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1
Bhattacharyya, Koyel. "The functionalization of white phosphorus towards metal phosphide nanoparticles and organophosphines." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30008/document.
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Ce manuscrit présente une synthèse originale de nanoparticules de nickel(0). L'utilisation d'un précurseur de dioléylamide de nickel(II) conduit à un procédé versatile, robuste, et sans eau pour la production de particules ajustables en taille entre 4 et 11 nm de diamètre. Cette méthode a été étendue pour former de petites nanoparticules de fer(0) et de cobalt(0). Ces particules ont été examinées en ce qui concerne l'activité catalytique, y compris l'hydrosilylation d'un alcène terminal, l'hydrogénation sélective du phénylacétylène en styrène, et la réduction sous-stoechiométrique de l'azote en tris(triméthylsilyl)amine. Le phosphore blanc (P4) a été réagi stoechiométriquement avec les nanoparticules métalliques pour former les nanoparticules de phosphure métallique correspondantes. Le phosphore blanc a été alternativement fonctionnalisé en utilisant un superhydrure (LiBEt3H) pour former une espèce phosphanide stabilisée au borane, LiPH2(BEt3)2. Cette espèce a été utilisée pour synthétiser diverses phosphines, y compris la phosphine, la tris(triméthylsilyl)phosphine, et les triaroylphosphines. Les adduits labiles de triéthylborane ont été remplacés par BH3, ce qui a donné lieu à la formation de LiPH2(BH3)2, qui peut avoir des applications dans la formation de polymères P-BThis manuscript presents an original synthesis of nickel(0) nanoparticles. The use of a nickel(II) dioleylamide precursor results in a versatile, robust, water-free method for the production of size-tunable particles between 4 - 11 nm in diameter. This method was extended to form small iron(0) and cobalt(0) nanoparticles. These particles were examined for catalytic activity, including the hydrosilylation of a terminal alkene, the selective hydrogenation of phenylacetylene to styrene, and the substoichiometric reduction of nitrogen to tris(trimethylsilyl)amine. White phosphorus (P4) was stoichiometrically reacted with the metal(0) nanoparticles to form the corresponding metal phosphide nanoparticles. White phosphorus was alternatively functionalized using superhydride (LiBEt3H) to form a borane-stabilized phosphanide species, LiPH2(BEt3)2. This species was used to synthesize various phosphines, including phosphine, tris(trimethylsilyl)phosphine, and triaroylphosphines. The labile triethylborane adducts were replaced by BH3, resulting in the formation of LiPH2(BH3)2, which may have applications in the formation of P-B polymers
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Armstrong, Kenneth Mark. "Catalytic synthesis of organophosphate plastics additives from white phosphorus." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2587.
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Triaryl phosphates were synthesized from white phosphorus and phenols in aerobic conditions and in the presence of iron catalysts and iodine. Full conversion to phosphates was achieved without the use of chlorine or chlorinated solvents, and the reactions do not produce acid waste. Triphenyl phosphate, tritolyl phosphate and tris(2,4-di-tert-butyl)phenyl phosphate were synthesized by this method with 100% conversion from P₄. Various iron(III) diketonates were used to catalyse the conversion. Mechanistic studies showed the reaction to proceed via the formation of phosphorus triiodide (PI₃), then diphenyl phosphoroiodidate (O=PI(OPh)₂) before the final formation of triphenyl phosphate (O=P(OPh)₃). The nucleophilic substitution of O=PI(OPh)₂ with phenol to form O=P(OPh)₃ was found to be the rate determining step. It was found that by modifying the reaction conditions the same catalytic systems could be used to synthesize triphenyl phosphite directly from P₄. Triphenyl phosphite was synthesized in selectivities of up to 60 %. The mechanism of these transformations was also elucidated. Independent syntheses of the intermediate in the reaction mechanism, O=P(OPh)₂I and its hydrolysis products diphenyl phosphate (O=P(OPh)₂OH) and tetraphenyl pyrophosphate ((O)P(OPh)₂-O-P(O)(OPh)₂) were developed from PI₃. The 2,4-di-tert-butyl phenol analogues of these compounds were also prepared. Bis-(2,4-di-tert-butylphenyl) phosphoroiodidate was then reacted with various alcohols to produce a series of mixed triorgano phosphates.
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Stephens, Frances H. (Frances Helen) 1977. "Activation of white phosphorus by molybdenum- and uranium tris-amides." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17841.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2004.Vita.
Includes bibliographical references.
Molybdaziridine-hydride Mo(H)([eta]²-Me₂C=NAr)(N[i-Pr]Ar)₂ (1, Ar = 3,5-C₆H₃Me₂) acts as a source of its three-coordinate isomer Mo(N[i-Pr]Ar)₃ (2). This relationship has been probed via an investigation of the coordination chemistry of 1 and Mo(N[t-Bu]Ar)3 (3), a bulky analog of 2, with isocyanides RNC (R = 1-adamantyl, tert-butyl) and white phosphorus (P₄). A comparison of the rates and activation parameters of these reactions indicates that 2 is not an intermediate on the pathway from 1 to products, but rather than the molybdaziridine-hydride "opens" upon substrate binding in an associative process. Synthesis and characterization of 1:1 and 1:2 isocyanide adducts of 2 and 3, and bridging and terminal Pn compounds of molybdenum derived from the element P4 and their alcoholysis products are presented. The uranium tris-amide compounds (THF)U(N[R]Ar)₃ (R = t-Bu, 1-Ad) reacted with white phosphorus. The unique products contain a square tetraphosphorus moiety characterized formally as the dianion P₄â¡â¡₂â. Structural and theoretical analyses are provided for this system.
by Frances H. Stephens.
Ph.D.
4
Dreyfuss, Sébastien. "Utilisation de phosphore blanc et d'aminophosphines pour la formation de nanocristaux d'InP." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30100/document.
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Ce travail de thèse porte sur la synthèse de nanocristaux de phosphure d'indium (InP) et en particulier sur l'utilisation de précurseurs phosphorés tels que le phosphore blanc et les aminophosphines. Les nanocristaux d'InP sont des matériaux semi-conducteurs prometteurs dans le cadre d'applications biologiques et optoélectroniques grâce à leur faible toxicité et à leurs spectres d'absorption et de fluorescence dans le visible. En outre, le phosphore blanc, allotrope le plus réactif du phosphore, est un produit industriel fabriqué à très grande échelle. Il est en effet à l'origine de tous les produits phosphorés à bas degrés d'oxydation tels que les phosphines. Sa fonctionnalisation directe visant à former des espèces chimiques nouvelles ou valorisables est un domaine de recherche actif. Alors que les nanocristaux d'InP sont traditionnellement synthétisés en utilisant une silylphosphine comme précurseur phosphoré, une nouvelle méthodologie reposant sur l'utilisation d'aminophosphines a émergé. Les aminophosphines étant plus facilement accessibles et manipulables que les silylphosphines, il s'agit d'une avancée importante pour le développement des nanocristaux d'InP. C'est pourquoi nous avons étudié précisément le mécanisme de formation de ces nanocristaux, en nous appuyant notamment sur la RMN, la spectrométrie de masse et les calculs DFT. Cette compréhension fine du mécanisme a permis l'optimisation de la synthèse des nanocristaux d'InP.L'utilisation du phosphore blanc pour former des nanocristaux d'InP repose sur la formation de nanoparticules d'indium monodisperses puis sur l'incorporation du phosphore à l'intérieur des nanoparticules. En partant d'une méthodologie de synthèse de nanoparticules d'indium de la littérature, nous avons découvert le paramètre central de la synthèse : la présence d'une quantité bien précise d'eau dans le solvant. Les nanoparticules d'indium ainsi formées sont oxydées en surface et doivent être activées afin de réagir avec le phosphore blanc.Enfin, la fonctionnalisation moléculaire du phosphore blanc avec des borohydrures pour former des liaisons P-H et par voie radicalaire pour former des silylphosphines est présentéeCe travail de thèse porte sur la synthèse de nanocristaux de phosphure d'indium (InP) et en particulier sur l'utilisation de précurseurs phosphorés tels que le phosphore blanc et les aminophosphines. Les nanocristaux d'InP sont des matériaux semi-conducteurs prometteurs dans le cadre d'applications biologiques et optoélectroniques grâce à leur faible toxicité et à leurs spectres d'absorption et de fluorescence dans le visible. En outre, le phosphore blanc, allotrope le plus réactif du phosphore, est un produit industriel fabriqué à très grande échelle. Il est en effet à l'origine de tous les produits phosphorés à bas degrés d'oxydation tels que les phosphines. Sa fonctionnalisation directe visant à former des espèces chimiques nouvelles ou valorisables est un domaine de recherche actif. Alors que les nanocristaux d'InP sont traditionnellement synthétisés en utilisant une silylphosphine comme précurseur phosphoré, une nouvelle méthodologie reposant sur l'utilisation d'aminophosphines a émergé. Les aminophosphines étant plus facilement accessibles et manipulables que les silylphosphines, il s'agit d'une avancée importante pour le développement des nanocristaux d'InP. C'est pourquoi nous avons étudié précisément le mécanisme de formation de ces nanocristaux, en nous appuyant notamment sur la RMN, la spectrométrie de masse et les calculs DFT. Cette compréhension fine du mécanisme a permis l'optimisation de la synthèse des nanocristaux d'InP.L'utilisation du phosphore blanc pour former des nanocristaux d'InP repose sur la formation de nanoparticules d'indium monodisperses puis sur l'incorporation du phosphore à l'intérieur des nanoparticules. En partant d'une méthodologie de synthèse de nanoparticules d'indium de la littérature, nous avons découvert le paramètre central de la synthèse : la présence d'une quantité bien précise d'eau dans le solvant. Les nanoparticules d'indium ainsi formées sont oxydées en surface et doivent être activées afin de réagir avec le phosphore blanc.Enfin, la fonctionnalisation moléculaire du phosphore blanc avec des borohydrures pour former des liaisons P-H et par voie radicalaire pour former des silylphosphines est présentée
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Janat, Mohamad Mussaddak. "Phosphorus fractions, movement and fertilizer requirements of grapes grown on White House soil." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184754.
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A two-year fertilizer study on a mature vineyard of Vita vinifera, C. V. Cabernet Sauvignon and Sauvignon blanc, has been conducted on White House sandy loam (fine, mixed, thermic Ustollic Haplargid), at Page Ranch, International Agricultural Center. Furthermore, eleven different varieties grown at Page Ranch and treated with different levels of nitrogen fertilizer were tested for total P content in plant tissue and NO₃-N. Moreover, in another site with similar soil, a Cabernet Sauvignon grown at the Vina Sonoita Vineyard was treated with both soil and foliar applications of P fertilizer, and was tested for total P content in plant tissue. Soil phosphorus (P) fractions of the White House soil were determined in order to evaluate the various forms of soil P and determine the most important form which contributes most to the availability index. The objectives of this study were to study the various inorganic P forms of White House soil, compare two methods of extracting available P (Olsen and Bray P.), and examine the relationships between soil pH, extractable Al, Fe, Mn, and Zn with the availability index of soil P. Furthermore, the effect of P rates and placement on the P status of plant tissue, grape yield, wine quality and petiole-P to blade-P ratio had been investigated. Three different placements of surface, 25 and 50 cm depth at rates of 88 g of P and 80 g of N per vine, were in RCB design in 1987. In 1988, three P rates of 0, 88, and 176 g of P and 207.5 g N per vine, and the two mentioned varieties CS and SB were arranged in RCB design with factorial type. The results showed that placements did not have a significant effect of P status in plant tissue and grape yield. Yet grapes showed a significant response to P fertilizer in terms of increasing P content in plant tissues and grape yield. Petiole P to Blade P ratios were calculated for the CS, and SB grown at Page Ranch, as well as for CS grown at Sonoita vineyard. This ratio is a good indicator for diagnosis of P status in a given vineyard. Nitrogen stress had its clear and profound effect on P content of grape petioles.
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Hoidn, Christian M. [Verfasser], and Robert [Akademischer Betreuer] Wolf. "Functionalization of White Phosphorus Mediated by Low Valent Cobalt Complexes / Christian M. Hoidn ; Betreuer: Robert Wolf." Regensburg : Universitätsbibliothek Regensburg, 2020. http://d-nb.info/1203875053/34.
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Nuruzzaman, Mohammad. "Phosphorus benefits of white lupin, field pea and faba bean to wheat production in Western Australian soils." University of Western Australia. School of Plant Biology, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0094.
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[Truncated abstract] Soils of Western Australian cropping regions are very low in phosphorous. White lupin, chickpea, and faba bean are being increasingly used in rotations with wheat on these soils. Yield of wheat after a legume crop is frequently higher than its yield after wheat. It has been reported that in addition to nitrogen, legumes can also contribute to improve the availability of phosphorous for the subsequent crops. This PhD research project aimed at optimising the economic returns of wheat-legume rotations through more efficient use of P fertiliser in the legume phase as well as enhanced availability of soil P in the subsequent wheat phase
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Zhu, Yiyong. "Adaptation of plasma membrane H+ ATPase of proteoid roots of white lupin (Lupinus albus L.) under phosphorus deficiency." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=97252732X.
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Ratliff, Tera Jean. "Nitrogen and Phosphorus Availability in Forests of Varying Ages in the Bartlett Experimental Forest White Mountains, New Hampshire." Miami University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=miami1343771632.
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Tailliez, Antoine. "Effet de l’exsudation de citrate chez le lupin blanc sur la phytodisponibilité de l’uranium." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4335/document.
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L’étude proposée s’inscrit dans un contexte de contamination croissante de la pédosphère et fait le choix d’appréhender cette problématique via une approche centrée sur la rhizospère et sur les mécanismes gouvernant son évolution. Ces travaux s'intéressent à la relation entre l’uranium – un métal naturel ubiquiste non-essentiel – et le citrate – un acide organique de faible poids moléculaire exsudé par certaines espèces végétales poussant sur un milieu pauvre en phosphore. Parmi ces espèces particulières le lupin blanc (Lupinus albus) fait office de plante modèle. Un sol naturellement riche en uranium prélevé à l’affleurement d’une veine de pechblende a été étudié. L’objectif du travail a été de savoir si l’activité racinaire est suffisante pour provoquer la remobilisation de l’uranium dans la solution du sol et favoriser son transfert. Le système sol/plante a été étudié sur rhizotest et de manière découplée en hydroponie et en réacteurs fermés. Il a été démontré que la présence d’uranium dans un milieu contrôlé (hydroponie) stimule l’exsudation de citrate chez les lupins blancs qui ne sont pas carencés en phosphore et que cette exsudation de citrate favorise la solubilisation de l’uranium dans la solution du sol en réacteurs fermés. Ces résultats ont été confirmés par les observations faites sur rhizotest même si les valeurs obtenues dans ce cas étaient plus nuancées. Ceci justifie les approches utilisées et met en évidence leur complémentarité. Les résultats obtenus ont également permis d’apporter des informations concernant la toxicité de l’uranium, son internalisation dans les cellules racinaires ainsi que sur son transfert des racines aux parties aériennesThe present study is related to the context of pedosphere contamination increasing and chose to consider this issue through a focus on rhizosphere and mechanisms that govern its evolution. This work is oriented on the relation between uranium – a non-essential ubiquitous metal – and citrate – a low molecular weight organic acid exudated by specific species when grown on a phosphorus-deficient environment. Among these particular species white lupine (Lupinus albus) is considered as a model species. Furthermore, a natural soil containing huge amounts of uranium has been collected at the outcrop of a pitchblende vein and used during some experiments. The main aim of this PhD thesis was to determine if the root activity of white lupine is sufficient to cause the remobilization of uranium into soil solution and so to promote the transfer of this contaminant to the plant. The soil/plant system has been studied with rhizotests and by combining datas obtained with hydroponics experiments and batches tests. It has been demonstrated that the presence of uranium in a controlled growth medium (hydropony) stimulates citrate exudation in P-sufficient white lupine. More, this citrate exudation enhances uranium solubilization in soil solution in batches. These results have been confirmed by observations on rhizotest even if the values in this case were more nuanced. This justifies the employed approaches and highlights their coherence and complementarity. The results also allowed to provide additional information concerning uranium toxicity, its internalization in root cells as well as its transfer from roots to aerial parts
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Yan, Xiao. "Phosphors for lighting applications." Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/6954.
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Trivalent rare earth cations (RE3+) activated nanometre-sized Y2O2S and Gd2O2S phosphors were prepared by converting hydroxycarbonate precursor powders during a firing process. The precursors were prepared using the urea homoprecipitation method. The choice of host crystal and dopant were optimised to meet the specific requirements for practical applications in the field of lighting, X-ray detection, and displays. Parameters that affect the luminescent properties of the resulting phosphors, such as doping concentration, excitation mechanism, firing temperature, and host lattice were investigated. Tb3+ and Er3+ co-doped Y2O2S and Gd2O2S were studied for their upconversion properties under 632.8 nm red laser excitation. The intensities of UC emission were affected by both doping concentration and host lattices. Tb3+ and Er3+ co-doped Y2O2S was found to show strong downconversion from Tb3+ and upconversion from Er3+. The presence of the Er3+ cations directly affects the Tb3+ down-converting properties by acting as centres for energy transfer. The possible energy transfer between Gd3+ and Er3+ should be responsible for the different trend of Er3+ upconversion intensity in Y2O2S and Gd2O2S. It has been established that the Tb3+ and Er3+ co-doped system is superior than the Yb3+ and Er3+ co-doped one. In the latter system the presence of Yb3+ reduces the efficiency of both upconversion and downconversion emission under red laser excitation. These phosphors show potential applications in the security and anti-fraud field. The novel ZnS:Mn QDs were prepared and successfully incorporated into GaN based photonic crystal (PC) holes to efficiently produce white light. The crystal structure and luminescent properties of the ZnS:Mn QDs were investigated as well as the factors affecting the filling rate. Zn1-xCdxS:Mn QDs were also investigated. The addition of Cd cations leads to a red shift in the PL excitation spectra of the Zn1-xCdxS:Mn QDs. The crystal structures and surface properties were also affected by the presence of Cd. Monodisperse PbS QDs with particle size of ~5 nm has been obtained using a similar aqueous reaction method.
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Al-Waisawy, Sara S. "Investigation of Color Phosphors for Laser-Driven White Lighting." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1417065501.
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Nishiura, Shotaro. "Preparation and Optical Properties of Rare Earth Doped Ceramic Phosphors for White Light Emitting Diode." Kyoto University, 2013. http://hdl.handle.net/2433/175019.
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Kyoto University (京都大学)0048
新制・課程博士
博士(人間・環境学)
甲第17670号
人博第637号
新制||人||153(附属図書館)
24||人博||637(吉田南総合図書館)
30436
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授 田部 勢津久, 教授 杉山 雅人, 教授 加藤 立久
学位規則第4条第1項該当
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Clark, Kristin Dumboski. "The efficacy of 37% phosphoric acid + Mi Paste Plus on remineralization of enamel white spot lesions." Thesis, University of Iowa, 2011. https://ir.uiowa.edu/etd/938.
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Purpose: This in vitro study evaluated the effectiveness of using a 37% phosphoric acid liquid etchant along with MI Paste Plus™ powered technology compared to using MI Paste Plus™ alone or to an artificially created saliva solution in decreasing the demineralization and enhancing the remineralization of artificial carious lesions created on extracted human teeth. The teeth were analyzed and compared using polarized light microscopy, quantitative light-induced fluorescence, and digital photography.
Materials and Methods: One hundred three recently extracted non-carious human third molar teeth without observable white-spot lesions, decalcification, or dental fluorosis were selected for this twelve day study and randomly divided into four treatment groups as follows:
Group 1 (Control) - Artificial saliva solution (27 teeth)
Group 2 (MIP) - MI Paste Plus™ application for 30 minutes daily for 12 days (26 teeth)
Group 3 (15MIP) - 15 second etch every third day and MI Paste Plus™ application for 30 minutes daily for 12 days (25 teeth)
Group 4 (1MIP) - 1 minute etch on day one ONLY and application of MI Paste Plus™ for 30 minutes daily for 12 days (25 teeth).
Results: Results of one<–>way ANOVA revealed there was a significant effect for the type of treatment on the lesion depth (p = 0.0027). The post-hoc Tukey-Kramer's test indicated there was a statistically significant difference between the two groups (15MIP and 1MIP) that incorporated an acid etch in combination with MI Paste Plus™ and the group with exposure to MI Paste Plus™ alone (MIP). In addition, results of one<–>way ANOVA showed that there was no statistically significant effect for type of treatment on the change in fluorescence (p = 0.1417) or the change in density (p = 0.1934).
Conclusions: The results of the present study revealed there was a significant effect for the type of treatment on the lesion depth (p = 0.0027). However, the only significant difference found was between the two groups (15MIP and 1MIP) that incorporated an acid etch in combination with MI Paste Plus™ and the group with exposure to MI Paste Plus™ alone (MIP). Thus, daily applications of MI Paste Plus™, with or without an acid etch, did not produce a statistically significant difference in mean lesion depth when compared to the control (artificial saliva group). In addition, the results of the present study showed that there was no statistically significant effect for type of treatment on the change in fluorescence (p = 0.1417) or the change in density (p = 0.1934). Further research is needed to evaluate MI Paste Plus™ capability in prevention of demineralization and/or enhancement of remineralization by conducting randomized clinical trials.
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Feng, Ya-Hsuan, and 馮雅瑄. "Reaction Studies of the Mo-Mo Quintuple Bond with Aza-Containing Arenes, Nitriles and White Phosphorus." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/apazj2.
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碩士國立清華大學
化學系所
106
This thesis reports reactions of the amidinate-supported quintuply bonded dimolybdenum complex, Mo2[μ-2-HC(N-2,6-iPr2C6H3)2]2 (1), with various aza-containing arenes, nitriles, and P4. Two different products was obtained from the reaction of 1 and 2,2'-bipyridine, Mo2(μ-η2-1,2:η2-4,5-C10H8N2)[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (2) and (η2-C10H8N2)2Mo2[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (3). In complex 3, 2,2'-bipyridine coordinated to Mo centers via its lone pairs of nitrogen atoms, which is the usual coordination mode of the aza-containing arenes. By contrast, 2,2'-bipyridine of 2 coordinates to Mo centers through an η4-bonding mode. Treatment of 1 with isoquinoline, quinoxaline, or quinoline generated the quadruply bonded dimolybdenum compounds, Mo2(μ-η2-1,2:κ1-4-R)[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (R = C9H7N (4), C8H6N2(5)), and Mo2(H)(μ-κ2-C9H7N)[μ-κ2-HC(N-2, 6-iPr2C6H3)2]2 (6), respectively. It is interesting to note that both complexes 4 and 5 contain η3-bound arene ligands, while C-H bond activation was oberved in complex 6. The reactions of 1 with methy-l-4-cyanobenzoate, 4-methoxybenzonitrile, or 1,8-naphthalenedicarbonitrile led to the isolation of [2+2+2] cycloaddition products: Mo2[μ-κ2-NC(R)C(R)N][μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (R = C6H4CO2CH3 (7), C6H4OCH3 (8), C5H3 (9)), respectively. On the other hand, 1 reacted with 4-(dimethylamino)benzonitrile to yield C-H bond activation product [κ1-NCC6H4N(CH3)2][μ-κ1-NC(H)C6H4NH(CH3)2]Mo2[μ-κ2-HC(N-2,6-iPr2C6H3) (N-2-iPr-6-CH(κ1-CH2)CH3-C6H3][μ-κ2-HC(N-2,6-iPr2C6H3)2] (10). It is noteworthy that we isolated interesting compounds (C16H8)(μ-κ2-N2)2{Mo2[μ-κ2-HC(N-2,6-iPr2C6H3)2]2}2 (11) and [μ-κ1-N:μ-κ2-N-(C6H5CN)2]2Mo2[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (12) from the reactions of 1 with 1,2-benzenedicarbonitrile, or [1,1'-biphenyl]-2,2'-dicarbonitrile, respectively. Moreover, we successfully synthesized a novel cyclic-P5 bound dimolybdenum dimer, (μ-η2:η2-P5)2[Mo2{μ-κ2-N-HC(2,6-iPr2C6H3)2}2]2 (15). Further reduction of complex 15 by KC8 led to the formation of the first cyclo-P5 anion coordinated dimolybdenum complex, (μ-[K222-cryptand][Mo2(μ-η2:η2-P5){μ-κ2-N-HC(2,6-iPr2C6H3)2}2].
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Neijat, Mohamed. "Nutrient dynamics and production performance of Shaver White laying hens housed in either enriched or conventional cage systems over an entire production cycle." 2011. http://hdl.handle.net/1993/4788.
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The current data provide estimates of the flow of nitrogen (N), calcium (Ca) and phosphorus (P) in Shaver White layers housed under conventional cage (CC) and enriched cage (EC) systems from 19 to 63 wks of age. The experiment was conducted at the University of Manitoba poultry unit. Both feed disappearance (P < 0.01) (92.5 vs. 95.0 ± 0.6 g/hen/d, DM basis) and manure output (P < 0.01) (79.8 vs. 91.3 ± 1.2 g/hen/d, fresh basis and 27.0 vs. 28.1 ± 0.2 g/hen/d, DM basis) were lower in hens housed in EC compared to CC. Manure DM was 34.1 and 31.0 ± 0.3% for EC and CC, respectively. Feed conversion ratio; body weight; and egg production, weight and mass were not significantly different between the two systems. Although there was no difference in the overall manure N (EC: 1.94 vs. CC: 1.96 ± 0.02 g/hen/d, respectively), N balance was greater (P < 0.05) for the CC compared to EC system (85.0 vs. 30.2 ± 13.6 mg/hen/d, respectively). Lower (P < 0.01) Ca and P excretions were observed in EC (Ca: 2.11 vs. 2.29 ± 0.04 and P: 0.619 vs. 0.643 ± 0.005 g/hen/d) compared to CC. Overall egg N output was similar between the systems. Although lower Ca deposition (P < 0.0001) (2.07 vs. 2.13 ± 0.01 g/hen/d) and output (P < 0.05) (38.3 vs. 38.8 ± 0.15 mg/g egg) were noted in eggs from EC compared to CC, shell quality measurements were not different between the two systems. In addition, Ca outputs in eggs expressed as a proportion of Ca intake in both systems were similar (56.5 vs. 56.6 ± 0.51). Although overall mean P retention (-7.22 vs. -7.45 ± 0.71% P intake) was not different between the two groups of hens, Ca retention was higher (P < 0.05) in EC than CC hens (-1.37 vs. -4.76 ± 0.89% Ca intake, respectively). In addition to providing environmental enrichment and maintaining the production performance to the levels of those achieved by CC systems, EC may also help in reducing Ca and P excretions and improving their efficiency of utilization.
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Persson, Lynn. "The use of sediment and phosphorus loading models to evaluate nonpoint source management practices in the White Clay Lake watershed." 1985. http://catalog.hathitrust.org/api/volumes/oclc/12798604.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 1985.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 178-207).
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Miles, Neil. "Pasture responses to lime and phosphorus on acid soils in Natal." Thesis, 1986. http://hdl.handle.net/10413/9621.
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Zhu, Yiyong [Verfasser]. "Adaptation of plasma membrane H+ ATPase of proteoid roots of white lupin (Lupinus albus L.) under phosphorus deficiency / submitted by Yiyong Zhu." 2004. http://d-nb.info/97252732X/34.
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Stouder, Michael David Wayne. "Nutrient and Contaminant Export Dynamics in a Larger-order Midwestern Watershed: Upper White River, Central Indiana, USA." Thesis, 2010. http://hdl.handle.net/1805/2276.
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Indiana University-Purdue University Indianapolis (IUPUI)The transport of excess nutrients, sediment, and other contaminants to surface waters has been shown to cause a number of environmental and human health concerns. An understanding of the export pathways that these contaminants follow to surrounding water bodies is crucial to the anticipation and management of peak concentration events. Several studies have demonstrated that the majority of annual contaminant loading in the Midwest occurs during periods of elevated discharge. However, many studies use a limited number of sampling points to determine concentration patterns, loadings, and fluxes which decreases accuracy. Through high-resolution storm sampling conducted in a 2945 km2 (1137 mi2) area of central Indiana’s Upper White River Watershed, this research has documented the complex concentration signals and fluxes associated with a suite of cations, nutrients, and contaminants and isolated their primary transport pathways. Additionally, by comparing the results of similar studies conducted on smaller areas within this watershed, differences in concentration patterns and fluxes, as they relate to drainage area, have also been documented. Similar to the results of previous studies, NO3- concentrations lacked a well-defined relationship relative to discharge and was attributed to primarily subsurface contribution. DOC was exported along a shallow, lateral subsurface pathway, TP and TSS via overland flow, and TKN through a combination of both. Near or in-channel scouring of sediment increased DOC, TKN, TP, and TSS concentrations during Storm 2. Atrazine export was attributed to a combination of overland and subsurface pathways. 2-MIB and geosmin derived from different sources and pathways despite being produced by similar organisms. 2-MIB concentration patterns were characterized by dilution of an in-stream source during Storm 1 and potential sediment export during Storm 2 while in-stream concentrations or a sediment source of geosmin was rapidly exhausted during Storm 1. Many of the concentration patterns were subject to an exaggerated averaging effect due to the mixing of several larger watersheds, especially during Storm 1. This research illustrates the need for high-frequency sampling to accurately quantify contaminant loads for total maximum daily load (TMDL) values, developing best management practices (BMPs), and confronting the challenges associated with modeling increasingly larger-scale watersheds.
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Liu, Xiaoqiang. "Coupled biogeochemical cycles in riparian zones with contrasting hydrogeomorphic characteristics in the US Midwest." Thesis, 2013. http://hdl.handle.net/1805/3756.
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Indiana University-Purdue University Indianapolis (IUPUI)Numerous studies have investigated the fate of pollutants in riparian buffers, but few studies have focused on the control of multiple contaminants simultaneously in riparian zones. To better understand what drives the biogeochemical cycles of multiple contaminants in riparian zones, a 19-month study was conducted in riparian buffers across a range of hydrogeomorphic (HGM) settings in the White River watershed in Indiana. Three research sites [Leary Webber Ditch (LWD), Scott Starling (SS) and White River (WR)] with contrasting hydro-geomorphology were selected. We monitored groundwater table depth, oxidation reduction potential (ORP), dissolved oxygen (DO), dissolved organic carbon (DOC), NO3-, NH4+, soluble reactive phosphorus (SRP), SO42- , total Hg and methylmercury (MeHg). Our results revealed that differences in HGM conditions translated into distinctive site hydrology, but significant differences in site hydrology did not lead to different biogeochemical conditions. Nitrate reduction and sulfate re-oxidation were likely associated with major hydrological events, while sulfate reduction, ammonia and methylmercury production were likely associated with seasonal changes in biogeochemical conditions. Results also suggest that the LWD site was a small sink for nitrate but a source for sulfate and MeHg, the SS site was a small sink for MeHg but had little effect on NO3-, SO42- and SRP, and the WR was an intermediate to a large sink for nitrate, an intermediate sink for SRP, and a small source for MeHg. Land use and point source appears to have played an important role in regulating solute concentrations (NO3-, SRP and THg). Thermodynamic theories probably oversimplify the complex patterns of solute dynamics which, at the sites monitored in the present study, were more strongly impacted by HGM settings, land use, and proximity to a point source.
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Dinh, Phuong Thi Yen. "The role of ethylene and auxin in responses of roots to phosphate supply in white clover (Trifolium repens L.) : a thesis presentation in partial fulfilment of the requirements for the degree of Master of Science in Plant Molecular Biology at Massey University, Palmerston North, New Zealand." 2009. http://hdl.handle.net/10179/1247.
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Phosphate (P) supply is one of the major determining factors to plant productivity, since the element affects the growth and the development of plants. In response to Pdeficiency treatment, plants display alterations in root system architecture caused by changes in primary root (PR) and lateral root (LR) length and LR density. In this thesis, the root growth of the agronomically important legume, white clover (Trifolium repens L.) was found to be slightly stimulated in terms of PR length, LR number and total LR length when plants were grown in a P-deficient media (0.01 mM orthophosphate; Pi) when compared with plants grown in a P-sufficient media (1.00 mM Pi) when using a hydroponic growth system. When plants are grown in a P-sufficient media, treatment with 100 nM exogenous 1- aminocyclopropane-1-carboxylic acid (ACC) and exogenous auxin (5 nM 1- naphthylacetic acid, NAA) resulted in significant increases in white clover PR length, LR number and LR length. However, when ethylene action or auxin transport were inhibited using 300 ppm 1-methylcyclopropene (1-MCP) and 100 nM 1-Nnaphthylphthalamic acid (NPA), respectively, root growth was significantly reduced which suggests roles for ethylene and auxin in mediating white clover root growth. To examine the effects of these hormones on plants grown in P-deficient media, 100 nM ACC treatment significantly enhanced the stimulatory effects of growth on Pdeficient media only, while exposure of plants to P-deficiency alone was sufficient to significantly neutralise the inhibitory effects of 1-MCP on root growth. Hence, exposure to P-deficiency is proposed to increase either ethylene biosynthesis or ethylene sensitivity in white clover roots. In contrast, for plants grown in P-deficient media, treatment with 5 nM NAA significantly abolished the stimulation of white clover root growth observed with P-deficiency so it is proposed that exposure to Pdeficiency increases either auxin biosynthesis or auxin sensitivity, but the 5nM NAA concentration used was too high to stimulate root growth. Using DR5p::GUS transgenic white clover, auxin activity was found in the root tips and root primordia. Using these plants, it is suggested that P-deficient treatment and ACC treatment influenced white clover root growth through an increase in auxin sensitivity. Overall, ethylene and auxin are found to be essential in mediating white clover root growth in P-sufficiency, and also in mediating root responses to P-deficiency through changes in terms of the biosynthesis and the sensitivity of these two hormones.
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Kuo, Hsuan-Wei, and 郭炫偉. "The Spectrum Analysis and Prediction of Phosphor-converted White LED with Green and Red Phosphors." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/76794747574256952040.
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碩士明新科技大學
光電系統工程系碩士班
103
Generally, the phosphor-converting white Light-Emitting-Diode (LED) packages are typically fabricated by blue chip coated with green and red phosphors. However, for the phosphor-converting white LED with green and red phosphors, the re-absorption between green and red phosphors would introduce intensity deviations of the green and red emissions. The package engineers will pay a lot of effort and take excessive time to achieve the correct chromaticity of the white LEDs. In this study, we provide a method to predict the spectrum of the white LEDs through experimental analysis. With the spectrum model, the deviations of the CIE 1931 x and y between the prediction and real sample is less than 0.002; the deviation of the CCT between the prediction and real sample is less than 20K; the deviation of the CRI between the prediction and real sample is less than 3. Finally, we provide a good method to predict the spectrum of the phosphor-converting white LED with green and red phosphors with high accuracy.
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Kuo-ChingCheng and 鄭國清. "The Synthesis of Silicate Phosphors for Near Ultraviolet Excitation and Application of Phosphor Films for Replaceable White LED." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/66674523212508314978.
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碩士國立成功大學
電機工程學系
104
In this study, BaZr1-yHfySi3O9: Eu2+ and Li2SrSi1-yTiyO4: Eu2+ silicate phosphors were synthesized by the solid-state reaction method, which could be well excited by near-ultraviolet (UV) light. Using near-UV light-emitting diode (LED) chip to excite cyan and yellow color phosphors was a feasible way to generate white light. However, due to higher operating temperature for UV-LEDs, phosphors with better thermal stability became crucial. Thus, this work focused on improving the thermal stability and the luminous intensity. The thermal stability of the former was improved with increasing the concentration of Hf4+ ions. T50 value (the temperature at which the emission intensity falls to 50% of that at room temperature) was enhanced from 230 to 281 °C. Besides, the emission intensity of the latter was enhanced 14.15% by doping Ti4+. Because of their broad excitation spectra, these phosphors could be applied on the near-UV LEDs to form the phosphor-converted white LEDs (pc-WLEDs). The thermal stability of BaZr1-yHfySi3O9:Eu2+ phosphors enhanced due to the substitution of Zr4+ by Hf4+ ions, which affected smaller lattice vibrations by phonons from heating. Therefore, the activation energy was increased from 0.374 to 0.3832 eV, reducing the probabilities of non-radiative reaction. However, due to the doping of Hf4+, the emission intensity decreased apparently with the increasing concentration of Hf4+ with impurity phase.Finally, NH4Cl was added to raw material as flux and promoted the crystallization reaction. The optimal concentration of NH4Cl was found to be 6 wt%. Besides, Li2SrSi1-yTiyO4: Eu2+phosphors were doped by Ti4+, which leads to larger crystallite size, from 65.71 to 70.47 nm. The optimal concentration of Ti4+ was 2 mol% and the emission intensity could depend on the crystallite size. For the WLED application, BaZr1-yHfySi3O9:Eu2+ cyan phosphors and commercial (Ba, Sr, Ca)2SiO4:Eu2+ yellow phosphors were combined with near-UV-LEDs (λex=395-400 nm) to generate white light. In the past, the conventional dispensing technology was directly coating on chip. In this study, the reflector cup was combined with phosphor films to form replaceable white LEDs. It takes significant advantages for practical applications such as detachable, low-cost, and one LED with various parameters for characteristics of white LED. By modulating number of different pieces of phosphor films, it is suitable to find the optimal characteristics of the white LEDs. The optimum luminous efficiency, CIE coordinates, and CRI of the final proposed devices were 20.9158 lm/W, (0.325, 0.358), and 80.47, respectively.
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Yang, Yen-Ting, and 楊妍庭. "Study of Phosphor Sedimentation Phenomenon of Phosphor-Converted White Light Emitting Diodes." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/qxhcjy.
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碩士國立高雄應用科技大學
電子工程系碩士班
103
By combining a blue light emitting diode (LED) as the light emitter and a yellow Ce3+:YAG phosphor mixed in silicone matrix, a white LED (WLED) has been fabricated. Batches of WLED are prepared by non curing of uniform mixture of Ce3+:YAG phosphors and silicone encapsulation. We record and plot its sedimentation phenomenon during twelve hours. The curve represents the color rendering properties of WLEDs and we select five specific points of time to analysis color rendering properties. Another batch of WLED with a complete curing process has been fabricated to compare color rendering properties, the effect of color shift, and optical properties with previous results. We define three periods in the curve to show different sedimentation phenomena, which are extreme period, variation period and stable period. When a WLED is at the beginning of variation period, it can get more color shift after curing. When a WLED is at the final stage of variation period, it can get less color shift after curing. When a WLED is at extreme period, it can get the best situation after curing. Therefore, the timing to cure and complete WLED fabrication is very important. In this thesis, we provide a way to select a best time of curing in fabricating WLEDs. This result can be a reference for the WLED fabrication.
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Liu, Yu-Cheng, and 劉育成. "The field emission device of green yellow and white phosphors." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/64063286849519204362.
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碩士南台科技大學
光電工程系
96
In this research, we studied field emission display. Phosphors and carbon nano-tubes (CNTs) are screen-printed onto ITO glass for preparation of anode and cathode plate. We investigated the field emission performance of different cathode-plates using a diode structure. Current density of cathode plate increases with increasing CNTs content. Three types of phosphors which emit green, yellow and white light, respectively, are used in this study. The luminous performance is explored. Additionally, we investigated several parameters might influence the luminous performance including heating temperature of anode plate and the thickness of phosphors.
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Wang, Jen-li, and 王仁里. "Luminescence properties of white-emitting phosphor SrSiO3 doped Dy3+ for use in white LEDs." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/2t8cw4.
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碩士國立中山大學
光電工程研究所
95
White light generation through phosphors excitation by UV-LED has become an important subject in WLED. In our study, compounds of SrSiO3：Dy3+ white-emitting phosphors are synthesized via hydrothermal method. In this study, the effects of annealing temperature, annealing time, contents of Dy3+ on the relative emission intensity of the phosphors are judicially investigated. Meanwhile, WLED produces a plenty of heat energy to cause phosphors high temperature when WLED is excited by electrical energy. The emission spectra of the phosphors are investigated excited by Hg arc lamp (λ=365nm) under high temperature environment. Another, two distinct emission bands from SrSiO3：Dy3+ phosphors are found to be around 480nm and 572nm when the phosphor is excited by Hg arc lamp(λ=365nm). The combination of these two emissions forms a white light like color to naked eyes, showing that SrSiO3：Dy3+ presents to be a promising phosphor for applications in fabricating white-light-emitting diodes through UV pumping.
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Sun, Sheng-Hsuan, and 孫聖宣. "Investigation the Properties of the Ca2-xMgxZnMoO6 Pseudo White-Light Phosphors." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/s83qvg.
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Hsu, Chia-Hao, and 許家豪. "Preparation and Photoluminescence Properties ofPotential Phosphors for White Light-Emitting Diodes." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/t5j2d8.
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博士國立臺灣大學
化學工程學研究所
98
To overcome the drawbacks of the phosphors for UV-LEDs, such as low thermal stability, short excitation wavelength (< 350 nm) and poor color tunability, the nephelauxetic (covalency) theory, crystal-field theory and energy transfer mechanisms are applied to improve the luminescent properties. In addition, it is known that the thermal stability of the phosphors strongly depends on the covalency of the host materials. In this study, four types of phosphors (oxides, oxynitrides, nitrides and carbonitrides) with increased covalency were prepared, and the luminescent properties were investigated. Sr2CeO4 phosphors have broad excitation bands in the range of 200 to 450 nm. Sn4+ ions were doped in the host materials to shift the highest excitation peak from 296 to 346 nm. Upon the excitation at around 346 nm, the intensity of the blue emission peak at 483 nm was enhanced 39% as compared to that of undoped Sr2CeO4 phosphors. In the second section, the energy transfer mechanism of MgY4Si3O13:Ce3+, Mn2+ phosphors from Ce3+ to Mn2+ was revealed to be dipole-quadrupole interaction. As the Mn2+ concentration increased, the Mn2+ emission intensity increased and the Ce3+ emission intensity decreased. This resulted in shifting the chromaticity coordinates of the prepared phosphors from the blue, white to orange region. In the third section, the oxynitride-based SrSi2O2N2 phosphors with high covalency were selected as the host materials. As Ce3+ and Tb3+ ions were co-doped into SrSi2O2N2, the energy transfer process occurred. With increasing the Tb3+ concentration, the emitting colors of SrSi2O2N2: Ce3+, Tb3+ phosphors shifted from the blue towards green region. The increased temperatures caused the reduction of the emission intensity of the prepared phosphors due to the thermal quenching effects. It is found the prepared SrSi2O2N2-based phosphors have excellent thermal stability. In the fourth section, oxynitride-based phosphors CaSi2O2N2 were selected as the host materials. Increasing the Eu2+ concentration of the Ce3+ and Eu2+-codoped phosphors led the excitation wavelength to shift from 330 to 352 nm and the excitation intensity to increase. In addition, the Eu2+ emission (550 nm) intensity increased and Ce3+ emission (470 nm) intensity decreased, leading the emitting colors of the prepared phosphors to shift from the blue to yellowish green region. In the fifth section, the nitridosilicate (CeSi3N5) and carbonitride (Y2Si4N6C) phosphors with high covalency were selected as the host materials. For CeSi3N5 phosphors, the wavelength of the maximum excitation peak was at 353 nm. The emission spectrum exhibited an intense blue emission at 453 nm. When Tb3+ ions were doped, the emitting colors shifted from the blue to greenish blue. For Ce3+-doped Y2Si4N6C phosphors, the incorporation of La3+ ions led the emitting colors of (Y, La)2Si4N6C: Ce3+ phosphors to vary from the yellowish green to blue region. The blue shift in emission bands was due to the variation in the crystal-field strength around the activators. In addition, the excellent thermal stability of Y2Si4N6C-based phosphors was revealed.
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Yang, Chih-Chiang, and 楊智強. "Research of White LEDs with Electrophoretic Deposition of Phosphor." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/33829789069277491949.
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碩士崑山科技大學
電機工程研究所
98
White Light Emitting Diode (WLED) is an environment-friendly and energy-saving light source ; as compared to traditional light sources, the WLED has long life with power-saving, environment-friendly, and many other advantages, has been considered as the core of the solid state lighting in the future. The method of traditional packages for white LED is powder-doped with a large number of silicone, in this way, we will meet the problem of phosphor powder settlement in the baking process, the settlement of phosphor powder, results in the uneven white light, the emitted light with non-uniform color, partial blue or yellow light. If we want to apply the white LED to luminaire or backlight module, the light color must be required to be very uniform to avoid the spot phenomenon. This article explores to the method of electrophoretic deposition, mix the YAG (Yttrium aluminum garnet, YAG) powder with the solution of isopropyl alcohol and magnesium nitrate. The YAG:Ce3+ itself is not electrically-conductive, by adding the magnesium nitrate, make the Mg＋attach to YAG:Ce3+ so the phosphor will be positively charged. Plating the YAG:Ce3+ on the chip surface uniformly by the method of electrophoretic deposition to improve the uniformity of the white LED phosphor and ensure the uniformity of white light. At the same coordinates, we compare the color uniformity of traditional packaging method and electrophoretic deposition, from the experimental results we can know, the CIE (X) and CIE (Y) difference of traditional packaging is 0.0165 and 0.0271 respectively ; as for the electrophoretic deposition, the CIE (X) and CIE (Y) difference is 0.0138 and 0.0246 ; besides the difference of CIE is smaller, the color temperature is also more concentrated. From the experimental results we can find, the electrophoretic deposition can be used to improve the CIE uniformity from each angle of the white LED.
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Chen, Ching-Yi, and 陳靜儀. "Study of multi-function phosphor modeling for white LEDs." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/41403929323744117088.
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博士國立中央大學
光電科學與工程學系
101
In this thesis, we studies the precise phosphor modeling of the white LEDs. We have developed the CRI calculation modeling, optical modeling, and thermal modeling of the phosphor. It can be applied for the material selection before the white light LED packaging and analysis of efficiency and color performance of white LEDs. The color variation due to the heating can be further analyzed. Firstly, the prediction calculation of CRI performance have been performed by a linearly calculation model. The mapping of CRI distribution on the color coordinate has been calculated by the adjusting of spectra ratio of blue chip and two color phosphor. The calculation results have been verified by the experiments of real package. The developed calculation modeling is simple and useful for predicting chromatic behaviors of a white LED with two phosphors. In the optical modeling, the scattering light can be simulated with Mie scattering based on Monte Carlo ray tracing in phosphor layer. Then use the experiment result and combine the simulation to fitting the effective absorption and conversion coefficients. Since the ability of absorption of the phosphor depend on the wavelength of excitation light, we combine the absorption spectrum of the green phosphor with the ratio of the phosphor absorption to modify the output spectrum of blue light. And we use the absorption spectrum of the red phosphor and the emission spectrum of the green phosphor to analysis the re-absorption effect. Finally, with the verification of real packages and the simulations, we successfully demonstrate the two phosphors model with double layers. The development of phosphor optical modeling can be applied to any recipe of phosphors for the prediction of chromatic performance and the analysis of package efficiency of white LED with difference package. In the thermal modeling, we combine the thermal effect of the phosphor with the optical model to build up the thermal model of phosphor. The thermal model can simulate color coordinate with various temperature. Finally, we can predict the variation of color behavior with different operation temperature in the white LED package.
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Chen, Kuo-Ju, and 陳國儒. "Development of Phosphors for White Light-Emitting Diodes through Combinatorial Chemistry approach." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/06102307645853081331.
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碩士國立臺灣師範大學
光電科技研究所
98
In 1996, the first white light-emitting diode (WLED) was developed by Nichia Chemical Company, Japan. The advantages of WLED are small size, lower heat generation, long lifetimes and many more favorable properties. The conventional lamp could be replaced by WLED. The luminous efficiency has been improved by 60 lm/W in 2005 to 150 lm/W in 2010. WLED will become the newest lighting source in twenty-first century. However, the above mentioned strategy of white light generation faces serious problems such as low conversion of blue LED, low color rendering index, high color temperature and so on. For this reason, UV excitable phosphors have attracted much attention to improve the drawbacks. UV-LED fitted with three phosphors emitting blue, red and green, this type offers superior color uniformity with a high color rendering index and excellent quality of light. The aim of this study is to focus on UV excitable phosphate which has high luminous efficiency and high stability. The work is to use the combinatorial chemistry to develop (Y,Gd)VO4 phosphor. The host matrixes were doped with different rare earth elements such as Bi3+ ions and Eu3+ ions. The purposes of combinatorial chemistry approach are initial -selected and fast- optimize. In order to verify the results in combinatorial chemistry approach, using the solid-state reaction to synthesis vanadate phosphor. According to the bulk sample, they will be discussed the further luminous properties and energy transfer mechanism. Finally, a practical white LED lamp has been prepared from an optimal (Y0.956Bi0.040Eu0.004)VO4 phosphor and a commercially available blue phosphor of Sr3MgSiO8:Eu2+ (3128) which lead to obtain the color rendering index (Ra) up to 90.3.
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Lin, Chih-How, and 林志豪. "Studies and Applications of CdSe/ZnSe Quantum Dots for White LED's Phosphors." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/68604483176171639809.
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碩士國立清華大學
材料科學工程學系
94
We present a novel method for detecting the quantum dots’ (QDs) stability at room temperature. The device is fabricated by combining blue InGaN chips with luminescent colloidal core-shell CdSe-ZnSe QDs. We design a simple holder to fix the SMD-LED for ensuring detected position always the same. Although using the QDs as phosphor for the fabrication of LED is more easily, however, the QDs are unstable owing to lattice mismatch, photooxidation and thermal aggregation. Therefore, we encapsulate QDs into PMMA to protect QDs from oxidation and aggregation. By this way we can improve the stability of QDs at room temperature which increases the feasibility for replacing the phosphors such as YAG with QDs. Finally，we use this technique to fabricate WLED(White Light Emitting Diode)，it not only shows the good stability but also exhibits good properties on efficiency and purity of white light.
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Chen, Chun-Ting, and 陳俊廷. "Synthesis and Luminescent Properties of Novel Phosphors for White-Light-Emitting Diodes." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/30550910473375542823.
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碩士中原大學
化學工程研究所
105
In recent years, white light-emitting diodes (W-LEDs) has become attractions due to their high brightness, environmentally friendly, long lifetime, well energy efficiency, and less power consumption. Therefore, it is considered as a new next generation light source. However, they fail to achieve higher color rendering because of the lack of red component in blending of different color phosphors. Hence, it is necessary to find red emission phosphors for application. In this study, we discussed on two kinds of rare earth ions and successfully synthesized the samples via a high temperature solid state reaction at air atmosphere. The rare earth ion as mentioned in this thesis are europium and samarium, which could emit red and orange-red emission light when excited by n-UV chip or blue LED chip. To further discussion, we used a series of analysis such as X-ray diffraction, crystal structure refinement, photoluminescence (PL) spectra, temperature-dependence photoluminescence (TL) spectra, EL spectra, decay lifetime, diffuse reflection spectra, LED fabrication, CIE coordinate and so on to identify the luminescent properties of NaYPO4F:Eu3+, La5BSi2O13:Eu3+, Ca2Y8(SiO4)6O2:Sm3+ and La6Ba4Si6O24F2:Sm3+ phosphors.
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Chen, Yow-Renn, and 陳佑任. "Electroluminescence characteristics of white light sulfide phosphors prepared by solid-state sintering." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/16554914302181681550.
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碩士國立高雄應用科技大學
電子與資訊工程研究所碩士班
96
Abstract Zinc sulfide (ZnS) phosphor and strontium sulfide (SrS) is a kind of II-VI sulfide semiconductor with band-gap of 3.66 and 4.32 eV, respectively. ZnS is a direct band-gap material and has great potential been an optoelectronic material. With its large band-gap, various radiation wavelengths could be obtained by doping transition or rare earth metal ions. The major and important applications of phosphor are in light sources, display devices, and high energy radiation detector. In this study, we mixed blue-green phosphor and orange-yellow phosphor to perform the white light emission. The blue-green phosphor was prepared by SrS:CeF3 and SrS:CeO2. The orange-yellow phosphor was prepared by ZnS:MnO2. ZnS and SrS phosphors were prepared using solid state sintering method and doped with MnO2 (0.6 mol%), CeF3 (2.0 mol%) and CeO2 (1.5 mol%), respectively. The optima emission efficiency of phosphor was achieved when the phosphors was synthesized at temperature 1200oC for 1 hour under N2 atmosphere. Then, the SrS:Ce (blue-green) and ZnS:Mn (yellow-orange) phosphors were mixed by different weight percents to generate white-light emission. In addition, in this study, we offered two improvement method for the EL device, the first one was synthesize white light emission phosphor; and the second was grinding 1~4 hour for annealing to improve the flaw. Photoluminescence (PL) was used to analyze the luminescence of the phosphors. The CIE color coordinates were measured with a colorimeter (Minolta CS-100A, Japan) excited by an ultraviolet (UV) lamp.
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邱創弘. "Synthesis and Luminescence Characterization of Novel Phosphors for White-light-emitting diodes." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/84966756206180097083.
Full textAbstract:
博士國立交通大學
應用化學系所
96
We have successfully synthesized four types of intense red-emitting tungsto-molybdates (all for Eu3+-doped luminescent materials), and one type of emission-tunable phosphor (Eu2+/Mn2+-codoped) via solid-state reaction technique at high temperature. First, AB(WO4)2-x(MoO4)x have been investigated and reported. When the molybdenum content is increased, the lithium europium double tungsto-molybdate shows stronger red emission at 615nm by exciting at near-UV wavelength of 394 nm. The CIE chromaticity coordinates were found to be (0.66, 0.33) for AB(MoO4)2 and it reached the same level as the commodity phosphor Y2O2S:Eu3+. The color-rendering index (Ra) value of the WL-LED based on AB(MoO4)2 was found to be 67.8, approaching that (Ra~70.8) of the other WL-LED based on the commodity of La2O2S:Eu3+. Specifically, the CRI-No.9 value showing color reproduction in the red region has been improved from -15.20 to 53.05 for the WL-LEDs using AB(MoO4)2 as the red-emissive component. Subsequently, we have investigated the luminescence of a series of M5B(WO4)4-x(MoO4)x (M = I, J, K) phosphors and discovered that J5B(WO4)4-x(MoO4)x exhibit the most intense red-emission among the three investigated. The intensity of 5D0→7F2 transition reaches a maximum when the relative ratio of W/Mo is 1:1. In addition, J5B(WO4)2(MoO4)2 has also been proved to be a good phosphor showing no concentration quenching because the special structure of it. The color-rendering index (Ra) of a typical WL-LED based on J5B(WO4)2(MoO4)2 was found to be 82.3, higher than that (i.e., Ra~70.8) obtained for the WL-LED fabricated using the commodity of La2O2S:Eu3+. Particularly, the CRI-No.9 value, showing color reproduction in the red region, has been improved from -15.20 to 82.89. Both A3B2C3(WO4)8-x(MoO4)x:Eu3+ and G2(WO4)3-x(MoO4)x:Eu3+ show excitation band around near-UV region, and enhanced red emissions under 394 nm light excitation. The two kinds of phosphors exhibit equally that the intensity of 5D0→7F2 transition reaches a maximum when the relative ratio of W/Mo is 1:1. The CIE chromaticity coordinates were found to be (0.66,0.33) for all series of A3B2C3(WO4)8-x(MoO4)x:Eu3+, whereas that were found to be (0.67,0.33) for all G2(WO4)3-x(MoO4)x:Eu3+ phosphors. For each of the phosphors, the relative luminance was found to be larger than either Y2O2S:Eu3+ or La2O2S:Eu3+. We have also studied on series of MAxOyN:Eu2+ (M = I, J, K) phosphors. We have observed that KAxOyN:Eu2+ exhibit the broad blue emission band centering at 444 nm among the three investigated. The effect of chemical compositions on the luminescence properties of KAxOyN:Eu2+,Mn2+ has also been investigated. We have discovered that energy transfers from Eu2+ to Mn2+ by directly observing spectral overlap between the emission band of Eu2+ and the excitation transitions of Mn2+. With increasing Mn2+ content, the PL intensity at around 513 nm of Mn2+ was observed to increase systematically, whereas that of Eu2+ was discovered to decrease gradually. The energy transfer efficiency (ηT) from Eu2+ to Mn2+ has been found to increase gradually with increasing Mn2+ dopant contents.
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Chen, Po-Way, and 陳柏偉. "Effect of Blending Different Types of ZnS Phosphors on the White Electroluminescence." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/55630993788084265431.
Full textAbstract:
碩士國立成功大學
材料科學及工程學系碩博士班
92
This research is to investigate the effect of mixing methods and parameters on luminescent properties of blending the blue-green and orange of ZnS phosphors. This study is also to examine the optical performance of ZnxCd1-xS：Cu, Cl synthesized by solid state with various x values as well as with different copper concentration. The X-ray diffraction was utilized to characterize the crystal structure of prepared ZnCdS. The optical properties were measured, including Photo- luminescence ( PL ) spectroscopy, Electro- luminescence ( EL ) spectroscopy, and Chromaticity coordinates(CIE). Blending of the blue-green and orange phosphors in the weight ratio of 1：5 . The high intensity of electroluminescence is achieved by suspending mixed phosphors in castor oil. It is found that the result in chromaticity coordinate (CIE) values of (0.322, 0.345) under 300V 1000Hz, which is located in white color region. However, the CIE values mentioned above was shifted a little to the green color. Furthermore, an equation and a correction parameter was generated from the laws of color addition and experimental results to evaluate the CIE values of mixing phosphors regarding to the weight ratios and the brightness difference of the blue-green and orange phosphors. In order to improve shift the CIE value to white light, the red electroluminescent phosphor was synthesized by alloying of ZnS and CdS. The results show that emission peak was located at 630nm and 665nm in red region, as x is equal to 0.4 and 0.3, respectively. And the best electroluminescence intensity was obtained by alloying 60 mole% of CdS in ZnS and doping 2600ppm copper.
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Chiu, Sheng-Huan, and 邱勝煥. "Enhancement of luminous efficiency by hybrid phosphor structure and flexible phosphor film in white LEDs." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/8492xb.
Full textAbstract:
碩士國立交通大學
光電工程研究所
102
Recently, white Light-emitting diodes (LEDs) have been regarded as the next generation of environment lighting sources because of its small size, high efficiency, and longer lifetime, especially in solid-state lighting (SSL). In this thesis, we developed the new phosphor coating structure to improve the luminous efficiency of white LED by enhancing the utilization of blue ray in the LED package, which has the great potential to use in the large area and high power lighting application. First of all, the flexible phosphor film structure by spin coating method for both cold and warm white LED is demonstrated. The experiment result shows that the flexible phosphor film structure yielded higher lumen efficiency intensity than a conventional dispense structure due to the utilization of blue light. In addition, the flexible phosphor film is also combined with flip chip package to produce white light and proved that such techniques can produce highly efficient lighting source. Secondly, we demonstrated a novel “hybrid” phosphor structure for white LED. The hybrid phosphor structure produces more efficient luminosity than the conventional remote and conformal phosphor structures. Using a TFCalc32 simulation, the electric intensity of the hybrid phosphor structure was calculated for various thicknesses, and the enhanced use of blue rays was verified. Moreover, the hybrid phosphor structure shows more uniform angular correlated color temperature (CCT) by using ZrO2-dispensed and texture PDMS film-attached methods, respectively. Therefore, the hybrid structure provides an appropriate solution for the white LEDs.
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Lin, Ming-Te, and 林明德. "Study of Ring Remote Phosphor for White LED Optical structure." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/34654708495890403263.
Full textAbstract:
博士國立中央大學
機械工程研究所
100
In this thesis, we analysis the package efficiency and the CRI based on the different phosphor-packaged LEDs. First, we design an inverted cone lens with its side of the lens around a ring phosphor layer structure in the transmissive package for the phosphor layer. The optimized lens not only reduces chip absorption probability of phosphor layer emission light but also enhances the package extraction efficiency. Second, we discuss about the LEDs with the reflective package for the phosphor layer. We mixed BaSO4 and phosphor in the reflective case. We find out the condition high color rendering index due to different proportions with phosphor and BaSO4. Finally, we make several samples of white LED products based on our result. We successfully get the LEDs with high efficiency and high color rendering index and verify our simulation.
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Kong, Hsieng-jen, and 孔祥仁. "Study of phosphor characteristic for high-power white LED package." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/88451570421095057342.
Full textAbstract:
碩士國立中央大學
光電科學研究所
97
In this thesis, we study YAG phosphor characteristic including scattering model, absorption coefficient and conversion efficiency. Mie scattering theory and Monte-Carlo ray tracing are used to describe the scatter of light in the phosphor layer. By fitting absorption coefficient and conversion efficiency of phosphor through experiment and simulation, we have successfully built an optical phosphor model. Furthermore, via using different blue sources to analyze absorption coefficient and conversion efficiency of phosphor, the validity of phosphor model is enhanced. Finally, since re-absorption effect decreases absorption coefficient and conversion efficiency, we analyze this effect by comparing different spectra from experiments.
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Lin, Yu-Lin, and 林育霖. "Optimization of The Backend Phosphor Process for White LED Package." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/73exn6.
Full textAbstract:
碩士國立虎尾科技大學
光電與材料科技研究所
102
The LED lighting has become the main stream of the next generation''s lighting source. As high efficiency has been emphasized nowadays the cost consideration is indeed one of the important factor that makes LED the main lighting source. Under the requirement of low cost, the cost for packaging is relatively more important as high illumination and CRI are being considered. In order to achieve a better efficiency, recent LED process introduces the centrifugal sedimentation process technology to accelerate the sedimentation of phosphor and shortens the process waiting time to reduce the packaging cost. However, the cost of introducing centrifugal process is the consumption of phosphor. According to the past studies, using the centrifugal process would consume 4% more phosphor under the same color temperature. As the packaging process emphasizes every bit on cost reduction, it is helpful for cost control if the phosphor usage could be reduced. This research took EMC 3535 as the lighting component for testing and studied on utilizing different conditions and measures for glue solidification in order to reduce phosphor consumption during packaging process and thereby reduce the packaging cost furthermore. From the test result we concluded that by using the hot plate to heat up the frame the glue could be solidified in a short time. Under such method by changing the phosphor proportion in the phosphor glue, the CIE position could be maintained the same after centrifugal processing and presents no difference in illumination and CRI comparison. Therefore, using the hot plate as the solidification method the consumption of phosphor could be effectively reduced. The test in this research showed that under the requirement of same color temperature it could reduce 5% of phosphor consumption
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Tu, Huang-Tsung, and 凃皇總. "The characteristics of white LEDs with curved remote phosphor layer." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/92338106137051542844.
Full textAbstract:
碩士明新科技大學
電子工程研究所
102
For the phosphor-converted LEDs (pcLEDs), the enhancement of the package efficiency is always an important issue. For the typical structures of the pcLEDs, a phosphor layer is close to the contour of the LED chip. Then a large portion of converted light from the phosphor would impinge on the LED chip and be absorbed by the LED chip. Therefore, the package efficiency of the pcLEDs will be low. To improve the package efficiency for pcLEDs, the remote phosphor structure with the phosphor layer placed at a sufficiently large distance from the LED chip was proposed. The remote phosphor structure lowers the probability of a light from the phosphor and directly hitting the absorptive LED chip, thereby improving the package efficiency. However, for the conventional remote phosphor structure with flat remote phosphor layer, there is still a large probability of a light being trapped in the flat remote phosphor layer owing to the total internal reflection on the interface between phosphor layer and air. Therefore, the efficiency of the pcLEDs with remote phosphor structure will be limited. In this paper, a new packaging structure of white LEDs that employs a curved remote phosphor layer for remote phosphor configuration is proposed. The pcLED with curved remote phosphor structure will promotea high package efficiency owing to the low total internal reflection on the interface between phosphor layer and air. The optical simulations were used to analysis the package efficiency and angular chromaticity of the curved remote phosphor structures with different curvatures. At the meantime, the pcLEDs with the some configurations were packaged and measured to conform the simulation results for the curved remote phosphor structures.
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Chen, Chiao-wen, and 陳巧雯. "The Study of High Power White Phosphor-Conversion LED Package." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/36663890116136963317.
Full textAbstract:
碩士國立中山大學
光電工程研究所
94
Light emitting diodes (LEDs) are generally used in daily life. Our major target is to increase the brightness of LED. We study the package of white phosphor-conversion light emitting diodes (PC-LEDs) and analyze the effect on the luminous flux and color temperature from different locations and concentrations of phosphor coatings and deposition of phosphor. In this study, the color temperature and luminous flux are measured. When the phosphor is placed on the top of the reflected cup with 1.5% of concentration, or on the bottom with 7% of concentration, or when it fills the reflected cup with 1.5% of concentration, the luminous flux is about 40 lm under the CIE 1931 color coordinate of (0.33,0.33). We also studied the effect on deposition of phosphor of two different viscosities of resin used to package white PC-LED. The luminous flux which is packaged with higher viscosity resin is about 12% higher than the one found with the lower viscosity resin. After two hours of deposition, the luminous flux of the white PC-LED which is packaged with the resin of lower viscosity increased 4%, and the one packaged with the resin of higher viscosity increased 7%.
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Lin, Yi-Shan, and 林益山. "Synthesis and Characterization of Yttrium Aluminum Garnet Phosphors for White Light Emitting Diodes." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/18933718291224459529.
Full textAbstract:
碩士國立臺灣大學
化學研究所
93
It has been about 10 years since the company of Nichia in Japan realized the white light emitting diodes (WLEDs) by combination of the blue chip with yttrium aluminum garnet (YAG) which emits yellow color. In the past years, various methods were reported in the use of different chips and phosphors and the applications of WLEDs were also noticed in various fields. At the same time, the studies of the UV-LED with phosphors were carried out. It is expected to use the WLEDs as the ideal lighting device in 2010. Eventhough various methods have been developed over the period of time for the construction of WLEDs, there still exists some disadvantages. Firstly, preparation of LEDs by mixing more than two different phosphors results in different levels of energy transfer efficiency and decay rate for every phosphor. Secondly, the difficulties in the improvement of UV-LED efficacy still need been examined. Even now the most stable way to produce WLEDs is the combination of the blue chip and phosphors emitting yellow light as mentioned above. Nevertheless, the energy transfer efficiency and the absorbance to different excited energy of phosphors are needed to be improved in present time. In this work, we substituted the Tb3+ into the crystal of the yttrium aluminum garnet structure and investigated its properties. Except being as sensitizers, Tb3+ ions substitute Y3+ to form the host as the terbium-yttrium aluminum garnet structure, which influenced the emission character of activators. We also introduced fluxes in the synthesis of phosphors to change crystallite-formation processes. The flux addition during synthesis enhances the emission efficiency of phosphors which is superior to commercially available phosphor. We proposed the possible mechanisms for the transition and energy-transfer process of electrons by the investigation of VUV-PL spectra, low-temperature PL spectra, and solid state NMR spectra. In this work, we utilized X-ray diffraction (XRD) to investigate the crystal phase and long range ordering. In regard to the luminescent properties such as excitation and emission spectra, photoluminescence spectrometer (PL) was used. We also investigated luminescent properties by PL spectra excited by VUV synchrotron radiation source and the PL spectra at low temperature to study the energy transfer processes. The SEM was used to analysis the particle size and morphology of phosphors. The TGA/DSC analyses were performed to examine the weight lost process and chemical reactions during the heat treatment. We also utilized the SS.-NMR to investigate the coordination environments of critical elements. Some results of this study are already published in J. Electrochem. Soc. [152, J41 (2005)]. Three more manuscripts are under preparation (Chem. Mater.; J. Electrochem. Soc.; J. Lumin.) and four patents have been filed from the outcome of results.
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Chang, Shuo-Chieh, and 張碩傑. "The effect of laser speckle on phosphor converted white light color uniformity for laser-excited white light application." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/8u2u3w.
Full textAbstract:
碩士國立臺灣科技大學
色彩與照明科技研究所
104
In this thesis, we study the optical characteristics of the phosphor converted white light excited by blue laser light source. Due to the high coherence of the laser light source, laser speckle cause by interference is unavoidable. In order to understand the influence of laser speckle on phosphor converted white light, we did a series of experiments and simulations to accurately build the phosphor and speckle model, and analyzed the relationship between the speckle contrast of laser speckle and the color difference of the white light on the surface of the phosphor and the white light projected on the screen by the collimating lens. The result shows that when the speckle contrast of the laser speckle decrease below 10%, the color performance of the white light excited by speckled light is almost the same as the white light excited by speckle-free light.
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Li, Jia-Lin, and 李佳霖. "The optoelectronic analysis white LED chip applied by yellow phosphor film." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/46309361008418329435.
Full textAbstract:
碩士雲林科技大學
光學電子工程研究所
97
In 1996, Nichia Chemical Company in Japan developed yttrium aluminum garnet (YAG) phosphor which can emit yellow fluorescence by blue light excitation, This technology also can lead to high-efficiency white light. White LED is a new product in illumination field and its marketing potential is also highly expected. In comparison with bulbs and fluorescent lamps, white LED has some advantages, such like smaller volume, low heat generation, lower operating power, longer lifetime, higher response speed and lower environmental impact. In my thesis, optoelectronic analysis of white LED chip applied by yellow phosphor film will be discussed. There are two components making up for white LED. The largest different design of new structure in our study is to coat a yellow phosphor thin film on the back of blue LED. Comparing to conventional white LED which is casted phosphor epoxy on the LED lead frame, our white LED has some advantages, such as the phosphor layer is uniform, lower cost, convenient process and higher radiant efficiency. And in our study, optoelectronic properties of our new white chip structure design such like different chip sizes, different thickness of phosphor layer, different glue will be discussed.
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Huang, Yu-Hang, and 黃桓俞. "Study of white Light-emitting diode with a jet phosphor layer." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/19249232433006185390.
Full textAbstract:
碩士崑山科技大學
電子工程研究所
99
Light Emitting Diode (LED) is an environmentally friendly energy saving lighting, this study proposes a novel pulse jet (Pulsed Jet) phosphor technology, YAG:Ce3+ evenly spread terror on the blue grain, improve and enhance the luminous efficiency white uniform; the other hand, anti-doping in the phosphor powder in precipitation can reduce the amount of fluorescent powder to add and improve saturation current and improve light efficiency. In this study, the first use of Pulsed Jet YAG:Ce3+ Blu-ray crystal, The results indicate that Pulsed Jet terror way of flux coating can be improved 7.08%, the uniformity of terror than the traditional way of phosphor coating to enhance the 7%, Pulsed Jet Tu terror way of phosphor thickness of 216 μm; the other hand, settling on anti-doped YAG:Ce3+, 2.9% to enhance the luminous flux; the last use of Pulsed Jet YAG:Ce3+ and doped precipitated powder coated anti-terror Blu-ray crystal, luminous flux than the traditional LED upgrade 10.3%, but when the operation current of 900 mA, Pulsed Jet precipitated powder anti-doping in YAG:Ce3+ high power LED''s luminous flux than in the undoped high-power LED just high-throughput improved 18%。
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Chen, Cheng-Chien, and 陳正健. "Study of Package Efficiency and Reliability of Phosphor-converted White LED." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/34123725679877053009.
Full textAbstract:
博士國立中央大學
光電科學與工程學系
101
In this thesis, we analyzed the package efficiency of white light LEDs and proposed a method to evaluate the lifetime of LED lamps rapidly. Based on the well-constructed YAG phosphor optical model, we analyzed the difference of package efficiency with six different package structures under the same correlated color temperature. And we discussed the influence of the package loss by changing the reflectivity of the substrate and the absorption coefficient of the die. Then we verified the experimental results with simulation data and investigated the difference of package loss with experimental package. In order to figure out the effect of different thickness and concentration of phosphors on the performance of LEDs, we demonstrated a method to calculate the phosphor particle numbers and studied the relationship among phosphor particle numbers, light output and correlated color temperature of LEDs under remote package type and dispensing package type. And we can simplify the parameter of LED package by using phosphor particle numbers. Finally, we proposed a method to estimate the lifetime of LED lamps quickly and this method can reduce the time for detection. We applied the accelerated test method to build up the relationship among the junction temperature of LEDs and lifetime, then we established the function of lighting decay and difference of junction temperature, we also decided the method to get the initial points. Finally, we combined all those methods to evaluate the lifetime of LEDs lamps rapidly and verified the results with the experimental data. And we suggested a value of lighting decay for the practical application.
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Chen, Ching-Yi, and 陳靜儀. "The study of optical modeling of silicate phosphor for white LED." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/58412756928074354085.
Full textAbstract:
碩士國立中央大學
光電科學研究所
96
In this thesis, we study the optical model to precisely describe optics and color distribution of the lights emitted by a blue LED covered with silicate phosphors. The optical model starts Mie scattering model and Monte Carlo ray tracing to describe the scattering of the lights when they are propagated in the phosphors, and the ray tracing is performed with blue and yellow rays. Through simulation and experimental measurement, we have successfully built an optical model, which can be applied to decide some package parameters in a white LED and to avoid color dispersion of the light pattern. Besides, we observed some interesting effects such as thermal decay and re-absorption of the phosphors. These effects could limit the validity of the optical model and need more study to make the optical model more correct.
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Ting, Zi-yan, and 丁姿妍. "Optical Modeling of YAG Phosphor in Higher Concentration for White LEDs." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/u724se.
Full textAbstract:
碩士國立中央大學
照明與顯示科技研究所
102
In this thesis, we have successfully built up an optical modeling of YAG phosphor in higher concentration with conformal coating. The optical modeling process includes scattering modeling, absorption coefficient and conversion efficiency. We simulate the scattering properties in YAG phosphor with Mie scattering theory based on Monte Carlo ray tracing. The simulation includes the optical behaviors of blue lights and yellow lights. The experimental measurement results are applied to figure out the absorption coefficient and conversion efficiency. Since the absorption and the emission of the phosphor is a function of incident wavelength, we introduce a β factor to increase the accuracy of phosphor simulation. Finally, we analyze the spectrum, color coordinate, packaging efficiency, and angular correlated color temperature distribution of white LEDs at different correlated color temperatures for the experimental and simulative results to verify the precision.