No description available.

Experiment was done in 2005–2006 years in the base of Vilnius pedagogical university in Chemistry institute. The title of this experiment is „Formation peculiarity of copper aluminates“. The author of this experiment is Jurgita Rakauskaitė and the director of this experiment is doc. dr. Raimondas Giraitis. The aim of this work was to synthesize CuAlO2 and CuAl2O4 from compounds of certain copper, alunimium nitrates and sulfates, and to compare dependance of copper aluminates formation on time and temperature. Firstly, reagents were crushed into powder, pressed and heated, changing heating time and temperature. For the reseach were used these methods: microstructural analysis, differential thermal analysis (DTA), X – ray difractional (XRD) analysis and scanning electron microscopy (SEM). When all the reseaches were finished, these conclusions were made: CuAl2O4 from nitrates begins to form at 750oC and CuAl2O4 from sulfates begins its crystalisation at 700oC. When the temperature is higher than 950oC, formation of CuAlO2 begins. The higher the temperature is, the less time the copper aluminates take to form. Copper aluminates, formed from solid phase, made small crystals and formed from liquid phase made big various shape crystals.

by Li, Tsui Kiu = 納米鋁酸鋰網絡增強的鋁基複合材料的製造和表徵 / 李翠翹. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Li, Tsui Kiu = Na mi lü suan li wang luo zeng qiang de lü ji fu he cai liao de zhi zao he biao zheng / Li Cuiqiao. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iv / Table of contents --- p.vi / List of tables --- p.ix / List of figures --- p.xii / Chapter Chapter 1. --- Introduction / Chapter 1.1. --- Metal matrix composites (MMCs) --- p.1-2 / Chapter 1.1.1. --- Introduction --- p.1-2 / Chapter 1.1.2. --- Aluminum-based metal matrix composites (Al-MMCs) --- p.1-2 / Chapter 1.1.3. --- Applications of MMCs --- p.1-3 / Chapter 1.1.3.1. --- Automotive applications --- p.1-3 / Chapter 1.1.3.2. --- Aerospace applications --- p.1-4 / Chapter 1.1.4. --- Fabrication methods of metal matrix composites --- p.1-5 / Chapter 1.1.4.1. --- Stir casting --- p.1-5 / Chapter 1.1.4.2. --- Liquid metal infiltration --- p.1-5 / Chapter 1.1.4.3. --- Powder metallurgy --- p.1-6 / Chapter 1.1.4.4. --- The ex-situ sintering method --- p.6 / Chapter 1.1.4.5. --- The in-situ sintering method --- p.1-7 / Chapter 1.2. --- The Al-γ-LiA102 MMC --- p.1-7 / Chapter 1.2.1. --- Lithium aluminate (LiA102) --- p.1-8 / Chapter 1.2.2. --- Applications ofγ-LiA102 --- p.1-8 / Chapter 1.2.2.1. --- Ceramic matrices in molten carbonate fuel cell (MCFC) --- p.1-8 / Chapter 1.2.2.2. --- Tritium breeder materials in nuclear fusion reactors --- p.1-9 / Chapter 1.2.3. --- Fabrication methods ofγ-LiA102 --- p.1-10 / Chapter 1.2.3.1. --- Solid state reaction methods --- p.1-10 / Chapter 1.2.3.2. --- Sol-gel methods --- p.1-11 / Chapter 1.2.3.3. --- Hydrothermal treatment --- p.1-13 / Chapter 1.2.3.4. --- Ultrasonic Spray Pyrolysis --- p.1-13 / Chapter 1.2.3.5. --- The templated wet-chemical process --- p.1-13 / Chapter 1.2.3.6. --- Tape-casting --- p.1-14 / Chapter 1.2.3.7. --- Combustion Synthesis --- p.1-14 / Chapter 1.3. --- Previous works --- p.1-15 / Chapter 1.4. --- Current works --- p.1-16 / Chapter 1.5. --- Thesis layout --- p.1-17 / References / Chapter Chapter 2. --- Methodology and Instrumentation / Chapter 2.1. --- Introduction --- p.2-2 / Chapter 2.2. --- Powder Metallurgy --- p.2-2 / Chapter 2.3. --- Fabrication methods --- p.2-3 / Chapter 2.3.1. --- Tube furnace sintering --- p.2-3 / Chapter 2.3.2. --- Arc melting --- p.2-4 / Chapter 2.3.3. --- Annealing --- p.2-5 / Chapter 2.3.4. --- Sodium hydroxide etching --- p.2-5 / Chapter 2.4. --- Characterization methods --- p.2-6 / Chapter 2.4.1. --- Thermal analysis - Differential thermal analysis (DTA) --- p.2-6 / Chapter 2.4.2. --- Physical property analysis - Thermomechanical analyzer (TMA) --- p.2-6 / Chapter 2.4.3. --- Physical property analysis - The Archimedes' method --- p.2-7 / Chapter 2.4.4. --- Physical property analysis-Surface area and porosimetry analyzer --- p.2-8 / Chapter 2.4.5. --- Physical property analysis - Microhardness test --- p.2-9 / Chapter 2.4.6. --- Microstructural analysis - Scanning electron Microscopy (SEM) --- p.2-9 / Chapter 2.4.7. --- Surface morphology analysis - Atomic Force Microscopy (AFM) --- p.2-10 / Chapter 2.4.8. --- Phase determination - X-ray Diffractometry (XRD) --- p.2-11 / References / Chapter Chapter 3. --- Al-y-LiA102 MMC samples prepared by arc-melting / Chapter 3.1. --- Introduction --- p.3-2 / Chapter 3.2. --- Experimental details --- p.3-3 / Chapter 3.3. --- XRD analysis --- p.3-4 / Chapter 3.4. --- Microstructures --- p.3-5 / Chapter 3.5. --- NaOH etching time effects --- p.3-5 / Chapter 3.6. --- The 2-minute-etched sample --- p.3-6 / Chapter 3.7. --- Physical properties analysis --- p.3-7 / Chapter 3.7.1. --- Apparent density --- p.3-7 / Chapter 3.7.2. --- Microhardness --- p.3-7 / Chapter 3.7.3. --- BET analysis --- p.3-8 / Chapter 3.8. --- Formation mechanism ofγ-LiA102 network --- p.3-9 / Chapter 3.9. --- Effects ofLi20 contents --- p.3-10 / Chapter 3.9.1. --- Effects of Li2O contents on structure and compositions of MMCs --- p.3-10 / Chapter 3.9.2. --- Effects of Li2O- contents on coefficient of thermal expansion (CTE) --- p.3-11 / Chapter 3.10. --- Conclusions --- p.3-12 / References / Chapter Chapter 4. --- Al-y-LiAlO2 MMCs samples prepared by furnace sintering / Chapter 4.1. --- Introduction --- p.4-2 / Chapter 4.2. --- Experimental details --- p.4-2 / Chapter 4.3. --- The effects of sintering temperature --- p.4-3 / Chapter 4.3.1. --- Microstructures --- p.4-3 / Chapter 4.3.2. --- XRD analysis --- p.4-4 / Chapter 4.4. --- Prolonged NaOH etching --- p.4-5 / Chapter 4.5. --- Effects of annealing temperature --- p.4-7 / Chapter 4.6. --- DTA analysis of over-etched sample --- p.4-7 / Chapter 4.7. --- Thermal stability of the as-synthesized γ-LiA1O2 powders --- p.4-8 / Chapter 4.8. --- Conclusions --- p.4-9 / References / Chapter Chapter 5. --- Y-LiA1O2 pellets / Chapter 5.1. --- Introduction --- p.5-2 / Chapter 5.2. --- Experimental details --- p.5-2 / Chapter 5.3. --- Pellets fabricated by method 1 --- p.5-3 / Chapter 5.4. --- CTE and volume fraction of MMCs --- p.5-4 / Chapter 5.5. --- Pellets fabricated by method II --- p.5-5 / Chapter 5.6. --- Comparisons of γ-LiA1O2 fabricated by method I and method II --- p.5-6 / Chapter 5.7. --- Conclusions --- p.5-7 / References / Chapter Chapter 6. --- Conclusions and future works / Chapter 6.1. --- Conclusions --- p.6-2 / Chapter 6.2. --- Suggestions for future work --- p.6-3 / Chapter 6.2.1. --- Stability test of y-LiA1O2 in molten carbonates --- p.6-3 / Chapter 6.2.2. --- Investigation of the pore size distribution of γ-LiAIO2 network --- p.6-4 / Chapter 6.2.3. --- Fabrication of Al-γ-LiA1O2 MMC by hot isotatic pressing --- p.6-4 / Chapter 6.2.4. --- Mechanical tests --- p.6-4 / Chapter 6.2.5. --- Development of gas sensors --- p.6-5 / References

Thesis (M.S.) -- Mississippi State University. Dave C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.

Les recherches actuelles sur les nanoparticules luminescentes sont motivées par le développement d'applications innovantes comme par exemple des nouveaux systèmes transparents d'éclairage ou de visualisation. Pour cela, il est intéressant de trouver des voies de synthèses originales permettant de préparer des nanoparticules individualisées et bien dispersées d'oxydes présentant des propriétés optiques spécifiques ou mieux adaptées aux systèmes envisagés. Cependant ces composés cristallisent généralement à haute température. Trois difficultés se présentent alors pour leur synthèse : le contrôle de la taille et de l'état d'agrégation des particules à ces températures, le contrôle de leur stoechiométrie et du degré d'oxydation des ions dopants. Ce travail de thèse a consisté principalement à mettre au point un procédé de synthèse original d'oxydes de la famille des silicates et des aluminates. La présence d'une matrice minérale solide pendant le traitement thermique à haute température, permet de limiter la croissance des particules et de conserver leur état de dispersion pendant la calcination. Les résultats sont encourageants puisque des suspensions de particules bien cristallisées, de taille variant de 50 à 100 nm ont pu être synthétisées après des traitements thermiques supérieurs à 800°C.

Le marché de l’éclairage est un marché de masse à diffusion large en pleine mutation face aux nouvelles contraintes environnementales. Il s’inscrit dans une démarche de préservation de l’environnement avec une volonté européenne de voir sa consommation énergétique réduite de 20% d’ici 2020. Les luminophores jouent un rôle prépondérant dans les performances des systèmes d’éclairage utilisant comme sources d’excitations des LEDs bleues ou UV, ou encore un plasma (Xe-Ne), où ils permettent de convertir les photons incidents (VUV, UV ou bleus) en lumière visible. Dans le cadre de cette thèse, nous nous sommes intéressés à la production de lumière blanche. Pour obtenir une couleur la plus proche du blanc idéal et répondant aux mieux au cahier des charges de l’éclairage domestique, une amélioration des performances des luminophores utilisés classiquement est nécessaire. Au cours de ces travaux nous avons porté notre attention sur deux aluminates de formulations Y3Al5O12 dopé Ce3+ (YAG :Ce) et BaMgAl10O17 dopé Eu2+ (BAM :Eu). L’aspect novateur repose d’une part sur la synthèse de ces luminophores sous forme de nanoparticules par des voies de synthèse originales (la voie solvothermale et la combustion assistée par micro-ondes respectivement) et d’autre part sur leur mise en forme (revêtements composites « luminophores/polymère »). Plusieurs techniques expérimentales (DRX, IR, Mössbauer, aimantation, MEB, MET,…) ont été utilisées afin de caractériser leurs propriétés structurales et morphologiques. L’étude des performances optiques de ces luminophores enregistrées sous excitations bleue, UV et/ou VUV nous a permis de mettre en évidence leur utilisation potentielle dans les nouveaux dispositifs d’éclairage : associés à d’autres luminophores (rouge pour le YAG :Ce; rouge et vert pour le BAM :Eu) en proportions adéquates, il est possible de générer de la lumière blanche présentant les propriétés escomptées. / Lighting market is a widespread distribution mass market undergoing radical transformation faced with new environmental restrictions. It fits into an environmental protection approach with a European will to reduce by 20% its energy consumption by 2020. Phosphors play a key role on performances of lighting devices where, combined with LEDs (blue or UV) or plasma (Xe-Ne) excitations, they provide visible light. In this work, we have focused on the generation of white light. In order to obtain a color closest to ideal white and meeting with the specifications of domestic lighting, it is necessary to improve the performances of traditional phosphors. Two aluminates have been investigated: Ce3+ doped Y3Al5O12 (YAG :Ce) and Eu2+ doped BaMgAl10O17 (BAM :Eu). On the one hand, innovation is based on unconventional synthesis methods allowing the preparation of nanostrutured phosphors (solvothermal and microwave induced solution combustion syntheses respectively) and on the other hand on their shaping (composite coatings « phosphors/polymer »). Structural and morphological features have been studied by means of several tools (XRD, IR, Mössbauer, magnetization, SEM, TEM,…). Finally, the optical properties of phosphors recorded upon blue, UV and/or VUV excitations have evidenced that they are suitable for applications in new lighting devices: their combination with other phosphors (red for YAG:Ce; red and green for BAM:Eu) in appropriate proportions allows producing white light with the required specifications.

In the first part, the mechanisms for the dissociation of TPA are studied under three types of conditions. The unimolecular dissociation is initiated by the breaking of either the N-Calpha and Calpha -Cbeta bonds and leads to many complicated processes. Within the confined space inside neutral zeolite channels, the diffusion of H radicals enhances a cycle of reactions, which accounts for the experimental observation of dipropylamine and monopropylamine. In the presence of an acidic site, the dissociation of TPA goes through catalyzed successive steps to produce ammonia and propylene molecules. / In the last part, two distinct paths are proposed to investigate the carbon nanotube growth mechanism using benzene as the growth seed and propylene as carbon resource. There is an incremental aromatization process, involving both alkylation and dehydrogenation, that leads to linked aromatic rings to form either (3,3) tube or (4,2) tube. Two paths are identified, one via toluene and the other via cumene. The cumene path is more favorable as the barrier is significant lower. / In the second part, A T5 cluster model is used to investigate mechanisms of propylene aromatization to benzene, which involves chemisorption, dimerization, cyclization and dehydrogenation. Propylene can be chemisorbed to form two distinct products, n-propoxide and i-propoxide, which can further be dimerizated to form longer chain olefins 1-hexene and 2-hexene (from n-propoxide), and 4-methyl-1-pentene and 4-methyl-2-penetene (from i-propoxide). Initiated by H2 elimination, these dimerization products can further go through cyclization process to generated either 6-member ring cyclohexene or 5-member ring methyl-cyclopentene. Catalyzed by zeolite, cyclohexene can directly dehydrogenate to form benzene whereas methyl-cyclopentene can dehydrogenate to form fulven, an isomer to benzene. Under acidic zeolite environment, a fulvene can readily be transformed to the thermodynamically more stable benzene. / The growth mechanisms of mono-sized and parallel-aligned single wall carbon nanotube (CNT) in the microporous channels of AlPO4-5 are investigated by density functional theory calculations. Detailed mechanisms are proposed for the decomposition of TPA, the formation of aromatic ring, and the growth of carbon nanotubes. / Liu, Jianwen. / Adviser: Zhifeng Liu. / Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: . / Thesis submitted in: December 2008. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 98-99). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

No description available.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1959. / Includes bibliographical references (p. 92-95).

Šiame darbe vienfazis perovskito struktūros gadolinio aliuminatas GdAlO3 zolių-gelių metodu buvo gautas 1000 oC temperatūroje, gadolinio jonų šaltiniu naudojant Gd2O3, kompleksus sudarančiu reagentu – 1,2 etandiolį, natūralią vyno rūgštį, citrinų rūgštį arba citrinų rūgšties ir etanolamino mišinį. Sintetinant GdAlO3, gautų tyrimų rezultatai parodė, kaip yra svarbu zolių gelių procese pasirinkti tinkamas pradines medžiagas bei kompleksus su metalais sudarančius reagentus: gadolinio jonų šaltiniu naudojant Gd2O3 buvo gauti geresni rezultatai nei naudojant Gd(NO3)3•6H2O, vienfazis GdAlO3 gali būti sėkmingai susintetintas kompleksus sudarančiu reagentu naudojant tiek natūralią vyno rūgštį, tiek 1,2 etandiolį, tiek citrinų rūgštį, tiek citrinų rūgšties ir etanolamino mišinį. Nustatyta, kad sintetinant stronciu pakeistus gadolinio aliuminatus Gd1–xSrxAlO3– (x = 0,10, 0,25, 0,50, 0,75), tinkamesnis gadolinio jonų šaltinis yra gadolinio oksidas nei gadolinio nitratas heksahidratas, kompleksus sudarantis reagentas – EDTA nei natūrali vyno rūgštis. Vienfazis perovskito struktūros stronciu pakeistas gadolinio aliuminatas Gd0,90Sr0,10AlO3– buvo susintetintas zolių-gelių metodu 1000 oC temperatūroje, gadolinio jonų šaltiniu naudojant Gd2O3, stroncio jonų šaltiniu – Sr(NO3)2, kompleksus sudarančiu reagentu – EDTA. Be to, 800 ºC iškaitinimo temperatūra yra per maža šiems junginiams sintetinti. Pirmą kartą pasiūlytas vandeninis zolių gelių metodas lantano ir gadolinio kobaltatams... [toliau žr. visą tekstą] / In the present thesis the reported results let us to conclude that the developed aqueous sol–gel procedure could be successfully used for the low-temperature synthesis of monophasic perovskite gadolinium aluminate ceramics. It was also demonstrated that the selection of raw materials for the sol–gel processing should be done with care. Monophasic perovskite structure gadolinium aluminate GdAlO3 has been synthesized by sol gel synthesis method at 1000 oC, using gadolinium oxide as gadolinium raw material and 1.2 ethanediol, natural tartaric acid, citric acid or mixture of citric acid and ethanolamine as complexing agent. According to the XRD results, the Gd2O3 instead of Gd(NO3)36H2O preferably should be used as starting material for the preparation of GdAlO3. Monophasic perovskite structure strontium substituted gadolinium aluminate Gd0.90Sr0.10AlO3– was synthesized by the same sol gel synthesis method at 1000 oC, using gadolinium oxide as gadolinium raw material, strontium nitrate as strontium ion source and EDTA as complexing agent. It was proved that better gadolinium ion source is gadolinium oxide than gadolinium nitate hexahydrate, better complexing agent – EDTA than natural tartaric acid in the synthesis of GdAlO3 and strontium substituted Gd1–xSrxAlO3– (x = 0.10, 0.25, 0.50, 0.75) samples. According to the XRD results, increasing amount of strontium reduces amount of peaks of perovskite structure gadolinium aluminate. Besides, 800 ºC temperature is too low for the... [to full text]