchange (ETDEWEB)

Jayasudha, S., E-mail: jsnair.india@gmail.com [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Madhukumar, K.; Nair, C.M.K.; Nair, Resmi G. [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India); Rajesh, S. [Department of Materials & Ceramic Engineering, University of Aveiro, Aveiro 3810-193 (Portugal); Elias, T.S. [State Institute of Cancer Research, Medical College P.O., Thiruvananthapuram 695011 (India); Anandakumar, V.M. [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India); State Institute of Cancer Research, Medical College P.O., Thiruvananthapuram 695011 (India); Department of Materials & Ceramic Engineering, University of Aveiro, Aveiro 3810-193 (Portugal); Gopakumar, N. [Mahatma Gandhi College, Kesavadasapuram, Pattom Palace P.O., Thiruvananthapuram 695004 (India)

2017-03-15

Thermoluminescence (TL) characteristics of SrSO{sub 4}:Eu nanostructured phosphor under gamma excitation has been studied and their suitability for environmental radiation dosimetry applications is discussed. The dopant level is tuned for optimum TL response. The effect of radiation dose and heating rate were investigated. The phosphor preserves linearity in the low dose region, 0.1 Gy to 20 Gy. PL studies of irradiated and un-irradiated phosphors reveal that the dopant Eu exists in divalent state and are the luminescence emission centres in the material. The fading properties of SrSO{sub 4}:Eu phosphor are observed to be better than that of the commercial dosimeters TLD-200 and TLD-400. The kinetic parameters are calculated using Chen's method and initial rise method and verified by Computerized Glow curve Deconvolution (CGCD). The sensitivity of the synthesized phosphor is found to be very high when compared with that of the commercial standard dosimeter CaSO{sub 4}:Dy. The phosphor is found to be stable for short term radiation monitoring.

The immiscible aqueous solutions of alkyl phosphates. Study for the purpose of uranium extraction from phosphoric acid solutions

International Nuclear Information System (INIS)

Mauborgne, Bernard

1979-01-01

Systems of immiscible aqueous solutions composed by a phase rich in mineral salt and by another phase almost totally containing an organic salt, have been studied for years, with quaternary ammonium salts with an organic cation. The objective of this research is to study systems symmetric to the previous ones, i.e. with organic anions such as alkyl phosphates, and then to try to understand mechanisms of extraction of metals in these environments. Based on properties of immiscible aqueous solutions, an original three-phase process of liquid-liquid extraction has been developed, and is used to separate uranium in phosphoric acids with better performance than the existing industrial processes [fr

A novel KMgPO{sub 4}:Tb{sup 3+}(KMPT) phosphor for radiation dosimetry

Energy Technology Data Exchange (ETDEWEB)

Palan, C.B., E-mail: chetanpalan27@gmail.com [Department of Physics, Sant Gadge Baba Amravati University, Amravati 44602 (India); Bajaj, N.S. [Department of Physics, Toshniwal ACS College, Sengaon, Hingoli 431542 (India); Soni, A. [Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai 400094 (India); Omanwar, S.K. [Department of Physics, Sant Gadge Baba Amravati University, Amravati 44602 (India)

2016-08-15

The polycrystalline sample of KMgPO{sub 4}:Tb{sup 3+}(KMPT) phosphor was successfully synthesized by using solid state method. The X-ray powder diffraction, photoluminescence (PL) emission and excitation spectra, thermoluminescence (TL) and optically stimulated luminescence (OSL) were thoroughly measured. The PL spectra of as-prepared KMPT phosphor showed characteristic blue-green emission, when excited by 226 nm under UV excitation. The optimum PL intensity was observed at 0.01 mol concentration of Tb{sup 3+}ions and this phosphor used for remaining studies. The TL glow curve of KMPT phosphor consist two characterized peaks, which were deconvoluted and the kinetic parameters i.e. trap depth or activation energy, order of kinetic and frequency factor determined by using peak shape method. TL sensitivity of KMPT phosphors was found to be 10% than that of TL sensitivity of TLD-500 phosphor. The OSL sensitivity of KMPT was 0.92 times than OSL sensitivity of α-Al{sub 2}O{sub 3}:C phosphor. The OSL decay curve KMPT phosphor consist of three component having photoionization cross sections were found to be 0.26548×10{sup −17}, 0.220×10{sup −17}, 2.92×10{sup −17} cm{sup 2}. The KMPT phosphor showed linear dose response in range 100–6000 mGy and fading of KMPT phosphor was found to be 31% in 15 days. The Minimum detectable dose (MDD) was found to be 0.39 mGy with corresponding 3σ back ground. The phosphor shows good dosimetry properties such as sensitivity, dose response, MDD, Fading.

Physicochemical Study of Irradiated polypropylene/Organo :Modified Montmorillonite Composites by Using Electron Beam Irradiation Technique

International Nuclear Information System (INIS)

Hassan, M.S.

2008-01-01

Polypropylene/ Organo modified montmorillonite composites (PP/ OMMT) were prepared by melt blending with a twin screw extruder. The thermal properties by thermo gravimetric analysis (TGA), the dispersion of OMMT of macromolecules by X-ray diffraction (XRD), mechanical properties and the morphology by scanning electron microscopy (SEM) were investigated. The effect of electron beam irradiation on these properties was also studied. The results showed an intercalation between the silicate layers and the PP polymer matrix. The (PP/ OMMT) composites exhibit higher thermal stability and lower mechanical properties than pure polypropylene

Aerodynamic properties of six organo-mineral fertiliser particles

Directory of Open Access Journals (Sweden)

Marcello Biocca

2013-09-01

Full Text Available Agricultural fertilisers are generally applied by means of centrifugal disk spreaders. The machinery, the working conditions and the physical characteristics of fertilizers (including the aerodynamic characteristics of particles may affect the behaviour of particles after the discarding from the spreader. We investigated the aerodynamic properties of organo-mineral fertilisers (a class of slow release fertilisers that are less investigated since they are relatively new in the market using a vertical wind tunnel similar to an elutriator. In the same time, the morphological characteristics of individual fertilizer particles were measured by means of an image analysis procedure. In the study we compare six different fertilisers and we discuss the suitability of the employed methods. The results provide the terminal velocity – Vt – (the velocity value that overcome the gravity force of the particles of the particles, ranging from 8.60 to 9.55 m s-1, and the relationships between Vt and some physical properties (mass, shape, dimensions of the fertilizers. Moreover, the results of field distribution trials show the behaviour of the tested fertilizers during practical use. Such data can contribute to enhance the quality of application of these products in field.

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

Phosphor plate mammography: contrast studies and clinical experience

International Nuclear Information System (INIS)

Chang, C.H.J.; Martin, N.L.; Templeton, A.W.; Cook, L.T.; Harrison, L.A.; McFadden, M.A.; Dwyer, S.J. III; Spicer, J.; Crystal, J.M.

1992-01-01

Mammography and accurate microcalcification detection require very good spatial resolution. We have compared the diagnostic capabilities of reduced-exposure, third-generation, 5 cycles/mm computed radiography (CR) phosphor plates with conventional screen-film in 67 patients. No difference in diagnostic accuracy was detected. The digital characteristics of storage phosphor plates erabled us to study the relationship between contrast and spatial resolution. We developed a computer program to identify a single 100 μm pixel in a digital image and assign various gray levels to that pixel. Using this model, we determined that, for our 5 cycles/mm CR system, the imaged contrast of a 100 μm object was 62% of the original contrast. Current 5 cycles/mm phosphor plate systems cannot adequately detect microcalcifications that approximate 100 μm or smaller unless a magnification technique is used. (orig.)

Persistent phosphors for painting, medical and biological applications

International Nuclear Information System (INIS)

Nazarov, M.

2013-01-01

Multiphase micro and nanoparticle persistent phosphors are synthesized and applied for different fields including painting, medical and biological investigations. A lot of examples show a broad range of applications of persistent luminescence from bulk materials to high tech products, especially in medicine. The development of high efficiency nanosized phosphor makes it possible to propose persistent materials as very good candidates for photodynamic therapy of cancer. An artificial block from slag, concrete, and sand covered with SrAl 2 O 4 :Eu 2+ , Dy 3+ based phosphor is prepared, and a new direction in biology for algae cultivation and artificial reef is discussed. For the first time, underwater luminescence is experimentally studied under real sea conditions. Bright blue-green long-lasting afterglow is registered at a depth of 5 m. The fishes are attracted by the light of the artificial reef. (author)

Measurement of thermal neutron fluence with CaSO4 thermoluminescent phosphors

International Nuclear Information System (INIS)

Liu Jinhua; Su Jingling; Wei Zemin

1984-01-01

During neutron irradiation, some TL phosphors were activated. After leaving the irradiation field the TL phosphor produced self-irradiation. The TL output of self-dose was only related to the original neutron fluence and independent of the γ-radiation. Several CaSO 4 TL phosphors were made. They were CaSO 4 :Dy, CaSO 4 :Dy-Teflon, CaSO 4 :Dy mixed with Dy 2 O 3 , CaSO 4 :Mn mixed with Dy 2 O 3 . The linearity, and lower detection limits of these TL phosphors were measured. The thermal neutron response of CaSO 4 :Mn mixed with Dy 2 O 3 was 64 R/(10 10 cm -2 ) and the lower detection limit was 1.3x10 5 cm -2

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.

Method for separating mono- and di-octylphenyl phosphoric acid esters

International Nuclear Information System (INIS)

Arnold, W.D. Jr.

1977-01-01

A method for separating mono-octylphenyl phosphoric acid ester and di-octylphenyl phosphoric acid ester from a mixture thereof comprises reacting the ester mixture with a source of lithium or sodium ions to form a mixture of the phosphate salts; contacting the salt mixture with an organic solvent which causes the dioctylphenyl phosphate salt to be dissolved in the organic solvent phase and the mono-octylphenyl phosphate salt to exist in a solid phase; separating the phases; recovering the phosphate salts from their respective phases; and acidifying the recovered salts to form the original phosphoric acid esters

Importance of Microbial Activity On Groundwater Iodate and Organo-Iodine Speciation and Mobility At Two DOE Sites

Energy Technology Data Exchange (ETDEWEB)

Santschi, Peter H. [Texas A & M Univ., College Station, TX (United States); Xu, Chen [Texas A & M Univ., College Station, TX (United States); Schwehr, Kathleen A. [Texas A & M Univ., College Station, TX (United States); Kaplan, Daniel I. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Yeager, Chris M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2016-03-01

Iodine (I) occurs in multiple oxidation states in aquatic systems in the form of organic and inorganic species (iodide and iodate). This fact leads to complex biogeochemical cycling of Iodine and its long-lived isotope, ¹²⁹I, a major by-product of nuclear fission. Results from our newly developed, sensitive and rapid method for speciated isotopic ratios (¹²⁹I/¹²⁷I) via GC-MS, which compare favorably with Accelerator Mass Spectroscopy, demonstrate that the mobility of ¹²⁹I species greatly depends on the type of I species and its concentration, pH, and sediment redox state. At ambient concentrations (~10⁷ M), I- and IO^-3 are significantly retarded by sorption to mineral surfaces and covalent binding to aromatic moieties in natural organic matter (NOM), even when NOM is present at low concentrations such as occur at Hanford. At concentrations traditionally examined in sorption studies (≥ 10^-4 M), I- travels along with the water. Iodate removal can also occur through incorporation into CaCO₃ crystal lattice, e.g., at the Hanford Site. Removal of iodine from the groundwater through interaction with NOM is complicated by the release of mobile organo-I species, as was observed at SRS and Hanford. A small fraction of NOM that is bound to iodine can behave as a mobile organo-I source, a process that we were able to numerically simulate. Field and laboratory studies evaluating the cause for steady increases in ¹²⁹I concentrations (up to 1000 pCi L-1) emanating from radiological basins at SRS indicate that an increase of 0.7 pH units in groundwater over 17 years can account for the observed increased groundwater ¹²⁹I concentrations. Bacteria from a ¹²⁹I-contaminated aerobic aquifer at the F-area of SRS can accumulate I- at environmentally relevant concentrations (10^-7 M), and enzymatically oxidize I-, which together with microbially produced Mn

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

Recovery of zinc in phosphor wastes via electrokinetic treatments

International Nuclear Information System (INIS)

Yu, M.Y.; Wang, H. Paul; Chen, C.Y.; Hsiung, T.-L.; Wei, Yu-Ling; Tai, H.-S.; Chiang, K.-C.

2007-01-01

Speciation of zinc in phosphor wastes during electrokinetic treatments has been studied by in situ X-ray absorption near edge structure (XANES) spectroscopy in the present work. The least-square fits of the in situ XANES spectra show that the major zinc species in the phosphor waste are ZnS (77%), ZnO (10%), and Zn(OH) 2 (13%). During the electrokinetic treatment for 90 min, 25% of ZnS and 4% of ZnO are dissolved. About 42% of zinc is enriched on the cathode under the electric field (5 V/cm). Prolonging the electrokinetic treatment time to 4 h under the electric field of 5 V/cm, at least 80% of zinc in the phosphor waste can be recovered

Quantitative Characterization of Phosphor Detector for Fusion Plasmas

International Nuclear Information System (INIS)

Baciero, A.; Zurro, B.; McCarthy, K. J.

2004-01-01

Experiments made to characterize phosphor screens with application as broadband radiation detectors, are described. Several radiation sources, covering the spectral range between the ultraviolet and X ray, were used. In addition, details are given of three original phosphor-screen-based detectors that were designed for use as broadband detectors in magnetically confined fusion devices. The first measurements obtained with these detectors in plasmas created in the TJ-II stellarator device are presented together with the analysis performed. (Author)

Electroluminescent efficiency of alternating current thick film devices using ZnS:Cu,Cl phosphor

International Nuclear Information System (INIS)

Sharma, Gaytri; Han, Sang Do; Kim, Jung Duk; Khatkar, Satyender P.; Rhee, Young Woo

2006-01-01

ZnS:Cu,Cl phosphor is prepared with the help of low intensity milling of the precursor material in two step firing process. The synthesized phosphor is used for the preparation of alternating current thick film electroluminescent (ACTFEL) devices with screen-printing method. The commission international de l'Eclairge (CIE) color co-ordinates of the ACTFEL devices prepared by these phosphor layers shows a shift from bluish-green to green region with the change in the amount of Cu in the phosphor. The various parameters to improve the efficiency and luminance of the devices have also been investigated. The brightness of the ac thick film EL device depends on the particle size of the phosphor, crystallinity, amount of binding material and applied voltage. The EL device fabricated with phosphor having average particle size of 25 μm shows maximum luminescence, when 60% phosphor concentration is used with respect to binding material. EL intensity is also linearly dependent on frequency. It is due the increase of excitation chances of the host matrix or dopant ions with increasing frequency

Persistent luminescence, TL and OSL characterization of beta irradiated SrAl2O4:Eu2+, Dy3+ combustion synthesized phosphor

International Nuclear Information System (INIS)

Zúñiga-Rivera, N.J.; García, R.; Rodríguez-Mijangos, R.; Chernov, V.; Meléndrez, R.; Pedroza-Montero, M.; Barboza-Flores, M.

2014-01-01

The persistent luminescence (PLUM), thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of strontium aluminates co-doped with Eu +2 and Dy +3 exposed to beta radiation is reported. The phosphor was synthesized by the combustion synthesis method employing a highly exothermic redox reaction between the metal nitrates [Al(NO 3 ) 3 , Sr(NO 3 ) 2 , Eu(NO 3 ) 3 and Dy(NO 3 ) 3 ] and organic fuel carbohydrazide (CH 6 N 4 O). The long decay PLUM emission, TL and OSL were measured as a function of beta radiation dose. A wide emission band centered at 510 nm (green) related to Eu 2+ ions and lattice defects were observed for the synthesized samples. The presence of a variety of defects and aggregates were responsible for the observed broad 100 °C peaked TL glow curve of the irradiated sample which is composed of several overlapped TL peaks. The existence of multiple trapping levels, with different trapping/detrapping probabilities, is behind the particular features for the PLUM, TL and OSL emissions. We conclude that in the SrAl 2 O 4 :Eu 2+ , Dy 3+ phosphors, the low temperature TL peaked around 30–75 °C is responsible for the PLUM emission and those around 100 °C were related to very stable trapping states which provide suitable radiation storage properties to be used as a PLUM/TL/OSL radiation phosphor

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.

Photocatalytic Activity and Optical Properties of Blue Persistent Phosphors under UV and Solar Irradiation

Directory of Open Access Journals (Sweden)

C. R. García

2016-01-01

Full Text Available Blue phosphorescent strontium aluminosilicate powders were prepared by combustion synthesis route and a postannealing treatments at different temperatures. X-ray diffraction analysis showed that phosphors are composed of two main hexagonal phases: SrAl2O4 and Sr3Al32O51. The morphology of the phosphors changed from micrograins (1000°C to a mixture of bars and hexagons (1200°C and finally to only hexagons (1300°C as the annealing temperature is increased. Photoluminescence spectra showed a strong blue-green phosphorescent emission centered at λem=455 nm, which is associated with 4f65d1→4f6  (8S7/2 transition of the Eu2+. The sample annealed at 1200°C presents the highest luminance value (40 Cd/m2 with CIE coordinates (0.1589, 0.1972. Also, the photocatalytic degradation of methylene blue (MB under UV light (at 365 nm was monitored. Samples annealed at 1000°C and 1300°C presented the highest percentage of degradation (32% and 38.5%, resp. after 360 min. In the case of photocatalytic activity under solar irradiation, the samples annealed at 1000°C, 1150°C, and 1200°C produced total degradation of MB after only 300 min. Hence, the results obtained with solar photocatalysis suggest that our powders could be useful for water cleaning in water treatment plants.

Promotion of Crystal Growth on Biomass-based Carbon using Phosphoric Acid Treatments

Directory of Open Access Journals (Sweden)

Liwei Yu

2015-02-01

Full Text Available The effect of phosphoric acid treatments on graphitic microcrystal growth of biomass-based carbons was investigated using X-ray diffraction, infrared spectroscopy, and Raman spectroscopy. Although biomass-based carbons are believed to be hard to graphitize even after heat treatments well beyond 2000 °C, we found that graphitic microcrystals of biomass-based carbons were significantly promoted by phosphoric acid treatments above 800 °C. Moreover, twisted spindle-like whiskers were formed on the surface of the carbons. This suggests that phosphorus-containing groups turn graphitic microcrystalline domains into graphite during phosphoric acid treatments. In addition, the porous texture of the phosphoric acid-treated carbon has the advantage of micropore development.

Phosphors for near UV-Emitting LED's for Efficacious Generation of White Light

Energy Technology Data Exchange (ETDEWEB)

McKittrick, Joanna [Univ. of California, San Diego, CA (United States)

2013-09-30

1) We studied phosphors for near-UV (nUV) LED application as an alternative to blue LEDs currently being used in SSL systems. We have shown that nUV light sources could be very efficient at high current and will have significantly less binning at both the chip and phosphor levels. We identified phosphor blends that could yield 4100K lamps with a CRI of approximately 80 and LPWnUV,opt equal to 179 for the best performing phosphor blend. Considering the fact that the lamps were not optimized for light coupling, the results are quite impressive. The main bottleneck is an optimum blue phosphor with a peak near 440 nm with a full width half maximum of about 25 nm and a quantum efficiency of >95%. Unfortunately, that may be a very difficult task when we want to excite a phosphor at ~400 nm with a very small margin for Stokes shift. Another way is to have all the phosphors in the blend having the excitation peak at 400 nm or slightly shorter wavelength. This could lead to a white light source with no body color and optimum efficacy due to no self-absorption effects by phosphors in the blend. This is even harder than finding an ideal blue phosphor, but not necessarily impossible. 2) With the phosphor blends identified, light sources using nUV LEDs at high current could be designed with comparable efficacy to those using blue LEDs. It will allow us to design light sources with multiple wattages using the same chips and phosphor blends simply by varying the input current. In the case of blue LEDs, this is not currently possible because varying the current will lower the efficacy at high current and alter the color point. With improvement of phosphor blends, control over CRI could improve. Less binning at the chip level and also at the phosphor blend level could reduce the cost of SSL light sources. 3) This study provided a deeper understanding of phosphor characteristics needed for LEDs in general and nUV LEDs in particular. Two students received Ph.D. degrees and three

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.

Phosphorous Diffuser Diverged Blue Laser Diode for Indoor Lighting and Communication

KAUST Repository

Chi, Yu-Chieh

2015-12-21

An advanced light-fidelity (Li-Fi) system based on the blue Gallium nitride (GaN) laser diode (LD) with a compact white-light phosphorous diffuser is demonstrated for fusing the indoor white-lighting and visible light communication (VLC). The phosphorous diffuser adhered blue GaN LD broadens luminescent spectrum and diverges beam spot to provide ample functionality including the completeness of Li-Fi feature and the quality of white-lighting. The phosphorous diffuser diverged white-light spot covers a radiant angle up to 120o with CIE coordinates of (0.34, 0.37). On the other hand, the degradation on throughput frequency response of the blue LD is mainly attributed to the self-feedback caused by the reflection from the phosphor-air interface. It represents the current state-of-the-art performance on carrying 5.2-Gbit/s orthogonal frequency-division multiplexed 16-quadrature-amplitude modulation (16-QAM OFDM) data with a bit error rate (BER) of 3.1 × 10−3 over a 60-cm free-space link. This work aims to explore the plausibility of the phosphorous diffuser diverged blue GaN LD for future hybrid white-lighting and VLC systems.

Optimization and complexing agent-assisted synthesis of green SrAl{sub 2}O{sub 4}: Eu{sup 2+}, Dy{sup 3+} phosphors through sol–gel process

Energy Technology Data Exchange (ETDEWEB)

Du, Hongli; Shan, Wenfei; Wang, Liying; Xu, De; Yin, Hao [School of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Chen, Yanwen [Hunan Labour Protection Institute of Nonferrous Metals, Changsha 410014 (China); Guo, Dongcai, E-mail: dcguo2001@hnu.edu.cn [School of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Hunan Provincial Key Laboratory for Cost-effective Utilization of Fossil Fuel Aimed at Reducing Carbon-dioxide Emissions, Changsha 410082 (China)

2016-08-15

A novel Eu{sup 2+}–Dy{sup 3+}co-doped strontium aluminate green long-lasting phosphors were synthesized via conventional sol–gel method with citric acid and polyethylene glycol used as chelating agent, respectively. Orthogonal experiments were employed to optimize the main synthesis conditions and obtain the optimum technological parameters. Subsequently, the crystal structure, morphology, decay curve and luminescence property of the composites were characterized. X-ray diffraction (XRD) showed that the samples were composed of single-phase SrAl{sub 2}O{sub 4}. Scanning electron microscopy (SEM) revealed that the resultant nanoparticles performed graininess with a size of 100 nm around. The excitation and emission spectra indicated that, excitation broadband chiefly lay in the ultraviolet range, and nanocrystalline particles emitted strong light at 510 nm, which corresponding to the typical characteristic 5d–4f transition of Eu{sup 2+} ion excited at around 360 nm. The long afterglow photoluminescence of nanoparticles SrAl{sub 2}O{sub 4}: Eu{sup 2+}, Dy{sup 3+} (denoted as SAO: ED) was observed in the dark with the naked eye even after the removal of the excitation light. The luminescence properties suggested that SAO: ED phosphor may be regarded as a potential green phosphor candidate for near-UV and blue light-emitting diodes (LEDs).

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.

Flocculation of suspended matter in a crude wet phosphoric acid (Algeria)

International Nuclear Information System (INIS)

Brikci Nigassa, M.; Bensebaa, A.

1994-11-01

Prior to the recovery of uranium, a pre-treatment of the phosphoric acid is necessary to remove soluble impurities of different origins. In this work, synthetic flocculants have been used. the influence of operating conditions on flocculation and filtration, such as, type of flocculants, polymer concentration, temperature, mixing and time of agitation, has been studied for both aged and fresh phosphoric acid. It has been shown that synthetic flocculants can be used for flocculation ins a phosphoric acid medium and that flocculation and filtration processes are strongly linked

Scaling Up: Kilolumen Solid-State Lighting Exceeding 100 LPW via Remote Phosphor

Energy Technology Data Exchange (ETDEWEB)

Waqidi Falicoff

2008-09-15

This thirty-month project was successful in attaining its ambitious objectives of demonstrating a radically novel 'remote-phosphor' LED light source that can out-perform conventional conformal coated phosphor LED sources. Numerous technical challenges were met with innovative techniques and optical configurations. This product development program for a new generation of solid-state light sources has attained unprecedented luminosity (over 1 kilo-lumen) and efficacy (based on the criterion lumens per 100mw radiant blue). LPI has successfully demonstrated its proprietary technology for optical synthesis of large uniform sources out of the light output of an array of separated LEDs. Numerous multiple blue LEDs illuminate single a phosphor patch. By separating the LEDs from the phosphor, the phosphor and LEDs operate cooler and with higher efficiency over a wide range of operating conditions (from startup to steady state). Other benefits of the system include: better source uniformity, more types of phosphor can be used (chemical interaction and high temperatures are no longer an issue), and the phosphor can be made up from a pre-manufactured sheet (thereby lowering cost and complexity of phosphor deposition). Several laboratory prototypes were built and operated at the expected high performance level. The project fully explored two types of remote phosphor system: transmissive and reflective. The first was found to be well suited for a replacement for A19 type incandescent bulbs, as it was able to replicate the beam pattern of a traditional filament bulb. The second type has the advantages that it is pre-collimate source that has an adjustable color temperature. The project was divided in two phases: Phase I explored a transmissive design and Phase II of the project developed reflective architectures. Additionally, in Phase II the design of a spherical emitting transmissive remote phosphor bulb was developed that is suitable for replacement of A19 and

Zero- and two-dimensional hybrid carbon phosphors for high colorimetric purity white light-emission.

Science.gov (United States)

Ding, Yamei; Chang, Qing; Xiu, Fei; Chen, Yingying; Liu, Zhengdong; Ban, Chaoyi; Cheng, Shuai; Liu, Juqing; Huang, Wei

2018-03-01

Carbon nanomaterials are promising phosphors for white light emission. A facile single-step synthesis method has been developed to prepare zero- and two-dimensional hybrid carbon phosphors for the first time. Zero-dimensional carbon dots (C-dots) emit bright blue luminescence under 365 nm UV light and two-dimensional nanoplates improve the dispersity and film forming ability of C-dots. As a proof-of-concept application, the as-prepared hybrid carbon phosphors emit bright white luminescence in the solid state, and the phosphor-coated blue LEDs exhibit high colorimetric purity white light-emission with a color coordinate of (0.3308, 0.3312), potentially enabling the successful application of white emitting phosphors in the LED field.

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.

A study of the fixing of phosphoric ions by zirconium-montmorillonite; Etude de la fixation d'ions phosphoriques par la montmorillonite-zirconium

Energy Technology Data Exchange (ETDEWEB)

Bittel, R; Boursat, C; Platzer, R [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

In connection with the research carried out on the purification of nuclear reactor water, we have undertaken a study of the ion-exchange properties of acid montmorillonite. In a previous paper, we described the preparation of zirconium-montmorillonite small plate. The present article aims to study some of the properties of the clay obtained. We have observed that zirconium-montmorillonite fixes very strongly the phosphorus from solutions of phosphoric acid or of phosphates: on 1 g of clay it is possible to fix 1,2 milli-atoms-gram of zirconium and the zirconium montmorillonite itself fixes 2,1 milli-atoms-gram of phosphorus. An explanation of these experimental results, which is as much chemical as mineralogical, is the hypothesis that the fixing of phosphoric ions modifies the distribution of the ions between the platelets and precipitates a very slightly soluble product of the type diphospho-zirconic acid. (author) [French] En rapport avec des recherches sur I'epuration de l'eau des reacteurs nucleaires nous avons entrepris une etude sur les proprietes d'echangeur d'ions de la montmorillonite-acide. Dans une precedente publication, nous avons decrit la preparation des plaquettes de montmorillonite-zirconium. La presente communication a pour but d'etudier quelques proprietes de l'argile obtenue. Nous avons constate que la montmorilionite-zirconium fixe le phosphore de solutions d'acide phosphorique ou de phosphate avec une grande intensite: sur 1 g d'argile, on peut fixer 1,2 atomes-gramme de zirconium, et la montmorillonite-zirconium fixe a son tour 2,1 milli-atomesgramme de phosphore. Une explication des resultats experimentaux, tant d'ordre chimique que d'ordre mineralogique, consiste en l'hypothese suivant laquelle la fixation d'ions phosphoriques modifierait la repartition des ions entre les feuillets avec precipitation du compose tres peu soluble (type: acide diphosphozirconique). (auteur)

Synthesis and characterization of new polyimide/organo clay nano composites containing benzophenone moieties in the main chain

International Nuclear Information System (INIS)

Faghihi, K.; Ashouri, M.; Feyzi, A.

2013-01-01

A series of nano composites consist of organic polyimide and organo-modified clay content varying from 0 to 5 wt %, were successfully prepared by in situ polymerization. Polyimide used as a matrix of nano composite was prepared through the reaction of 1,4-bis [4-aminophenoxy] butane and 3,3,4,4-benzophenone tetra carboxylic dianhydride in N,N-dimethylacetamide (Dmac). The resulting nano composite films were characterized by Ft-IR spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. (Author)

Synthesis and characterization of new polyimide/organo clay nano composites containing benzophenone moieties in the main chain

Energy Technology Data Exchange (ETDEWEB)

Faghihi, K.; Ashouri, M.; Feyzi, A., E-mail: k-faghihi@araku.ac.ir [Arak University, Faculty of Science, Organic Polymer Chemistry Research Laboratory, 38158-879 Arak (Iran, Islamic Republic of)

2013-08-01

A series of nano composites consist of organic polyimide and organo-modified clay content varying from 0 to 5 wt %, were successfully prepared by in situ polymerization. Polyimide used as a matrix of nano composite was prepared through the reaction of 1,4-bis [4-aminophenoxy] butane and 3,3,4,4-benzophenone tetra carboxylic dianhydride in N,N-dimethylacetamide (Dmac). The resulting nano composite films were characterized by Ft-IR spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. (Author)

Technique of proton and phosphorous MR spectroscopy; Technik der Protonen- und Phosphor-MR-Spektroskopie

Energy Technology Data Exchange (ETDEWEB)

Backens, M. [Universitaetsklinikum des Saarlandes, Klinik fuer Diagnostische und Interventionelle Neuroradiologie, Homburg/Saar (Germany)

2017-06-15

Magnetic resonance spectroscopy (MRS) is an important non-invasive method that can reveal the concentration and spatial distribution of particular biochemically relevant tissue metabolites. Proton MRS is routinely applicable in the clinical setting providing good quality results even with a moderate magnetic field strength of 1.5 T. Relative values of metabolite concentrations are mostly used for the assessment of metabolic disorders. Absolute quantification of metabolites can be achieved by means of internal or external reference scans. Phosphorous MRS extends the range of detectable molecules to energy and cell membrane metabolism. The lower detection limit of metabolite concentrations is in the range of some mmol/kg. Depending on the magnetic field strength, MRS enables a spatial resolution of a few milliliters. The use of phosphorous MRS is considerably limited because higher field strengths of at least 3.0 T and additional expensive hardware for signal processing are required. (orig.) [German] Die MR-Spektroskopie (MRS) ist eine wichtige nichtinvasive Untersuchungsmethode, die Konzentration und raeumliche Verteilung einiger biochemisch relevanter Metaboliten im Gewebe ermitteln kann. Die Protonenspektroskopie ist klinisch etabliert, in der Routine einfach durchfuehrbar und liefert bereits bei einer Magnetfeldstaerke von 1,5 T qualitativ gute Ergebnisse. Fuer die Beurteilung von Stoffwechselveraenderungen werden Metabolitenkonzentrationen meist als Relativwerte angegeben. Mithilfe interner oder externer Referenzmessungen sind auch absolute Metabolitenkonzentrationen berechenbar. Die Phosphorspektroskopie erweitert den Bereich der detektierbaren Molekuele auf den Energie- und Zellmembranstoffwechsel. Die minimale nachweisbare Metabolitenkonzentration liegt bei einigen mmol/kg. Abhaengig von der Magnetfeldstaerke ist eine raeumliche Aufloesung der MRS von wenigen Millilitern erreichbar. Der Einsatz der Phosphor-MRS wird dadurch erheblich eingeschraenkt, dass sie

Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope

Energy Technology Data Exchange (ETDEWEB)

Engelsen, Daniel den; Harris, Paul G.; Ireland, Terry G., E-mail: terry.ireland@brunel.ac.uk; Fern, George R.; Silver, Jack

2015-10-15

Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated. - Highlights: • Contrast enhancement are observed in secondary electron and cathodoluminescent images of phosphor particles sitting on top of others. • Backscattered electrons largely explain the observed contrast enhancement. • After glow effects in CL-micrographs of phosphors enable the determination of decay times. • Phosphor saturation can be used to determine the decay time of individual spectral transitions.

Rapid formation of red long afterglow phosphor Sr3Al2O6:Eu2+, Dy3+ by microwave irradiation

International Nuclear Information System (INIS)

Zhang Ping; Xu Mingxia; Zheng Zhentai; Sun Bo; Zhang Yanhui

2007-01-01

A new red long afterglow phosphor Sr 3 Al 2 O 6 :Eu 2+ , Dy 3+ nanocrystalline particles were prepared using a microwave oven operated at a frequency of 2.45 GHz and a power of 680 W in a weak reductive atmosphere. The phosphor nanocrystalline particles were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. The results reveal that the samples are composed of single Sr 3 Al 2 O 6 phase. The obtained nanocrystalline particles show small size (80-100 nm) and spherical shape. The excitation and emission spectra indicate that excitation broadband chiefly lies in visible range and the nanocrystalline particles emit strong light at 612 nm under around 473 nm excitation. The effect of Eu 2+ doping concentrations of the samples on the emission intensity is studied systematically. Furthermore, comparing with conventional heating method, the microwave method has the advantages such as short heating time and low energy consumption. However, the decay speed of the afterglow for Sr 3 Al 2 O 6 :Eu 2+ , Dy 3+ nanocrystalline particles is faster than that obtained by the conventional heating method

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.

Critical issues in enhancing brightness in thin film phosphors for flat-panel display applications

International Nuclear Information System (INIS)

Singh, R.K.; Chen, Z.; Kumar, D.; Cho, K.; Ollinger, M.

2002-01-01

Thin film phosphors have potential applications in field emission flat-panel displays. However, they are limited by the lower cathodoluminescent brightness in comparison to phosphor powders. In this paper, we have investigated the critical parameters that need to be optimized to increase the brightness of phosphor thin films. Specifically, we studied the role of surface roughness and optical properties of the substrate on the brightness of the phosphor films. Thin Y 2 O 3 :Eu phosphor films were deposited on various substrates (lanthanum aluminate, quartz, sapphire, and silicon) with thicknesses varying from 50 to 500 nm. A model that accounts for diffuse and specular or scattering effects has been developed to understand the effects of the microstructure on the emission characteristics of the cathodoluminescent films. The results from the model show that both the optical properties of the substrate and the surface roughness of the films play a critical role in controlling the brightness of laser deposited phosphor films

Mechanoluminescence and photoluminescence of Pr3+ activated KMgF3 phosphor

International Nuclear Information System (INIS)

Dhoble, S.J.; Kher, R.S.; Furetta, C.

2003-01-01

A Czochralski method for the preparation of crystalline KMgF 3 : Pr phosphors are reported. Photoluminescence (PL) and mechanoluminescence (ML) characteristics are studied. Photoluminescence of Pr 3+ activated KMgF 3 shows the strong emission of Pr 3+ ions were observed at 498 and 650 nm by excitation of 213 mn. ML of KMgF 3 : Pr 3+ shows two peaks, which have been observed in ML intensity versus time curve. The ML peak shows the recombination of electrons with free radical (anion radical produced by γ-irradiation) released from two type traps during the mechanical pressure applied on KMgF 3 : Pr 3+ phosphor. It has a supra linear ML response with γ-ray exposure and a negligible fading. These properties of phosphor should be suitable in dosimetry of ionization relation using ML technique. Therefore the KMgF 3 : Pr 3+ phosphor proposed for ML dosimetry of ionization radiations. (Author)

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.

Characterization of metallic surfaces in phosphorous-bronze ordered packings

International Nuclear Information System (INIS)

Sandru, Claudia; Titescu, Gh.

1997-01-01

Copper and its alloys, particularly the phosphorous bronze, are characterized by a high water wettability as compared with other materials. This feature led to utilization of phosphorous bronze in fabrication of contact elements, a packing type equipping the distillation columns. For heavy water separation by isotopic distillation under vacuum, ordered packings of phosphorous bronze networks were fabricated. The superior performances of these packings are determined by the material and also by the geometrical form and the state of the metallic surface. Thus, a procedure of evaluating the wettability has been developed, based on tests of the network material. The results of the tests constitute a criterion of rating the functional performances of packings, particularly of their efficiencies. Also, investigation techniques of the chemical composition and of the thickness of superficial layer on the packing were developed. It was found that the packing surface presents a layer of about 5-20 μm formed mainly by oxides of copper, tin, and, depending on the packing treatment, of oxides of other elements coming from the treatment agent. The paper presents characterization of phosphorous bronze treated with potassium permanganate, a specific treatment for improving the functional performances of the packings used in the heavy water concentration and re-concentration installations

Monitoring organo chlorine pesticides in surface and ground water in San Juan (Argentina); Determinacion de pesticiddas organoclorados en aguas superficiales y subterraneas de la provincia de San Juan (Argentina)

Energy Technology Data Exchange (ETDEWEB)

Omar, B.; Suero, E.; Augusto, M.; Gimenez, M.; Flores, N.

2003-07-01

The level of contamination with organo chlorine pesticides and the occurrence of their degradation products in the basins of the two main rivers. San Juan and Jackal, of the Province of San Juan, Argentina, were determined. Surface and groundwater samples from both river basins were evaluated by capillary GC and results confirmed with Mass Spectrometry. Chemicals investigated were 16 organo chlorine pesticides. For a total number of 314 samples, the percentage of positive samples ranged from 68.6% for Heptachlor to 16% for Aldrin. concentration values and the percentage of positive samples in groundwater were significantly lower than those found in surface water. Samples taken in different seasons did not show significant differences. (Author) 18 refs.

Study of some thermoluminescent phosphors for the dosimetry of ionizing radiations

International Nuclear Information System (INIS)

Jaafari, M.

1983-01-01

Thermoluminescence dosimetry techniques are reviewed and interactions radiation matter are recalled. The need for new phosphors is evidenced. Numerous phosphors are examined and calcium, strontium and barium sulfides are synthetized and deposited on glass supports. The thermoluminescence of the dosimeters obtained with these materials is analyzed [fr

Parenting style and conduct problems in children: Case report of deliberate self poisoning in a Nigerian child

Directory of Open Access Journals (Sweden)

M F Tunde-Ayinmode

2011-06-01

Full Text Available The correlation between psychosocially unhealthy parenting styles and child psychopathology has been established. This case report describes how chronic harsh and overbearing paternal parenting style tipped a young boy into deliberate self poisoning with the aid of organo-phosphorous chemicals (rat poison. This report is purposed to increase the interest of physicians and psychiatrists in parenting style research and in how potentially its modification could be a therapeutic and preventive tool.

Ultraviolet dosimetry using thermoluminescent phosphors - an update

International Nuclear Information System (INIS)

Nagpal, J.S.

1998-04-01

Intrinsic response of various thermoluminescent (TL) materials such as CaSO 4 (Dy, Eu, Mn, Sm, Tb, or Tm), LiF (Mg, Cu, P), Mg 2 SiO 4 :Tb, CaF 2 :Dy, CaF 2 :Tb, ThO 2 :Tb and Al 2 O 3 (Si, Ti); cathodoluminescent phosphors Y 3 Al 5 O 12 :Ce, Y 3 Al 5 O 12 :Tb and Y(V,P)O 4 :Eu; and fluorescent lamp phosphors calcium halophosphate (Mn,Sb) and Ce Mg aluminate (Eu, Tb) to ultraviolet (UV) radiations has been studied. Intrinsic TL response of most of the phosphors is rate (radiant flux) dependent. For the first time, UV response of the materials is reported for a fixed total radiant energy (total UV dose), at a single radiant flux (260 μW.cm -2 ), for an appropriate comparison. A wide range of UV sensitivity is observed. Studies conducted using UV radiation from two unfiltered low pressure mercury lamps show significant differences in glow curves, as compared to those obtained with nearly monochromatic UV radiations. Photons of wavelength 365 nm induce bleaching of TL induced by 254 nm photons, in most of the materials. Sequential/tandem exposures to 254 nm and 365 nm photons have yielded new but alarming results in CaF 2 :Tb. Preferential induction and bleaching of specific TL glow peaks by 365 nm and 254 nm photons are interesting characteristics discovered in CaSO 4 :Eu. Photoluminescence studies of Tb 3+ and Eu 3+ activated phosphors have augmented the inferences drawn from the bleaching effects produced by 365 nm photons. Earlier work carried out on phototransferred thermoluminescence of CaSO 4 :Dy-teflon dosimeters, TLD-100, Mg 2 SiO 4 :Tb and Al 2 O 3 (Si,Ti) has also been reviewed. (author)

Oxidation-extraction of uranium from wet-process phosphoric acid

International Nuclear Information System (INIS)

Lawes, B.C.

1985-01-01

The invention involves an improvement to the reductive stripping process for recovering uranium values from wet-process phosphoric acid solution, where uranium in the solution is oxidized to uranium (VI) oxidation state and then extracted from the solution by contact with a water immiscible organic solvent, by adding sufficient oxidant, hydrogen peroxide, to obtain greater than 90 percent conversion of the uranium to the uranium (VI) oxidation state to the phosphoric acid solution and simultaneously extracting the uranium (VI)

Radionuclide concentrations in raw and purified phosphoric acids from Brazil and their processing wastes: implications for radiation exposures.

Science.gov (United States)

da Conceição, Fabiano Tomazini; Antunes, Maria Lúcia Pereira; Durrant, Steven F

2012-02-01

Radionuclides from the U and Th natural series are present in alkaline rocks, which are used as feedstock in Brazil for the production of raw phosphoric acid, which can be considered as a NORM (naturally occurring radioactive material). As a result of the purification of raw phosphoric acid to food-grade phosphoric acid, two by-products are generated, i.e., solid and liquid wastes. Taking this into account, the main aim of this study was to evaluate the fluxes of natural radionuclide in the production of food-grade phosphoric acids in Brazil, to determine the radiological impact caused by ingestion of food-grade phosphoric acid, and to evaluate the solid waste environmental hazards caused by its application in crop soils. Radiological characterization of raw phosphoric acid, food-grade phosphoric acid, solid waste, and liquid waste was performed by alpha and gamma spectrometry. The (238)U, (234)U, (226)Ra, and (232)Th activity concentrations varied depending on the source of raw phosphoric acid. Decreasing radionuclides activity concentrations in raw phosphoric acids used by the producer of the purified phosphoric acid were observed as follows: Tapira (raw phosphoric acid D) > Catalão (raw phosphoric acids B and C) > Cajati (raw phosphoric acid A). The industrial purification process produces a reduction in radionuclide activity concentrations in food-grade phosphoric acid in relation to raw phosphoric acid produced in plant D and single raw phosphoric acid used in recent years. The most common use of food-grade phosphoric acid is in cola soft drinks, with an average consumption in Brazil of 72 l per person per year. Each liter of cola soft drink contains 0.5 ml of food-grade phosphoric acid, which gives an annual average intake of 36 ml of food-grade phosphoric acid per person. Under these conditions, radionuclide intake through consumption of food-grade phosphoric acid per year per person via cola soft drinks is not hazardous to human health in Brazil

Novel Br-DPQ blue light-emitting phosphors for OLED.

Science.gov (United States)

Dahule, H K; Thejokalyani, N; Dhoble, S J

2015-06-01

A new series of blue light-emitting 2,4-diphenylquinoline (DPQ) substituted blue light-emitting organic phosphors namely, 2-(4-methoxy-phenyl)-4-phenyl-quinoline (OMe-DPQ), 2-(4-methyl-phenyl)-4-phenylquinoline (M-DPQ), and 2-(4-bromo-phenyl)-4-phenylquinoline (Br-DPQ) were synthesized by substituting methoxy, methyl and bromine at the 2-para position of DPQ, respectively by Friedländer condensation of 2-aminobenzophenone and corresponding acetophenone. The synthesized phosphors were characterized by different techniques, e.g., Fourier transform infra-red (FTIR), differential scanning calorimeter (DSC), UV-visible absorption and photoluminescence spectra. FTIR spectra confirms the presence of chemical groups such as C=O, NH, or OH in all the three synthesized chromophores. DSC studies show that these complexes have good thermal stability. Although they are low-molecular-weight organic compounds, they have the potential to improve the stability and operating lifetime of a device made out of these complexes. The synthesized polymeric compounds demonstrate a bright emission in the blue region in the wavelength range of 405-450 nm in solid state. Thus the attachment of methyl, methoxy and bromine substituents to the diphenyl quinoline ring in these phosphors results in colour tuning of the phosphorescence. An electroluminescence (EL) cell of Br-DPQ phosphor was made and its EL behaviour was studied. A brightness-voltage characteristics curve of Br-DPQ cell revealed that EL begins at 400 V and then the brightness increases exponentially with applied AC voltage, while current-voltage (I-V) characteristics revealed that the turn on voltage of the fabricated EL cell was 11 V. Hence this phosphor can be used as a promising blue light material for electroluminescent devices. Copyright © 2014 John Wiley & Sons, Ltd.

[The spectrogram characteristics of organic blue-emissive light-emitting excitated YAG : Ce phosphor].

Science.gov (United States)

Xi, Jian-Fei; Zhang, Fang-Hui; Mu, Qiang; Zhang, Mai-Li

2011-09-01

It is demonstrated that the panchromatic luminescence devices with organic blue-emissive light-emitting was fabricated. This technique used down conversion, which was already popular in inorganic power LEDs to obtain white light emission. A blue OLED device with a configuration of ITO/2T-NATA (30 nm)/AND : TBPe (50 Wt%, 40 nm)/Alq3 (100 nm)/LiF(1 nm)/Al(100 nm) was prepared via vacuum deposition process, and then coated with YAG : Ce phosphor layers of different thicknesses to obtain a controllable and uniform shape while the CIE coordinates were fine tuned. This development not only decreased steps of technics and degree of difficulty, but also applied the mature technology of phosphor. The results showed that steady spectrogram was obtained in the devices with phosphor, with a best performance of a maximum luminance of 13 840 cd x m(-2) which was about 2 times of that of the devices without phosphor; a maximum current efficiency of 17.3 cd x A(-1) was increased more two times more than the devices without phosphor. The emission spectrum could be adjusted by varying the concentration and thickness of the phosphor layers. Absoulte spectrogram of devices was in direct proportion with different driving current corresponding.

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)

Determination of the activity concentration of 230Th in phosphoric acids produced in Brazil

International Nuclear Information System (INIS)

Taddei, M.H.T.; Ferreira, M.T.; Fukuma, H.T.; Xavier, T.T.; Sousa, F.V.T.S.

2017-01-01

The high uranium phosphate rock from Itataia, Brazil, was processed using the wet route in the dihydrate system to manufacture phosphoric acid. The uranium contained in phosphoric acid was recovered by the solvent extraction technique. The distribution of the long half-life radionuclides from the decay series of 238 U and 232 Th were evaluated in these processes. The 26 Ra, 228 Ra and 210 Pb radionuclides were found predominantly in phosphogypsum, while the isotopes of 228 Th, 230 Th and 232 Th predominated in phosphoric acid after extracting uranium. The main concern in the commercialization of phosphoric acid that will be produced in the Itataia plant is in relation to the content of 230 Th. This work determined the content of these radionuclides in phosphoric acid from different locations in the country in order to compare

Boron-Containing Red Light-Emitting Phosphors And Light Sources Incorporating The Same

Science.gov (United States)

Srivastava, Alok Mani; Comanzo, Holly Ann; Manivannan, Venkatesan

2006-03-28

A boron-containing phosphor comprises a material having a formula of AD1-xEuxB9O16, wherein A is an element selected from the group consisting of Ba, Sr, Ca, Mg, and combinations thereof; D is at least an element selected from the group consisting of rare-earth metals other than europium; and x is in the range from about 0.005 to about 0.5. The phosphor is used in a blend with other phosphors in a light source for generating visible light with a high color rendering index.

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.

Phosphors containing boron and metals of Group IIIA and IIIB

Science.gov (United States)

Setlur, Anant Achyut; Srivastava, Alok Mani; Comanzo, Holly Ann; Manivannan, Venkatesan

2006-10-31

A phosphor comprises: (a) at least a first metal selected from the group consisting of yttrium and elements of lanthanide series other than europium; (b) at least a second metal selected from the group consisting of aluminum, gallium, indium, and scandium; (c) boron; and (d) europium. The phosphor is used in light source that comprises a UV radiation source to convert UV radiation to visible light.

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.

Transport of phosphoric acid through supported liquid membrane

International Nuclear Information System (INIS)

Zayzafoon, G.; Yassine, T.; Baidoun, R.

2003-01-01

The transport of phosphhoric acid through liquid membranes of amylalkohol, 1-octanol and 2-octanol was studied. It was found that phosphoric acid is transfered from feed side to strip side and the transport increased with the concentration of phosphoric acid up to 5M. The permeability in each membrane was determined for 5M phosphoic acid. It was found that the permeability values are 1.45 x 10 1 0 m 2 s 1 for amylakohol and ∼ 1x10 1 0 m 2 s 1 for each of 1-octanol and 2-octanol

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.

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

Photoluminescence properties of Eu(3+)/ Sm(3+) activated CaZr4(PO4)6 phosphors.

Science.gov (United States)

Nair, Govind B; Dhoble, S J

2016-09-01

Solid state reaction method was employed for the synthesis of a series of CaZr4(PO4)6: Eu(3+)/Sm(3+) phosphors. The red-emitting CaZr4(PO4)6:Eu(3+) phosphors can be efficiently excited at 396 nm and thereby, exhibit a strong red luminescence predominantly corresponding to the electric dipole transition at 615 nm. Under 405 nm excitation, CaZr4(PO4)6:Sm(3+) phosphors display orange emission with color temperatures approximately around 2200 K. The acquired results reveal that CaZr4(PO4)6: RE(3+) (RE = Eu, Sm) phosphors could be potential candidates for red and orange emitting phosphor, respectively, for UV/blue-pump LEDs.

Technology of uranium recovery from wet-process phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Inoue, Katsutoshi [Saga Univ. (Japan). Faculty of Science and Engineering; Nakashio, Fumiyuki

1982-12-01

Rock phosphate contains from 0.005 to 0.02 wt.% of uranium. Though the content is a mere 5 to 10 % of that in uranium ore, the total recovery of uranium is significant since it is used for fertilizer manufacture in a large quantity. Wet-process phosphoric acid is produced by the reaction of rock phosphate with sulfuric acid. The recovery of uranium from this phosphoric acid is mostly by solvent extraction at present. According to U/sup 4 +/ or UO/sub 2//sup 2 +/ as the form of its existence, the technique of solvent extraction differs. The following matters are described: processing of rock phosphate; recovery techniques including the extraction by OPPA-octyl pyrophosphoric acid for U/sup 4 +/, and by mixed DEHPA-Di-(2)-ethylhexyl phosphoric acid and TOPO-tryoctyl phosphine oxide for UO/sub 2//sup 2 +/, and by OPAP-octylphenyl acid phosphate for U/sup 4 +/; the recent progress of the technology as seen in patents.

Instense red phosphors for UV light emitting diode devices.

Science.gov (United States)

Cao, Fa-Bin; Tian, Yan-Wen; Chen, Yong-Jie; Xiao, Lin-Jiu; Liu, Yun-Yi

2010-03-01

Ca(x)Sr1-x-1.5y-0.5zMoO4:yEu3+ zNa+ red phosphors were prepared by solid-state reaction using Na+ as charge supply for LEDs (light emitting diodes). The content of charge compensator, Ca2+ concentration, synthesis temperature, reaction time, and Eu3+ concentration were the keys to improving the properties of luminescence and crystal structure of red phosphors. The photoluminescence spectra shows the red phosphors are effectively excited at 616 nm by 311 nm, 395 nm, and 465 nm light. The wavelengths of 395 and 465 nm nicely match the widely applied emission wavelengths of ultraviolet or blue LED chips. Its chromaticity coordinates (CIE) are calculated to be x = 0.65, y = 0.32. Bright red light can be observed by the naked eye from the LED-based Ca0.60Sr0.25MoO4:0.08Eu3+ 0.06Na+.

Near-infrared dyes and upconverting phosphors as biomolecule labels and probes

Science.gov (United States)

Patonay, Gabor; Strekowski, Lucjan; Nguyen, Diem-Ngoc; Seok, Kim Jun

2007-02-01

Near-Infrared (NIR) absorbing chromophores have been used in analytical and bioanalytical chemistry extensively, including for determination of properties of biomolecules, DNA sequencing, immunoassays, capillary electrophoresis (CE) separations, etc. The major analytical advantages of these dyes are low background interference and high molar absorptivities. NIR dyes have additional advantages due to their sensitivity to microenvironmental changes. Spectral changes induced by the microenvironment are not desirable if the labels are used as a simple reporting group, e.g., during a biorecognition reaction. For these applications upconverting phosphors seem to be a better choice. There are several difficulties in utilizing upconverting phosphors as reporting labels. These are: large physical size, no reactive groups and insolubility in aqueous systems. This presentation will discuss how these difficulties can be overcome for bioanalytical and forensic applications. During these studies we also have investigated how to reduce physical size of the phosphor by simple grinding without losing activity and how to attach reactive moiety to the phosphor to covalently bind to the biomolecule of interest. It has to be emphasized that the described approach is not suitable for medical applications and the results of this research are not applicable in medical applications. For bioanalytical and forensic applications upconverting phosphors used as reporting labels have several advantages. They are excited with lasers that are red shifted respective to phosphorescence, resulting in no light scatter issues during detection. Also some phosphors are excited using eye safe lasers. In addition energy transfer to NIR dyes is possible, allowing detection schemes using donor-acceptor pairs. Data is presented to illustrate the feasibility of this phenomenon. If microenvironmental sensitivity is required, then specially designed NIR dyes can be used as acceptor labels. Several novel dyes

Why do proton conducting polybenzimidazole phosphoric acid membranes perform well in high-temperature PEM fuel cells?

Science.gov (United States)

Melchior, Jan-Patrick; Majer, Günter; Kreuer, Klaus-Dieter

2016-12-21

Transport properties and hydration behavior of phosphoric acid/(benz)imidazole mixtures are investigated by diverse NMR techniques, thermogravimetric analysis (TGA) and conductivity measurements. The monomeric systems can serve as models for phosphoric acid/poly-benzimidazole membranes which are known for their exceptional performance in high temperature PEM fuel cells. 1 H- and 31 P-NMR data show benzimidazole acting as a strong Brønsted base with respect to neat phosphoric acid. Since benzimidazole's nitrogens are fully protonated with a low rate for proton exchange with phosphate species, proton diffusion and conduction processes must take place within the hydrogen bond network of phosphoric acid only. The proton exchange dynamics between phosphate and benzimidazole species pass through the intermediate exchange regime (with respect to NMR line separations) with exchange times being close to typical diffusion times chosen in PFG-NMR diffusion measurements (ms regime). The resulting effects, as described by the Kärger equation, are included into the evaluation of PFG-NMR data for obtaining precise proton diffusion coefficients. The highly reduced proton diffusion coefficient within the phosphoric acid part of the model systems compared to neat phosphoric acid is suggested to be the immediate consequence of proton subtraction from phosphoric acid. This reduces hydrogen bond network frustration (imbalance of the number of proton donors and acceptors) and therefore also the rate of structural proton diffusion, phosphoric acid's acidity and hygroscopicity. Reduced water uptake, shown by TGA, goes along with reduced electroosmotic water drag which is suggested to be the reason for PBI-phosphoric acid membranes performing better in fuel cells than other phosphoric-acid-containing electrolytes with higher protonic conductivity.

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).

UV excited downconversion luminescence properties of Eu3+: NaZnPO4 phosphors

Science.gov (United States)

Mukhopadhyay, Lakshmi; Rai, Vineet Kumar

2018-05-01

The structural and optical properties of Eu3+: NaZnPO4 phosphors prepared by chemical coprecipitation method have been studied. The phase formation and morphology of the phosphors have been confirmed by the X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM) analysis. The downconversion emission spectra upon 392 nm excitation exhibit five emission bands centred at ˜ 575 nm, ˜ 590 nm, ˜ 612 nm, ˜ 660 nm and ˜ 702 nm corresponding to the 5D0→7F0, 5D0→7F1, 5D0→7F2, 5D0→7F3 and 5D0→7F4 transitions of Eu3+ ions respectively. The observed downconversion emission peaks can be explained with the help of suitable energy level diagram. The CIE chromaticity diagram shows the purity of the emitted colour from the prepared phosphors. The present phosphors emit in intense red region which shows the applicability of the phosphors in red light emitting display devices.

Structural optimization for remote white light-emitting diodes with quantum dots and phosphor: packaging sequence matters.

Science.gov (United States)

Xie, Bin; Chen, Wei; Hao, Junjie; Wu, Dan; Yu, Xingjian; Chen, Yanhua; Hu, Run; Wang, Kai; Luo, Xiaobing

2016-12-26

White light-emitting diodes (WLEDs) with quantum dots (QDs) and phosphor have attracted tremendous attentions due to their excellent color rendering ability. In the packaging process, QDs layer and phosphor-silicone layer tend to be separated to reduce the reabsorption losses, and to maintain the stability of QDs surface ligands. This study investigated the packaging sequence between QDs and phosphor on the optical and thermal performances of WLEDs. The output optical power and PL spectra were measured and analyzed, and the temperature fields were simulated and validated experimentally by infrared thermal imager. It was found that when driven by 60 mA, the QDs-on-phosphor type WLEDs achieved luminous efficiency (LE) of 110 lm/W, with color rendering index (CRI) of Ra = 92 and R9 = 80, while the phosphor-on-QDs type WLEDs demonstrated lower LE of 68 lm/W, with Ra = 57 and R9 = 24. Moreover, the QDs-on-phosphor type WLEDs generated less heat than that of another, consequently the highest temperature in the QDs-on-phosphor type was lower than another, and the temperature difference can reach 12.3°C. Therefore, in terms of packaging sequence, the QDs-on-phosphor type is an optimal packaging architecture for higher optical efficiency, better color rendering ability and lower device temperature.

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.

Rare Earth Free Zn3V2O8 Phosphor with Controlled Microstructure and Its Photocatalytic Activity

Directory of Open Access Journals (Sweden)

Hom Nath Luitel

2013-01-01

Full Text Available Microsphere of rare earth free phosphor, Zn3V2O8, with broadband yellowish white emission was synthesized by combustion route and compared with the hydrothermal, sol-gel, and solid state reaction methods. The phosphor samples were characterized by X-ray diffraction and scanning electron microscopy. UV-visible absorption and photoluminescence (PL emission and excitation spectra were investigated for these phosphors. Zn3V2O8 phosphor containing 10 mol% of H3BO3 flux exhibited enhanced PL emission showing broadband from 450 nm to 750 nm. Effect of stoichiometry of Zn and V on the host lattice and its effect on the PL emission spectra were studied. Series of Mg3V2O8, Ca3V2O8, and Sr3V2O8 phosphors were also synthesized and compared to the Zn3V2O8 phosphor in terms of PL emission and internal quantum yield, and it was found that Zn3V2O8 is the most efficient phosphor among the other phosphors studied with quantum yield of 60%. The visible light irradiated photocatalytic activity of these phosphors was investigated and it was found that the hydrothermal Zn3V2O8 exhibited enhanced activity.

Composability in quantum cryptography

International Nuclear Information System (INIS)

Mueller-Quade, Joern; Renner, Renato

2009-01-01

If we combine two secure cryptographic systems, is the resulting system still secure? Answering this question is highly nontrivial and has recently sparked a considerable research effort, in particular, in the area of classical cryptography. A central insight was that the answer to the question is yes, but only within a well-specified composability framework and for carefully chosen security definitions. In this article, we review several aspects of composability in the context of quantum cryptography. The first part is devoted to key distribution. We discuss the security criteria that a quantum key distribution (QKD) protocol must fulfill to allow its safe use within a larger security application (e.g. for secure message transmission); and we demonstrate-by an explicit example-what can go wrong if conventional (non-composable) security definitions are used. Finally, to illustrate the practical use of composability, we show how to generate a continuous key stream by sequentially composing rounds of a QKD protocol. In the second part, we take a more general point of view, which is necessary for the study of cryptographic situations involving, for example, mutually distrustful parties. We explain the universal composability (UC) framework and state the composition theorem that guarantees that secure protocols can securely be composed to larger applications. We focus on the secure composition of quantum protocols into unconditionally secure classical protocols. However, the resulting security definition is so strict that some tasks become impossible without additional security assumptions. Quantum bit commitment is impossible in the UC framework even with mere computational security. Similar problems arise in the quantum bounded storage model and we observe a trade-off between the UC and the use of the weakest possible security assumptions.

Preparation and Characterization of UV Emitting Fluoride Phosphors for Phototherapy Lamps

Science.gov (United States)

Belsare, P. D.; Moharil, S. V.; Joshi, C. P.; Omanwar, S. K.

2011-10-01

The use of ultraviolet radiation for the treatment of various skin diseases is well known for long time. Phototherapy employs ultraviolet-blue radiation to cure skin diseases. The basis of phototherapy is believed to be the direct interaction of light of certain frequencies with tissue to cause a change in immune response. Currently dermatologists use UV lamps having specific emissions in UV region for treating various skin diseases. The treatment of skin diseases using artificial sources of UV radiation is now well established and more than 50 types of skin diseases are treated by phototherapy. This is an effective treatment for many skin disorders, such as psoriasis, vitiligo, ofujis disease, morphea , scleroderma, cutaneous T-cell lymphoma, lupus erythematosus, hyperbilirubinemia commonly known as infant jaundice, acne vulgaris, This paper reports photoluminescence properties of UV emitting fluoride phosphors prepared by wet chemical method. Emission characteristics of these phosphors are found similar to those of commercial UV lamp phosphors with comparable intensities. The usefulness of UV emitting fluoride phosphor is discussed in the paper.

Occurrence and distribution of polycyclic aromatic hydrocarbons in organo-mineral particles of alluvial sandy soil profiles at a petroleum-contaminated site

International Nuclear Information System (INIS)

Lu, Zhe; Zeng, Fangang; Xue, Nandong; Li, Fasheng

2012-01-01

The occurrence and the distribution of 16 USEPA priority pollutants polycyclic aromatic hydrocarbons (PAHs) were investigated in two alluvial sandy soil profiles and in their four sizes of organo-mineral particles ( 200 μm coarse sand) beside a typical oil sludge storage site in eastern China. PAHs were mainly enriched in the surface soil (0–20 cm) and the concentrations declined in deeper soils, from 3.68 to 0.128 μg/g in profile 1 and 10.8 to 0.143 μg/g in profile 2 (dry wt.). The PAHs in the upper soil layers of this study site mainly came from combustion pollution, whereas in the lower soil layers petroleum contamination became the major source of PAHs. The content of different sized organo-mineral particles of this alluvial sandy soil decreased in the following order: fine sand > coarse sand > silt > clay. X-ray diffraction (XRD) results showed that all the different sized soil fractions of this study site were dominated by quartz, calcite and feldspar. The particle surface became smoother with size increasing as shown by scanning electron microscope (SEM) images. PAH concentrations varied largely in different sized soil fractions. The highest PAH concentration was associated with clay and decreased in the order: clay > silt > coarse sand > fine sand. Soil organic matter (SOM) content, mineral composition and particle surface characteristics were suggested as three main factors affecting the distribution of PAHs in different sized organo-mineral particles. This study will help to understand the distribution and transport characteristics of PAHs in soil profiles at petroleum-contaminated sites. -- Highlights: ► PAH concentrations varied largely in different sized fractions. ► The highest PAH concentrations were associated with clay and decreased in the order: clay > silt > coarse sand > fine sand. ► Soil organic matter (SOM) is an important factor to dominate the distribution of PAHs in this study site.

Occurrence and distribution of polycyclic aromatic hydrocarbons in organo-mineral particles of alluvial sandy soil profiles at a petroleum-contaminated site

Energy Technology Data Exchange (ETDEWEB)

Lu, Zhe [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Anwai, Dayangfang 8, Beijing 100012 (China); Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2 (Canada); School of Environment, Renmin University of China, Zhongguancun Street 59, Beijing 100872 (China); Zeng, Fangang [School of Environment, Renmin University of China, Zhongguancun Street 59, Beijing 100872 (China); Xue, Nandong [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Anwai, Dayangfang 8, Beijing 100012 (China); Li, Fasheng, E-mail: ligulax@vip.sina.com [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Anwai, Dayangfang 8, Beijing 100012 (China)

2012-09-01

The occurrence and the distribution of 16 USEPA priority pollutants polycyclic aromatic hydrocarbons (PAHs) were investigated in two alluvial sandy soil profiles and in their four sizes of organo-mineral particles (< 2 {mu}m clay, 2-20 {mu}m silt, 20-200 {mu}m fine sand, and > 200 {mu}m coarse sand) beside a typical oil sludge storage site in eastern China. PAHs were mainly enriched in the surface soil (0-20 cm) and the concentrations declined in deeper soils, from 3.68 to 0.128 {mu}g/g in profile 1 and 10.8 to 0.143 {mu}g/g in profile 2 (dry wt.). The PAHs in the upper soil layers of this study site mainly came from combustion pollution, whereas in the lower soil layers petroleum contamination became the major source of PAHs. The content of different sized organo-mineral particles of this alluvial sandy soil decreased in the following order: fine sand > coarse sand > silt > clay. X-ray diffraction (XRD) results showed that all the different sized soil fractions of this study site were dominated by quartz, calcite and feldspar. The particle surface became smoother with size increasing as shown by scanning electron microscope (SEM) images. PAH concentrations varied largely in different sized soil fractions. The highest PAH concentration was associated with clay and decreased in the order: clay > silt > coarse sand > fine sand. Soil organic matter (SOM) content, mineral composition and particle surface characteristics were suggested as three main factors affecting the distribution of PAHs in different sized organo-mineral particles. This study will help to understand the distribution and transport characteristics of PAHs in soil profiles at petroleum-contaminated sites. -- Highlights: Black-Right-Pointing-Pointer PAH concentrations varied largely in different sized fractions. Black-Right-Pointing-Pointer The highest PAH concentrations were associated with clay and decreased in the order: clay > silt > coarse sand > fine sand. Black-Right-Pointing-Pointer Soil organic

Rare earth elements recycling from waste phosphor by dual hydrochloric acid dissolution

International Nuclear Information System (INIS)

Liu, Hu; Zhang, Shengen; Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin; Volinsky, Alex A.

2014-01-01

Highlights: • The article provides a new method for recycling rare earth (RE) from waste phosphor. • When compared with the traditional methods, leach rate was much higher. • Y–Eu concentrate and Tb–Ce concentrate were obtained successively. • It would reduce the burden of later extraction, separation and purification. - Abstract: This paper is a comparative study of recycling rare earth elements from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare earth phosphor (Y 0.95 Eu 0.05 ) 2 O 3 in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce 0.67 Tb 0.33 MgAl 11 O 19 ) and the Blue phosphor (Ba 0.9 Eu 0.1 MgAl 10 O 17 ) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO 2 are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications

Process engineering challenges of uranium extraction from phosphoric acid on industrial scale

International Nuclear Information System (INIS)

Mouriya, Govind; Singh, Dhirendra; Nath, A.K.; Majumdar, D.

2014-01-01

Heavy Water Board (HWB) is a constituent unit of the Department of Atomic Energy. One of the diversified activities undertaken by HWB is pursuing exploitation of non-conventional resources for recovery of uranium from wet phosphoric acid being the most prominent one. Amongst the feasible processes for recovery of uranium from phosphoric acid is solvent extraction. Use of in-house solvent produced by HWB, is another key driver. To garner necessary information for developing the industrial scale facilities, the process has been studied in the laboratory scale, mini scale, bench scale at Heavy Water Plant, Talcher. The process was subsequently scaled up to an industrial prototype scale unit and was set up as a Technology Demonstration Plant coupled with a commercial phosphoric acid plant. The plant has successfully processed more than 2 lakh m 3 of wet phosphoric acid and all the parameters including the product, Yellow Cake have been qualified. No adverse effect has been observed in the fertilizer produced. The main characteristics of the process and subsequent process innovations are discussed in this paper. These innovations have been carried out to overcome hurdles faced during commissioning and subsequent operations of the Plant. The innovations include improved pretreatment of the wet phosphoric acid for feeding to the extraction cycle, improved control of the first cycle chemical environment, reducing the strength of the phosphoric acid used for stripping, reducing the number of equipment and machineries, alteration in solvent composition used in the first and second cycle in the solvent extraction units of the plant. (author)

Study of phase transformation processes in steel after phosphor ion implantation and following thermal treatment

International Nuclear Information System (INIS)

Zhetbaev, A.K.; Vereshchak, N.F.; Satpaev, K.K.; Dosmagambetov, T.D.; Serikbaeva, Z.T.

1999-01-01

In the paper process of phase transformation after phosphor ion implantation in steel-45 and annealing in vacuum at 1000 deg C and irradiation by various doses of phosphor ions with energy 100 keV an accelerator are researched by conversion electron method. The phosphor overall solubility in iron is equal 4.53 %. Implantation dose below 6·10 17 ions/cm 2 allows increase phosphor ions content in implantation region to 35 %. Therefore, iron phosphides (Fe 3 P, Fe 2 P and Fe P) forming are possible. (author)

Synthesis and complex forming property of phosphor acid derivatives

International Nuclear Information System (INIS)

Babaev, B.N.

2004-01-01

Full text:With the aim to get new effective and selective extra gents of noble and non-ferrous metals from acid solution and industrial sewage, research of the dependence of 'structure effectiveness' the various phosphor acid derivatives with logical changeable structure (thio phosphor acids, derivatives of dialkoxythiophosphor, O-alkyl-methylphosphon, alkylphenylphosphon, diphenylphosphine acids also 4 methyl-1,3,2 dioxaphosphorinane) which contain different functional groups, the remains of heterocyclic amines and alkaloids, new derivatives of some analytical reagents were synthesized. The structure of synthesized compounds is approved by the results of IR-, PMR-, mass-spectrum analyze. Researching mass-spectrum decay of synthesized phosphor acid derivatives we defined that differing from O-dihexyl-S-propargyl-benzylthio phosphat, mass spectrum decay of O-dialkyl-S-(piperdynobutin-2-il)thio phosphat is characterized by the appearing [M-H] + ions and during the decay ions with high intensiveness are formed. Fragmentation of M + O-alkyl-O-(aminoalkyl)phenylphosphonate proceeds in various directions and characterized with the great number of phosphor containing ions, the possession of the second phenyl radical in the molecule of diphenylphosphon acid derivatives changes the fragmentation of molecular ion of diphenylphosphon acid derivatives. The process of extraction of noble (Au, Ag, Pt, Pd, Os) metals from hydrochloric-sulphur-nitrogen acid medium was analyzed by radioactive indicator's method. It was noticed that structure, strength, conformation of compounds, the temperature, of acid medium (0,1-10 M) and the nature of acids (HCL, H 2 SO 4 , HNO 3 ) could have strong influence to the effectiveness of metal extraction. During the research of metals extraction from pure solutions we can see the followings: 1) There are such substances, which can be used as effective group reagent towards the Au, Ag and Pd. 2) Derivatives with acetylene extract ions of gold from

Influence of dome phosphor particle concentration on mid-power LED thermal resistance

NARCIS (Netherlands)

Alexeev, A.; Martin, G.; Hildenbrand, V.D.; Bosschaart, K.J.

2016-01-01

The modern white mid-power LEDs usually contain phosphor particles encapsulated in silicone dome material. The particles convert the blue light emitted from the epitaxial layer and play significant role in thermal processes of LED packages. In this paper the influence of the phosphor particles

Alternative magnesium source for phosphorous recovery – a feasibility and economic analysis

DEFF Research Database (Denmark)

Quist-Jensen, Cejna Anna; Jørgensen, Mads Koustrup; Christensen, Morten Lykkegaard

Conventional reservoirs of phosphorous are in high risk of depletion in near future, thus nontraditional and sustainable recovery-practices are essential to ensure its adequate supply in future. Today phosphorous is being recovered from wastewater at industrial scale by addition of MgCl2. However...

A neutral-beam profile monitor with a phosphor screen and a high-sensitivity camera for the J-PARC KOTO experiment

Science.gov (United States)

Matsumura, T.; Kamiji, I.; Nakagiri, K.; Nanjo, H.; Nomura, T.; Sasao, N.; Shinkawa, T.; Shiomi, K.

2018-03-01

We have developed a beam-profile monitor (BPM) system to align the collimators for the neutral beam-line at the Hadron Experimental Facility of J-PARC. The system is composed of a phosphor screen and a CCD camera coupled to an image intensifier mounted on a remote control X- Y stage. The design and detailed performance studies of the BPM are presented. The monitor has a spatial resolution of better than 0.6 mm and a deviation from linearity of less than 1%. These results indicate that the BPM system meets the requirements to define collimator-edge positions for the beam-line tuning. Confirmation using the neutral beam for the KOTO experiment is also presented.

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 ...

Anodic luminescence, structural, photoluminescent, and photocatalytic properties of anodic oxide films grown on niobium in phosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Stojadinović, Stevan, E-mail: sstevan@ff.bg.ac.rs [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Tadić, Nenad [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Radić, Nenad [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Stefanov, Plamen [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, 1113 Sofia (Bulgaria); Grbić, Boško [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Vasilić, Rastko [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia)

2015-11-15

Graphical abstract: - Highlights: • Anodic luminescence is correlated to the existence of morphological defects in the oxide. • Spectrum under spark discharging reveals only oxygen and hydrogen lines. • Oxide films formed under spark discharging are crystallized and composed of Nb{sub 2}O{sub 5}. • Photocatalytic activity and photoluminescence of Nb{sub 2}O{sub 5} films increase with time. - Abstract: This article reports on properties of oxide films obtained by anodization of niobium in phosphoric acid before and after the dielectric breakdown. Weak anodic luminescence of barrier oxide films formed during the anodization of niobium is correlated to the existence of morphological defects in the oxide layer. Small sized sparks generated by dielectric breakdown of formed oxide film cause rapid increase of luminescence intensity. The luminescence spectrum of obtained films on niobium under spark discharging is composed of continuum radiation and spectral lines caused by electronic spark discharging transitions in oxygen and hydrogen atoms. Oxide films formed before the breakdown are amorphous, while after the breakdown oxide films are partly crystalline and mainly composed of Nb{sub 2}O{sub 5} hexagonal phase. The photocatalytic activity of obtained oxide films after the breakdown was investigated by monitoring the degradation of methyl orange. Increase of the photocatalytic activity with time is related to an increase of oxygen vacancy defects in oxide films formed during the process. Also, higher concentration of oxygen vacancy defects in oxide films results in higher photoluminescence intensity.

Preparation of polymer-organo clay nano composites through the spray drying process

International Nuclear Information System (INIS)

Bernardo, Paulo R.A.; Pessan, Luiz A.; Carvalho, Antonio J.F. de; Vidotti, Suel E.

2011-01-01

The objective of the work was the study and preparation of polymer nano composites with montmorillonite organo clays (MMT) through the spray drying process. A new technique was proposed and tested to obtaining polymer nano composites, based on the use of the spray drying process to produce a nano composite with high clay content. The process consisted of the following stages: clay intercalation in water solution, with after addition of polyvinyl alcohol (PVOH) and a hydro soluble polyester ionomer (GEROLPS20) as exfoliation agents; spray drying the mixture obtained; incorporation powder in EVOH, PET e PP matrix. The effects of exfoliation agent on morphological and thermal properties of the nano composites were studied by XRD, transmission electron microscopy (TEM) and TGA. The results demonstrate that the process of spray drying is an innovative way to obtain a nano composite with high clay content. (author)

Fate and behavior of an organo-borate in the soil-plant system

International Nuclear Information System (INIS)

Adriano, D.C.; Mills, G.L.; Afre, J.L.; Hart, R.J.

1984-01-01

An organo-borate, sodium tetraphenylboron (NaTPB), is used to precipitate radiocesium in high level nuclear wastes in conjunction with the 'glassification' of these wastes for long-term storage. Because of the possibility of this compound interacting with the environment through land application of the waste supernate or ground burial of the waste 'saltblocks', studies were undertaken to evaluate the environmental chemistry of this compound. Results indicate that the parent compound, NaTPB, is unstable in the soil-plant system, yielding two primary degradation products, biphenyl and diphenylborinic acid. Plant growth and B uptake data further indicate that the growth of plants was more deleteriously affected by NaTPB soil treatment than by comparable soil treatment with boric acid, in spite of the much greater uptake of B from boric acid. This can be attributed to the hypothesized aggravating effect of biphenyl on plant growth. (author)

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)

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

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 .

Stacking dependence of carrier transport properties in multilayered black phosphorous

Science.gov (United States)

Sengupta, A.; Audiffred, M.; Heine, T.; Niehaus, T. A.

2016-02-01

We present the effect of different stacking orders on carrier transport properties of multi-layer black phosphorous. We consider three different stacking orders AAA, ABA and ACA, with increasing number of layers (from 2 to 6 layers). We employ a hierarchical approach in density functional theory (DFT), with structural simulations performed with generalized gradient approximation (GGA) and the bandstructure, carrier effective masses and optical properties evaluated with the meta-generalized gradient approximation (MGGA). The carrier transmission in the various black phosphorous sheets was carried out with the non-equilibrium green’s function (NEGF) approach. The results show that ACA stacking has the highest electron and hole transmission probabilities. The results show tunability for a wide range of band-gaps, carrier effective masses and transmission with a great promise for lattice engineering (stacking order and layers) in black phosphorous.

Characterization of novel powder and thin film RGB phosphors for field emissions display application

International Nuclear Information System (INIS)

Chakhovskoi, A.G.; Hunt, C.E.

1996-01-01

The spectral response, brightness and outgassing characteristics of new, low-voltage phosphors for application in field-emission flat-panel displays, are presented. The tested phosphor materials include combustion synthesized powders and thin films prepared by RF-diode or magnetron sputtering, laser ablation and molecular beam epitaxy. These cathodoluminescent materials are tested with e-beam excitation at currents up to 50 μA within the 200-2000V (e.g. open-quotes low-voltageclose quotes) and 3-8 kV (e.g. open-quotes medium voltageclose quotes) ranges. The spectral coordinates are compared to commercial low-voltage P22 phosphors. Phosphor outgassing, as a function of time is measured with a residual gas analyzer at fixed 50 μA beam current in the low-voltage range. We find that levels of outgassing stabilize to low values after the first few hours of excitation. The desorption rates measured for powder phosphor layers with different thickness are compared to desorption from thin films

Preliminary study on preparation of BCNO phosphor particles using citric acid as carbon source

Energy Technology Data Exchange (ETDEWEB)

Nuryadin, Bebeh W.; Pratiwi, Tripuspita; Faryuni, Irfana D.; Iskandar, Ferry, E-mail: ferry@fi.itb.ac.id; Abdullah, Mikrajuddin; Khairurrijal [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Ganesha 10 Bandung, Indonesia 40132 (Indonesia); Ogi, Takashi; Okuyama, Kikuo [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, Japan 739-8527 (Japan)

2015-04-16

A citric acid was used as a carbon source in the preparation of boron carbon oxy-nitride (BCNO) phosphor particles by a facile process. The preparation process was conducted at relatively low temperature 750 °C and at ambient pressure. The prepared BCNO phosphors showed a high photoluminescence (PL) performance at peak emission wavelength of 470 nm under excitation by a UV light 365 nm. The effects of carbon/boron and nitrogen/boron molar ratios on the PL properties were also investigated. The result showed that the emission spectra with a wavelength peak ranging from 444 nm to 496 nm can be obtained by varying carbon/boron ratios from 0.1 to 0.9. In addition, the observations showed that the BCNO phosphor material has two excitation peaks located at the 365 nm (UV) and 420 nm (blue). Based on these observations, we believe that the citric acid derived BCNO phosphor particles can be a promising inexpensive material for phosphor conversion-based white LED.

Combustion synthesis of red emitting borate host PDP phosphor YCaBO4: Eu3+

International Nuclear Information System (INIS)

Ingle, J.T.; Hargunani, S.P.; Sonekar, R.P.; Nagpure, P.A.; Omanwar, S.K.; Moharil, S.V.

2012-01-01

The red emitting borate host phosphor YCaBO 4 : Eu 3+ has been prepared by a novel solution combustion technique. The synthesis is based on the exothermic reaction between the fuel (Urea) and Oxidizer (Ammonium nitrate). The photoluminescence properties of the powder samples of YCaBO 4 : Eu 3+ has been investigated under UV and VUV excitation. The phosphor shows strong absorption in UV and VUV region and exhibits intense red emission upon excited by 254 nm UV and 173 nm VUV radiation. Under UV 254 nm excitation, YCaBO 4 : Eu 3+ exhibits intense red emission around 610 nm. Under VUV excitation of 173 nm, the phosphor emits intense red emission around 610 nm and few weak emissions. These weak emissions could be suppressed by annealing the sample repeatedly at proper temperature and the borate phosphor YCaBO 4 : Eu 3+ could be a good red emitting phosphor for PDP display and mercury free lamps. (author)

TBP degradation products. Separation and gas-chromatographic determination

International Nuclear Information System (INIS)

Kuada, T.A.; Alem, C.M.; Matsuda, H.T.; Araujo, B.F. de; Araujo, J.A de.

1991-11-01

A separation method for di butylphosphate, mono butylphosphate and phosphoric acid as degradation products in organic and aqueous streams of the process containing variable amounts of actinides and fission products is described. The products were separated by extraction and after methylation the final determination was carried out by gas chromatography. TPP was used as internal standard and 5 to 500 mg/L concentration range was determined with 1 to 10% deviation depending on the concentration of organo phosphates. (author)

[A novel ship-borne positive pressure solid phase extraction device to enrich organo chlorinated and pyrethroid pesticides in seawater].

Science.gov (United States)

Ye, Jianglei

2017-09-08

A novel solid phase extraction (SPE) device driven by positive pressure was developed instead of negative pressure from a vacuum pump, in order to enrich organo chlorinated and pyrethroid pesticides in seawater. The water sampling bottles and the pipelines which touch water samples were made of plastic material without chlorine. In order to ensure the sealing and firmness, the whole device were tightened with nut and bolt. The inner pressure (0.1-0.3 MPa) in the water sampling bottle was provided by the small air pump (powered by 12 V cell) controlled by a microprogrammed control unit (MCU) and pressure sensor to keep the water flow rate (4.0-6.0 mL/min). The pre-conditioned SPE column can be used for the enrichment of pesticides within four weeks, and the loaded SPE column can be eluted for detection within six weeks with recoveries greater than 80%. The linearity of the method was good with the correlation coefficient more than 0.9. The limits of quantification (LOQs) were 0.8-6 ng/L. The recoveries of the pesticides at three spiked levels (3 parallel samples) were 86.1%-95.5% with the relative standard deviations less than 10%. The benzene hexachlorides (BHCs) and dichloro-diphenyl-trichloroethanes (DDTs) were detected in seawater samples. The device has good application in enriching organo chlorinated and pyrethroid pesticides in seawater.

Cadmium elemination from phosphoric acid by ionic flotation

International Nuclear Information System (INIS)

Brikci-Nigassa, Mounir; Hamouche, Hafida

1995-11-01

The ion flotation process for the recovery of cadmium from wet phosphoric acid (30%P2O5) has been studied. This technique combines a chemical recation between the collector and the cadmium to form a precipitate (sublate) which is carried to the surface of the solution by air bubbles. the resulting foam containing the cadmium may then separated from solution. The influence of parameters such as collector and cadmium concentration as well as iron content have been investigated for the case a synthetic acid (30% P2O5). The result have been applied to the industrial phosphoric acid produced from Djebel Onk's phosphates (Algeria)

The chemistry of artificial lighting devices lamps, phosphors and cathode ray tubes

CERN Document Server

Ropp, Richard C

2013-01-01

Both the early use of artificial lighting and current manufacturing methods concerning incandescent and fluorescent lamps are covered in this book. The protocols for manufacture of fluorescent lamp phosphors and those used in cathode ray tubes are also treated in some detail. This text surveys the amazing, vast array of artificial lighting devices known to date in terms of how they arose and are, or have been used by mankind. A complete description of the formulations and methodology for manufacturing all known phosphors is given. The book will serve as a repository of such phosphor manufacturing methods, including that of cathode ray tube phosphors. Methods of manufacture of lamp parts are also presented, including that of tungsten wire. The original approaches used are described as well as improvements in technology. These will serve as comparative methods for present day manufacture of these components. A history of the lamp industry is presented. Several methods are given which may serve as a source for f...

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.

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.

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.

Flotation of uranium values using di (2-ethyl hexyl) phosphoric acid

International Nuclear Information System (INIS)

Singh, Ajoy Kumar; Padmanabhan, N.P.H.; Sridhar, U.; Krishna Rao, N.

1998-01-01

The use of solvent extractants for mineral flotation, especially for difficult-to-float minerals, is gaining importance as they are highly selective to specific metal ions and form strong and stable complexes mostly by chelation. Studies carried out with di(2 ethyl hexyl) phosphoric acid (D2EHPA) (an organic solvent used in the extraction of uranium from phosphoric acid) as collector for flotation of uranium minerals from ore samples of Domiasiat, Meghalaya and Jaduguda, Bihar have yielded encouraging results. Although flotation of uranium minerals using other solvent extractants like tributyl phosphoric acid (TBP) has been studied, the uraninite-D2EHPA system has not been tested so far. This technical note puts on record the findings of the preliminary studies carried out. (author)

On the corrosion behaviour of phosphoric irons in simulated concrete pore solution

International Nuclear Information System (INIS)

Sahoo, Gadadhar; Balasubramaniam, R.

2008-01-01

The corrosion behaviour of three phosphoric irons P 1 (Fe-0.11P-0.028C), P 2 (Fe-0.32P-0.026C) and P 3 (Fe-0.49P-0.022C) has been studied in simulated concrete pore solution (saturated Ca(OH) 2 solution) containing different chloride concentration. This has been compared with that of two commercial concrete reinforcement steels, a low carbon steel TN (Fe-0.148C-0.542Mn-0.128Si) and a microalloyed corrosion resistant steel CS (Fe-0.151C-0.088P-0.197Si-0.149Cr-0.417Cu). The beneficial aspect of phosphoric irons was revealed from potentiodynamic polarization experiments. The pitting potentials and pitting nucleation resistances for phosphoric irons and CS were higher than that for TN. Electrochemical impedance spectroscopy (EIS) studies revealed thickening and growth of passive film as a function of time in case of phosphoric irons and CS in saturated Ca(OH) 2 pore solutions without chloride and in the same solution with 0.05% Cl - and 0.1% Cl - . In case of TN, breakdown of passive film resulted in active corrosion in simulated pore solution containing 0.1% Cl - . Linear polarization resistance measurements complemented EIS results. Visual observations indicated that phosphoric iron P 3 was immune to corrosion even after 125 days of immersion in saturated Ca(OH) 2 solution containing 5% NaCl. The good corrosion resistance of phosphoric irons in simulated concrete pore solution containing chloride ions has been related to the formation of phosphate, based on ultraviolet spectrophotometric analysis and Pourbaix diagram of phosphorus-water system

Rare earth elements recycling from waste phosphor by dual hydrochloric acid dissolution

Energy Technology Data Exchange (ETDEWEB)

Liu, Hu [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Shengen, E-mail: zhangshengen@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Pan, Dean; Tian, Jianjun; Yang, Min; Wu, Maolin [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Volinsky, Alex A. [Department of Mechanical Engineering, University of South Florida, Tampa, FL 33620 (United States)

2014-05-01

Highlights: • The article provides a new method for recycling rare earth (RE) from waste phosphor. • When compared with the traditional methods, leach rate was much higher. • Y–Eu concentrate and Tb–Ce concentrate were obtained successively. • It would reduce the burden of later extraction, separation and purification. - Abstract: This paper is a comparative study of recycling rare earth elements from waste phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red rare earth phosphor (Y{sub 0.95}Eu{sub 0.05}){sub 2}O{sub 3} in waste phosphor is dissolved during the first step of acid leaching, while the Green phosphor (Ce{sub 0.67}Tb{sub 0.33}MgAl{sub 11}O{sub 19}) and the Blue phosphor (Ba{sub 0.9}Eu{sub 0.1}MgAl{sub 10}O{sub 17}) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO{sub 2} are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the rare earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications.

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.

Mechano-luminescence studies of nano ZnMgAl10O17:Eu phosphor under UV irradiation

Science.gov (United States)

Verma, Akshkumar; Verma, Ashish; Panda, Maheswar

2018-05-01

ZnMgAl10O17:Eu nano phosphors were prepared successfully, using the combustion route by employing urea as a fuel. The structural, and Morphological, properties were measured using x-ray diffraction (XRD) Scanning electron microscopy (SEM) transition electron microscopy. The BET surface area of sample were found to be of ˜13.92 m2/g. The ML (Mechano-luminescence) were measured to the home made instrument. The phosphor showed more strong and high ML intensity to the without UV irradiated material. Therefore ZnMgAl10O17:Eu2+ phosphor may use as a damage sensor and dosimetry material. The ML emission spectra of the Zn0.99MgAl10O17:Eu0.01 phosphor showed the characteristic Eu2+ emission peaks ˜453nm (blue) originating from the transitions 4f65d1→4f7, Therefore ZnMgAl10O17:Eu2+ phosphor may use as a blue phosphor material.

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.)

Recovery of uranium in the production of concentrated phosphoric acid by a hemihydrate process

International Nuclear Information System (INIS)

Nakajima, S.; Miyamoto, M.

1983-01-01

Nissan Chemical Industries as manufacturers of phosphoric acid have studied the recovery of uranium, based on a concentrated phosphoric acid production process. The process consists of two stages, a hemihydrate stage with a formation of hemihydrate and a filtration section, followed by a dihydrate stage with hydration and a filtration section. In the hemihydrate stage, phosphate is treated with a mixture of phosphoric acid and sulphuric acid to produce phosphoric acid and hydrous calcium sulphate; the product is recovered in the filtration section and its concentration is 40-50% P 2 O 3 . In the dihydrate stage, the hemihydrate is transformed by re-dissolution and hydration, producing hydrous calcium sulphate, i.e. gypsum. This process therefore comprises two parts, each with different acid concentrations. As the extraction of uranium is easier in the case of a low concentration of phosphoric acid, the process consists of the recovery of uranium starting from the filtrate of the hydration section. The tests have shown that the yield of recovery of uranium was of the order of 80% disregarding the handling losses and no disadvantageous effect has been found in the combination of the process of uranium extraction with the process of concentrated phosphoric acid production. Compared with the classical process where uranium is recovered from acid with 30% P 2 O 5 , the process of producing high-concentration phosphoric acid such as the Nissan process, in which the uranium recovery is effected from acid with 15% P 2 O 5 from the hydration section, presents many advantages [fr

Thermoluminescent dosimetry of new phosphors of Zn O exposed to beta radiation

International Nuclear Information System (INIS)

Cruz V, C.; Burruel I, S.E.; Grijalva M, H.; Barboza F, M.; Bernal, R.

2004-01-01

In this work, we report the thermoluminescence dosimetry of a new Zn O phosphor obtained by annealing of Zn S powder precipitated when Zn S films were grown by employing a CBD method. The collected Zn S powder was pressed in a die to form pellets which were subjected to different thermal treatments under air atmosphere. X-ray diffraction (XRD) patterns and energy-dispersive X-ray Spectrometry (EDS) analyses confirmed the transformation of Zn S to Zn O. The phosphors thus obtained were exposed to high doses of beta radiation and their thermoluminescent dosimetry show that these new phosphors are materials suitable to be used in high dose thermoluminescence dosimetry. (Author)

Combination of carbon dot and polymer dot phosphors for white light-emitting diodes.

Science.gov (United States)

Sun, Chun; Zhang, Yu; Sun, Kai; Reckmeier, Claas; Zhang, Tieqiang; Zhang, XiaoYu; Zhao, Jun; Wu, Changfeng; Yu, William W; Rogach, Andrey L

2015-07-28

We realized white light-emitting diodes with high color rendering index (85-96) and widely variable color temperatures (2805-7786 K) by combining three phosphors based on carbon dots and polymer dots, whose solid-state photoluminescence self-quenching was efficiently suppressed within a polyvinyl pyrrolidone matrix. All three phosphors exhibited dominant absorption in the UV spectral region, which ensured the weak reabsorption and no energy transfer crosstalk. The WLEDs showed excellent color stability against the increasing current because of the similar response of the tricolor phosphors to the UV light variation.

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.

Composing the Curriculum: Teacher Identity

Science.gov (United States)

Lewis, Rebecca

2012-01-01

What is composing and how is it valued? What does a good education in composing look like; what constraints hinder it and is it possible to overcome such constraints? Can composing be a personal, creative and valuable activity for the school student? What role does the teacher play in all of this? These are questions that I discuss in this…

Phosphors for solid-state lighting: New systems, deeper understanding

Science.gov (United States)

Denault, Kristin Ashley

We explore the structure-composition-property relationships in phosphor materials using a multitude of structural and optical characterization methods including high resolution synchrotron X-ray and neutron powder diffraction and total scattering, low-temperature heat capacity, temperature- and time-resolved photoluminescence, and density functional theory calculations. We describe the development of several new phosphor compositions and provide an in-depth description of the structural and optical properties. We show structural origins of improved thermal performance of photoluminescence and methods for determining structural rigidity in phosphor hosts that may lead to improved luminescent properties. New white light generation strategies are also explored. We begin by presenting the development of a green-yellow emitting oxyfluoride solid-solution phosphor Sr2Ba(AlO4F)1- x(SiO5)x:Ce3+. An examination of the host lattice, and the local structure around the Ce3+ activator ions points to how chemical substitutions play a crucial role in tuning the optical properties of the phosphor. The emission wavelength can be tuned from green to yellow by tuning the composition, x. Photoluminescent quantum yield is determined to be 70+/-5% for some of the examples in the series with excellent thermal properties. Phosphor-converted LED devices are fabricated using an InGaN LED and are shown to exhibit high color rendering white light. Next, we identify two new phosphor solid-solution systems, (Ba1- xSrx)9 Sc2Si6O24:Ce3+,Li+ and Ba9(Y1-ySc y)2Si6O24:Ce3+. The substitution of Sr for Ba in (Ba1-xSrx ) 9Sc2Si6O24:Ce 3+,Li + results in a decrease of the alkaline earth-oxygen bond distances at all three crystallographic sites, leading to changes in optical properties. The room temperature photoluminescent measurements show the structure has three excitation peaks corresponding to Ce3+ occupying the three independent alkaline earth sites. The emission of (Ba 1- xSrx) 9Sc2Si 6O24:Ce3

Process for recovery of uranium from wet process phosphoric acid

International Nuclear Information System (INIS)

Wiewiorowski, T.K.; Thornsberry, W.L. Jr.

1978-01-01

Process is claimed for the recovery of uranium from wet process phosphoric acid solution in which an organic extractant, containing uranium values and dissolved iron impurities and comprising a dialkylphosphoric acid and a trialkylphosphine oxide dissolved in a water immiscible organic solvent, is contacted with a substantially iron-free dilute aqueous phosphoric acid to remove said iron impurities. The removed impurities are bled from the system by feeding the resulting iron-loaded phosphoric acid to a secondary countercurrent uranium extraction operation from which they leave as part of the uranium-depleted acid raffinate. Also, process for recovering uranium in which the extractant, after it has been stripped of uranium values by aqueous ammonium carbonate, is contacted with a dilute aqueous acid selected from the group consisting of H 2 SO 4 , HCl, HNO 3 and iron-free H 3 PO 4 to improve the extraction efficiency of the organic extractant

Modeling Phosphorous Losses from Seasonal Manure Application Schemes

Science.gov (United States)

Menzies, E.; Walter, M. T.

2015-12-01

Excess nutrient loading, especially nitrogen and phosphorus, to surface waters is a common and significant problem throughout the United States. While pollution remediation efforts are continuously improving, the most effective treatment remains to limit the source. Appropriate timing of fertilizer application to reduce nutrient losses is currently a hotly debated topic in the Northeastern United States; winter spreading of manure is under special scrutiny. We plan to evaluate the loss of phosphorous to surface waters from agricultural systems under varying seasonal fertilization schemes in an effort to determine the impacts of fertilizers applied throughout the year. The Cayuga Lake basin, located in the Finger Lakes region of New York State, is a watershed dominated by agriculture where a wide array of land management strategies can be found. The evaluation will be conducted on the Fall Creek Watershed, a large sub basin in the Cayuga Lake Watershed. The Fall Creek Watershed covers approximately 33,000 ha in central New York State with approximately 50% of this land being used for agriculture. We plan to use the Soil and Water Assessment Tool (SWAT) to model a number of seasonal fertilization regimes such as summer only spreading and year round spreading (including winter applications), as well as others. We will use the model to quantify the phosphorous load to surface waters from these different fertilization schemes and determine the impacts of manure applied at different times throughout the year. More detailed knowledge about how seasonal fertilization schemes impact phosphorous losses will provide more information to stakeholders concerning the impacts of agriculture on surface water quality. Our results will help farmers and extensionists make more informed decisions about appropriate timing of manure application for reduced phosphorous losses and surface water degradation as well as aid law makers in improving policy surrounding manure application.

Planar measurements of spray-induced wall cooling using phosphor thermometry

Science.gov (United States)

Dragomirov, Plamen; Mendieta, Aldo; Abram, Christopher; Fond, Benoît; Beyrau, Frank

2018-03-01

The wall cooling induced by spray impingement is investigated using phosphor thermometry. Thin coatings of zinc oxide (ZnO) phosphor were applied with a transparent chemical binder onto a steel surface. Instantaneous spatially resolved temperatures were determined using the spectral intensity ratio method directly after the injection of UV-grade hexane onto the surface using a commercial gasoline injector. The investigations showed that 2D temperature measurements with high spatial and shot-to-shot precision of, respectively, 0.5 and 0.6 K can be achieved, allowing the accurate resolution of the cooling induced by the spray. The presence of a liquid film over the phosphor coating during measurements showed no noticeable influence on the measured temperatures. However, in some cases a change in the intensity ratio at the spray impingement area, in the form of a permanent "stain", could be observed after multiple injections. The formation of this stain was less likely with increasing annealing time of the coating as well as lower plate operating temperatures during the injection experiments. Finally, the experimental results indicate a noticeable influence of the thickness of the phosphor coating on the measured spray-induced wall cooling history. Hence, for quantitative analysis, a compromise between coating thickness and measurement accuracy needs to be considered for similar applications where the heat transfer rates are very high.

Natural Radiation in byproducts of the production of phosphoric acid

International Nuclear Information System (INIS)

Silveira, Marcilei A. Guazzelli da; Cardoso, L.L.; Medina, N.H.

2014-01-01

Natural radiation is the largest source of radiation exposure to which man is subject. It is formed basically by cosmic radiation and the radionuclides present in the Earth crust, as 40 K and the elements of the decay series of 232 Th and 238 U. Phosphate ores, which constitutes the raw material for the production of phosphoric acid, have a high rate of natural radiation from the decay series of 232 Th and 238 U. Phosphogypsum, which is naturally radioactivity, is a by-product of the production of phosphoric acid by the wet method. For each ton of phosphoric acid it is produced about 4.5 tons of phosphogypsum. This work presents the analysis of samples collected in all stages of the manufacturing process of phosphoric acid, which generates the phosphogypsum. Gamma-ray spectrometry was used to measure the concentration of the elements of the decay series of 232 Th and 238 U. All analyzed samples showed a high concentration of radionuclides, promoting the need for further steps in the process in order to reduce the presence of such radionuclides in the phosphogypsum. The results indicate the radionuclide 238 U has higher contribution in some samples of the intermediate stages of the process. All samples exceeded the international average range of human exposure to terrestrial gamma radiation, which is 0.3 to 1.0 mSv/year. (author)

Kinetic parameters and TL mechanism in cadmium tetra borate phosphor

International Nuclear Information System (INIS)

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

2014-01-01

Polycrystalline powder samples of cadmium tetra borate were synthesized by a simple solid state sintering technique and gamma irradiated sample showed a simple Thermoluminescence (TL) glow peak around 460 K. The TL kinetic parameters of gamma irradiated phosphor were determined by initial rise (IR), isothermal decay (ID), peak shape (PS), variable heating rate (VHR) and glow curve de-convolution method. The kinetic parameters such as activation energy (E), frequency factor (s) and order of kinetics (b) were calculated by IR, ID, PS and VHR methods are in the order of ∼1.05 eV, 10 9 –10 12 s −1 and 1.58, respectively. From the results of TL and PL emission studies carried out on the phosphor revealed that the defect centers related to TL is different from that for PL. EPR measurements were carried out to identify the defect centers formed in cadmium tetra borate phosphor on gamma irradiation. Based on EPR studies the mechanism for TL process in cadmium tetra borate is proposed in this paper -- Highlights: • Polycrystalline powder samples of undoped cadmium tetra borate synthesized. • Cadmium tetra borate phosphor exhibits a dosimetric peak at 458 K. • Kinetic parameters of the trap responsible for TL evaluated. • TL mechanism is proposed from TL to EPR correlation studies

Kinetic parameters and TL mechanism in cadmium tetra borate phosphor

Energy Technology Data Exchange (ETDEWEB)

Annalakshmi, O. [Radiological Safety Division, Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Jose, M.T., E-mail: mtj@igcar.gov.in [Radiological Safety Division, Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Sridevi, J. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai 600 020, Tamilnadhu (India); Venkatraman, B. [Radiological Safety Division, Materials Physics 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 600 020, Tamilnadhu (India)

2014-03-15

Polycrystalline powder samples of cadmium tetra borate were synthesized by a simple solid state sintering technique and gamma irradiated sample showed a simple Thermoluminescence (TL) glow peak around 460 K. The TL kinetic parameters of gamma irradiated phosphor were determined by initial rise (IR), isothermal decay (ID), peak shape (PS), variable heating rate (VHR) and glow curve de-convolution method. The kinetic parameters such as activation energy (E), frequency factor (s) and order of kinetics (b) were calculated by IR, ID, PS and VHR methods are in the order of ∼1.05 eV, 10{sup 9}–10{sup 12} s{sup −1} and 1.58, respectively. From the results of TL and PL emission studies carried out on the phosphor revealed that the defect centers related to TL is different from that for PL. EPR measurements were carried out to identify the defect centers formed in cadmium tetra borate phosphor on gamma irradiation. Based on EPR studies the mechanism for TL process in cadmium tetra borate is proposed in this paper -- Highlights: • Polycrystalline powder samples of undoped cadmium tetra borate synthesized. • Cadmium tetra borate phosphor exhibits a dosimetric peak at 458 K. • Kinetic parameters of the trap responsible for TL evaluated. • TL mechanism is proposed from TL to EPR correlation studies.

The role of organo-mineral interactions on the capacity of soils to store carbon

Science.gov (United States)

Georgiou, K.; Abramoff, R. Z.; Riley, W. J.; Torn, M. S.

2017-12-01

Observed patterns of soil organic carbon (SOC) content across geochemical regimes are signatures of process and provide opportunities to understand the underlying decomposition and stabilization mechanisms that can guide their representation in models. The type of sorption equation used in soil decomposition models has large implications for both SOC stock and its temperature sensitivity. Here we compared different model formulations of SOC sorption to mineral surfaces, motivated by the myriad of chemical associations between organic and mineral surfaces, and used laboratory and field incubations to inform model parameters. We explored linear, Langmuir, and Freundlich adsorption models, where the latter emerges from heterogeneous compositions of substrate and surface components. We show the effect of model representations on predicted trends of SOC as a function of mineralogy and discuss the role of soil C saturation on emergent patterns. Specifically, our results highlight that the response of mineral-associated (`protected') SOC to changes in plant C inputs depends greatly on the C saturation deficit of the soil and thus, the representation of organo-mineral interactions in models can lead to nonlinear steady-state responses in protected SOC. We also find that, consistent with field experiments, the trend in protected SOC and mineral C saturation capacity is linear, but, interestingly, the slope depends on the degree of C saturation. We contend that this latter finding is an important consideration for field studies that did not find a universal slope and interpreted this as an inability of mineralogy to explain observed patterns. Our results also suggest that warming affects this slope, with higher temperatures causing a decrease in the amount of protected C for a given saturation capacity and C input rate. This means that more C inputs will be needed to keep the same amount of protected C at higher temperatures. Organo-mineral interactions play a key role in

Quality parameters evaluation for the determination of available phosphorous in soils

International Nuclear Information System (INIS)

Garcia Galvis, John Brynner; Ballesteros, Maria Ines

2006-01-01

There are some colorimetric procedures for determining available phosphorous in soils, and phosphorous is evaluated by means of a blue complex (phosphomolybdic acid); in one of the methods, color appear when ascorbic acid is used as reductor agent, and in the other when stannous chloride is used. Both methods use the same extractive solution bray i i due to its good response for acid soil cultures, like most Colombian soils are. When the two methodologies were compared it was found that the most sensible method and with the best limit of detection and quantification was the one that uses ascorbic acid, antimonious and potassium tartrate. Its variation coefficients and standard deviation were lower, and for this reason it is considered as the most precise method for phosphorous determination

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.)

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)

Influence of pH-control in phosphoric acid treatment of zinc oxide

Energy Technology Data Exchange (ETDEWEB)

Onoda, H., E-mail: onoda@kpu.ac.jp [Department of Informatics and Environmental Sciences, Kyoto Prefectural University (Japan); Chemel, M. [Ecole de Biologie Industrielle, CERGY Cedex (France)

2017-04-15

Zinc oxide is often used as a white pigment for cosmetics; however, it shows photocatalytic activity that causes decomposition of sebum on the skin when exposed to the ultraviolet radiation in sunlight. In this work, zinc oxide was reacted with phosphoric acid at various pH values to synthesize a novel white pigment for cosmetics. The chemical composition, powder properties, photocatalytic activities, colors, and smoothness of these pigments were studied. The obtained materials exhibited X-ray diffraction peaks relating to zinc oxide and phosphate after phosphoric acid treatment. The ratio of zinc phosphate to zinc oxide was estimated from inductively coupled plasma - atomic emission spectroscopy results. Samples treated at pH 4-7 yielded small particles with sub-micrometer sizes. The photocatalytic activity of zinc oxide became lower after phosphoric acid treatment. Samples treated at pH 4-7 showed the same reflectance as zinc oxide in both the ultraviolet and visible ranges. Adjustment of the pH was found to be important in the phosphoric acid treatment of zinc oxide. (author)

Modeling quantum noise of phosphors used in medical X-ray imaging detectors

CERN Document Server

Kalivas, N; Cavouras, D; Costaridou, L; Nomicos, C D; Panayiotakis, G S

1999-01-01

The noise properties of the granular phosphor screens, which are utilized in X-ray imaging detectors, are studied in terms of the quantum noise transfer function (QNTF). An analytical model, taking into account the effect of K-characteristic X-rays reabsorption within the phosphor material and the optical properties of the phosphor, was developed. The optical properties of the phosphor material required by the model were obtained from literature, except for the optical diffusion length (sigma) that was determined by data fitting and was found to be 26 cm sup 2 /g. The deviation between theoretical and experimental data is sigma depended. Specifically for sigma=26 cm sup 2 /g and sigma=25 cm sup 2 /g the respective deviations between experimental and predicted results were 0.698% and -1.597%. However for relative differences in sigma more than 15% from the value 26 cm sup 2 /g, the corresponding deviations exceed by 6 times the value of 0.698%. The model was tested via comparison to experimental results obtain...

Synthesis, crystal structure and characterizations of a new red phosphor K{sub 3}EuB{sub 6}O{sub 12}

Energy Technology Data Exchange (ETDEWEB)

Zhao, Dan, E-mail: iamzd1996@163.com [College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo, Henan, 454000 (China); State Key Laboratory of Structural Chemistry, Fuzhou, Fujian, 350002 (China); Ma, Fa-Xue; Wu, Zhi-Qiang; Zhang, Lei [College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo, Henan, 454000 (China); Wei, Wei, E-mail: wwei@cnu.edu.cn [Department of Chemistry, Capital Normal University, Beijing, 100048 (China); Yang, Juan; Zhang, Rong-Hua; Chen, Peng-Fei; Wu, Shan-Xuan [College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo, Henan, 454000 (China)

2016-10-01

A new potassium europium borate K{sub 3}EuB{sub 6}O{sub 12} has been prepared using a high temperature molten salt method and structurally characterized by single crystal X-ray diffraction (SC-XRD) analyses. Its structure features a three-dimensional (3D) framework composed of isolated [B{sub 5}O{sub 10}]{sup 5−} anions that are bridged by K{sup +} and Eu{sup 3+} ions. In this structure, one crystallographic distinct atom site is mixed occupied by K/Eu at a molar ratio of 1:1. The self-activated photoluminescence (PL) of K{sub 3}EuB{sub 6}O{sub 12} was studied. The excitation spectrum covers a wide range from 322 to 466 nm, which suggests that the K{sub 3}EuB{sub 6}O{sub 12} phosphors can be effectively excited by a near-UV light source. The emission spectrum consists of groups of lines in the red spectral region due to the {sup 5}D{sub 0}→{sup 7}F{sub j} (j = 1, 2, 3, 4) electronic transitions of Eu{sup 3+} ions, with the most intense line at 611 nm. We may expect that K{sub 3}EuB{sub 6}O{sub 12} has the potential to be a red phosphor pumped by near-UV LED chips. - Highlights: • A new red phosphor K{sub 3}EuB{sub 6}O{sub 12} was prepared. • The crystal structure of K{sub 3}EuB{sub 6}O{sub 12} was determined for the first time. • The photoluminescence properties of K{sub 3}EuB{sub 6}O{sub 12} are studied. • K{sub 3}EuB{sub 6}O{sub 12} show intense self-activated red emission under near-UV light excitation.

Luminescence behaviors of Eu- and Dy-codoped alkaline earth metal aluminate phosphors through potassium carbonate coprecipitation

Energy Technology Data Exchange (ETDEWEB)

Liang, Chen-Jui, E-mail: cjliang@fcu.edu.tw; Siao, Hao-Yi

2016-07-01

An electronic energy mechanism of activator and sensitizer was established to describe the luminescence behaviors of Eu- and Dy-codoped M(II)Al{sub 2}O{sub 4} (M(II) = Ba, Sr, Ca, Mg) phosphors through potassium carbonate coprecipitation. Experimental results demonstrated that the prepared phosphors exhibited superior crystallinity at a temperature lower than 950 °C. The phosphors are ordered according to emission intensity as follows Ca- > Ba- > Sr- > Mg-containing phosphors. The energy level for Eu{sup 2+} 4f{sup 6}5d{sup 1} → 4f{sup 7}, Eu{sup 3+4}D{sub 0} → {sup 7}F, and Dy{sup 3+4}F{sub 9/2} → {sup 6}H transitions and the effects of nephelauxetic and crystal field in Ba-, Sr-, and Ca-containing phosphors were discussed. The energy gap, (hv){sub em}, between 5d and 4f of Eu{sup 2+} ion is strongly affected by host composition, crystal field strength, and nephelauxetic effect. The infrared emission of 4f{sub 9/2} → 6h for Dy{sup 3+} is merely depend on the transfer of energy from Eu{sup 2+} upon excited. Ca-containing phosphor with maximum (hv){sub em} is attributed to the lowest bond length of Ca−O and highest ionization potential of Ca{sup 2+} ion, which leads to the effects of crystal field and nephelauxetic greater than that in the other phosphors. - Highlights: • The list of the collected figure captions: • Develop a new coprecipitation method to prepare high efficiency phosphors. • Obtain superior crystallinity with lower calcination temperature. • Luminescence behavior of Eu- and Dy-codoped on aluminate phosphors is discussed. • Investigate the effects of alkaline earth metal containing on crystal field and nephelauxetic.

Developing Quantum Dot Phosphor-Based Light-Emitting Diodes for Aviation Lighting Applications

International Nuclear Information System (INIS)

Wu, F.; Dawei, Z.; Shuzhen, S.; Yiming, Z.; Songlin, Z.; Jian, X.

2012-01-01

We have investigated the feasibility of employing quantum dot (QD) phosphor-based light-emitting diodes (LEDs) in aviation applications that request Night Vision Imaging Systems (NVIS) compliance. Our studies suggest that the emerging QD phosphor-based LED technology could potentially be superior to conventional aviation lighting technology by virtue of the marriage of tight spectral control and broad wavelength tunability. This largely arises from the fact that the optical properties of semiconductor nano crystal QDs can be tailored by varying the nano crystal size without any compositional changes. It is envisioned that the QD phosphor-based LEDs hold great potentials in cockpit illumination, back light sources of monitor screens, as well as the LED indicator lights of aviation panels.

Chemical process for recovery of uranium values contained in phosphoric mineral lixivia

International Nuclear Information System (INIS)

Conceicao, E.L.H. da; Awwal, M.A.; Coelho, S. V.

1980-01-01

A recovery process of uranium values from phosporic mineral lixivia for obtaining uranio oxide concentrate adjusted to specifications of purity for its commercialization the process consists of the adjustment of electromotive force of lixiviem to suitable values for uranium extraction, extraction with organic solvent containing phosphoric acid ester and oxidant reextraction from this solvent with phosphoric acid solution, suggesting a new solvent extraction containing synergetic mixture of di-2-ethyl hexyl phosphoric acid and tri-octyl phosphine, leaching this solvent with water and re-extraction/precipitation with ammonium carbonate solution, resulting in the formation of uranyl tricarbonate and ammonium, that by drying and calcination gives the uranium oxide with purity degree for commercialization. (M.C.K.) [pt

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).

Evaluation of characteristics of x-ray phosphors and hybrid scintillators

International Nuclear Information System (INIS)

Winter, John M. Jr.; Jones, Thomas S.

1999-01-01

Glass x-ray scintillators produce very high resolution images but suffer diminished brightness at x-ray energies below about 150 kV. This produces a loss in effective imaging due to the very low light flux, just at energies where many high resolution applications require the maximum image fidelity. Many phosphors produce substantially more light at these energy levels, but lack the resolution needed for critical industrial applications. A family of hybrid scintillators consisting of a scintillating fiber-optic base coupled to a thin coating of a high resolution phosphor is being developed. To facilitate evaluation of these hybrids and to measure their performance compared to other alternatives, a specialized real time x-ray imaging system was constructed and integrated with a microfocus x-ray source. This imaging system is described, and the results of a program to evaluate the brightness, resolution, and contrast sensitivity of a number of glass scintillators, phosphors, and hybrid imaging screens is presented

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)

Spectral-converting study of La{sub 1−m−n}Er{sub m}Yb{sub n}OCl (m=0.001–0.2, n=0–0.1) 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)

2014-09-15

Optical materials composed of La{sub 1−m−n}Er{sub m}Yb{sub n}OCl (m=0.001–0.2, n=0–0.1) solid solution were prepared via a solid-state reaction using excess NH{sub 4}Cl flux at 950 °C for 30 min. X-ray diffraction patterns of La{sub 1−m}Er{sub m}OCl were compared upon altering the molar ratios of the flux to the La{sup 3+} (Er{sup 3+}, Yb{sup 3+}) ions. By means of photoluminescence spectra, the dependence of the luminescence intensity as a function of the Er{sup 3+} content and the color CIE coordinates of the Er{sup 3+}-doped layered LaOCl compounds were also investigated under excitation by near-ultraviolet (NUV) and visible light. The spectral conversion properties of Er{sup 3+} and Er{sup 3+}–Yb{sup 3+} ions doped into LaOCl phosphors were elucidated under diode-laser irradiation of 980 nm in wavelength. The desired up-conversion of the emitting light, passing throughout the green, orange, and red regions of the spectrum, was achieved by appropriate Er{sup 3+} and/or Yb{sup 3+} concentrations in the LaOCl host structure under 980-nm-excitation light, while its mechanism in the phosphors was described by an energy-level schematic. Up-conversion emission spectra and the dependence of the emission intensity on pump power in the La{sub 0.89}Er{sub 0.1}Yb{sub 0.01}OCl phosphor were investigated under diode-laser irradiation of both wavelengths, 980 and 1550 nm. - Highlights: • Flux-assisted La{sub 1−m−n}Er{sub m}Yb{sub n}OCl (m=0.001–0.2, n=0–0.1) phosphors were prepared. • Distinctive photoluminescence properties of Er{sup 3+}-doped LaOCl were investigated. • Spectral converting properties of Er{sup 3+} and Yb{sup 3+} in LaOCl phosphors were elucidated. • Up-conversion mechanisms are proposed on the basis of an energy-level diagram. • Dependence of the emission intensity on pump power in the phosphor was investigated.

Fire severity effects on ash extractable Total Phosphorous

Science.gov (United States)

Pereira, Paulo; Úbeda, Xavier; Martin, Deborah

2010-05-01

Phosphorous (P) is a crucial element to plant nutrition and limits vegetal production. The amounts of P in soil are lower and great part of this nutrient is absorbed or precipitated. It is well known that fire has important implications on P cycle, that can be lost throughout volatilization, evacuated with the smoke, but also more available to transport after organic matter mineralization imposed by the fire. The release of P depends on ash pH and their chemical and physical characteristics. Fire temperatures impose different severities, according to the specie affected and contact time. Fire severity is often evaluated by ash colour and this is a low-cost and excellent methodology to assess the fire effects on ecosystems. The aim of this work is study the ash properties physical and chemical properties on ash extractable Total Phosphorous (TP), collected in three wildfires, occured in Portugal, (named, (1) Quinta do Conde, (2) Quinta da Areia and (3) Casal do Sapo) composed mainly by Quercus suber and Pinus pinaster trees. The ash colour was assessed using the Munsell color chart. From all three plots we analyzed a total of 102 ash samples and we identified 5 different ash colours, ordered in an increasing order of severity, Very Dark Brown, Black, Dark Grey, Very Dark Grey and Light Grey. In order to observe significant differences between extractable TP and ash colours, we applied an ANOVA One Way test, and considered the differences significant at a p<0.05. The results showed that significant differences in the extractable TP among the different ash colours. Hence, to identify specific differences between each ash colour, we applied a post-hoc Fisher LSD test, significant at a p<0.05. The results obtained showed significant differences between the extractable TP from Very dark Brown and Black ash, produced at lower severities, in relation to Dark Grey, Very Dark Grey and Light Grey ash, generated at higher severities. The means of the first group were higher

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)

Calculated energy dependence of CaSO4:Dy TL phosphor and phosphor embedded Teflon for X and gamma rays

International Nuclear Information System (INIS)

Chang, J.-K.; Nam, Y.-M.; Kim, J.-L.; Chang, S.-Y.; Kim, B.-H.

2001-01-01

The energy dependence of a CaSO 4 :Dy TL phosphor for 21 monoenergetic photons of energy ranging from 0.01 to 3 MeV was calculated by using MCNP4A code. The calculation results show good agreement with those of other authors within ± 5% relative error. Calculations and experiments are also performed to determine the energy dependence of CaSO 4 : Dy phosphor with Dy concentrations from 0.01 to 1.5 mol %, and with the compositions of TL-Teflon from 10 to 90 wt %. The calculated energy responses show good agreement with the experiment results within ± 20% relative error except for a concentration lower than 0.1 mol % Dy and the low energy regions of M30 (Eave.=20 keV) and M60 (Eave.=34 keV). For the TL-Teflon mixture, the energy dependence shows an decreasing trend with the increase of Teflon concentration in MCNP calculation but shows no dependence for TL-Teflon mixture proportions in experiment. These differences are due to the non-homogeneous distribution of Dy concentration and the effect of large grain size in the phosphors. The energy dependence of the 30 wt/o CaSO 4 (0.1 mol%;Dy) and 70 wt/o Teflon that is placed behind the filters of plastic, aluminum, copper, tin and lead with a thickness from 0.1 to 2 mm were calculated, respectively

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

International Nuclear Information System (INIS)

Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M.; Sapsay, V.I.; Klymchuk, D.O.; Puziy, A.M.

2012-01-01

Highlights: ► Phosphoric acid activation results in formation of carbons with acidic surface groups. ► Maximum amount of surface groups is introduced at impregnation ratio 1.25. ► Phosphoric acid activated carbons show high capacity to copper. ► Phosphoric acid activated carbons are predominantly microporous. ► Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S BET = 2081 m 2 /g, V tot = 1.1 cm 3 /g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0–2.6), weakly acidic carboxylic (pK = 4.7–5.0), enol/lactone (pK = 6.7–7.4; 8.8–9.4) and phenol (pK = 10.1–10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

Energy Technology Data Exchange (ETDEWEB)

Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M. [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine); Sapsay, V.I.; Klymchuk, D.O. [M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2 Tereshchenkivska St., 01601 Kyiv (Ukraine); Puziy, A.M., E-mail: alexander.puziy@ispe.kiev.ua [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine)

2012-11-15

Highlights: Black-Right-Pointing-Pointer Phosphoric acid activation results in formation of carbons with acidic surface groups. Black-Right-Pointing-Pointer Maximum amount of surface groups is introduced at impregnation ratio 1.25. Black-Right-Pointing-Pointer Phosphoric acid activated carbons show high capacity to copper. Black-Right-Pointing-Pointer Phosphoric acid activated carbons are predominantly microporous. Black-Right-Pointing-Pointer Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 Degree-Sign C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S{sub BET} = 2081 m{sup 2}/g, V{sub tot} = 1.1 cm{sup 3}/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Dosimetry characteristics of thermoluminescent Li2B4O7:Cu phosphor

International Nuclear Information System (INIS)

Lakshmanan, A.R.; Chandra, B.; Bhatt, R.C.

1981-01-01

Preliminary investigations on the radiation dosimetry characteristics of Li 2 B 4 O 7 :Cu TLD phosphor are described. The major TL peak in this phosphor occurs at 230 0 C and its TL sensitivity to gamma radiation is two to three times higher than that of LiF TLD-100. The gamma dose Vs TL response of this peak is linear (within +- 20%) in the dose range 0.3 mGy-3x10 2 Gy above which saturation sets in. Its TL response for 30 keV X-rays is about 20% lower than that for 60 Coγ-rays. On annealing at 300 0 C, the phosphor gets slightly discoloured (brownish). This results in the reduction of the TL sensitivity by about 20 - 25%. The phosphor does not exhibit either sensitization or damage even after a gamma dose of 10 3 Gy. The TL emission spectrum has a broad peak at 360 nm. The intrinsic TL sensitivity of virgin Li 2 B 4 O 7 :Cu to 253.7 nm UV radiation is nearly 50 times higher than that of CaSO 4 :Dy. The post-irradiation fading in Li 2 B 4 O 7 :Cu at ambient temperature and humidity conditions is, however, less than 10% in 17 days. These characteristics indicate that Li 2 B 4 O 7 :Cu is a promising phosphor for ionizing as well as UV radiation dosimetry. (author)

Reactivity of the cadmium ion in concentrated phosphoric acid solutions.

Science.gov (United States)

De Gyves, J; Gonzales, J; Louis, C; Bessiere, J

1989-07-01

The solvation transfer coefficients which characterize the changes of ion reactivity with phosphoric acid concentration have been calculated for cadmium from the constants of the successive chloride complexes, and for silver and diethyldithiophosphate from potentiometric measurements. They evidence the strong desolvation of the cadmium species in concentrated phosphoric acid media, causing a remarkable increase of its reactivity. They allow the results of liquid-liquid extraction, precipitation and flotation reactions to be correctly interpreted and their changes to be foreseen when the reagents are modified.

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.

Separation and preconcentration trace amounts of gold by using modified organo nanoclay closite 15A

Directory of Open Access Journals (Sweden)

Sayed Zia Mohammadi

2010-01-01

Full Text Available The application of organo nanoclay 5-(4-dimethylamino-benzylidene rhodanine-immobilized as a new, easily prepared, and stable solid sorbent for preconcentration trace amounts of Au(III ions in aqueous solution is presented. The sorption of Au(III ions was quantitative in the pH range of 2-4, and quantitative desorption occurred instantaneously with 10.0 mL of a mixture containing 0.5 mol L-1 Na2S2O3 and KSCN. Various parameters, such as the effect of pH, breakthrough volume, extraction time, and interference of a large number of anions and cations have been studied. The proposed method has been applied for determination of trace amount of gold in water samples.

A Visual Detection System for Determining Tritium Surface Deposition Employing Phosphor Coated Materials

International Nuclear Information System (INIS)

Gentile, C.A.; Skinner, C.H.; Young, K.M.; Zweben, S.J.

1999-01-01

A method for visually observing tritium deposition on the surface of the Tokamak Fusion Test Reactor (TFTR) deuterium-tritium (D-T) tiles is being investigated at the Princeton Plasma Physics Laboratory. A green phosphor (P31, zinc sulfide: copper) similar to that used in oscilloscope screens with a wavelength peak of 530 nm was positioned on the surface of a TFTR D-T tile. The approximately 600 gram tile, which contains approximately 1.5 Ci of tritium located on the top approximately 1-50 microns of the surface, was placed in a two liter lexan chamber at Standard Temperature and Pressure (STP). The phosphor plates and phosphor powder were placed on the surface of the tile which resulted in visible light being observed, the consequence of tritium betas interacting with the phosphor. This technique provides a method of visually observing varying concentrations of tritium on the surface of D-T carbon tiles, and may be employed (in a calibrated system) to obtain quantitative data

Investigation of thermoluminescence and electron-vibrational interaction parameters in SrAl2O4:Eu2+, Dy3+ phosphors

International Nuclear Information System (INIS)

Pardhi, Shilpa A.; Nair, Govind B.; Sharma, Ravi; Dhoble, S.J.

2017-01-01

Combustion synthesis method was employed for the synthesis of green-emitting monoclinic SrAl 2 O 4 :Eu 2+ , Dy 3+ phosphors. The phase-purity of the prepared phosphors were examined using X-ray diffraction (XRD). The prepared phosphors exhibited green light emission with the peak centred at 510 nm, under 350 nm UV excitation. The excitation and emission spectra were analysed and the parameters of electron-vibrational interaction (EVI), such as the Huang–Rhys factor, effective phonon energy and zero-phonon line position were estimated using the spectrum fitting method. Thermoluminescence (TL) behaviour of the as-prepared phosphors were analysed for UV and 137 Cs γ-ray source irradiation. TL glow curves for UV-irradiated SrAl 2 O 4 :Eu 2+ , Dy 3+ phosphors were analysed. - Highlights: • Photoluminescence and thermoluminescence properties of SrAl 2 O 4 :Eu 2+ ,Dy 3+ phosphors were analysed. • Electron-vibrational interaction (EVI) parameters of SrAl 2 O 4 :Eu 2+ ,Dy 3+ phosphors were determined. • The phosphors are found to exhibit green light emission.

Enhanced luminescence in SrMgAl(x)O(17±δ):yMn4+ composite phosphors.

Science.gov (United States)

Cao, Renping; Sharafudeen, Kaniyarakkal N; Qiu, Jianrong

2014-01-03

Red-emitting SrMgAlxO17±δ:yMn(4+) composite phosphors (x=10-100; y=0.05-4.0 mol%) are synthesized by solid-state reaction method in air. Addition of Al2O3 leads to the formation of two concomitant phases, i.e., SrMgAl10O17 and Al2O3 phases in the composite phosphor. Red emission from Mn(4+) ions in the composite phosphors is greatly enhanced due to multiple scattering and absorption of excitation light between SrMgAl10O17 and Al2O3 phases. SrMgAlxO17±δ:yMn(4+) composite phosphors would be a promising candidate as red phosphor in the application of a 397 nm near UV-based W-LED. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of anions in pure and commercial phosphoric acid by ion chromatography and manual of 792 basic IC

International Nuclear Information System (INIS)

Al-Kabani, F.; Abdulbaki, M. K.

2007-01-01

A method for determination of anions in pure and concentrated phosphoric and samples (85%) and commercial phosphoric acid ion chromatography was developed, in order to control the specification of phosphoric acid produced in the pilot plant for phosphoric acid purification. The accuracy of the method was studied and the standard deviation was found to be between 0.09 and 0.10. Operation instructions of 792 Basic IC was described. (author)

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...

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.

Spectroscopic properties of Eu{sup 3+}:KLa(WO{sub 4}){sub 2} novel red phosphors

Energy Technology Data Exchange (ETDEWEB)

Rasu, K. Kavi; Balaji, D.; Babu, S. Moorthy, E-mail: babusm@yahoo.com

2016-02-15

Eu{sup 3+}:KLa(WO{sub 4}){sub 2} (Eu:KLW) phosphors were prepared through Pechini type sol–gel method. Low temperature synthesis was achieved through polyesterification between citric acid and ethylene glycol during the growth procedure. The properties of phosphors were analysed using X-ray diffractogram (XRD), scanning electron microscopy (SEM), Raman and luminescence spectroscopy. An effective energy transfer from the tungstate matrix to the activator Eu{sup 3+} was observed. Intense red emission in Eu:KLW phosphors was observed while excited with f–f transitions of Eu{sup 3+}. The Judd–Ofelt (J–O) intensity parameters Ω{sub 2} and Ω{sub 4} were obtained from the emission intensities of {sup 5}D{sub 0}→{sup 7}F{sub 2},{sub 4,} respectively by taking the magnetic dipole {sup 5}D{sub 0}→{sup 7}F{sub 1} emission band intensity as reference. The CIE colour co-ordinates of the Eu:KLW red phosphors was calculated (x=0.650, y=0.348), which are close to NTSC standard values. - Highlights: • Eu:KLW phosphors were synthesized by pechini type sol–gel method. • Structural, morphological, vibrational and luminescence properties were well investigation. • Eu{sup 3+}:KLa(WO{sub 4}){sub 2} phosphors has strong red emission at about 615 nm ({sup 5}D{sub 0}→{sup 7}F{sub 2}) under the excitation of near UV and blue LEDs regions. • Decay measurement and Judd–Ofelt parameter were calculated and dicussed. • These phosphors can serve as a potential candidate for red source for White LEDs application.

The preparation of 32P labelled phosphorous acid

International Nuclear Information System (INIS)

Henderson, D.; Jenkinson, A.; Sorby, P.

1986-11-01

Phosphorous acid labelled with 32 P has been prepared, on a small scale, starting from neutron-irradiated phosphorus. The compound is intended for tracer studies in the development of novel fungicides

Developing Quantum Dot Phosphor-Based Light-Emitting Diodes for Aviation Lighting Applications

Directory of Open Access Journals (Sweden)

Fengbing Wu

2012-01-01

Full Text Available We have investigated the feasibility of employing quantum dot (QD phosphor-based light-emitting diodes (LEDs in aviation applications that request Night Vision Imaging Systems (NVIS compliance. Our studies suggest that the emerging QD phosphor-based LED technology could potentially be superior to conventional aviation lighting technology by virtue of the marriage of tight spectral control and broad wavelength tunability. This largely arises from the fact that the optical properties of semiconductor nanocrystal QDs can be tailored by varying the nanocrystal size without any compositional changes. It is envisioned that the QD phosphor-based LEDs hold great potentials in cockpit illumination, back light sources of monitor screens, as well as the LED indicator lights of aviation panels.

Structural and luminescence properties of yellow Y3Al5012:Ce3+ thin film phosphors prepared by Pulsed Laser Deposition

CSIR Research Space (South Africa)

Dejene, FB

2012-07-01

Full Text Available of the phosphore/epoxy hybrid system is the difficulty of achieving uniform emission of white light from the LED. In order to overcome the challenges of using mixtures of phosphore powders and epoxies thin film phosphore has been used. In this study, YAG phosphore...

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.

UV absorption coefficients of Y2(1-x-y)Gd2xEu2yO3 phosphors

International Nuclear Information System (INIS)

Ling, M.; Yocom, P.W.; Soules, T.F.

1990-01-01

The ability of a phosphor to absorb 254 nm excitation is important in the development of phosphors for fluorescent lamps. Recently the optical properties of phosphor coating were modeled using ray tracing Monte-Carlo techniques. These calculations provided a relationship between absorptance measured on a semi-infinite plaque at a given wavelength and the product of the absorption coefficient of the phosphor and its particle diameter. The purpose of this work is to provide experimental data for comparison with the calculated data, to demonstrate a technique for obtaining absorption coefficients and to provide UV absorption coefficients obtained in this way for important yttrium oxide europium red-emitting phosphors

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.

The influence of organo-bentonite clay on the processing and mechanical properties of nylon 6 and polystyrene composites

International Nuclear Information System (INIS)

Araujo, E.M.; Melo, T.J.A.; Santana, L.N.L.; Neves, G.A.; Ferreira, H.C.; Lira, H.L.; Carvalho, L.H.; A'vila, M.M.; Pontes, M.K.G.; Araujo, I.S.

2004-01-01

The influence of organoclay on the processing and mechanical properties of nylon 6 and polystyrene was investigated. A bentonite sample from Boa Vista/PB, Northeast of Brazil, was treated with alkyldimethylbenzylammonium chloride. After the treatment, the powder was characterized by thermal analysis and infrared spectroscopy. Composites were prepared by using a Torque rheometer. The results show the intercalation of quaternary ammonium salt in the structure of bentonite and organo-bentonite produced significant changes on the processing of the nylon 6 and polystyrene with increase in the viscosity and rigidity. However, the mechanical properties of polystyrene/organoclay system did not show significant changes

Use of secondary phosphorescence for determination of the dose absorbed in dosimetric phosphors

CERN Document Server

Yaek, I V

2002-01-01

The measuring method of optically stimulated persistence (OSP) based on both the time division of the stimulating irradiation and luminescent response registration was applied for the radiation dosimetry. It was shown that the stimulation by the short-wave radiation crossing with spectrum of the dosimetric phosphor is possible. The spectrum of the stimulation of industry dosimetric phosphors was measured. The characteristics of the OSP registration for the phosphors which has manganese Mn sup 2 sup + as the activator is considered. Decay time of inner center luminescence is 40-50 ms. This method is used for the dosimetry of the natural quartzes to determine their age.

Optical enhancement of phosphor-converted wLEDs using glass beads

Science.gov (United States)

Güner, Tuğrul; Şentürk, Ufuk; Demir, Mustafa M.

2017-10-01

YAG:Ce3+ is a yellow-source compound commonly used in phosphor conversion layers for direct coating or remote phosphor configurations in LED illumination. This material, however, suffers from a high correlated color temperature, and low color-rendering index due to its deficiency in the red spectrum. In this study, glass beads (GB) with an average particle diameter of 10 μm were introduced to the conversion layer of a YAG:Ce3+ particulate-filled polydimethylsiloxane matrix composite structure and found to improve the optical features of the resulting composite.

Uranium recovery from wet process phosphoric acid

International Nuclear Information System (INIS)

1980-01-01

In the field of metallurgy, specifically processes for recovering uranium from wet process phosphoric acid solution derived from the acidulation of uraniferous phosphate ores, problems of imbalance of ion exchange agents, contamination of recycled phosphoric acid with process organics and oxidizing agents, and loss and contamination of uranium product, are solved by removing organics from the raffinate after ion exchange conversion of uranium to uranous form and recovery thereof by ion exchange, and returning organics to the circuit to balance mono and disubstituted ester ion exchange agents; then oxidatively stripping uranium from the agent using hydrogen peroxide; then after ion exchange recovery of uranyl and scrubbing, stripping with sodium carbonate and acidifying the strip solution and using some of it for the scrubbing; regenerating the sodium loaded agent and recycling it to the uranous recovery step. Economic recovery of uranium as a by-product of phosphate fertilizer production is effected. (author)

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

Development of Efficient UV-LED Phosphor Coatings for Energy Saving Solid State Lighting

International Nuclear Information System (INIS)

Uwe Happek

2006-01-01

The University of Georgia, in collaboration with GE Global Research, has investigated the relevant quenching mechanism of phosphor coatings used in white light devices based on UV LEDs. The final goal of the project was the design and fabrication of a high-efficacy white light UV-LED device through improved geometry and optimized phosphor coatings. At the end of the research period, which was extended to seamlessly carry over the research to a follow-up program, we have demonstrated a two-fold improvement in the conversion efficiency of a white light LED device, where the increase efficacy is due to both improved phosphor quantum efficiency and lamp geometry. Working prototypes have been displayed at DOE sponsored meetings and during the final presentation at the DOE Headquarters in Washington, DC. During the first phase of the project, a fundamental understanding of quenching processes in UV-LEDs was obtained, and the relationships that describe the performance of the phosphor as a function of photon flux, temperature, and phosphor composition were established. In the second phase of the project, these findings were then implemented to design the improved UV-LED lamp. In addition, our research provides a road map for the design of efficient white light LEDs, which will be an important asset during a follow-up project led by GE

Persistent luminescence, TL and OSL characterization of beta irradiated SrAl{sub 2}O{sub 4}:Eu{sup 2+}, Dy{sup 3+} combustion synthesized phosphor

Energy Technology Data Exchange (ETDEWEB)

Zúñiga-Rivera, N.J. [Departamento de Física, Posgrado en Nanotecnología, Universidad de Sonora, Hermosillo, Sonora 83000 (Mexico); García, R.; Rodríguez-Mijangos, R.; Chernov, V.; Meléndrez, R.; Pedroza-Montero, M. [Departamento de Investigación en Física, Universidad de Sonora, Hermosillo, Sonora 83000 (Mexico); Barboza-Flores, M., E-mail: mbarboza@cifus.uson.mx [Departamento de Investigación en Física, Universidad de Sonora, Hermosillo, Sonora 83000 (Mexico)

2014-05-01

The persistent luminescence (PLUM), thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of strontium aluminates co-doped with Eu{sup +2} and Dy{sup +3} exposed to beta radiation is reported. The phosphor was synthesized by the combustion synthesis method employing a highly exothermic redox reaction between the metal nitrates [Al(NO{sub 3}){sub 3}, Sr(NO{sub 3}){sub 2}, Eu(NO{sub 3}){sub 3} and Dy(NO{sub 3}){sub 3}] and organic fuel carbohydrazide (CH{sub 6}N{sub 4}O). The long decay PLUM emission, TL and OSL were measured as a function of beta radiation dose. A wide emission band centered at 510 nm (green) related to Eu{sup 2+} ions and lattice defects were observed for the synthesized samples. The presence of a variety of defects and aggregates were responsible for the observed broad 100 °C peaked TL glow curve of the irradiated sample which is composed of several overlapped TL peaks. The existence of multiple trapping levels, with different trapping/detrapping probabilities, is behind the particular features for the PLUM, TL and OSL emissions. We conclude that in the SrAl{sub 2}O{sub 4}:Eu{sup 2+}, Dy{sup 3+} phosphors, the low temperature TL peaked around 30–75 °C is responsible for the PLUM emission and those around 100 °C were related to very stable trapping states which provide suitable radiation storage properties to be used as a PLUM/TL/OSL radiation phosphor.

Application of a precipitation method for uranium recovery from abu-zaabal phosphoric acid plant, Egypt

International Nuclear Information System (INIS)

El-hazek, N.M.T.; Hussein, E.M.

1995-01-01

Current industrial recovery of uranium from 30% phosphoric acid-produced by the dihydrate process-is based on solvent extraction method. Uranium recovery from concentrated phosphoric acid (45-52% p o5 ) produced by evaporation of the 30% acid or directly produced by the hemihydrate process, by solvent extraction is difficult to apply in practice. In addition to possible contamination of the acid by the organic solvents and/or their deterioration. This paper investigates the possibility of applying a precipitation method (Weterings and Janssen, 1985) for uranium recovery from both low (28% P 2 O 5 ) and high (48% P 2 O 5 ) concentration phosphoric acids produced by abu-zaabal phosphoric acid plant (Abuzaabal fertilizers and chemicals Co., Egypt). The 28% acid produced by H 2 SO 4 dihydrate method and the 48% acid produced by evaporation of the 28% acid The applied precipitation method depends on using NH 4 F as a uranium precipitant from both low and high concentration phosphoric acids in presence of acetone as a dispersing agent. All the relevant factors have been studied

Development of Dy3+ activated K2MgP2O7 pyrophosphate phosphor for energy saving lamp

International Nuclear Information System (INIS)

Kohale, R.L.; Dhoble, S.J.

2013-01-01

Present work reports, synthesis of Dy 3+ activated K 2 MgP 2 O 7 pyrophosphate phosphor by using modified solid state diffusion that has been studied for its X-ray diffraction pattern (XRD). Furthermore, the chromaticity coordinate values were estimated from emission spectra of K 2 MgP 2 O 7 . The photoluminescence emission spectra of the phosphors having an excitation at around 351 nm (mercury free) showed two distinguishing bands centered at around 485 nm (blue) and 575 nm (yellow) corresponding to 4 F 9/2 → 6 H 15/2 and 4 F9 /2 → 6 H 13/2 transitions of Dy 3+ , respectively. These phosphors have strong absorption in the near UV region. K 2 MgP 2 O 7 pyrophosphate phosphor is suitable for color converter using UV light as the primary light source, which can be used as a blue/yellow phosphor excited by n-UV LED chip and mixed with other color emission phosphors to obtain white light. The 300–400 nm is Hg-free excitation (mercury excitation is 85% 254 nm wavelength of light and 15% other wavelengths), which is characteristic of solid-state lighting phosphors. Hence PL emission in trivalent dysprosium may be efficient photoluminescent materials for solid-state lighting phosphors. The intact study reveals that the present phosphor have promising applications in the lamp industry especially for solid state lighting (mercury-free excited lamp phosphor) and white light LED. -- Highlights: ► Dy 3+ activated pyrophosphate based phosphor prepared by modified solid state diffusion. ► PL emission spectrum of Dy 3+ ion under 351 nm excitation (Hg-free). ► PL emission at 485 nm (blue), 575 nm (yellow) emission. ► K 2 MgP 2 O 7 : Dy 3+ is expected to be a potential candidate for application in n-UV white LEDs and solid state lighting

Process for the winning of a concentrate containing uranium and purified phosphoric acid, as well as the concentrate containing uranium and purified phosphoric acid obtained by this process

International Nuclear Information System (INIS)

1980-01-01

The uranium containing concentrate and purified phosphoric acid are obtained by treating wet phosphoric acid with an inorganic fluorine compound (ammonium fluoride) and an aliphatic ketone (acetone) in the presence of a reducing agent (finely divided iron). The ketone is added first and the formed uranium precipitate is separated from the solution. If the fluorine compound is added first, the yield is lowered by a factor of 2. (Th.P.)

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.)

Continuous tests of Phosphoric Acid - dihydrate process - from phosphatic concentrate of Itataia-CE ore

International Nuclear Information System (INIS)

Santos Benedetto, J. dos.

1984-01-01

A consolidation of principal studies and continuous tests done with phosphatic concentrated of Itataia ore intending phosphoric acid production by humid-route dihydrate way process is presented. The production of phosphoric acid is applied in uranium extraction process by solvents. (author) [pt

Crystal structure, thermally stability and photoluminescence properties of novel Sr10(PO4)6O:Eu2+ phosphors

International Nuclear Information System (INIS)

Guo, Qingfeng; Liao, Libing; Mei, Lefu; Liu, Haikun

2015-01-01

A series of novel luminescent phosphors Sr 10 (PO 4 ) 6 O:Eu 2+ with apatite structure were synthesized via a high temperature solid-state reaction. The phase structure, photoluminescence (PL) properties, the PL thermal stability, as well as the fluorescence decay curves of the samples were investigated to characterize the resulting samples, and the selected Sr 9.97 (PO 4 ) 6 O:0.03Eu 2+ phosphor exhibits strong thermal quenching resistance, retaining the luminance of 88.73% at 150 °C. The quenching concentration of Eu 2+ in Sr 10 (PO 4 ) 6 O was about 0.03 attributing to the dipole–quadrupole interaction. The Sr 10 (PO 4 ) 6 O:Eu 2+ phosphor exhibited a broad-band blue emission at 439 nm upon excitation at 346 nm. The results indicate that Sr 10 (PO 4 ) 6 O:Eu 2+ phosphors have potential applications as near UV-convertible phosphors for white-light UV LEDs. - Graphical abstract: Sr 10 (PO 4 ) 6 O:Eu 2+ phosphors have potential applications as near UV-convertible phosphors for white-light UV LEDs. - Highlights: • Sr 9.97 (PO 4 ) 6 O:0.03Eu 2+ phosphor exhibits strong thermal quenching resistance. • Two different Eu 2+ emission centers exists in Sr 10 (PO 4 ) 6 O. • The activation energy was also estimated for the Eu 2+ luminescence center

Inorganic-Organic hybrid materials for uranium extraction from phosphoric acid

International Nuclear Information System (INIS)

El-Mourabit, Sabah

2013-01-01

Phosphate rocks are industrially processed in large quantities to produce phosphoric acid and fertilisers. These rocks contain significant concentration of uranium (50 to 300 ppm) which could be interesting for nuclear industry. This work deals with the valorisation of uranium as a by-product from fertiliser industry. The aim of this study is to develop a hybrid material, constituted of an inorganic solid support grafted with an extractant (complexing molecule), which can extract selectively uranium from phosphoric acid medium. The first step of our approach was to identify an inorganic support which is stable under these particular conditions (strong acidity and complexing medium). The chemical and mechanical stability of different meso-porous materials, such as silica, glass and carbon was studied. In a second phase, we focused on the identification and the optimisation of complexing molecules, specific of uranium in phosphoric acid. These ligands were then grafted on the most stable solids. Finally, the efficiency of these hybrid systems was evaluated through different tests of extraction, selectivity and de-extraction. (author) [fr

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.

Integrated chemical process for exothermic wave synthesis of high luminance YAG:Ce phosphors

International Nuclear Information System (INIS)

Won, C.W.; Nersisyan, H.H.; Won, H.I.; Youn, J.W.

2011-01-01

In this paper, high-luminance yellow-emitting Y 3 Al 5 O 12 :Ce 3+ phosphor (YAG:Ce) microparticles were prepared in a solid flame using a 1.425Y 2 O 3 +2.5Al 2 O 3 +0.15CeO 2 +k(KClO 3 +urea)+mNH 4 F precursor mixture (here k is the number of moles of the KClO 3 +urea red-ox mixture, and m is the number of moles of NH 4 F). The self-sustaining combustion process for the entire reaction sample was provided by the heat generated from the KClO 3 +urea mixture. Parametric studies demonstrated that the maximum temperature in the combustion wave varied from 885 to 1200 deg. C for k=2.0-3.0 mole and m=0-1.5 mole. X-ray analysis results showed that the product obtained in the solid flame consisted of Y 3 Al 5 O 12 :Ce 3+ and KCl phases. Therefore, after dissolving potassium chloride in distillated water, pure-phase YAG:Ce phosphor powder was obtained. The as-prepared YAG:Ce phosphor particles had diameters of 10-25 μm and good dispersity and exhibited luminescence properties comparable to those of YAG:Ce phosphor powders prepared by conventional high-temperature processing. - Highlights: → A new solid-flame strategy was developed for synthesizing high-luminance YAG:Ce phosphor. → Adding KClO 3 +CO(NH 2 ) 2 +NH 4 F mixture to oxide powders provides a low-temperature combustion process. → YAG:Ce phosphor particles 10-25 μm in diameter were obtained at 1000-1100 deg. C within tens of seconds. → As-prepared YAG:Ce emission intensity was 90.1-103.2% compared to that of the reference sample.

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

Gamma radiation induced sensitization and photo-transfer in Mg2SiO4:Tb TLD phosphor

International Nuclear Information System (INIS)

Lakshmanan, A.R.; Vohra, K.G.

1979-01-01

Mg 2 SiO 4 :Tb TLD phosphor was found to show enhanced TL sensitivity to both gamma and UV radiations after high pre-gamma exposures (>100 R) and a post-annealing treatment at 300 0 C for 1 h. Maximum sensitization factors of 2.8 and 55 were obtained at the pre-expsoure levels of 5.2x10 1 C/kg and 1.3x10 3 C/kg for gamma and UV test radiations respectively. The near constancy of the intensity of the residual TL (RTL) peak at 500 0 C for the sensitized sample with increasing test-gamma exposures has ruled out the re-trapping model proposed earlier for the gamma radiation induced sensitization in this phosphor. The Tsub(max) for the sensitized phosphor was found to occur at a higher temperature compared to that for the virgin phosphor. The dependence of sensitization on RTL was explained qualitatively on the basis of competition between sensitization traps (having higher energy than the dosimetry traps) and RTL traps while capturing the charge carriers generated during the test-gamma exposure. The sensitization observed in this phosphor to UV test radiation was found to be a consequence of the photo-transfer of charge carriers from deep (RTL) traps to the shallow (dosimetry) traps. The reduction in RTL peak (500 0 C) intensity of the sensitized sample with increasing test-UV exposure has demonstrated the photo-transfer mechanism in this phosphor. The TL response of the virgin Mg 2 SiO 4 :Tb phosphor was found to be supralinear to both gamma and UV radiations. The TL response of the sensitized phosphor was found to be linear to gamma radiation and sublinear to UV radiation. (Auth.)

Evaluation of new and conventional thermoluminescent phosphors for environmental monitoring using automated thermoluminescent dosimeter readers

International Nuclear Information System (INIS)

Rathbone, B.A.; Endres, A.W.; Antonio, E.J.

1994-10-01

In recent years, there has been considerable interest in a new generation of super-sensitive thermoluminescent (TL) phosphors for potential use in routine personnel and environmental monitoring. Two of these phosphors, α-Al 2 O 3 :C and LiF:Mg,Cu,P, are evaluated in this paper for selected characteristics relevant to environmental monitoring, along with two conventional phosphors widely used in environmental monitoring, LiF:Mg,Ti and CaF 2 :Dy. The characteristics evaluated are light-induced fading, light-induced background, linearity and variability at low dose, and the minimum measurable dose. These characteristics were determined using an automated commercial dosimetry system (Harshaw System 8800) and routine processing protocols. Annealing and readout protocols for each phosphor were optimized for use in a large-scale environmental monitoring program

Direct digital radiography versus storage phosphor radiography in the detection of wrist fractures

Energy Technology Data Exchange (ETDEWEB)

Peer, Siegfried; Neitzel, Ulrich; Giacomuzzi, Salvatore M.; Pechlaner, Sigurd; KUenzel, Karl Heinz; Peer, Regina; Gassner, Eva; Steingruber, Iris; Gaber, O.; Jaschke, Werner

2002-04-01

AIM: To define the value of digital radiography with a clinical flat panel detector system for evaluation of wrist fractures in comparison with state of the art storage phosphor radiography. MATERIAL AND METHODS: Hard copy images of 26 fractured wrist specimens were acquired with the same exposure dose on a state of the art storage phosphor radiography system and a clinical flat panel detector. Image features like cortical bone surface, trabecular bone, soft tissues and fracture delineation were independently analysed by 4 observers using a standardised protocol. Image quality ratings were evaluated with an analysis of variance (ANOVA). RESULTS: Flat panel detector radiographs were rated superior with respect to cortical and trabecular bone representation as well as fracture evaluation, while storage phosphor radiographs produced better soft tissue detail. CONCLUSION: In some of the observed image quality aspects, the performance of caesium iodide/amorphous silicon flat panel detector exceeds state of the art storage phosphor radiography. This makes it well suited for skeletal imaging particularly in trauma as seen in the detection of wrist fractures. Peer, S. et al. (2002)

PREPARATION AND PROPERTIES OF ALKALI-ACTIVATED CEMENT CONTAINING PHOSPHOROUS SLAG AND FLY ASH

Directory of Open Access Journals (Sweden)

Duo You

2016-03-01

Full Text Available Phosphorous slag is an industrial waste which potentially pollutes environments. The aim of the present work is to use phosphorous slag as a raw material to produce alkali-activated cement. The influence of mix proportion of phosphorous slag and fly ash, alkali content and modulus of water glass on the properties of alkali-activated phosphorous slag and fly ash cement (AA-PS-FA-C was studied. The results show that AA-PS-FA-C with normal setting performance and desirable mechanical properties can be prepared using water glass as the activator. Changing the fly ash content in the range of 0-40 wt% has only a small influence on the setting time of AA-PS-FA-C. The strengths significantly decrease when the fly ash content exceeds 30 wt%. The carbonation resistance of AA-PS-FA-C is similar to that of ordinary Portland cement (OPC, while the frost resistance is much better. The hardened paste of AA-PS-FA-C is much more compact than OPC paste.

Direct digital radiography versus storage phosphor radiography in the detection of wrist fractures

International Nuclear Information System (INIS)

Peer, Siegfried; Neitzel, Ulrich; Giacomuzzi, Salvatore M.; Pechlaner, Sigurd; KUenzel, Karl Heinz; Peer, Regina; Gassner, Eva; Steingruber, Iris; Gaber, O.; Jaschke, Werner

2002-01-01

AIM: To define the value of digital radiography with a clinical flat panel detector system for evaluation of wrist fractures in comparison with state of the art storage phosphor radiography. MATERIAL AND METHODS: Hard copy images of 26 fractured wrist specimens were acquired with the same exposure dose on a state of the art storage phosphor radiography system and a clinical flat panel detector. Image features like cortical bone surface, trabecular bone, soft tissues and fracture delineation were independently analysed by 4 observers using a standardised protocol. Image quality ratings were evaluated with an analysis of variance (ANOVA). RESULTS: Flat panel detector radiographs were rated superior with respect to cortical and trabecular bone representation as well as fracture evaluation, while storage phosphor radiographs produced better soft tissue detail. CONCLUSION: In some of the observed image quality aspects, the performance of caesium iodide/amorphous silicon flat panel detector exceeds state of the art storage phosphor radiography. This makes it well suited for skeletal imaging particularly in trauma as seen in the detection of wrist fractures. Peer, S. et al. (2002)

Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope.

Science.gov (United States)

den Engelsen, Daniel; Harris, Paul G; Ireland, Terry G; Fern, George R; Silver, Jack

2015-10-01

Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Uranium recovery from the concentrated phosphoric acid prepared by the hemi-hydrate process

Energy Technology Data Exchange (ETDEWEB)

Fouad, E A; Mahdy, M A; Bakr, M Y [Nuclear materials authority, Cairo, (Egypt); Zatout, A A [Faculty of engineering, Alex. university, Alex, (Egypt)

1995-10-01

It has been proved that the uranium dissolution from El-sebaiya phosphate ore was possible by using 10 Kg of K Cl O{sub 4}/ ton rock during the preparation of high strength phosphoric acid using the hemi hydrate process. In the present work, effective extraction of uranium (about 90%) from the high strength phosphoric acid using a new synergistic solvent mixture of 0.75 M D 2 EHPA/0.1 M TOHPO had been a success. Stripping of uranium from the organic phase was possible by 10 M phosphoric acid while the direct precipitation of uranium concentrate from the later was feasible by using N H{sub 4} F in presence of acetone. 8 figs.

Uranium recovery from the concentrated phosphoric acid prepared by the hemi-hydrate process

International Nuclear Information System (INIS)

Fouad, E.A.; Mahdy, M.A.; Bakr, M.Y.; Zatout, A.A.

1995-01-01

It has been proved that the uranium dissolution from El-sebaiya phosphate ore was possible by using 10 Kg of K Cl O 4 / ton rock during the preparation of high strength phosphoric acid using the hemi hydrate process. In the present work, effective extraction of uranium (about 90%) from the high strength phosphoric acid using a new synergistic solvent mixture of 0.75 M D 2 EHPA/0.1 M TOHPO had been a success. Stripping of uranium from the organic phase was possible by 10 M phosphoric acid while the direct precipitation of uranium concentrate from the later was feasible by using N H 4 F in presence of acetone. 8 figs

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.

Red carbon dots-based phosphors for white light-emitting diodes with color rendering index of 92.

Science.gov (United States)

Zhai, Yuechen; Wang, Yi; Li, Di; Zhou, Ding; Jing, Pengtao; Shen, Dezhen; Qu, Songnan

2018-05-29

Exploration of solid-state efficient red emissive carbon dots (CDs) phosphors is strongly desired for the development of high performance CDs-based white light-emitting diodes (WLEDs). In this work, enhanced red emissive CDs-based phosphors with photoluminescence quantum yields (PLQYs) of 25% were prepared by embedding red emissive CDs (PLQYs of 23%) into polyvinyl pyrrolidone (PVP). Because of the protection of PVP, the phosphors could preserve strong luminescence under long-term UV excitation or being mixed with conventional packaging materials. By applying the red emissive phosphors as the color conversion layer, WLEDs with high color rendering index of 92 and color coordinate of (0.33, 0.33) are fabricated. Copyright © 2018 Elsevier Inc. All rights reserved.

Potential tunable white-emitting phosphor LiSr4(BO3)3:Ce3+, Eu2+ for ultraviolet light-emitting diodes

International Nuclear Information System (INIS)

Wang Qian; Deng Degang; Hua Youjie; Huang Lihui; Wang Huanping; Zhao Shilong; Jia Guohua; Li Chenxia; Xu Shiqing

2012-01-01

A novel Ce 3+ /Eu 2+ co-activated LiSr 4 (BO 3 ) 3 phosphor has been synthesized by traditional solid-state reaction. The samples could display varied color emission from blue towards white and ultimately to yellow under the excitation of ultraviolet (UV) light with the appropriate adjustment of the relative proportion of Ce 3+ /Eu 2+ . The resonance-type energy transfer mechanism from Ce 3+ to Eu 2+ in LiSr 4 (BO 3 ) 3 :Ce 3+ , Eu 2+ phosphors is dominant by electric dipole–dipole interaction, and the critical distance is calculated to be about 29.14 Å by the spectra overlap method. White light was observed from LiSr 4 (BO 3 ) 3 :mCe 3+ , nEu 2+ phosphors with chromaticity coordinates (0.34, 0.30) upon 350 nm excitation. The LiSr 4 (BO 3 ) 3 :Ce 3+ , Eu 2+ phosphor has potential applications as an UV radiation-converting phosphor for white light-emitting diodes. - Highlights: ► White light was observed from the novel phosphor with chromaticity coordinate (0.34, 0.30). ► Resonant energy transfer between Ce 3+ and Eu 2+ occurs in the novel phosphor. ► This novel phosphor has potential applications as a UV-driven light-emitting phosphor.

A Study of Clay-Epoxy Nanocomposites Consisting of Unmodified Clay and Organo Clay

Directory of Open Access Journals (Sweden)

Graham Edward

2006-04-01

Full Text Available Clay-epoxy nanocomposites were synthesized from DGEBA resin and montmorillonite clay with an in-situ polymerization. One type of untreated clay and two types of organo clay were used to produce the nanocompsoites. The aims of this study were to examine the nanocomposite structure using different tools and to compare the results between the unmodified clay and modified clays as nanofillers. Although diffractogram in reflection mode did not show any apparent peak of both types of materials, the transmitted XRD (X-Ray Difraction graphs, DSC (Differential Scanning Calorimeter analysis and TEM (Transmission Electron Microscope images revealed that the modified clay-epoxy and unmodified clay-epoxy provides different results. Interestingly, the micrographs showed that some of the modified clay layers possessed non-exfoliated layers in the modified clay-epoxy nanocomposites. Clay aggregates and a hackle pattern were found from E-SEM images for both types of nanocomposite materials. It is shown that different tools should be used to determine the nanocomposite structure.

Investigation on photoluminescence, electrical and positron lifetime of Eu"3"+ activated Gd_2O_3 phosphors

International Nuclear Information System (INIS)

Selvalakshmi, Thangaraj; Sellaiyan, Selvakumar; Uedono, Akira; Chandra Bose, Arumugam

2015-01-01

In the present study, red emitting Gd_2O_3:Eu"3"+ phosphors are prepared by citrate-based sol–gel process and the as-prepared samples are annealed at various annealing temperatures. The photoluminescence properties of Gd_2O_3:Eu"3"+ is explained from the excitation and emission spectra. The excitation spectra include peaks corresponding to charge transfer and 4f–4f transitions of Eu"3"+ and Gd"3"+. The phosphors exhibit a weak energy transfer process from Gd"3"+ to Eu"3"+. Under the excitation of 254 nm, a sharp red emission peak is observed at 611 nm and the emission intensity increases with the annealing temperature. The presence of defects in the phosphor is investigated by positron annihilation lifetime and Doppler broadening spectroscopy. The relation between visible emission and lattice defects of the phosphors is presented. The electrical and dielectric properties of the phosphor are also discussed in detail. Such red emitting phosphors pave the way towards the fabrication of light emitting diodes (LEDs). - Highlights: • Positron annihilation lifetime spectroscopy of Gd_2O_3:Eu"3"+. • Relation between positron lifetime and photoluminescence. • Conductivity and dielectric properties of Gd_2O_3:Eu"3"+.

X-ray image converters utilizing rare earth phosphor mixtures

International Nuclear Information System (INIS)

Rabatin, J.G.

1982-01-01

In an X-ray screen comprising a transparent support with a photographic film on each side, each film has a coating of a phosphor mixture comprising polyhedral Gd 2 O 2 S:Tb of average size 6 to 20 μ and plate-like LnOX:Tm of average size 2 to 12 μ wherein Ln=La or Gd, X=Cl or Br and Tm is present from 0.05 to 1 mole %. The mixture gives improved resolution and reduces the problem of light crossing over the transparent support. According to whether blue sensitive or green sensitive film is used, the ratio of phosphors is varied. U.V. absorbing and light reflecting layers may be incorporated in the structure. (author)

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.

Effect of temperature during UV and gamma irradiations of TL phosphor CaSO4:Dy

International Nuclear Information System (INIS)

Nagpal, J.S.; Pendurkar, H.K.

1979-01-01

Temperature is an important parameter in thermoluminescence studies. Irradiation at enhanced temperatures reduces the γ response of TL phosphor CaSO 4 :Dy. However, in the presence of fluorescent lights, the γ response of the phosphor is enhanced by approximately 20% for temperatures around 60-100 0 C. If the phosphor temperature during UV exposure is kept high, the integrated TL output continues to increase until it reaches 18 times at 160 0 C as compared to that produced by UV exposure at room temperature. (Auth.)

Phosphoric acid fuel cell R and D activities at KACST

International Nuclear Information System (INIS)

Ghouse, M.; Aba-Oud, H.; Ba-Junaid, M.; Al-Garni, M.; Quadri, M.I.

1993-01-01

The PAFC (Phosphoric Acid Fuel Cell) activities are directed towards the development of components of single cell and experimental stacks at KACST. The main aim of the present task is to design and construct a 1 kW PAFC Stack and demonstrate it by integrating with an electrolyser using a DC current generated by a photovoltaic power source. This paper describes the preparation of porous teflon bonded gas diffusion carbon electrodes and their evaluation as single phosphoric acid fuel cells using hydrogen as a fuel and oxygen/air as an oxidant. 6 figs., 2 tabs., 15 refs

Properties of precipitates formed during ammonization of extractional phosphoric acid

International Nuclear Information System (INIS)

Zakharova, B.S.; Komissarova, L.N.; Naumov, S.V.; Traskin, V.Yu.

1992-01-01

Dimensions of precipitated rare-earth phosphate particles -(0.1 μm)- are near the boundary of colloidal system sedimentation stability range at neutralization of extraction phosphoric acid. Thus, formation of multiple aggregates of colloidal particles results in immediate sedimentation of the precipitate. Processes occurring within the system may be described using second order reaction equation. Average efficient size of precipitates grows at reduction of reaction mixture pH. About 30% of rare-earth elements and yttrium in the extraction phosphoric acid is extracted from it; concentration of rare-earth elements, yttrium and scandium in precipitate is maximum 2 mass. %

UV and VUV characteristics of (YGd)2O3:Eu phosphor particles prepared by spray pyrolysis from polymeric precursors

International Nuclear Information System (INIS)

Kim, E.J.; Kang, Y.C.; Park, H.D.; Ryu, S.K.

2003-01-01

Red-emitting (YGd) 2 O 3 :Eu phosphor particles, with high luminescence efficiency under vacuum ultraviolet (VUV) and ultraviolet (UV) excitation, were prepared by a large-scale spray pyrolysis process. To control the morphology of phosphor particles under severe preparation conditions, spray solution with polymeric precursors were introduced in spray pyrolysis. The prepared (YGd) 2 O 3 :Eu phosphor particles had spherical shape and filled morphology even after post-treatment irrespective of Gd/Y ratio. In the case of solution with polymeric precursors, long polymeric chains formed by esterification reaction in a hot tubular reactor; the droplets turned into viscous gel, which retarded the precipitation of nitrate salts and promoted the volume precipitation of droplets. The brightness of (YGd) 2 O 3 :Eu phosphor particles increased with increasing gadolinium content, and the Gd 2 O 3 :Eu phosphor had the highest luminescence intensity under UV and VUV excitation. The maximum peak intensity of Gd 2 O 3 :Eu phosphor particles under UV and VUV were 118 and 110% of the commercial Y 2 O 3 :Eu phosphor particles, respectively

Rapid synthesis of spherical-shaped green-emitting MgGa2O4:Mn2+ phosphor via spray pyrolysis

International Nuclear Information System (INIS)

Choi, Sungho; Kim, Kyoungun; Moon, Young-Min; Park, Byung-Yoon; Jung, Ha-Kyun

2010-01-01

Simple, one-step synthesis of spherical-shaped powder phosphors with aqueous precursors via a spray pyrolysis method is reported. Green-emitting MgGa 2 O 4 :Mn 2+ phosphor with a controlled shape was successfully obtained by spraying under a reductive atmosphere (N 2 + H 2 carrier gas) without high-temperature post-heat treatment. In addition, the corresponding powder phosphors were well dispersed and showed a clean surface morphology compared to an existing cumbersome process using high-temperature post-annealing. The new method may help to prevent surface residual non-radiative defect sites. The result of highly luminescent and spherical morphology, non-aggregated powder phosphor by this procedure holds promise for a cost-effective and rapid synthesis process for conventional inorganic phosphors.

Incompatibility of sensitisation and re-estimation of lithium fluoride thermoluminescent phosphor

International Nuclear Information System (INIS)

Bartlett, D.T.; Sandford, D.J.

1978-01-01

A technique of useful sensitisation of lithium fluoride thermoluminescent phosphor has been reported by Mayhugh and Fullerton, (USAEC Report COO-1105-209, 1974). This technique differs from that previously described (Cameron and Zimmerman, USAEC Report COO-1105-102, 1965) in that during the anneal at 300 degrees C which follows the high pre-dose, the phosphor is simultaneously exposed to 254 nm ultraviolet light. It is reported that this method removes interfering centres and hence reduces the lowest detectable dose. Sensitisation also has the advantages of improved tissue equivalence and increased range of linearity. However, a disadvantage of both techniques of sensitisation is that for sensitised phosphor, absorbed doses cannot be re-estimated by photo-transferred thermoluminescence. Results are compared for discs of lithium fluoride in PTFE, some of which were sensitised by each method, and some left unsensitised. It is concluded that for routine personal dosimetry the disadvantages of the loss of the facility to re-estimate absorbed dose outweighs the reported advantages of sensitisation. (author)

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

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.

Design analysis of phosphor-free monolithic white light-emitting-diodes with InGaN/ InGaN multiple quantum wells on ternary InGaN substrates

Directory of Open Access Journals (Sweden)

Yu Kee Ooi

2015-05-01

Full Text Available Phosphor-free monolithic white light emitting diodes (LEDs based on InGaN/ InGaN multiple quantum wells (MQWs on ternary InGaN substrates are proposed and analyzed in this study. Simulation studies show that LED devices composed of multi-color-emitting InGaN/ InGaN quantum wells (QWs employing ternary InGaN substrate with engineered active region exhibit stable white color illumination with large output power (∼ 170 mW and high external quantum efficiency (EQE (∼ 50%. The chromaticity coordinate for the investigated monolithic white LED devices are located at (0.30, 0.28 with correlated color temperature (CCT of ∼ 8200 K at J = 50 A/cm2. A reference LED device without any nanostructure engineering exhibits green color emission shows that proper engineered structure is essential to achieve white color illumination. This proof-of-concept study demonstrates that high-efficiency and cost-effective phosphor-free monolithic white LED is feasible by the use of InGaN/ InGaN MQWs on ternary InGaN substrate combined with nanostructure engineering, which would be of great impact for solid state lighting.

Design analysis of phosphor-free monolithic white light-emitting-diodes with InGaN/ InGaN multiple quantum wells on ternary InGaN substrates

Energy Technology Data Exchange (ETDEWEB)

Ooi, Yu Kee, E-mail: Yu.Kee.Ooi@rit.edu; Zhang, Jing, E-mail: Jing.Zhang@rit.edu [Department of Electrical and Microelectronics Engineering, Rochester Institute of Technology, Rochester, New York 14623 (United States)

2015-05-15

Phosphor-free monolithic white light emitting diodes (LEDs) based on InGaN/ InGaN multiple quantum wells (MQWs) on ternary InGaN substrates are proposed and analyzed in this study. Simulation studies show that LED devices composed of multi-color-emitting InGaN/ InGaN quantum wells (QWs) employing ternary InGaN substrate with engineered active region exhibit stable white color illumination with large output power (∼ 170 mW) and high external quantum efficiency (EQE) (∼ 50%). The chromaticity coordinate for the investigated monolithic white LED devices are located at (0.30, 0.28) with correlated color temperature (CCT) of ∼ 8200 K at J = 50 A/cm{sup 2}. A reference LED device without any nanostructure engineering exhibits green color emission shows that proper engineered structure is essential to achieve white color illumination. This proof-of-concept study demonstrates that high-efficiency and cost-effective phosphor-free monolithic white LED is feasible by the use of InGaN/ InGaN MQWs on ternary InGaN substrate combined with nanostructure engineering, which would be of great impact for solid state lighting.

The Bio-accessibility of Synthetic Fe-Organo Complexes in Subsurface Soil with Elevated Temperature: a Proxy for the Vulnerability of Mineral Associated Carbon to Warming Rachel C. Porras, Peter S. Nico, and Margaret Torn Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA

Science.gov (United States)

Porras, R. C.; Hicks Pries, C.

2015-12-01

Globally, subsurface soils (>30 cm) represent an important reservoir of soil organic carbon (SOC). However, the vulnerability of this deep SOC and, in particular mineral-associated SOC, to warming, and its potential to amplify the effects of climate change is highly uncertain. To gain insight into the bio-accessibility and temperature sensitivity of mineral-associated organic C, we conducted a series of incubations using soils collected from three depths (0-10, 50-60, and 80-90 cm) under coniferous forest. The soils are moderately acidic (mean pH=6.5) sandy, mixed, mesic Ultic Haploxeralfs. To understand how mechanisms controlling SOC bio-accessibilty or temperature sensitivity differ with depth and with the properties of Fe-organo complexes (i.e.,degree of crystallinity, amount of reactive surface area, or surface saturation), we used a 13C labeled glucose substrate to prepare synthetic Fe-organo complexes spanning a range of crystallinity and mineral surface saturation. The synthetic Fe-organo complexes were then added to soil from three depths. The soils containing the 13C labeled Fe-organo adduct were incubated at two temperatures (ambient and +4°C) and respired 13CO2 was measured and used to estimate flux rates. Differences in measured 13CO2 fluxes as a function of depth, surface loading, and mineral properties are discussed in terms of their implications for the temperature sensitivity of mineral protected organic carbon in subsurface soils.

Pattern Recognition of the Presence and Distribution of Organo chlorine Pesticides in Sediment of Cameron Highlands, Malaysia

International Nuclear Information System (INIS)

Md Pauzi Abdullah; Naghmeh Saadati; Wan Mohd Afiq Wan Mohd Khalik

2015-01-01

This study aimed to assess the environmental situation of 18 organo chlorine pesticides (OCPs), of which some are members of Persistent Organic Pollutants (POPs) in the sediment of an intensive agriculture area as well as popular tourism destination of Cameron Highlands, Malaysia. A total of 56 surface sediment samples were collected at eight selected sampling points along the two main rivers in the area namely Telom and Bertam Rivers during the dry and wet seasons in 2011. The OCPs levels detected were between 0.41 - 82.16 (mean of 21.33 ± 18.54) ng/ g of dry weight. A total of 15 OCPs namely 4,4' DDT, 4,4' DDD, 4,4' DDE, γ-HCH, β- HCH, aldrin, dieldrin, endrin, endosulfan I, endosulfan II endosulfan sulfate, heptachlor and heptachlor epoxide were detected in all sediment samples. Multivariate analysis of the 15 detected OCPs with respect to the type of land-use shows that endosulfan I was found around the tea plantation areas; γ-HCH was found near vegetable plantation areas; 4,4 ' DDE and aldrin were found near Blue Valley station; and endrin, heptachlor, 4,4 ' DDD, 4,4 ' DDT, and heptachlor epoxide were found in the nearby villages. Four clusters (C1; 1, C2; 1, C3; 2 and C4; 4 stations) were generated using a cluster analysis method. Four latent factors (74.36 % of total variance) were identified by principle component and factor analysis method. Three classifications namely tea plantations, vegetable plantations, and villages provide 83.90 % of the composition pattern of 15 OCPs, whereas 3 OCPs are significant components in discriminating organo chlorine pesticides contamination detected in sediment samples. Pollutants seemed to enter the river through the run-off from agricultural areas and villages. HCH isomer (β-HCH) was mostly found in the downstream stations of the rivers. (author)

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).

Application of a precipitation method for uranium recovery from Abu-Zaabal phosphoric acid plant, egypt

International Nuclear Information System (INIS)

El-Hazek, N.M.T.; Hussein, E.M.

1997-01-01

Current industrial recovery of uranium from 30% phosphoric acid-produced by the dihydrate process-is based on solvent extraction method. Uranium recovery from concentrated phosphoric acid (45-52% P 2 O 5 ) produced by evaporation of the 30% acid or directly produced by the hemihydrate process, by solvent extraction is difficult to apply in practice. In addition to possible contamination of the acid by the organic solvents and/or their deterioration. This paper investigates the possibility of applying a precipitation method (Weterings and Janssen, 1985) for uranium recovery from both low (28% P 2 O 2 ) and high (48% P 2 O 5 ) concentration phosphoric acids produced by abu-Zaabal phosphoric acid plant (abu-Zaabal fertilizers and chemicals Co., Egypt). The 28% acid produced by H 2 SO 4 dihydrate method and the 48% acid produced by evaporation of the 28% acid

Analysis of green luminescent Tb3+:Ca4GdO(BO3)3 powder phosphor

International Nuclear Information System (INIS)

Vengala Rao, B.; Rambabu, U.; Buddhudu, S.

2007-01-01

This paper reports on the emission analysis of a green luminescent Tb 3+ :Ca 4 GdO(BO 3 ) 3 powder phosphor based on the measurements of excitation, emission and lifetimes. Besides this, we have also observed an intense green emission from this powder phosphor under an UV source. The emission transitions of ( 5 D 4 →7 F 3,4,5,6 ) with λ exci =257 nm have been measured. Particularly, the green emission transition ( 5 D 4 →7 F 5 ) at 553 nm has been found to be more prominent and intense. Such green strong emission displaying powder phosphor will find applications in the development of coated screens in certain electronic systems. Apart from the emission analysis of this phosphor, XRD, SEM and FTIR studies have also been carried out in order to understand the structural details of it

Nanopatterned yttrium aluminum garnet phosphor incorporated film for high-brightness GaN-based white light emitting diodes

International Nuclear Information System (INIS)

Cho, Joong-yeon; Park, Sang-Jun; Ahn, Jinho; Lee, Heon

2014-01-01

In this study, we fabricated high-brightness white light emitting diodes (LEDs) by developing a nanopatterned yttrium aluminum garnet (YAG) phosphor-incorporated film. White light can be obtained by mixing blue light from a GaN-based LED and yellow light of the YAG phosphor-incorporated film. If white light sources can be fabricated by exciting proper yellow phosphor using blue light, then these sources can be used instead of the conventional fluorescent lamps with a UV source, for backlighting of displays. In this work, a moth-eye structure was formed on the YAG phosphor-incorporated film by direct spin-on glass (SOG) printing. The moth-eye structures have been investigated to improve light transmittance in various optoelectronic devices, including photovoltaic solar cells, light emitting diodes, and displays, because of their anti-reflection property. Direct SOG printing, which is a simple, easy, and relatively inexpensive process, can be used to fabricate nanoscale structures. After direct SOG printing, the moth-eye structure with a diameter of 220 nm was formed uniformly on the YAG phosphor-incorporated film. As a result of moth-eye patterning on the YAG phosphor-incorporated film, the light output power of a white LED with a patterned YAG phosphor-incorporated film increased to up to 13% higher than that of a white LED with a non-patterned film. - Highlights: • GaN-based high-brightness white LED was prepared using patterned YAG phosphor-incorporated films. • Direct hydrogen silsesquioxane printing was used to form moth-eye patterns on the YAG films. • The electroluminescence intensity of the white LED was enhanced by up to 14.9%

Nanopatterned yttrium aluminum garnet phosphor incorporated film for high-brightness GaN-based white light emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Cho, Joong-yeon; Park, Sang-Jun [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Ahn, Jinho, E-mail: jhahn@hanyang.ac.kr [Department of Material Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Heon, E-mail: heonlee@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

2014-11-03

In this study, we fabricated high-brightness white light emitting diodes (LEDs) by developing a nanopatterned yttrium aluminum garnet (YAG) phosphor-incorporated film. White light can be obtained by mixing blue light from a GaN-based LED and yellow light of the YAG phosphor-incorporated film. If white light sources can be fabricated by exciting proper yellow phosphor using blue light, then these sources can be used instead of the conventional fluorescent lamps with a UV source, for backlighting of displays. In this work, a moth-eye structure was formed on the YAG phosphor-incorporated film by direct spin-on glass (SOG) printing. The moth-eye structures have been investigated to improve light transmittance in various optoelectronic devices, including photovoltaic solar cells, light emitting diodes, and displays, because of their anti-reflection property. Direct SOG printing, which is a simple, easy, and relatively inexpensive process, can be used to fabricate nanoscale structures. After direct SOG printing, the moth-eye structure with a diameter of 220 nm was formed uniformly on the YAG phosphor-incorporated film. As a result of moth-eye patterning on the YAG phosphor-incorporated film, the light output power of a white LED with a patterned YAG phosphor-incorporated film increased to up to 13% higher than that of a white LED with a non-patterned film. - Highlights: • GaN-based high-brightness white LED was prepared using patterned YAG phosphor-incorporated films. • Direct hydrogen silsesquioxane printing was used to form moth-eye patterns on the YAG films. • The electroluminescence intensity of the white LED was enhanced by up to 14.9%.

Uranium recovery from wet process phosphoric acid

International Nuclear Information System (INIS)

Carrington, O.F.; Pyrih, R.Z.; Rickard, R.S.

1981-01-01

Improvement in the process for recovering uranium from wetprocess phosphoric acid solution derived from the acidulation of uraniferous phosphate ores by the use of two ion exchange liquidliquid solvent extraction circuits in which in the first circuit (A) the uranium is reduced to the uranous form; (B) the uranous uranium is recovered by liquid-liquid solvent extraction using a mixture of mono- and di-(Alkyl-phenyl) esters of orthophosphoric acid as the ion exchange agent; and (C) the uranium oxidatively stripped from the agent with phosphoric acid containing an oxidizing agent to convert uranous to uranyl ions, and in the second circuit (D) recovering the uranyl uranium from the strip solution by liquid-liquid solvent extraction using di(2ethylhexyl)phosphoric acid in the presence of trioctylphosphine oxide as a synergist; (E) scrubbing the uranium loaded agent with water; (F) stripping the loaded agent with ammonium carbonate, and (G) calcining the formed ammonium uranyl carbonate to uranium oxide, the improvement comprising: (1) removing the organics from the raffinate of step (B) before recycling the raffinate to the wet-process plant, and returning the recovered organics to the circuit to substantially maintain the required balance between the mono and disubstituted esters; (2) using hydogren peroxide as the oxidizing agent in step (C); (3) using an alkali metal carbonate as the stripping agent in step (F) following by acidification of the strip solution with sulfuric acid; (4) using some of the acidified strip solution as the scrubbing agent in step (E) to remove phosphorus and other impurities; and (5) regenerating the alkali metal loaded agent from step (F) before recycling it to the second circuit

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.

Semitechnical studies of uranium recovery from wet process phosphoric acid by liquid-liquid-extraction method

International Nuclear Information System (INIS)

Poczynajlo, A.; Wlodarski, R.; Giers, M.

1987-01-01

A semitechnical installation for uranium recovery from wet process phosphoric acid has been built. The installation is based on technological process comprising 2 extraction cycles, the first with a mixture of mono- and dinonylphenylphosphoric acids (NPPA) and the second with a synergic mixture of di-/2-ethylhexyl/-phosphoric acid (D2EHPA) and trioctylphosphine oxide (TOPO). The installation was set going and the studies on the concentration distributions of uranium and other components of phosphoric acid have been performed for all technological circuits. 23 refs., 15 figs., 3 tabs. (author)

Solid-state actinide acid phosphites from phosphorous acid melts

International Nuclear Information System (INIS)

Oh, George N.; Burns, Peter C.

2014-01-01

The reaction of UO 3 and H 3 PO 3 at 100 °C and subsequent reaction with dimethylformamide (DMF) produces crystals of the compound (NH 2 (CH 3 ) 2 )[UO 2 (HPO 2 OH)(HPO 3 )]. This compound crystallizes in space group P2 1 /n and consists of layers of uranyl pentagonal bipyramids that share equatorial vertices with phosphite units, separated by dimethylammonium. In contrast, the reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup. Subsequent dilution in solvents and use of standard solution-state methods results in the crystallization of two polymorphs of the actinide acid phosphites An(HPO 2 OH) 4 (An=U, Th) and of the mixed acid phosphite–phosphite U(HPO 3 )(HPO 2 OH) 2 (H 2 O)·2(H 2 O). α- and β-An(HPO 2 OH) 4 crystallize in space groups C2/c and P2 1 /n, respectively, and comprise a three-dimensional network of An 4+ cations in square antiprismatic coordination corner-sharing with protonated phosphite units, whereas U(HPO 3 )(HPO 2 OH) 2 (H 2 O) 2 ·(H 2 O) crystallizes in a layered structure in space group Pbca that is composed of An 4+ cations in square antiprismatic coordination corner-sharing with protonated phosphites and water ligands. We discuss our findings in using solid inorganic reagents to produce a solution-workable precursor from which solid-state compounds can be crystallized. - Graphical abstract: Reaction of UO 3 and H 3 PO 3 at 100 °C and subsequent reaction with DMF produces crystals of (NH 2 (CH 3 ) 2 )[UO 2 (HPO 2 OH)(HPO 3 )] with a layered structure. Reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup and further solution-state reactions result in the crystallization of the actinide acid phosphites An(HPO 2 OH) 4 (An=U, Th), with a three-dimensional network structure, and the mixed acid phosphite–phosphite U(HPO 3 )(HPO 2 OH) 2 (H 2 O) 2 ·(H 2 O) with a layered structure. - Highlights: • U(VI), U(IV) and Th(IV) phosphites were synthesized by solution

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)

Bluish-green color emitting Ba2Si3O8:Eu2+ ceramic phosphors for white light-emitting diodes.

Science.gov (United States)

Xiao, F; Xue, Y N; Zhang, Q Y

2009-10-15

This paper reports on the structural and optical properties of Eu(2+) activated Ba(2)Si(3)O(8) ceramic phosphors synthesized by a sol-gel method. The ceramic phosphors have been characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and fluorescence measurements. The structural characterization results suggest that the as-prepared phosphors are of single phase monoclinic Ba(2)Si(3)O(8) with rod-like morphology. A broad excitation band ranging from 300 to 410 nm matches well with the ultraviolet (UV) radiation of light-emitting diodes (LEDs). Upon 380 nm UV light excitation, these phosphors emit bluish-green emission centered at 500 nm with color coordination (x=0.25, y=0.40). All the obtained results indicate that the Ba(2)Si(3)O(8):Eu(2+) ceramic phosphors are promising bluish-green candidates for the phosphor-converted white LEDs.

Formulation and characterization of polyethylenes and organo-clays. Barrier properties of the obtained nano-composites; Formulation et caracterisation de polyethylenes charges avec des argiles. Proprietes barriere des nanocomposites obtenus

Energy Technology Data Exchange (ETDEWEB)

Wache, R

2004-10-01

The particularity of polymer layered silicate nano-composites is based on the exfoliation of the clay platelets in the polymer matrix. Therefore properties may be dramatically modified with very low clay loading. In this work polyethylene and organo-clay have been melt blended. Due to a lack of polarity, the polymer chains do not intercalate the clay stacking. However exfoliation is achieved using maleate polyethylene. We used this polymer as a compatibilizer to promote clay exfoliation in the polyethylene matrix. Partial exfoliation is obtained. Barrier properties of these materials have been characterized. Permeability is higher for the clay reinforced products than their matrix. To understand the poor permeability results a tortuosity model has been developed. The quality of the interface seems to be involved. Several organo-clays and compatibilizers have been tested to improve it. But for the concentrations of these products used polyethylene clay interactions always exist and lead to an increase of diffusion. (author)

Green synthetic strategy of BCNO nanostructure and phosphor-based light – Emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Kang, Yue [The Quartermaster Research Institute of General Logistics Department, Beijing 100010 (China); Yuan, Bo [Chemical Defense Institute of China, Beijing 100010 (China); Zhang, Dongjiu [Key Laboratory of Space Launching Site Reliability Technology, Hainan 570100 (China); Ma, Tian; Huang, Xiancong [The Quartermaster Research Institute of General Logistics Department, Beijing 100010 (China); Chu, Zengyong [College of Science, National University of Defense Technology, Changsha 410073 (China); Lai, Kan [The Quartermaster Research Institute of General Logistics Department, Beijing 100010 (China)

2016-11-15

BCNO phosphor has been paid much attention due to their unique physical, electronic and optical properties. Here we have successfully obtained BCNO nano-particle phosphor by microwave treating from boric acid, urea, and glucose at low temperatures and in short reaction time. Glucose decomposed into graphene quantum dots (GQDs), which facilitated the formation of hexagonal boron nitride (h-BN). Through our method, GQDs domains were uniformly incorporated into h-BN, leading to the formation of BCNO and decrease of bandgap. BCNO demonstrated excellent performance in light emitting diodes (LEDs) with green and blue light. We envision that this BCNO phosphor will enable the next generation blue and green LED devices due to the easiness of large scale fabrication at an economic cost.

Green synthetic strategy of BCNO nanostructure and phosphor-based light – Emitting diodes

International Nuclear Information System (INIS)

Kang, Yue; Yuan, Bo; Zhang, Dongjiu; Ma, Tian; Huang, Xiancong; Chu, Zengyong; Lai, Kan

2016-01-01

BCNO phosphor has been paid much attention due to their unique physical, electronic and optical properties. Here we have successfully obtained BCNO nano-particle phosphor by microwave treating from boric acid, urea, and glucose at low temperatures and in short reaction time. Glucose decomposed into graphene quantum dots (GQDs), which facilitated the formation of hexagonal boron nitride (h-BN). Through our method, GQDs domains were uniformly incorporated into h-BN, leading to the formation of BCNO and decrease of bandgap. BCNO demonstrated excellent performance in light emitting diodes (LEDs) with green and blue light. We envision that this BCNO phosphor will enable the next generation blue and green LED devices due to the easiness of large scale fabrication at an economic cost.

Extraction of uranium from phosphoric-hydrobromic acid mixture by N-lauryl tri alkyl methylamine

Energy Technology Data Exchange (ETDEWEB)

Guirguis, L A [Nuclear materials authority, Cairo, (Egypt); Tadros, N A [Hot laboratories center, atomic energy authority, Cairo, (Egypt)

1995-10-01

A uranium recovery process from phosphoric acid produced by the dihydrate method was elaborated. Decomposition of phosphate rock containing 0.02% U is carried out with sulphuric acid. Crude phosphoric acid is filtered off, steam concentrated to 45% P{sub 2} O{sub 5} (6.27 M) and then clarified with activated clay and carbon. The clear phosphoric acid is introduced to uranium extraction after the addition of 0.88 M hydrobromic acid by 0.134 M amberlite LA.2 and 5% decanol, as a modifier, in kerosene. While 10% ammonium sulphate solution is used for stripping. Over 90% uranium recovery is obtained. 6 figs., 1 tab.

Moisture Absorption Behaviour of Biopolymer Polycapralactone (PCL) / Organo Modified Montmorillonite Clay (OMMT) biocomposite films

Science.gov (United States)

Malik, Neetu; Shrivastava, Sharad; Bandhu Ghosh, Subrata

2018-04-01

Bio composite materials were fabricated using mixing biodegradable polymer polycaptalactone (PCL) and Organo Modified Montmorillonite Clay (OMMT) through solution casting. Various samples of bio composite films were prepared by varying the OMMT wt% composition by 0.1%, 0.5%, 1% and 1.5%. Thereafter, the density and water absorption of the composites were investigated with respect to immersion time in water. The moisture absorption results show that with an increase in weight percentage (from 0.1 to wt 1.5%) of OMMT within the bio polymer films, the absorption value of bio-nanocomposite films reduced rapidly from 34.4% to 22.3%. The density of hybrid composites also increased with increase in weight percentage of OMMT. The swelling characteristic of PCL increased with increasing % of OMMT clay. These results indicate that the optimized composition of constituents in composite membrane could effectively reduce the anhydrous conditions of bio-composite film.

Coupling of terminal alkynes and isonitriles by organo-actinide complexes: Scope and mechanistic insights

International Nuclear Information System (INIS)

Barnea, E.; Andrea, T.; Eisen, M. S.; Berthet, J.C.; Ephritikhine, M.

2008-01-01

The coupling reaction of terminal alkynes with several isonitriles, catalyzed by the neutral organo-actinide complexes Cp * 2 AnMe 2 (Cp * = C 5 Me 5 , An = Th, U) or the cationic complex [(Et 2 N) 3 U][BPh 4 ], yielded substituted α, β-acetylenic aldimines, in good to excellent yields. The reaction proceeded via a 1,1-insertion of the isonitrile carbon into a metal-acetylide bond, followed by a protonolysis by the acidic proton of the terminal alkyne. Additional insertion products were obtained by altering the catalyst and the reactant ratios. A plausible mechanism for the catalytic reaction is also presented, based on kinetics measurements and thermodynamic studies of the coupling reaction with Cp * 2 ThMe 2 or [(Et 2 N) 3 U][BPh 4 ] as catalysts. The reaction is first-order in catalyst and isonitrile and zero-order in alkyne. (authors)

Synthesis and photoluminescence study of rare earth activated phosphor Na2La2B2O7

International Nuclear Information System (INIS)

Nagpure, P.A.; Omanwar, S.K.

2012-01-01

The photoluminescence properties in UV and N-UV excitable range for the phosphors of Na 2 La 2 B 2 O 7 : RE (RE=Eu, Tb, Ce, Sm, Gd) are investigated. The solution combustion synthesis technique was employed for the synthesis of the phosphors Na 2 La 2 B 2 O 7 : RE. The photoluminescence measurements of the phosphors were carried out on a HITACHI F7000 Fluorescence Spectrophotometer. The PL and PL excitation (PLE) spectra indicate that the main emission wavelength of Na 2 La 2 B 2 O 7 : Eu are 591 and 615 nm, Na 2 La 2 B 2 O 7 : Ce shows dominating emission peak at 387 nm and Na 2 La 2 B 2 O 7 : Tb displays green emission at 493, 544, 593 and 620 nm at 254 nm excitation, while Na 2 La 2 B 2 O 7 : Sm shows the main emission peak wavelengths 566 and 604 nm at 405 nm excitation and Na 2 La 2 B 2 O 7 : Gd shows dominating emission peak at 312 nm at 274 nm excitation. These phosphors may provide a new kind of luminescent materials under ultraviolet and near ultraviolet excitation for various applications. - Highlights: ► We use the combustion technique for synthesis of Na 2 La 2 B 2 O 7 : RE phosphor. ► Phosphor Na 2 La 2 B 2 O 7 : Eu 3+ shows intense red emission under UV excitation. ► Phosphor Na 2 La 2 B 2 O 7 : Tb 3+ shows intense green emission under UV excitation. ► Phosphor Na 2 La 2 B 2 O 7 : Sm 3+ shows orange red emission under near UV excitation. ► Phosphors Na 2 La 2 B 2 O 7 : Ce 3+ and Na 2 La 2 B 2 O 7 : Gd 3+ show near UV and UVB emissions under UV excitation.

Treated Seawater as a Magnesium Source for Phosphorous Recovery from Wastewater—A Feasibility and Cost Analysis

Directory of Open Access Journals (Sweden)

Cejna Anna Quist-Jensen

2016-12-01

Full Text Available Conventional resources of phosphorous are at high risk of depletion in the near future due to current practices of its exploitation, thus new and improved exploration methodologies need to be developed to ensure phosphorous security. Today, some treatment plants recover phosphorous from municipal wastewater as struvite (MgNH4PO4·6H2O. Magnesium is often added to the wastewater as MgCl2·6H2O to facilitate the phosphorous recovery. However, the use of magnesium increases the costs of the process and is not aligned with sustainable development, therefore, alternative magnesium sources have to be found. The current study analyzes the feasibility of integrated membrane processes for magnesium recovery from seawater for utilization in the phosphorous recovery process. The integrated membrane systems consist of nanofiltration (NF, membrane distillation (MD, and membrane crystallization (MCr. The lowest associated cost is found for standalone NF treatment. However, the additional treatment with MD and MCr produces fresh water and salts like NaCl or potentially other valuable minerals at the expense of low-grade heat.

Synthesis and photoluminescence properties of red-emitting Y{sub 6}WO{sub 12}:Eu{sup 3+} phosphors

Energy Technology Data Exchange (ETDEWEB)

Chien, Tzu-Chin; Yang, Ji-Chun; Hwang, Chii-Shyang, E-mail: cshwang@mail.ncku.edu.tw; Yoshimura, Masahiro

2016-08-15

For a system of white-light-emitting diodes (WLEDs) fabricated using near-ultraviolet (UV) LED chips coated with RGB tri-color phosphors, the most important issue is enhancing the efficiency of the red phosphor. Y{sub 6}WO{sub 12}:Eu{sup 3+} phosphor is a potential material that can emit red color under near-UV excitation. This work investigated the luminescence properties of Y{sub 6}WO{sub 12}:Eu{sup 3+} under UV light excitation. The photoluminescence (PL) emission intensity of Eu{sub x}Y{sub 6–x}WO{sub 12} (x = 0.1–1.0) phosphor from the {sup 5}D{sub 0}→{sup 7}F{sub 2} transition increased with Eu{sup 3+} content until x = 0.9. For x > 0.9, the PL emission intensity decreased due to concentration quenching. The decay time of Eu{sub x}Y{sub 6–x}WO{sub 12} (x = 0.1–1.0) phosphor for the {sup 5}D{sub 0}→{sup 7}F{sub 2} transition was about 0.6–0.7 ms and did not decrease obviously, which means that there was no nonradiative energy transfer in the phosphor. The asymmetry ratio ({sup 5}D{sub 0} → {sup 7}F{sub 2}/{sup 5}D{sub 0} → {sup 7}F{sub 1}) of Eu{sub x}Y{sub 6–x}WO{sub 12} (x = 0.1–1.0) was about 2, which caused the PL emission intensity of Eu{sub x}Y{sub 6–x}WO{sub 12} (x = 0.1–1.0) phosphor from the {sup 5}D{sub 0}→{sup 7}F{sub 2} transition to be higher than that from the {sup 5}D{sub 0}→{sup 7}F{sub 1} transition. The chromaticity coordinates of the Eu{sub x}Y{sub 6–x}WO{sub 12} (x = 0.1–1.0) phosphor were close to the chromaticity coordinates of the standard red color. The Eu{sub x}Y{sub 6–x}WO{sub 12} (x = 0.9) phosphor showed the highest quantum efficiency. - Highlights: • Eu{sub x}Y{sub 6–x}WO{sub 12} (x = 0.1–1.0) phosphors were synthesized via a solid-state reaction. • Strongest excitation peaks observed at 392 nm (near UV) and 463 nm (blue). • The major emission peak of the red phosphor excited by 392 nm was at 605 nm. • The quantum efficiency of Eu{sub x}Y{sub 6–x}WO{sub 12} (x = 0.1–1.0) phosphors

Introduction of cooperating conductive components into the phosphor to improve the low voltage cathodoluminescence

International Nuclear Information System (INIS)

Shang, Chun Yu; Kang, Hui; Jiang, Hong Bo; Bu, Shu Po; Shang, Xiao Hong; Wu, Yan

2013-01-01

In order to improve the electric conductivity of Y 2 O 3 :Eu 3+ phosphor with the least amount of conductive component so as to maximize the improvement in low voltage cathodoluminescence, In 2 O 3 and Cu nanowires (NWs) were simultaneously introduced to form Cu NWs/In 2 O 3 -attached Y 2 O 3 :Eu 3+ phosphor. In 2 O 3 and Cu NWs play different roles in the formation of electrically conductive network, i.e., Cu NWs are suitable as conductive channels for charge transmission due to their one-dimensional morphology with large slenderness ratios, while the island-like In 2 O 3 condensates form local conductive contacts joining the adjacent Cu NWs. Meanwhile, In 2 O 3 forms attachment between Cu NWs and the phosphor. Owing to the cooperating effects between Cu NWs/In 2 O 3 conductive components in the phosphor, the efficiency in low voltage cathodoluminescence was significantly improved. -- Highlights: ► In 2 O 3 /Cu NWs were introduced in Y 2 O 3 :Eu 3+ phosphor to improve the low voltage cathodoluminescence. ► In 2 O 3 /Cu NWs play different key roles in the formation of electrically conductive network. ► The cooperating effect was proved by comparing the experimental data and the calculated results. ► The low voltage cathodoluminescence was significantly improved

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.

Wet chemical synthesis of LiBaF{sub 3} phosphor

Energy Technology Data Exchange (ETDEWEB)

Singh, Vartika S., E-mail: svmoharil@yahoo.com [Physics Department, Shri Ramdeobaba K.N. Engineering College, Katol Road, Nagpur 440 013 (India); Joshi, C.P. [Physics Department, Shri Ramdeobaba K.N. Engineering College, Katol Road, Nagpur 440 013 (India); Moharil, S.V. [Department of Physics, R.T.M. Nagpur University, Nagpur 440 010 (India)

2013-12-05

Highlights: •LiBaF{sub 3}:RE{sup 3+} phosphors synthesized by a simple wet chemical method. •Ce{sup 3+} and Tb{sup 3+} emissions observed in as-prepared powders without any thermal treatment. •Intense Eu{sup 2+} emission observed after annealing in reductive atmosphere. -- Abstract: LiBaF{sub 3} has great potential applications as X-ray storage phosphor, slow neutron imaging, scintillator, vacuum ultraviolet (VUV) optical lithography, etc. Conventionally, LiBaF{sub 3} is prepared by solid state reaction between the constituent fluorides. However, the preparation of phase pure material and especially single crystals is rather tricky due to incongruent melting. For the first time, a wet chemical preparation of rare earth activated LiBaF{sub 3} is described here. As precipitated powders containing Ce{sup 3+} or Tb{sup 3+} exhibited characteristic luminescence. For observing Eu{sup 2+} emission, it was necessary to heat the powders in a reductive atmosphere. It is suggested that phosphors prepared by this method may prove useful in applications like OSL, X-ray imaging, etc. which do not require large single crystals.

Defect mediated optical properties in ZnAl2O4 phosphor

Science.gov (United States)

Pathak, Nimai; Saxena, Suryansh; Kadam, R. M.

2018-04-01

The present work describes defect mediated optical properties in ZnAl2O4 phosphor material, synthesized through sol-gel combustion method, which has potential to be used both as a blue emitting phosphor material as well as white emitting, depending upon the annealing temperature during the synthesis procedure. Various defect centers such as anionic vacancy, cationic vacancy, antisite defects etc. create different electronic states inside the band gap, which are responsible for the multicolour emission. The interesting colour tunable emission characteristics can be linked with the various defect centers and their changes upon annealing.

Improved photoluminescence properties of a new green SrB2O4:Tb3+ phosphor by charge compensation

International Nuclear Information System (INIS)

Wu, Zhan-Chao; Wang, Ping; Liu, Jie; Li, Chao; Zhou, Wen-Hui; Kuang, Shao-Ping

2012-01-01

Highlights: ► New green-emitting SrB 2 O 4 :Tb 3+ phosphor was synthesized by solid-state reaction. ► Li + , Na + , and K + can all increase luminescent intensity of SrB 2 O 4 :Tb 3+ . ► Na + is the optimal charge compensator among Li + , Na + and K + . ► SrB 2 O 4 :Tb 3+ is a promising green phosphor for fabricating WLED. -- Abstract: A new green-emitting SrB 2 O 4 :Tb 3+ phosphor was synthesized by solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed all the samples with orthorhombic formation of SrB 2 O 4 . The excitation spectra indicate the phosphor can be effectively excited by near ultraviolet (NUV) light, making it attractive as conversion phosphor for LED applications. The phosphor exhibits a bright green emission with the highest photoluminescence (PL) intensity at 544 nm excited by 378 nm light. The critical quenching concentration of Tb 3+ in SrB 2 O 4 :Tb 3+ is about 10 mol%. The effects of charge compensators (Li + , Na + , and K + ) on photoluminescence of SrB 2 O 4 :Tb 3+ were also studied. The results show that the emission intensity can be improved by all the three charge compensators and Na + is the optimal one for SrB 2 O 4 :Tb 3+ . All properties show that the phosphor is a promising green phosphor pumped by NUV InGaN chip for fabricating white light-emitting diodes (WLEDs).

Design of a High-Power White Light Source with Colloidal Quantum Dots and Non-Rare-Earth Phosphors

Science.gov (United States)

Bicanic, Kristopher T.

This thesis describes the design process of a high-power white light source, using novel phosphor and colloidal quantum dot materials. To incorporate multiple light emitters, we generalized and extended a down-converting layer model. We employed a phosphor mixture comprising of YAG:Ce and K2TiF 6:Mn4+ powders to illustrate the effectiveness of the model. By incorporating experimental photophysical results from the phosphors and colloidal quantum dots, we modeled our system and chose the design suitable for high-power applications. We report a reduction in the correlated color temperature by 600K for phosphor and quantum dot systems, enabling the creation of a warm white light emission at power densities up to 5 kW/cm 2. Furthermore, at this high-power, their emission achieves the digital cinema initiative (DCI) requirements with a luminescence efficacy improvement up to 32% over the stand-alone ceramic YAG:Ce phosphor.

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.

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.

Uranium recovery from wet-process phosphoric acid with octylphenyl acid phosphate. Progress report

International Nuclear Information System (INIS)

Arnold, W.D.; McKamey, D.R.; Baes, C.F.

1980-01-01

Studies were continued of a process for recovering uranium from wet-process phosphoric acid with octylphenyl acid phosphate (OPAP), a mixture of mono- and dioctylphenyl phosphoric acids. The mixture contained at least nine impurities, the principal one being octyl phenol, and also material that readily hydrolyzed to octyl phenol and orthophosphoric acid. The combination of mono- and dioctylphenyl phosphoric acids was the principal uranium extractant, but some of the impurities also extracted uranium. Hydrolysis of the extractant had little effect on uranium extraction, as did the presence of moderate concentrations of octyl phenol and trioctylphenyl phosphate. Diluent choice among refined kerosenes, naphthenic mixtures, and paraffinic hydrocarbons also had little effect on uranium extraction, but extraction was much lower when an aromatic diluent was used. Purified OPAP fractions were sparingly soluble in aliphatic hydrocarbon diluents. The solubility was increased by the presence of impurities such as octyl phenol, and by the addition of water or an acidic solution to the extractant-diluent mixture. In continuous stability tests, extractant loss by distribution to the aqueous phase was much less to wet-process phosphoric acid than to reagent grade acid. Uranium recovery from wet-process acid decreased steadily because of the combined effects of extractant poisoning and precipitation of the extractant as a complex with ferric iron. Unaccountable losses of organic phase volume occurred in the continuous tests. While attempts to recover the lost organic phase were unsuccessful, the test results indicate it was not lost by entrainment or dissolution in the phosphoric acid solutions. 21 figures, 8 tables

Developing a rapid method for the determination of uranium in pure phosphoric acid and D2 EHPA

International Nuclear Information System (INIS)

Koudsi, Y.; Stas, J.; Al-Merey, R.; shaddoud, G.

1996-02-01

Arsenazo (III) used in titrate uranium spectrophotometrically in phosphoric acid after its extraction into organic phase. In this work we used arsenazo(III) to complex uranyl ion in pure phosphoric acid and in the aqueous phase. The spectrum of the complex shows that λ max is at 650 nm. The linearity of the method is corelated with acid molarity, it is (1 -4, 10 - 30, 10 - 40) ppm uranium for (0.2, 1, 2) M of phosphoric acid respectively. Uranium in D 2 EHPA stripped by phosphoric acid and then determined by this method. Also it has been applied to determine uranium in pure perchloric acid. The method is direct, rapid, very cheap and relatively accurate. (author)

Effect of UV irradiation on different types of luminescence of SrAl2 O4 :Eu,Dy phosphors.

Science.gov (United States)

Jha, Piyush

2016-11-01

This paper reports the luminescence behavior of Sr 0.097 Al 2 O 4 :Eu 0.01 ,Dy 0.02 phosphors under UV-irradiation. The effect of UV-irradiation on afterglow (AG), thermoluminescence (TL) and mechanoluminescence (ML) of Sr 0.097 Al 2 O 4 :Eu 0.01 ,Dy 0.02 phosphors is investigated. The space group of Sr 0.097 Al 2 O 4 :Eu 0.01 ,Dy 0.02 phosphors is monoclinic P2 1 . The prepared phosphors exhibit a long AG, intense TL and ML. It is found that the AG, ML intensity and TL increase with increasing duration of irradiation time. The ML intensity decreases with successive impact of the load onto the phosphors, whereby the diminished ML intensity can be recovered by UV-irradiation. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of methane annealing ambience on the structure and photoluminescence of BCNO phosphors

International Nuclear Information System (INIS)

Lu, Fang; Zhang, Xinghua; Lu, Zunming; Tang, Chengchun

2014-01-01

Green-emitting BCNO phosphors are synthetized by low temperature liquid method. And then the properties of structure and photoluminescence of BCNO phosphors annealed under methane ambience at 500–700 °C for 4 h and at 600 °C for 3–6 h are researched. When the phosphor was annealed for the same time period, the crystallinity was improved first and then became poor as the annealing temperature increased. In addition, the emission peak shifted to high wavelength, and the maximum shift span reached up to 40 nm. When the phosphor was annealed at the same temperature, the crystallinity was improved and the emission peak was red-shifted. The multi-peaks fitting results indicated that three luminescence mechanisms which were C-related defect, B–O luminescence center and other defects or vacancies played important roles in BCNO phosphors. - Highlights: • When the annealing time period was fixed to 4 h, the XRD results showed the crystallinity was improved at first and then became poor as the annealing temperature increased. Furthermore, the PL results indicated the emission peak was red-shifted and then blue-shifted and the maximum shift span reached up to 40 nm when the annealing temperature was 600 °C. • With regard to the samples annealed at 600 °C for 3, 4, 5 and 6 h respectively, the crystallinity was improved as the annealing time period prolonged. In addition, the emission peak was red-shifted first and then blue-shifted and the maximum shift span reached up to 40 nm when the annealing time was 4 h. • What's more, the three-peaks fitting graphs uncovered that the luminescence properties were decided by three mechanisms which were C-related defect, B–O luminescence center and other defects or vacancies. Therefore, the peakshift and luminescence intensity were influenced by the comprehensive superposition of these three factors. • In this work, we found the inter luminescence mechanisms of BCNO phosphor by the annealing experiments under methane

Les peintures marines antisalissures à base de polymères organostanniques Antifouling Marine Paints Containing Organo-Tin Polymers

Directory of Open Access Journals (Sweden)

Dawans F.

2006-11-01

Full Text Available Le dépôt des salissures marines sur les ouvrages immergés est influencé par plusieurs facteurs et il entraîne des conséquences néfastes, en particulier pour la maintenance des supports de plates-formes de production du pétrole en mer et pour la consommation d'énergie requise pour la propulsion des navires. Divers moyens de lutte antisalissure ont été envisagés parmi lesquels les peintures marines antisalissures occupent une place de choix. Ces peintures contiennent, en général, un composé métallique toxique envers les organismes marins d'origine animale ou végétale et différents mécanismes d'action ont été proposés. Les dérivés organostanniques sont des agents biocides très efficaces et lorsqu'ils sont liés chimiquement sur un polymère, en particulier sous forme de greffons, on obtient un contrôle amélioré de leur lixiviation dans la phase aqueuse et par conséquent la durée de vie du revêtement antisalissure est prolongée. La synthèse de polymères comportant un cation organostannique toxique peut être effectuée, soit par la polymérisation ou la copolymérisation de monomères insaturés organostanniques, soit par la réaction chimique de composés organostanniques avec un substrat polymère comportant des groupes fonctionnels appropriés. Les avantages et les inconvénients de diverses formulations de peintures à base de dérivés organostanniques sont discutés. Marine fouling deposits on submerged structures are influenced by several factors and bring about harmful consequences, especially with regard to offshore oil-production platform structures and for the energy consumption required for ship propulsion. Various antifouling methods have been considered, including antifouling marine coatings in particular. Such paints generally contain a metallic compound which is toxic with regard to marine organisms of animal or vegetable origin, and various action mechanisms have been proposed. Organo

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.

Development of an improved two-cycle process for recovering uranium from wet-process phosphoric acid

International Nuclear Information System (INIS)

Chen, H.M.; Chen, H.J.; Tsai, Y.M.; Lee, T.W.; Ting, G.

1987-01-01

An improved two-cycle separation process for the recovery of uranium from wet-process phosphoric acid by extraction with bis(2-ethylhexyl)phosphoric acid (D2EHPA) plus dibutyl butylphosphonate (DBBP) in kerosene has been developed and demonstrated successfully in bench-scale, continuous mixer-settler tests. The sulfuric acid and water scrubbing steps for the recycled extraction in the second cycle solve the problems of the contamination and dilution of the phosphoric acid by the ammonium ion and water and also avoid the formation of undesirable phosphatic precipitates during the subsequent extraction of uranium by recycled organic extractant

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.

A potential green emitting citrate gel synthesized NaSrBO3:Tb3+ phosphor for display application

Science.gov (United States)

Bedyal, A. K.; Kumar, Vinay; Swart, H. C.

2018-04-01

A potential green emitting NaSrBO3:Tb3+ (1-9 mol%) phosphor was synthesized by a citrate gel combustion method. X-ray diffraction patterns confirmed the monoclinic phase of the phosphor. The phosphor emitted intense green emission under near-UV and electron excitation due to the characteristic transitions 5D4→7F6(488 nm),5D4→7F5(544 nm),5D4→7F4(586 nm) and 5D4→7F3(622 nm) of Tb3+ ions. The optimal molar concentration of Tb3+ ions was found to be 6 mol%, after that concentration quenching occurred. The dipole-dipole interaction was found to be accountable for energy transfer between the Tb3+ ions. X-ray photoelectron spectroscopy was carried out to analyze the chemical states of the elements and suggest that terbium was mostly presented in the (+3) valance state in the phosphor. The approximated Commission Internationale de l‧Eclairage coordinates for the PL (0.31, 0.61) and CL (0.33, 0.57) were found to be very close to the well-known green emitting phosphor. The obtained results suggest that the studied phosphor could be an ultimate choice for green emission in display applications.

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.

Digital imaging using storage phosphor screens a film-less procedure to detect radiation

International Nuclear Information System (INIS)

Narayana Rao, A.V.S.S.; Mahajan, S.K.

1998-01-01

The imaging plate is a film-like radiation sensor comprising of specifically designed phosphors (photostimulable storage phosphors) that trap and store energy resulting from the decay of radioactive atoms in the sample. In a typical setup, samples containing radioactivity are placed next to the imaging plate for a duration of about 5-10 times less than that is needed for normal x-ray films. The stored energy is stable until scanned with a laser beam, which releases the energy as luminescence. Digital signal processing of the emitted light results in an image which represents a quantitative measure of the activity of the radiolabeled sample. This phosphor technology, launched in its first application to the medical x-ray diagnostic field, portends great promise in a wide range of newer scientific and technological applications. (author)

Mineral formation and organo-mineral controls on the bioavailability of carbon at the terrestrial-aquatic interface

Science.gov (United States)

Rod, K. A.; Smith, A. P.; Renslow, R.

2016-12-01

Recent evidence highlights the importance of organo-mineral interactions in regulating the source or sink capacity of soil. High surface area soils, such as allophane-rich or clay-rich soils, retain organic matter (OM) via sorption to mineral surfaces which can also contribute physical isolation in interlayer spaces. Despite the direct correlation between mineral surfaces and OM accumulation, the pedogenic processes controlling the abundance of reactive surface areas and their distribution in the mineral matrix remains unclear. As global soil temperatures rise, the dissolution of primary minerals and formation of new secondary minerals may be thermodynamically favored as part of soil weathering process. Newly formed minerals can supply surfaces for organo-metallic bonding and may, therefore, stabilize OM by surface bonding and physical exclusion. This is especially relevant in environments that intersect terrestrial and aquatic systems, such as the capillary fringe zone in riparian ecosystems. To test the mechanisms of mineral surface area protection of OM, we facilitated secondary precipitation of alumino-silicates in the presence of OM held at two different temperatures in natural Nisqually River sediments (Mt Rainier, WA). This was a three month reaction intended to simulate early pedogenesis. To tease out the influence of mineral surface area increase during pedogenesis, we incubated the sediments at two different soil moisture contents to induce biodegradation. We measured OM desorption, biodegradation, and the molecular composition of mineral-associated OM both prior to and following the temperature manipulation. To simulate the saturation of capillary fringe sediment and associated transport and reaction of OM, column experiments were conducted using the reacted sediments. More co-precipitation was observed in the 20°C solution compared to the 4°C reacted solution suggesting that warming trends alter mineral development and may remove more OM from solution

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

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.

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.

CaSO4:DY,Mn: A new and highly sensitive thermoluminescence phosphor for versatile dosimetry

Science.gov (United States)

Bahl, Shaila; Lochab, S. P.; Kumar, Pratik

2016-02-01

With the advent of newer techniques for dose reduction coupled with the development of more sensitive detectors, the radiation doses in radiological medical investigation are decreasing. Nevertheless, keeping the tenet in mind that all radiation doses could entail risk, there is a need to develop more sensitive dosimeters capable of measuring low doses. This paper gives the account of the development of a new and sensitive phosphor CaSO4:Dy,Mn and its characterization. The standard production procedure based on the recrystallization method was used to prepare CaSO4:Dy,Mn. The Thermoluminescence (TL) studies were carried out by exposing it with gamma radiation (Cs-137) from 10 μGy to 100 Gy. The theoretical studies to determine the number of peaks and kinetic parameters related to the TL glow peaks in CaSO4:Dy,Mn was performed using the Computerized Glow Curve Deconvolution (CGCD) method. Experiments were performed to determine optimum concentration of the dopants Dysprosium (Dy) and Mangnese (Mn) in the host CaSO4 so that maximum sensitivity of the phosphor may be achieved. The optimum dopant concentration turned out to be 0.1 mol%. As there were two dopants Dy and Mn their relative ratio were varied in steps of 0.025 keeping the concentration of total dopant (Dy and Mn) 0.1 mol% always. The maximum TL intensity was seen in the CaSO4:Dy(0.025),Mn(0.075) combination. The TL sensitivity of this phosphor was found to be about 2 and 1.8 times higher than that of popular phosphor CaSO4:Dy and LiF:Mg,Cu,P (TLD-700H) respectively. This new phosphor CaSO4:Dy,Mn showed fading of 11% which is similar to that of the standard phosphor CaSO4:Dy. The paper concludes that the new, highly sensitive TL phosphor CaSO4:Dy,Mn has shown higher sensitivity and hence the potential to replace commonly used CaSO4:Dy.

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)

Photoluminescence properties of a new orange-red-emitting Sm(3+)-La3SbO7 phosphor.

Science.gov (United States)

Li, Zeng-Mei; Deng, Li-Gang; Zhao, Shan-Cang; Zhang, Shu-Qiu; Guo, Chang-Ying; Liang, Jing-Yun; Yue, Hui; Wan, Chun-Yan

2016-03-01

The antimonate compound La3SbO7 has high chemical stability, lattice stiffness and thermal stability. Orange-red-emitting antimonate-based phosphors La3SbO7:xSm(3+) (x = 0.02, 0.05, 0.08, 0.10, 0.15, 0.20 and 0.25) were synthesized. The phase structure and photoluminescence properties of these phosphors were investigated. The emission spectrum obtained on excitation at 407 nm contained exclusively the characteristic emissions of Sm(3+) at 568, 608, 654 and 716 nm, which correspond to the transitions from (4)G5/2 to (6)H5/2, (6)H7/2, (6)H9/2 and (6)H11/2 of Sm(3+), respectively. The strongest emission was located at 608 nm due to the (4)G5/2→(6)H7/2 transition of Sm(3+), generating bright orange-red light. The critical quenching concentration of Sm(3+) in La3SbO7:Sm(3+) phosphor was determined as 10% and the energy transfer between Sm(3+) was found to be through an exchange interaction. The International Commission on Illumination chromaticity coordinates of the La3SbO7:0.10Sm(3+) phosphors are located in the orange-red region. The La3SbO7:Sm(3+) phosphors may be potentially used as red phosphors for white light-emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.

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.

Effect of phosphoric acid on the morphology and tensile properties of halloysite-polyurethane composites

Science.gov (United States)

Gaaz, Tayser Sumer; Luaibi, Hasan Mohammed; Al-Amiery, Ahmed A.; Kadhum, Abdul Amir H.

2018-06-01

The high aspect ratio of nanoscale reinforcements enhances the tensile properties of pure polymer matrix. The composites were first made by adding halloysite nanotubes (HNTs) at low weight percentages of 1, 2, and 3 wt% to thermoplastic polyurethane (TPU). Then, HNTs were phosphoric acid-treated before adding to TPU at same weight percentage to create phosphoric acid HNTs-TPU composites. The samples were fabricated using injection moulding. The HNTs-TPU composites were characterized according to the tensile properties including tensile strength, tensile strain and Young's modulus. The loading has shown its highest tensile values at 2 wt% HNTs loading and same findings are shown with the samples that treated with phosphoric acid. The tensile strength increased to reach 24.65 MPa compare with the 17.7 MPa of the neat TPU showing about 26% improvement. For the phosphoric acid-treated composites, the improvement has reached 35% compared to the neat sample. Regarding the tensile stain, the improvement was about 83% at 2 wt% HNTs loading. For Young's modulus, the results obtained in this study have shown that Young's modulus is linearly improved with either the loading content or the phosphoric acid treated achieving its highest values at 3 wt% HNTs of 14.53 MPa and 16.27 MPa for untreated and treated, respectively. FESEM results showed that HNTs were well dispersed in TPU matrix. Thus, HNTs-TPU has improved tensile properties compared with pure TPU due to the addition of nanofiller.

Shear bond strength of self-etch adhesives to enamel with additional phosphoric acid etching.

Science.gov (United States)

Lührs, Anne-Katrin; Guhr, Silke; Schilke, Reinhard; Borchers, Lothar; Geurtsen, Werner; Günay, Hüsamettin

2008-01-01

This study evaluated the shear bond strength of self-etch adhesives to enamel and the effect of additional phosphoric acid etching. Seventy sound human molars were randomly divided into three test groups and one control group. The enamel surfaces of the control group (n=10) were treated with Syntac Classic (SC). Each test group was subdivided into two groups (each n=10). In half of each test group, ground enamel surfaces were coated with the self-etch adhesives AdheSe (ADH), Xeno III (XE) or Futurabond NR (FNR). In the remaining half of each test group, an additional phosphoric acid etching of the enamel surface was performed prior to applying the adhesives. The shear bond strength was measured with a universal testing machine at a crosshead speed of 1 mm/minute after storing the samples in distilled water at 37 degrees C for 24 hours. Fracture modes were determined by SEM examination. For statistical analysis, one-way ANOVA and the two-sided Dunnett Test were used (p>0.05). Additional phosphoric etching significantly increased the shear bond strength of all the examined self-etch adhesives (padhesive fractures. For all the self-etch adhesives, a slight increase in mixed fractures occurred after conditioning with phosphoric acid. An additional phosphoric acid etching of enamel should be considered when using self-etch adhesives. More clinical studies are needed to evaluate the long-term success of the examined adhesives.

Analysis of phosphoric ore bacterial and eucaryal microbial diversity ...

African Journals Online (AJOL)

SAM

Received 30 July, 2013; Accepted 4 July, 2014. The aim ... using the single strand conformation polymorphism (SSCP) technique and ... Phosphoric industry generates a considerable quantity of ..... This phenomenon could well be the case for.

High color rendering index of remote-type white LEDs with multi-layered quantum dot-phosphor films and short-wavelength pass dichroic filters

Science.gov (United States)

Yoon, Hee Chang; Oh, Ji Hye; Do, Young Rag

2014-09-01

This paper introduces high color rendering index (CRI) white light-emitting diodes (W-LEDs) coated with red emitting (Sr,Ca)AlSiN3:Eu phosphors and yellowish-green emitting AgIn5S8/ZnS (AIS/ZS) quantum dots (QDs) on glass or a short-wavelength pass dichroic filter (SPDF), which transmit blue wavelength regions and reflect yellow wavelength regions. The red emitting (Sr,Ca)AlSiN3:Eu phosphor film is coated on glass and a SPDF using a screen printing method, and then the yellowish-green emitting AIS/ZS QDs are coated on the red phosphor (Sr,Ca)AlSiN3:Eu film-coated glass and SPDF using the electrospray (e-spray) method.To fabricate the red phosphor film, the optimum amount of phosphor is dispersed in a silicon binder to form a red phosphor paste. The AIS/ZS QDs are mixed with dimethylformamide (DMF), toluene, and poly(methyl methacrylate) (PMMA) for the e-spray coating. The substrates are spin-coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to fabricate a conductive surface. The CRI of the white LEDs is improved through inserting the red phosphor film between the QD layer and the glass substrate. Furthermore, the light intensities of the multi-layered phosphor films are enhanced through changing the glass substrate to the SPDF. The correlated color temperatures (CCTs) vary as a function of the phosphor concentration in the phosphor paste. The optical properties of the yellowish-green AIS/ZS QDs and red (Sr,Ca)AlSiN3:Eu phosphors are characterized using photoluminescence (PL), and the multi-layered QD-phosphor films are measured using electroluminescence (EL) with an InGaN blue LED (λmax = 450 nm) at 60 mA.

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

Structural and morphological changes in supramolecular-structured polymer electrolyte membrane fuel cell on addition of phosphoric acid

Science.gov (United States)

Hendrana, S.; Pryliana, R. F.; Natanael, C. L.; Rahayu, I.

2018-03-01

Phosphoric acid is one agents used in membrane fuel cell to modify ionic conductivity. Therefore, its distribution in membrane is a key parameter to gain expected conductivity. Efforts have been made to distribute phosphoric acid in a supramolecular-structured membrane prepared with a matrix. To achieve even distribution across bulk of the membrane, the inclusion of the polyacid is carried out under pressurized chamber. Image of scanning electron microscopy (SEM) shows better phosphoric acid distribution for one prepared in pressurized state. It also leads in better performing in ionic conductivity. Moreover, data from differential scanning calorimetry (DSC) indicate that the addition of phosphoric acid is prominent in the change of membrane structure, while morphological changes are captured in SEM images.

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

Defect-Induced Luminescence of a Self-Activated Borophosphate Phosphor

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