Dissertations / Theses: 'Solid State Reaction Mechanism'

1

Ina, Toshiaki. "Study on Cathodic Reaction Mechanism of All Solid State Electrochemical Devices." Kyoto University, 2012. http://hdl.handle.net/2433/157658.

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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16947号
人博第590号
新制||人||141(附属図書館)
23||人博||590(吉田南総合図書館)
29622
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授内本喜晴, 教授杉山雅人, 教授田部勢津久, 准教授藤原直樹, 准教授雨澤浩史
学位規則第4条第1項該当

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2

Fitzgerald, Emma T. "Studies of surface reaction mechanisms for chemical beam epitaxial growth." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317723.

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3

French, Catherine Louise. "Surface science investigations of reaction mechanisms in semiconductor growth and etching." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305988.

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4

Williams, Robert Earl Jr. "Simulation and Characterization of Cathode Reactions in Solid Oxide Fuel Cells." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16309.

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In this study, we have developed a dense La0.85Sr0.15MnO3-δ (LSM) Ce0.9Gd0.1O1.95 (GDC) composite electrode system for studying the surface modification of cathodes. The LSM and GDC grains in the composite were well defined and distinguished using energy dispersive x-ray (EDX) analysis. The specific three-phase boundary (TPB) length per unit electrode surface area was systematically controlled by adjusting the LSM to GDC volume ratio of the composite from 40% up to 70%. The TPB length for each tested sample was determined through stereological techniques and used to correlate the cell performance and degradation with the specific TPB length per unit surface area. An overlapping spheres percolation model was developed to estimate the activity of the TPB lines on the surface of the dense composite electrodes developed. The model suggested that the majority of the TPB lines would be active and the length of those lines maximized if the volume percent of the electrolyte material was kept in the range of 47 57%. Additionally, other insights into the processing conditions to maximize the amount of active TPB length were garnered from both the stereology calculations and the percolation simulations. Steady-state current voltage measurements as well as electrochemical impedance measurements on numerous samples under various environmental conditions were completed. The apparent activation energy for the reduction reaction was found to lie somewhere between 31 kJ/mol and 41 kJ/mol depending upon the experimental conditions. The exchange current density was found to vary with the partial pressure of oxygen differently over two separate regions. At relatively low partial pressures, i0 had an approximately dependence and at relatively high partial pressures, i0 had an approximately dependence. This led to the conclusion that a change in the rate limiting step occurs over this range. A method for deriving the electrochemical properties from proposed reaction mechanisms was also presented. State-space modeling was used as it is a robust approach to addressing these particular types of problems due to its relative ease of implementation and ability to efficiently handle large systems of differential algebraic equations. This method combined theoretical development with experimental results obtained previously to predict the electrochemical performance data. The simulations agreed well the experimental data and allowed for testing of operating conditions not easily reproducible in the lab (e.g. precise control and differentiation of low oxygen partial pressures).

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5

Murrell, M. P. "A study of the oxidation mechanisms of silicon, using nuclear reaction analysis." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293545.

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6

Levoguer, Carl Louis. "An investigation of surface reaction mechanisms during thin film growth of compound semiconductors." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260715.

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7

Xiao, Yao. "Analysis for reaction mechanism of cathode materials for lithium-sulfur batteries." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263747.

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京都大学
新制・課程博士
博士(人間・環境学)
甲第23286号
人博第1001号
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授内本喜晴, 教授田部勢津久, 教授高木紀明
学位規則第4条第1項該当
Doctor of Human and Environmental Studies
Kyoto University
DFAM

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8

Sarkar, Sujan K. "Reaction Mechanism and Detection of Elusive C, N, and O Centered Radicals and Intermediates in Solution and Solid State." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1448037904.

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9

Nagy, Péter. "Formation and Decomposition of Platinum–Thallium Bond, Kinetics and Mechanism. Structural Characterization of Some Metal Cyanides in the Solid State." Doctoral thesis, KTH, Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3803.

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The kinetic and mechanistic features of a new series ofplatinum-thallium cyano compounds containing a direct andunsupported by ligands metal-metal bond have been studied insolution, using standard mixandmeasurespectrophotometric technique and stoppedflow method.These reactions are interpreted as oxidative addition of the cspecies to the square planar Pt(CN)₄^2-complex. Each of these processes was found to befirst-order in Pt(CN)₄^2-, the corresponding TI^IIIcomplex and a cyanide ion donating species whichacts as a catalyst. Both di- and trinuclear complexes werestudied, and the kinetically significant thallium complexes intheir formation and the catalytically active cyanide sourcesare as follows: [(CN)₅PtTl(CN)₃]^3-: Tl(CN)₄(alkaline region), Tl(CN)₃(slightly acidic region) and CN; [(CN)₅PtTl(CN)]: Tl(CN)₂⁺and Tl(CN)₂⁺; [(CN)₅PtTlPt(CN)₅]^3-: [(CN)₅PtTl(CN)]and HCN. Appropriatemechanisms were postulated for the overall reactions in allcases, which include i) metalmetal bond formation stepand ii) coordination of an axial cyanide ion to the platinumcenter. Two experimentally indistinguishable kinetic modelswere proposed for the formation of the dinuclear complexeswhich are different in the sequence of the two steps. In thecase of the trinuclear complex, experimental evidence isavailable to exclude one of the alternative reaction paths, andit was proven that the metalmetal bond formation precedesthe axial cyanide coordination.

The cyanide ligands coordinated to TI^IIIin the PtTl complexes could be replacedsuccessfully with aminopolycarboxylates e.g.: mimda^2-, nta^3-, edta^4-. The [(CN)₅PtTl(edta)]^4-complex, with a direct metalmetal bond hasbeen prepared in solution by two different reactions: a)dissolution of [(CN)₅PtTl](s) in an aqueous solution of edta, b)directly from Pt(CN)₄^2-and Tl(edta)(CN)^2-. The decomposition reaction is greatlyaccelerated by cyanide and significantly inhibited by edta. Itproceeds through the [(CN)₅PtTl(CN)₃]^3-intermediate. The formation of [(CN)₅PtTl(edta)]^4-can proceed via two different pathways dependingon the ratio of the cyanide to the edta ligand concentrations.Thedirect pathat excess of edta means theformation of intermediate[(CN)4Pt···Tl(CN)(edta)]^4-, followed by a release of the cyanide from theTlcentre followed by coordination of a cyanide from thebulk to the Ptcentre of the intermediate. Theindirect pathdominates in the absence of extraedta and the formation of the PtTl bond occours betweenPt(CN)₄^2-and Tl(CN)4.

Homoligand MTl(CN)₄(M = Tl^I, K, Na) and, for the first time, Tl(CN)₃species have been synthesized in the solid stateand their structures solved by single crystal Xraydiffraction method. Interesting redox processes have been foundbetween TI^IIIand CNin nonaqueous solution and in Tl₂O₃-CNaqueous suspension. In the crystal structureof Tl(CN)₃·H₂O, the thallium(III) ion has a trigonal bypiramidalcoordination geometry with three cyanides in the trigonalplane, while an oxygen atom of the water molecule and anitrogen atom from a cyanide ligand attached to a neighboringthallium complex, form a linear OTlN fragment.Cyanide ligand bridges thallium units forming an infinitezigzag chain structure. Among the thallium(III) tetracyanocompounds, the isostructural M[Tl(CN)₄](M = Tl and K) and Na[Tl(CN)₄]·3H₂O crystallize in different crystal systems, but thethallium(III) ion has in all cases the same tetrahedralgeometry in the [Tl(CN)₄]unit.

Three adducts of mercury(II) (isoelectronic with TI^III) (K₂PtHg(CN)₆·2H₂O, Na₂PdHg(CN)₆·2H₂O and K₂NiHg(CN)₆·2H₂O) have been prepared from Hg(CN)₂and square planar transition metal cyanides M^II(CN)₄^2-and their structure have been studied by singlecrystal Xray diffraction, XPS and Raman spectroscopy inthe solid state. The structure of (K₂PtHg(CN)₆·2H₂O consists of strictly linear one dimensional wireswith Pt^IIand Hg^IIcenters located alternately, d_HgPt= 3.460 Å. The structure of Na₂PdHg(CN)₆·2H₂O and K₂NiHg(CN)₆·2H₂O can be considered as double salts, the lack ofheterometallophilic interaction between both the Hg^IIand Pd^IIatoms, d_HgPd= 4.92 Å, and Hg^IIand Ni^IIatoms, d_NiPd= 4.60 Å, seems obvious. Electronbinding energy values of the metallic centers measured by XPSshow that there is no electron transfer between the metal ionsin all three adducts. In solution, experimental findingsclearly indicate the lack of metalmetal bond formation inall studied Hg^IICN^-M^II(CN)4^2-systems (M = Pt, Pd and Ni). It is in contrary tothe platinumthallium bonded cyanides.

KEYWORDS:metalmetal bond, platinum, thallium,kinetics, mechanism, stopped flow, oxidative addition, cyanocomplexes, edta, redox reaction, metal cyanides, Xraydiffraction, Raman, NMR, mercury, palladium, nickel, onedimensional wire

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10

Fernández-Valverde, Suilma Marisela. "Echange isotopique dans des composes a valence mixte a l'etat solide." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13030.

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11

Purser-Hallard, Beatrice. "Kinetics and mechanisms of solid-state phase transitions and reactions." Thesis, Open University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422026.

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12

Rodriguez, Alonso Elvira. "Contribution to the study of formation mechanisms of condensable by-products from torrefaction of various biomasses." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/15784/1/Rodriguez_Alonzo_Elvira.pdf.

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The objective of the present work is to better understand chemical evolution of both solid and gaseous phases during torrefaction of various biomasses. Torrefaction experiments were carried out with a dynamic profile of temperatures between 200 and 300°C, under inert atmosphere, for pine, ash-wood, miscanthus and wheat straw. Mass loss and formation of condensable species were analyzed by TGA-GC-MS, and chemical evolution of solid phase was characterized by 13C CP/MAS solid-state NMR. Thirty condensable species could be detected; a half of these species were formed during the whole temperature range, and a third were formed by all biomass types. The main phenomena that occurred in solid phase were found to be decrystallization of cellulose, severe degradation of hemicellulose, devolatilization of acetyl groups, conservation of methoxyl groups and charring. It was also found that mass loss and chemical evolution of solid were not directly correlated for different biomasses. Based on the experimental results, a conceptual model was developed to describe biomass degradation duringtorrefaction. Thirty reactions were determined for the three major macromolecular constituents, namely cellulose, hemicellulose – represented by C5 and C6 sugars – and lignin – represented by H, G and S units. The main innovations of this model are in thedetailed approach of hemicellulose and lignin compositions, as well as in the prediction of sixteen condensable and five permanent species, and six forms of solid char, through chemically meaningful and stoichiometrically valid reactions.

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13

Paci, Benjamin. "Synthèse et caractérisation de polyimides semi-aromatiques obtenus par polymérisation à l'état solide de sel." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0137.

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Les polyimides sont des polymères a hautes performances souvent utilisés dans des environnements dits hostiles (hautes températures et hautes pressions, forts frottement, …). Ils sont connus pour leur forte résistance thermique et chimique mais aussi pour leur faible processabilité. La technique de synthèse la plus utilisée industriellement est celle utilisant les poly(acides amiques) comme intermédiaires, ce qui nécessite des solvants couteux et dangereux pour l’homme et l’environnement comme le crésol ou la N-methyl-2-pyrrolidone. Les polyimides semi-aromatiques ont eux des températures caractéristiques (fusion, transition vitreuse) plus basses que les polyimides aromatiques, ce qui permet d’augmenter leur processabilité (extrusion, injection). Une nouvelle technique de synthèse basée sur la polymérisation de sels précurseurs permet de synthétiser des polyimides (aromatiques ou non) en utilisant des solvants moins coûteux et moins dangereux. De nombreuses recherches ont été menées sur ce thème ces cinquante dernières années. À notre connaissance, cette technique n’est pas être utilisée industriellement. L’objectif de ces travaux de thèse consiste en la synthèse de polyimides semi aromatiques via la polymérisation à l’état solide de sels précurseur. Une étude préliminaire sur des molécules de faible masse molaire a permis de mettre en avant les paramètres critiques de l’étape de salification et le comportement thermique lors de l’imidification. Un protocole de salification et de polymérisation à l’état solide a été mis au point puis utilisé pour synthétiser trois polyimides semi-aromatiques présentant une solubilité accrue. Cette solubilité a permis une caractérisation complète des polymères, nous conduisant à un meilleur contrôle la synthèse. Des éléments de réponse au sujet des mécanismes réactionnels ont été proposés. Deux techniques visant le contrôle de la masse molaire des polymères synthétisés ont été testées puis comparées en termes d’efficacité et sur leur caractère industrialisable. Enfin, deux polymères synthétisés ont étés mis en œuvre puis caractérisés mécaniquement
Polyimides are known as high performance polymers, they are used in harsh environments (high temperatures, high pressure, …). They also have low processibility. The most used industrial synthesis process is using poly(amic acid) as reaction intermediate. This process requires high prices solvents that are harmful for human being and environment such as n-methyl-2-pyrrolidone and cresol. Semi-aromatic polyimides have lower characteristic temperatures and can thus be processed easily. A new way of synthesis based on salt polymerisation can be used to synthesize polyimides (aromatic or not), this process only needs simple solvents such as water or ethanol. Numerous researches have been made on this subject in the past 50 years. To our knowledge, this technique is not used at industrial scale. The goal of this work is to synthetize semi-aromatic polyimides using solid-state salt polymerisation. A preliminary examination on low weight molecules allowed us to highlight critical parameters on every step of reactions and thermal behaviour. Both salification and polymerization protocols are been made with the view to synthetize 3 soluble polyimides. This solubility allowed us to characterize our polymers and to enhance polymerization control. Those characterizations provided us answers on salification and polymerization mechanisms. Two molar mass control techniques have then been compared in terms of industrialization and efficiency. At the end, polymers have been synthetized, processed and then characterized in physic-chemical and mechanical ways

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14

Howell, Robert H. "Synthesis of fluorophlogopite using solid-state reaction techniques." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-03302010-020107/.

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15

Lechner, Ruep Ekkehard, Goetz Schuck, and Klaus Langer. "Mechanism of proton conduction in solid-state protonic conductors." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-186538.

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16

Netherton, Matthew Russell. "Asymmetric induction and reaction selectivity in solid state organic photochemistry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0012/NQ61151.pdf.

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17

Lee, Jong-Heon. "Synthesis of TiC by shock-assisted solid-state reaction sintering." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/32830.

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18

Ness, J. N. "The microstructure of reaction-bonded silicon carbide." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373687.

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19

Leoni, Stefano. "Theoretical and Experimental Investigations on Solid State Reactions: Phase Transition Mechanisms, Ionic Conduction, Domain Formation and Interface Reactivity." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-79219.

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In the practice of solid state chemistry, structural phase transitions are fairly common events. Nonetheless, their understanding, in terms of both: A rationalization of the observed changes in symmetry pattern and; An understanding of the mechanisms allowing for a particular transformation, are outstanding problems. The thermodynamic classification of phase transitions distinguishes between first and second order transitions, on the basis of the discontinuous behavior of quantities related to first or second derivatives of the free energy, respectively. Small atomic displacements are typically associated with second order phase transitions, and latent heat changes amount to a few calories per gram only. Additionally, the symmetries of the phases surrounding the transition are typically in the relation of a group and a subgroup. Reconstructive phase transitions, on the contrary, involve breaking of (large) parts of the bond scaffolding of the initial structure, and exhibit drastic changes at the transition point, with large latent heat and hysteresis effects. The corresponding atomic displacements can be in the order of the lattice parameters, and no group-subgroup is found, between the symmetry of the phases. These type of transitions have generally a strong first-order character. Landau theory accounts for continuous, second-order phase transitions. As a phenomenological theory, it does not establish the existence of a phase transition, which remains an experimental fact. It only bridges microscopic characteristics, like space-group symmetries and structural changes, or phonon softening effects, with measurable macroscopic quantities. Therein, distortions are carried by an order parameter, which fully specifies the form of the analytical variational free energy. The latter is continuous and derivable with respect to temperature, pressure and atomic displacement, at the transition point. First order, non-continuous phase transitions are still within the scope of Landau theory in the mentioned special case of the existence of a group-to-(isotropic) subgroup relationship. In the majority of cases, however, and for the most interesting phase transitions (for basic and applied research), such a relationship is missing, making the choice of an order parameter less straightforward. Most of the allotropic transformations of the elements, many intermetallic systems, and numerous insulating systems belongs to this class. This class also includes most interesting and fundamental electronic effects, like metallization in perovskites or spinel oxides for example. This very simple fact of a missing symmetry condition has helped reinforcing the opinion of first-order phase transitions being a world apart, and possibly contributed to discouraging a firm theory to develop, able to account for their transformation mechanisms and the change of physical properties across phase transition. The thermodynamic distinction between first and second order phase transitions is too narrow, as, in case of first order phase transitions, it embraces both weakly discontinuous transition and reconstructive ones, where bonds are being strongly modified. Especially, a mean to qualify the distance between two structures (geometric, with respect to symmetry, a.s.o.), is missing. Clearly, a group-subgroup relationship may, and typically does imply shortest shifting distances, as a tiny atomic displacement can already do for a symmetry lowering. Naively, missing such a relation means no constraints, and apparently no means to conclude at a connection of two structures in general, let alone a full mechanistic analysis. First order phase transitions proceed by nucleation and subsequent growth of the new phase from the initial one. Different from (second-order) continuous phase transitions, they do imply coexistence of the transforming motifs. The discontinuity in some order parameter between the two phases is driven by lowering of the free energy as the new phase forms. However, close to the transition, the original phase remains metastable, and a fluctuation is needed to cause the formation of the new phase to set in. Such a process responds to thermal changes, and depending on the height of the nucleation barrier, its rate may be slower or faster. In the former case, large deviations from equilibrium may be required to achieve transformation to the stable phase, which means that large hysteresis effects will be observed in the course of transformation. The intent of this work consists in giving a face to the intermediate configurations appearing in first order phase transitions, in solid-solid reconstructive processes. Apart of a mechanistic elucidation, consisting in answering the question “Which atomic displacements bring structural motif A into structural motif B ?”, another purpose of this work is a rather pedagogical one, that is, showing that first-order phase transitions can be understood in detail, not only in principle but in fact. The core of the examples illustrated in this work is concerned with phase transformations where pressure represents the thermodynamic controlling parameter. Pressure is extensively used in chemical synthesis, as a mean to achieve novel properties, optical or mechanical just to mention a few. Additionally, reports on novel high-pressure polymorphs are regularly appearing. In this sense, pressure is a relevant parameter for approaching fundamental questions in solid state chemistry.

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20

Astilean, Simion. "Transfert photoinduit de protons dans des cristaux mixtes pentacène/acide benzoi͏̈que caractérisé par spectroscopie optique." Grenoble 1, 1993. http://www.theses.fr/1993GRE10129.

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L'excitation optique a basse temperature du pentacene en site de substitution dans des cristaux d'acide benzoique conduit a l'apparition de nouvelles raies d'absorption correspondant a des sites de defaut (photosites). Ces defauts, qui disparaissent spontanement dans le noir, resultent d'un deplacement des protons acides de la matrice hors de leur position d'equilibre. Nous montrons que la deuteration des protons acides de la matrice entraine une diminution d'un facteur 10#4 du rendement de formation des photosites et d'un facteur 10#3 a 10#5 de la vitesse de la reaction retour, ce qui indique que tous ces processus sont domines par l'effet tunnel. Le mecanisme de cette reaction est elucide par l'etude de molecules de pentacene partiellement deuterees (preparees et caracterisees spectralement pour la premiere fois): la reaction a lieu a partir du premier etat singulet excite et la photoreactivite varie tres fortement (d'un facteur 1 a 10) avec le nombre et la position des atomes de deuterium du pentacene, montrant clairement que les atomes d'hydrogene du pentacene participent a la reaction. Le mecanisme propose est un transfert de proton entre la matrice et le colorant conduisant a un complexe protone (hydrogene) de pentacene tres instable, qui relaxe vers le pentacene dans l'etat fondamental, en rendant un proton a la matrice en position de defaut. Par ailleurs nous avons mis en evidence des communications spontanees et photoinduites entre les sites, comme cela a aussi ete observe dans des verres

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21

Boudghene, Stambouli Amine. "Degradation mechanism in zinc sulphide/manganese electroluminescent displays." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328389.

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22

Fujiwara, Koichi. "Synthesis of Fullerene Derivatives with Novel Structures by the Solid-State Reaction." 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149781.

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23

Hörmann, Ute. "Ultra-thin Ir-silicide layers solid state reaction and stress stabilised new phases /." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972173528.

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24

Mochulski, David. "Multiple reaction solid state kinetic parameter determination and its application to woody biomass." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/51179.

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The economic problem of sustainable and environmentally responsible energy production has prompted research into a number of potential alternatives to fossil fuels. Biomass gasification has been identified as one such alternative, but incomplete characterization of the process has hindered development. This thesis addresses the problem of predicting reaction rate behavior in the case of woody biomass and aids in identifying optimal feedstock composition. Black cottonwood (Populus trichocarpa) and Lodgepole pine (Pinus contorta) samples were characterized in terms of their primary component composition (lignin, cellulose, and hemicellulose) and then subjected to gasification experiments. This consisted of pyrolysis, under a nitrogen atmosphere, and then gasification, under a dry air atmosphere, while undergoing a linear temperature program in a thermogravimetric analyzer (TGA). Inspection of the experimental data indicated the presence of three simultaneous reactions. The data was then analyzed to recover the isoconversional activation energy trend, pre-exponential factors, and reaction mechanisms. Results indicated that the contributions of the three reactions did not correspond directly to lignin, cellulose, and hemicellulose contents, but, in the case of nitrogen pyrolysis, could be predicted by the knowledge of these components. Regarding air gasification, no significant correlations between reaction rate behavior and primary wood component fraction were found. Qualitatively, the work showed that the rate at which pyrolysis occurs is increased by high cellulose and hemicellulose contents, and decreased by large lignin contents. A detailed kinetic model describing both Poplar and Lodgepole pine pyrolysis behavior was also recovered and is reported in the body of the thesis.
Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate

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25

Dolgin, Benjamin Paul Johnson W. L. "Kinetics of the formation of an amorphous layer during a solid state reaction /." Diss., Pasadena, Calif. : California Institute of Technology, 1985. http://resolver.caltech.edu/CaltechETD:etd-03272008-090442.

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26

Chen, Kezheng. "Origin of Polarization Behavior in All-Solid-State Lithium-Ion Battery Using Sulfide Solid Electrolyte." Kyoto University, 2018. http://hdl.handle.net/2433/235998.

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Takasu, Ichiro. "The study of the coercivity mechanism of gas atomized P/M MnAlC permanent magnet." Thesis, University of Salford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360473.

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28

Atzmon, M. Johnson W. L. "A study of bulk amorphous alloys formed by solid-state reaction in elemental composites /." Diss., Pasadena, Calif. : California Institute of Technology, 1986. http://resolver.caltech.edu/CaltechETD:etd-03212008-081007.

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29

Inagaki, Taichi. "Theoretical Study on Mechanism and Dynamics of Hydrogen Transfer Reaction." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/189341.

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30

Hossbach, Karl. "Investigation of the microwave effect." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/16285.

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Over the past decades, microwave sintering has been investigated, and the effects of microwave sintering have been demonstrated, however there is still uncertainty as to what is causing the enhancements known as the microwave effect . For a better understanding of the microwave effect , the effect of microwaves on the pore size distribution during densification has been investigated for submicron-sized zinc oxide (ZnO), which was sintered with conventional heating and varying amounts of microwave power but always maintaining exactly the same time-temperature profile. Initially, the density of the sintered samples was measured and compared; this proved that the densification of the hybrid sintered samples was increased and that the higher the level of microwaves used, the more it enhanced the densification. After this, the porosity was investigated through the use of nitrogen adsorption analysis, mercury porosimetry and Field Emission Gun Scanning Electron Microscopy (FEGSEM). Initially, it was found that sintering with microwaves reduces pores faster than for conventional sintering as expected. However, the experiments also revealed that the mechanisms of the reduction in the porosity were not different for microwave sintering compared to conventional sintering. When the porosity was compared at equivalent densities, it was observed that there was no significant difference, either in terms of the amount of porosity or the microstructure development. Since the structural development was the same for both conventional and hybrid sintering, it was concluded that the cause for the enhancement of the densification was enhanced diffusion caused by an additional driving force induced by the microwave field. The investigation of the solid-state reaction between zinc oxide and alumina was designed to investigate whether the diffusion associated with reactions was also enhanced by the use of microwaves. Therefore, zinc oxide and alumina samples were reacted as diffusion couples using conventional and hybrid heating, the latter with varying amounts of microwave power. The analyses of the reaction layer using FEGSEM showed an increase in the reaction product layer thickness when hybrid heating was used, with a higher level of microwaves yielding more growth. These results supported the view that the enhanced reaction rates were caused by enhanced diffusion, again caused by an additional driving force induced by the microwave field. For both the densification and reaction cases, the most likely additional driving force is considered to be the ponderomotive effect.

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31

Yang, Yuan. "Graphene as a Solid-state Ligand for Palladium Catalyzed Cross-coupling Reactions." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5488.

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Palladium-catalyzed carbon-carbon cross-coupling reactions have emerged a broadly useful, selective and widely applicable method to synthesize pharmaceutical active ingredients. As currently practiced in the pharmaceutical industry, homogeneous Pd catalysts are typically used in cross-coupling reactions. The rational development of heterogeneous catalysts for cross-coupling reactions is critical for overcoming the major drawbacks of homogeneous catalysis including difficulties in the separation, purification, and quality control process in drug production. In order to apply heterogeneous catalysis to flow reactors that may overcome this limitation, the catalyst must be strongly bound to a support, highly stable with respect to leaching, and highly active. While the primary role of supports in catalysis has been to anchor metal particles to prevent sintering and leaching, supports can also activate catalytic processes. In this study, by using a xi combined theoretical and experimental method, we probed the effect of graphene as support in the complex reaction cycle of Suzuki reactions. The density functional theory study provides a fundamental understanding of how a graphene support strongly binds the Pd nanoparticles and act as both an efficient charge donor and acceptor in oxidation and reduction reaction steps. Theoretical investigations prove that the Pd-graphene interaction promotes electron flow between the metal cluster and the defected graphene to reduce reaction barrier. The ability for graphene to both accept and donate charge makes graphene an unusually suitable support for multi-step catalytic processes that involve both oxidation and reduction steps. The computer-aided catalyst design with the atomic precise accuracy demonstrates the Pd/graphene catalyst can be further optimized and the first-row transition metal nanoparticles have great potential to replace Pd to catalyze the Suzuki reaction. The corresponding experimental study shows that the method to immobilize the Pd nanoparticles on the graphene is crucial to increasing the reactivity and stability of the resulted catalyst. A comparison of the activation energy and turn over frequency for a series of supported and homogeneous catalysts indicates that exposing palladium-graphene to defect inducing microwave radiation results in dramatically lower activation energies and higher turnover frequencies. Furthermore, the heterogeneity tests demonstrate the Suzuki reactions are carried out on the surface of the immobilized Pd nanoparticle agreeing with the theoretical results. A method to engineer the 2-D graphene support to a 3-D structure to minimize the re-stacking and agglomeration of the graphene lattice will also be introduced in this study.

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32

Hong, Youlee. "Elucidation of Chain-Folding Structure and Crystallization Mechanism of Semicrystalline Polymer by Solid-State NMR." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430246993.

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33

WANG, SHIJUN. "CHAIN FOLDING AND CRYSTALLIZATION MECHANISM OF POLY(L-LACTIDE) AS INVESTIGATED BY SOLID STATE NMR." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1541091884494995.

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34

Wang, Tsueh-Hua. "A study of the electroluminescence properties of a-SiC:H thin-film light emitting diodes and the recombination mechanism of a-Si:H and its alloys." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242308.

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35

Pharaoh, Mark Wilson. "An investigation into the interface development in solid state reaction bonded platinum/yttria - stabilised tetragonal zirconia polycrystal composites." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293159.

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36

Lee, Yu-Chaun, and 李育全. "Direct Observation of Solid State Reaction of Si1-xGex Nanowires with Ni and Modulation of the Diffusion Mechanisms via Oxide Layer Managements." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/59eqpk.

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37

Chien, Kai-Jiun, and 簡楷峻. "Formation of PbTe phase by solid state reaction." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/a556xj.

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碩士
國立臺灣海洋大學
材料工程研究所
105
During mechanical alloying of Pb and Te elemental powder mixture, it is found the PbTe compound phase can be formed in a very short time of 1 minutes, the mechanical alloyed powders was completely transformed into PbTe phase with further milling to 15 minutes. This rapid alloying reaction mechanism may be in the course of the ball mill powder due to the impact of the ball milling instantaneous temperature rise to higher than the melting temperature, resulting in melting Pb powder and then if exposed to Te powder, because it is liquid will adhesion to Te powder surface, because of its interface is a solid (Te) / liquid (Pb) phase structure, so Te and Pb atoms at the interface will produce rapid interdiffusion or Pb / Te powder between the Self-propagating High-temperature Synthesis phenomenon, which lead to PbTe The alloy phase is formed in a very short time. The lead-tellurium pure element mixed powder were laser irradiation and sintering treatment, The mixed powder which has not been subjected to the ball milling treatment forms the PbTe alloy phase in the combustion synthesis reaction form, but also produce PbTeO3 oxide phase, Since the laser irradiation treatment is carried out in an almost anaerobic environment, the oxygen inside starting material may be the main cause of the emergence of oxides. However, XRD diffraction peak shows that the proportion of PbTeO3 in the sintered sample is higher than that of the laser treatment, this indicate the oxygen content exist in the sintering environment was responsible for the formation of high PbTeO3 phase.

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38

Prasad, Kshitij Chandra. "Preparation of CCTO Powder by Solid State reaction." Thesis, 2009. http://ethesis.nitrkl.ac.in/1062/3/kshitij_thesis.pdf.

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A stoichiometric amount of $CaCO_3,CuO,TiO_2$ was taken. The mixture was ground by agate mortar .On the ground mixture XRD analysis was performed. After confirming of the CCTO powder ,pellets were formed. They were fired at 1000°c for different time periods. Density was measured of the fired samples.

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39

Kobe, Jeffrey M. "Deuterium solid-state NMR and reaction kinetics studies of solid acid catalysts." 1996. http://catalog.hathitrust.org/api/volumes/oclc/35916148.html.

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1996.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 397-412).

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40

Liao, Shih-Chung, and 廖世忠. "The solid-state reaction at interface of Al/GaAs." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/87436794835000222681.

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41

Chen, Shuang. "Reaction selectivity and asymmetric synthesis in solid state organic photochemistry." Thesis, 2004. http://hdl.handle.net/2429/16882.

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The Norrish/Yang type II photochemistry of four bicyclo[3.3.1]nonyl phenyl ketones was studied in solution and in the crystalline state. In both media, the bicyclic ketones without a-methyl substituents were found to be photochemically inert, while the cc-methyl substituted ones underwent Yang photocyclization to give endo-aryl cyclobutanols as predominant products. An unusual 1,4-hydroxybiradical disproportionation reaction was also observed during the photolysis of the α-methylated bicyclo[3.3.1]nonyl phenyl ketones, although it was a minor process (< 5%). By utilizing the ionic chiral auxiliary method, chiral ammonium carboxylate salts (7 in total) were formed between optically pure amines and the achiral bicyclo[3.3.1]nonyl phenyl ketone derivative containing a carboxylic acid substituent. Photolysis of these salts in the solid state afforded the cyclobutanol product with fair to excellent enantiomeric excesses (45% - 96%). A homologous series of spirobicyclo[3.3.1]nonyl ketones (4 in total) was synthesized and their Norrish/Yang type II photochemistry was investigated both in solution and in the solid state. These compounds were chosen for investigation because the conformation of the 1,4-biradicals formed by γ-hydrogen atom abstraction could be varied in a regular and incremental fashion by changing the size of the ketone-containing spiro ring. X-ray crystallographic analysis of these compounds provided detailed information about the geometric factors responsible for the partitioning of the intermediate 1,4-hydroxybiradicals among cleavage, cyclization, and reverse hydrogen transfer. Parameters governing the efficiency of the type II cleavage and Yang cyclization were established, respectively. The results indicate that while geometry does have a strong influence on the 1,4-hydroxybiradical partitioning among cyclization, cleavage and reverse hydrogen transfer, a full understanding of the results requires that the strain involved in forming the cyclization products be taken into account. The ionic chiral auxiliary approach for asymmetric induction was also investigated in a c/s-bicyclo[4.3.0]non-8-ylacetophenone system, which undergoes the Norrish type II photocleavage reaction to yield a simple chiral alkene — cis-3a, 4, 5, 6, 7, 7a-hexahydro-1H-indene. Irradiation of chiral salts (5 in total) in the crystalline state gave enantioselectivities ranging from poor to moderate (ee = 11% - 67%). Single crystal X-ray diffraction studies were performed on a number of these compounds, and on this basis, the structure-reactivity relationships involved were discussed.
Science, Faculty of
Chemistry, Department of
Graduate

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42

Hsieh, Tzu-Feng, and 謝慈丰. "Study of solid-state Maillard reaction between glucose and asparagine." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/76490413615028452323.

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碩士
國立臺灣海洋大學
食品科學系
95
The application of Maillard reaction is really broad, not only including food and medicine domains but also having close connection with aging. Therefore, Maillard reaction is concerned as the main axle in this sutdy. The materials including anhydrous glucose (Glc), monohydrate L-asparagine (MLA) and Glc/MLA mixture, are used as research objects. Three analytic techniques are applied to study the structural changes of those materials affected by grinding and heating. Fouier transform infrared spectroscopy (FT-IR) is used to determine the molecular structure. The differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) are combined to investigate the temperature change, and loss of heat and weight of these materials due to thermal treatment. The result showed that grinding can reduce the particle size and increase functional surface area. Glc adsorbed the outside moisture and induces appearance of new peaks 1460, 997 and 838 cm-1. MLA should slightly intensity change. The structural stability of Glc was lesser than that of MLA, which might influence the structure change of their mixtures. On the other hand, by using non-destructively analytical equipments, DSC, TGA and thermo FT-IR, qualitative analysis is made on the molecular structure of those materials, with temperature up to 300oC by heating at a rate of 3oC /min. The result showed that heating process caused interaction between Glc/MLA. The degeneration of Glc/MLA occurred step by step (dehydration - and decarboxylation- response completely). The temperature-dependent FT-IR system was better than DSC to analyze Glc/MLA inferior unit denatured temperature. Maillard reaction was studied by using solid-state Glc/MLA model with different moisture. MLA monohydrate was found to loss 5.3% and 15.3% of molecular weight at 115-130oC and 135-150oC, respectirely, by using RH 50%. Those loss were caused to release of H2O and CO2, respectively. On the other hand, temperature of 150-165oC dectected a loss of unknown molecular weight 14. Using DSC, TGA and FT-IR technologies, Maillard reaction of Glc/MLA has been proved to finish at temperature 180oC, and the pathway was the same as strecker degradation. Key words: solid state reaction, grinding, Maillard reaction, structural change, temperature

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43

Lee, Wen-Jiung, and 李文景. "Solid State Reaction and Sintering Behavior of Strontium Barium Niobate." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/43858258350992584880.

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博士
國立成功大學
材料科學與工程學研究所
85
Strontium barium niobate (SBN) ceramic is a good electro-optic material and has been widely used. Though the properties of the single- crystal SBN have been intensively studied, there are still some restrictions in their applications because of the small size, low mechanical strength, and high cost. Hence, it has been intrigued to develop the strontium barium niobate ceramic. However, it was reported that highly dense SBN was difficult to fabricate when pressureless sintering was used. The purposes of this study were to evaluate the reaction kinetics and sintering behavior and the effect of atmospheres on reaction- and normal-sintering. The solid state reaction of SrNb2O6 (SN) and BaNb2O6 (BN) to form SrxBa1-xNb2O6 (SBN) at different temperatures and heating rates was investigated. The reaction kinetics were analyzed by X-ray diffraction for quenched samples and the internal standard method was used to quantify the extent of the reaction. A non-isothermal kinetic empirical model was employed to evaluate the activation energy and rate constant of reaction for forming SBN with different ratios of Sr/Ba. It was found that the kinetic form would change above and below a transition at about α≒60%， which might be due to the change of the frequency factor. As the heating rate and the ratio of Sr/Ba are increased, the fully reacted temperatures of SBN increase. It is suggested that SBN with a prepared ratio might form directly rather than a variety of SrxBa1-xNb2O6 during reaction. The reaction mechanism was suggested and discussed. The higher the molar ratio of Sr/Ba, the higher the activation energy for forming SBN. The sintering behavior and microstructural evolution of reaction-and normal-sintering have been investigated and compared. Hg-penetration was used to evaluate the pore size distribution and SEM was employed to observe the microstructural development during sintering. In comparing the densification behavior of the reaction sintering and normal sintering of SBN, it was observed that the densification rate of the former was slower during reaction but became higher after reaction. It was also found that the chemical reaction occurred prior to densification but a high-density and uniform microstructure obtained for the reaction- sintered sample was pronouncedly enhanced when the reaction was almost completed. A higher density (>98%Dth), uniform and fine-grained (3~4μm) microstructure of SBN could be achieved by using the reaction sintering. The sintering behavior of SrxBa1-xNb2O6 (x=0.5, 0.6, and 0.7) powders with similar particle size was studied. The modified statistical theory of sintering was used to evaluate the activation energy. It was found that the densification rate increased and the evaluated activation energy of SBN decreased with the increase of the molar ratio of Sr/Ba. It was observed that in sintering SBN50, below 1300℃, the densification rate decreased with the increase of the oxygen partial pressure, and above 1300℃, the oxygen partial pressure became insignificant influence on the densification. The relationship of sintering behavior and structure of SBN was discussed and the Nb5+ ion was suggested as the rate-limiting species in sintering SBN. The final relative density of the sample sintered in O2 could reach 98.7%Dth. Finally, based on the results of this study, it was found that the density of the reaction-sintered sample sintered at 1300℃ for 0.2~0.5h in O2 could have high density ~99%Dth and a uniform and fine microstructure. Moreover, if those samples were further heat-treated at appropriated conditions, their density could reach ~99.5%Dth and they would become translucent.

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44

Chung-ChiangKuo and 郭仲強. "Preparation and Spectroscopic property of YTiNbO6 by Solid-State Reaction." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/34253320305100461029.

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碩士
國立成功大學
材料科學及工程學系碩博士班
98
YTiNbO6:RE(RE=Dy、Er、Pr) and YTiNbO6:(Dy,Ta) phosphors were synthesized by solid state reaction in this work. The effects of rare earth ion concentration, distortion of host, sintering temperature, and the grain size, and morphology on the photoluminescent properties were investigated and optimized. 　　YTiNbO6:RE compounds of the Euxenite structure (PDF no.83.1318) were successfully synthesized by sintering at 1300℃. The fundamental absorption edge was calculated from the absorption spectra to be at 339.7nm, corresponding to the band-gap energy of 3.65eV. Under the excitation wavelength of 353nm, the dominant emission clusters were located around 482nm and 579nm, arising from the Dy3+ transitions 4F9/2→6H15/2 and 4F9/2→6H13/2 in YTiNbO6:Dy. The optimum doping level of Dy3+ in YTiNbO6:Dy was found to be 5mol%. The CIE chromaticity coordinate was at (0.31,0.37) for YTiNbO6:Dy, corresponding to a color tone of near-white. Under the charge-transfer excitation at 290nm, a broad emission at 400~670nm was observed in addition to the sharp lines from the Dy3+ transitions. This broad emission is thought to come from the NbO6 group of the host. When Nb was substituted by Ta, the road emission was increased with the Ta concentration and reached maxima for the pure Ta compound, i.e. YTiTaO6:Dy, indicating that TaO6 emits more efficient than NbO6 at this wavelength region. 　　The optical spectra of YTiNbO6:Er is dominated by the strong emission centered at 558nm. The optimum concentration for Er3+ was found to be 10 mol%. The CIE (x,y) coordinate of YTiNbO6:Er was calculated to be at (0.29,0.67), corresponding to the color tone of yellowish green. The optical spectra of YTiNbO6:Pr were characterized by a strong emission at the 615 nm, which came from the Pr3+ 1D2→3H4 and 3P0→3H6 transitions. The optimum concentration for Pr3+ was determined to be 0.5 mol%, and the (x,y) coordinate was at (0.67,0.33), having the red color. Keyword: phosphor, euxenite structure

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45

Chiang, Chen-Yu, and 蔣鎮宇. "The study on YAG transformation route via solid-state reaction." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/31577073416070187573.

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碩士
國立成功大學
資源工程學系碩博士班
96
In this study, the relationship between YAG crystallite size and phases synthesized by Al2O3 and Y2O3 powder was discussed. And how to synthesis YAG powder from product rapidly. The starting materials had granuleseeding YAG seed or not. The heat treatment include fast and slow treatment. Before heat treatment, two powder system had spray drying, and estimated phase formation and crystallite sizes by XRD( Scherrer formula ). The result showed that existed two kind of route by synthesized YAG with Solid-state reaction. One was Y+Al→YAG and onther was YAM→YAP→YAG. When using fast heat treatment, YAG was the first phase in Al2O3-Y2O3 system. The result was that had high free energy barrier so that hard to synthesized YAG powders rapidly. But for two kinds of routs, YAP was hard to phase transformation. The purpose of seeding YAG seed was transformation temperature ahead of time.

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46

He, Wei-Ying, and 何威穎. "Synthesis of Advanced Barium Titanate Powders by Solid State Reaction." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/20302324423289475304.

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碩士
遠東技術學院
機械研究所
94
The synthesis process of advanced BaTiO3 powders by traditional solid state reaction were studied in this paper. The affect of core-shell powders, two steps reaction process, and microwave heating on the BaTiO3 powders quality were also discussed. The purpose of this research was to develop advanced BaTiO3 powders which obtained uniformity particle size distribution. According to our experimental results, using the finer BaCO3 powders and TiO2 powders could reduce the synthesis temperature of BaTiO3 and reduce the tetragonal phase transformation temperature. The nuclei size of BaTiO3 was dominated by the TiO2 powders. Using the uniformity particle size distribution of TiO2 powders as raw materials, the advanced BaTiO3 powders were successfully synthesized. Two steps synthesis process were discussed in this paper. The first stage was mixing the materials that fixed the Ba/Ti mole ratio at 0.33, 0.47 and 0.53. According to the phase diagram, The above three compositions contained lower liquidus temperature than the materials with Ba/Ti mole ratio near 1. After the fist stage of calcine process, the BaCO3 powders were adding to adjust the Ba/Ti mole ratio near 1. The two steps synthesis process could reduce the synthesis temperature approximately 200 ℃. However, the BaTiO3 powders particle size uniformity was poor. Microwave heating could improve the heat homogeneous of the calcined powders compare to the traditional calcine process. Microwave heating also urges the atom vibration in the crystal lattice. According to the test results, microwave heating could improve the particle size distribution of BaTiO3 powders. Microwave heating could also decrease the BaTiO3 synthesis temperature being the enhancement of atoms vibration. The synthesis temperature of BaTiO3 powders could be reduced to 600 ℃ obviously by using the Core-Shell structure powders. Using the citric acid as the chelating agent and glycol as the cut off medicine could improve the distribution of Core-Shell powders. The narrow distribution of BaTiO3 powders was synthesized successfully by using the Core-Shell structure powders. Key Word:BaTiO3、micorwave、core-shell.

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47

Fu, Wen-Chuan, and 傅玟娟. "Study of yttrium aluminum garnet (YAG) via solid state reaction." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/90745473416862786807.

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碩士
南台科技大學
化學工程與材枓工程系
94
Yttrium aluminum garnet powder (YAG) was synthesized by a novel solid state reaction method. Three aluminum sources: boehmite, γ Al2O3 and α Al2O3 were estimated for the YAG formation. According to the experimental results, boehmite was the best aluminum source of YAG powder. Pure YAG phase identified by X-ray diffraction (XRD) was formed by pre aging at pH=1 and then heat treating at 1500℃ for 36 hr. The best cerium doping concentration of YAG was found at 0.05 at% which had the highest emission intensity at 535 nm as exciting at 470 nm. Increasing the cerium concentration, the emission intensity has decreased because the impurity phase of cerium oxide was found in the XRD pattern. The emission intensity of cerium doping YAG was increased by increasing the calcination temperature and increasing the heat treated time, respectively. In the second part of this study, the sintering property of YAG powder was studied. The powders pre treated at different temperatures for 10 hrs, respectively were sintered. The best pre treated temperature was at 600℃ which had the highest sintering density of pellet (90.5%). The low relative density of the pellet pre treated at 800℃ for 10 hr might be due to the low packing density. Adding TEOS could improve the YAG sintering. The mean relative density of sintered pellet with TEOS aid could reach to 99% as it pre treated at 600℃ and then sintered at 1650℃ for 5 hr. All sintered pellets with TEOS were appeared translucence.

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48

Li, Yi-Sheng, and 李易昇. "Properties of Ba5Nb4O15 microwave dielectric material by solid-state reaction." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/21001815003828438998.

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碩士
國立臺灣科技大學
機械工程系
104
The purpose of this study is to investigate the instability in the solid state sintering process of Ba5Nb4O15 microwave dielectric material quality factor. Ba5Nb4O15 material systems has a high quality factor (Q), high dielectric constant (K), and low temperature coefficient at resonant frequency(τf), which is widely used in research on microwave dielectric materials. However, most papers focus on the relationships between micro-wave properties and extrinsic parameters, few published papers investigates the phe-nomena between sintering temperature and dielectric properties. To prepare Ba5Nb4O15 microwave dielectric material with high quality factor , the study focused on three variants that influenced the quality factor.For most of the ce-ramic material system the sample gets densified with increase in sintering temperature. So, we took temperature as the first variant with temperature values 1190 oC, 1259 oC, 1345 oC, and 1520 oC. There may be a little error in aspect ratio while taking into ac-count for the commercial mass- production, so in order to realize whether the propor-tion of deviation affects the electrical properties, the second variant is the Ba/Nb molar ratio and values are 4.95: 4,5: 4,5.05: 4, The Nb2O5 powder provided by the vendor were of different phase, so the sample prepared from these powder will have different properties. Therefore, third variants is to use different phase of Nb2O5 viz. m-phase Nb2O5, o-phase Nb2O5 and (m + o) phase Nb2O5. This study is divided into three parts, the first part is to study the relation between the sintering temperature and electrical properties of the samples group together by keeping the same molar ratio and varying the phase of the Nb2O5 starting powder. Ab-normal grain growth was observed above 1345 oC temperature, resulting into low den-sified sample and in turn reduced quality factor. Sample sintered at 1259 oC showed better electrical properties.The second part is to investigate using different phase Nb2O5 keeping the molar ratio constant and sintering at 1259 oC. Ba5Nb4O15 samples with m-phase Nb2O5 showed better electrical properties. This can be attributed to the similarity in the structure of Nb2O5 and Ba5Nb4O15 which will ease the atomic diffu-sion and form a complete crystal. The third part is to investigate the prepared samples sintered at 1259 oC using the same m-Nb2O5 powder and varying the molar ratio. Molar ratio with 4.95 showed better electrical properties. So we can know from above three parts that m-phase Nb2O5 is the main reason affecting the quality factor, when we pre-pare using m-phase Nb2O5 at molar ratio 4.95 (Nb rich), we can get better microwave dielectric properties , quality factor (Qf ): 22370, dielectric constant (K): 36.3

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49

Ho, Jo-Hsuan, and 何若瑄. "Formation of Porous Heterostructure Nanowires through Solid-state Diffusion Reaction." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/57mucp.

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碩士
國立交通大學
材料科學與工程學系所
105
Metal oxide materials have been widely investigated owing to their various and excellent physical and chemical properties. Among these transitional metal oxides, zinc oxide and iron oxide each play an important role in applications of photoelectric and magnetic. Zinc oxide is naturally a direct band-gap, n-type semiconductor which has wide band-gap. As a result, it exhibits significant physical properties in optical, electrical and piezoelectric fields. Iron is known for its magnetic properties, which possesses various oxidation states, including wüstite(FeO), hematite(α-Fe2O3), maghemite(γ-Fe2O3) and magnetite(Fe3O4). In this study, we observe the diffusion behaviors between zinc oxide nanowire and iron metal by in-situ transmission electron microscope. Zinc oxide nanowires and iron metal are annealed under ultra-high-vacuum condition. By solid-state diffusion reaction, the Fe3O4 and ZnO/Fe3O4 heterostructure nanowires were formed. The diffusion of iron atoms in zinc oxide lattice can be observed at 800 K annealed for 10 minutes. As-formed porous Fe3O4 nanowire with voids can be divided into two types by their appearances : disc-like void and zigzag-like void. Disc-like voids are more common than zigzag-like voids. By HRTEM images and FFT diffraction pattern analysis, we found that disc-like voids formed along the close-packing plane of Fe3O4. Moreover, there is an epitaxial relationship between Fe3O4 crystal with disc-like voids and ZnO crystal. We also compare two voids type Fe3O4/ZnO heterostructure nanowires on the same sample. It indicated that the diffusion rate of disc-like Fe3O4 nanowire is much slower since it needs more time and energy to adjust the lattice mismatch and form epitaxial interface.

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50

Liu, Qi. "SYTHESIS OF MESOPOROUS PHOSPHATES VIA SOLID STATE REACTION AT LOW TEMPERATURE." 2010. http://hdl.handle.net/1805/2247.

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Abstract:

Indiana University-Purdue University Indianapolis (IUPUI)
Three parts consist of my thesis work centered on the synthesis of inorganic phosphates and then metal organic frame work (MOF). The first part is the synthesis of mesoporous chromium phosphates using the room temperature solid state reaction (SSR)approach. One of the major aims of this work is to fill the gap of lacking a low cost, low or zero pollution, easy method to synthesize phosphates. The room temperature solid state reaction has been demonstrated in this work is such a method. Mesoporous chromium phosphates were prepared using the solid state reaction at low temperature using CrCl3.6H2O, and NaH2PO4.2H2O as precursors and the surfactant cetyltrimethyl ammonium bromide (CTAB) as template. The synthesized chromium phosphates were characterized by XRD, EDS, HR-TEM, N2-physisorption, TG-DSC and UV-Vis spectroscopies. The results indicate that chromium phosphate mesophases were formed only at atomic ratios of P/Cr ≥ 1.8. The mesophase for P/Cr = 2.0 phosphate possessed the highest ordering of pore array, with a specific surface area as high as 250.78 m2/g and an average pore size of 3.48nm. The catalytic performance of the chromium phosphates was examined by employing a model reaction, namely the dehydration of isopropanol to propene. The results indicated that all synthesized chromium phosphates exhibited significantly higher isopropanol conversions and propene yields than that synthesized via the conventional precipitation route. The highest propene selectivity (96.43%) at the highest isopropanol conversion (93.10%) has been obtained over the mesoporous chromium phosphate catalyst synthesized with a P/Cr atomic ratio of 2.0. The formation mechanism of the mesoporous chromium phosphate was investigated by FTIR technique.The results show that CTAB template plays a key role in the formation of mesoporous chromium phosphates. Mesoporous lithium manganese phosphates were also successfully synthesized using the same approach of solid state reaction (SSR) at low temperature by using LiC2O3.6H2O, MnCl2.6H2O and NH4H2PO4.2H2O as precursors and the surfactant cetyltrimethyl ammonium bromide (CTAB) as template. The synthesized lithium manganese phosphates were characterized by XRD, EDS, SEM, HR-TEM, N2-physisorption. The results show that the synthesized meoporous lithium manganese phosphates exhibited a high specific surface area (256.63 m2/g) and a narrow pore size distribution. The electrochemical tests of Li-ion batteries were performed and the results show that the charge voltage could increase to be 3.60 V while the first time discharge capacity could be as high as 100 mAh/g. The Nitro-Cu-MOF complexes, a new class of metal organic frameworks, have been successfully synthesized using a conventional thermal reaction. The obtained Nitro-Cu-MOFs have a specific surface area of 576.27 m2/g and a pore volume of 0.32 m3/g.The gas uptake of the obtained Nitro-Cu-MOFs at 60 psi is 68 mg/g (sorbate/sorbent) at 298 K for carbon dioxide, which is much higher than that of the Cu-MOFs, 31 mg/g at 298 K for carbon dioxide.

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Dissertations / Theses on the topic 'Solid State Reaction Mechanism'

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