Dissertations / Theses on the topic 'Diamond formation'
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Newson, Pamela Lynn. "Studies of diamond film formation." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/30529.
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De, Weerdt Filip. "Spectroscopic studies of defects in diamond including their formation and dissociation." Thesis, King's College London (University of London), 2007. https://kclpure.kcl.ac.uk/portal/en/theses/spectroscopic-studies-of-defects-in-diamond-including-their-formation-and-dissociation(b05e7748-c1ff-4c57-9c24-ec5cb84baddf).html.
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Southworth, R. E. "The behaviour of the stable isotopes of nitrogen during diamond formation." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1478224/.
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The study of mantle diamonds offers the possibility to investigate the geodynamic carbon cycle with an unrivalled spatial and temporal scope. Impurities in diamond, of which nitrogen is the most common, provide a window into the cycling of mantle volatiles. The isotopic compositions of carbon and nitrogen for crustal and mantle derived samples are, on average, distinct, making the carbon and nitrogen isotopic systems potentially useful indicators of interactions between crustal and mantle volatiles. For peridotitic diamonds in particular there is a very large range in δ 15N (−40 to +15 ‰) with only a small range in δ 13C (−5 ± 3 ‰). These variations in diamonds can be attributed to multistage growth from isotopically distinct reservoirs or to fractionation processes operating during single growth steps, or perhaps both. In this thesis, data from mixed-habit diamonds shows that large kinetic fractionations are unlikely to occur in nature. Data from sub-lithospheric diamonds from Juina, and diamondites from Orapa show evidence of recycling of crustal fluids as well as evidence of the involvement of primordial nitrogen during diamond formation. These data lead to the creation of a preliminary model for the deep nitrogen cycle.
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Arunagiri, Tiruchirapalli Natarajan. "Interfacial Electrochemistry of Metal Nanoparticles Formation on Diamond and Copper Electroplating on Ruthenium Surface." Thesis, University of North Texas, 2003. https://digital.library.unt.edu/ark:/67531/metadc5526/.
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An extremely facile and novel method called spontaneous deposition, to deposit noble metal nanoparticles on a most stable form of carbon (C) i.e. diamond is presented. Nanometer sized particles of such metals as platinum (Pt), palladium (Pd), gold (Au), copper (Cu) and silver (Ag) could be deposited on boron-doped (B-doped) polycrystalline diamond films grown on silicon (Si) substrates, by simply immersing the diamond/Si sample in hydrofluoric acid (HF) solution containing ions of the corresponding metal. The electrons for the reduction of metal ions came from the Si back substrate. The diamond/Si interfacial ohmic contact was of paramount importance to the observation of the spontaneous deposition process. The metal/diamond (M/C) surfaces were investigated using Raman spectroscopy, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and x-ray diffractometry (XRD). The morphology (i.e. size and distribution) of metal nanoparticles deposits could be controlled by adjusting the metal ion concentration, HF concentration and deposition time. XRD data indicate the presence of textured and strained crystal lattices of Pd for different Pd/C morphologies, which seem to influence the electrocatalytic oxidation of formaldehyde (HCHO). The sensitivity of electrocatalytic reactions to surface crystal structure implies that M/C could be fabricated for specific electrocatalytic applications. The research also presents electroplating of Cu on ruthenium (Ru), which a priori is a promising barrier material for Cu interconnects in the sub 0.13 μm generation integrated circuits (ICs). Cu plates on Ru with over 90% efficiency. The electrochemical nucleation and growth studies using the potentiostatic current transient method showed a predominantly progressive nucleation of Cu on Ru. This was also supported by SEM imaging, which showed that continuous thin films of Cu (ca. 400 Å) with excellent conformity could be plated over Ru without dendrite formation. Scotch tape peel tests and SEM on Cu/Ru samples both at room temperature (RT) and after annealing at 800 oC, showed no sign of delamination of the Cu film from Ru indicating strong adhesion. XRD patterns from Cu/Ru samples at RT through 800 oC indicated Cu in its characteristic face centered cubic (fcc) form with (111) phase dominating. Most importantly no new XRD peak emerged, even after annealing to 800 oC showing Cu and Ru did not interact much. The excellent adhesion and lack of metallurgical interactions between Cu and Ru underscored the potential application of Ru as a new Cu diffusion barrier in the next generation ICs.
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Pujol, Solà Núria. "Diverse origin and processes in the formation of diamond and other exotic minerals in ophiolitic chromitites." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/672455.
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The discovery of ultra-high pressure (UHP), super-reduced (SuR), and continental crust-derived minerals in ophiolitic chromitites worldwide challenged the previous hypotheses for chromitite formation and motivated the proposal of complex geodynamic models involving UHP conditions of formation for the chromite or recycling of the ophiolitic rocks down to the Mantle Transition Zone (410 – 660 km depth). This thesis investigates in detail the chromitites and the associated ophiolitic rocks from the Moa-Baracoa massif, eastern Cuba, and Bou Azzer, Morocco, with emphasis on identifying the presence of exotic minerals, interpreting their formation, and understanding the related geodynamic processes.
The interaction of preexisting chromitites with evolved tholeiitic melts that triggered Fe-Ti-Zr metasomatism in the Potosí chromitites (eastern Cuba) is carefully investigated here. There is evidence of coarse granular textures and strongly variable mineralogy composed of recrystallized/neoformed Fe3+-Ti-rich chromite, Ti-rich amphibole, clinopyroxene, orthopyroxene, olivine, Mg-rich ilmenite, Zr-bearing oxides and silicates, and Fe-Cu-Ni sulfides. Thorough petrographic analysis coupled with the chemical composition of the mineral phases allowed to determine the sequence of mineral formation and to propose a two-stage genetic model: 1) the crystallization of an evolved MORB liquid, via fractional crystallization, produced water-rich residual melts strongly enriched in incompatible elements, and 2) batches of this evolved melt escaped and extensively reacted and metasomatized the surrounding chromitites. U/Pb dating of baddeleyite indicates that the age of the metasomatic event (134.4 ± 14 Ma) matches the age of magmatism related to ophiolite construction in eastern Cuba.
The high-Al chromitites of eastern Cuba contain exotic minerals of the three categories: diamond, oriented clinopyroxene and rutile lamellae, graphite-like amorphous carbon, moissanite, native Cu and Si, Fe-Mn alloys, zircon, corundum, and quartz. The studied diamond grains are nanometric in size, located in CH4-bearing fluid inclusions within olivine, and systematically associated with a typical serpentinization mineral assemblage composed of serpentine and magnetite. Textural-mineralogical evidences indicate that nanodiamond formed during low-pressure and low-temperature serpentinization in super-reduced microenvironments (log[fO2;MPa]=−45.3; ΔlogfO2[Iron-Magnetite]=−6.5). The other SuR minerals (moissanite, graphite-like amorphous carbon, native elements, and alloys) also formed in super-reduced CH4-rich microenvironments. On the other hand, nominally UHP phases such as the clinopyroxene lamellae formed as exsolutions after the crystallization of chromite or can represent silicate melt inclusions attached to the growing chromite grains. Oriented rutile lamellae formed after the interaction of chromitites with mafic magma. Finally, continental crust-derived minerals, such as zircon, likely represent xenocrystic material derived from the subducting slab that was entrapped by the chromitite parental melts.
The investigation of the Neoproterozoic Bou Azzer chromitites (Morocco) allowed the comparison with the younger Cretaceous Cuban chromitites and other Phanerozoic and Precambrian chromitites. It was possible to determine that the Bou Azzer chromitites formed in the fore-arc setting during subduction-initiation with two stages of evolution: 1) formation of intermediate-Cr chromitites from fore-arc basalts (FAB), and 2) formation of high-Cr chromitites after boninitic melts. These chromitites host inclusions of platinum group minerals and exotic minerals. The unusual mineralogy includes oriented clinopyroxene lamellae, moissanite, native Cu, diaspore, and zircon formed after chromite crystallization and post-magmatic serpentinization processes, thus completely ruling out UHP conditions.
Altogether, the results of these investigations represent the first descriptions of exotic minerals in the Cuban and Moroccan ophiolites. The corresponding discussions allowed to reject hypotheses of ultra-high pressure formation or recycling for the studied chromitites and the associated ophiolitic sequences and to ultimately provide simpler formation models for the exotic minerals. Additionally, the investigation provided definitive evidence for the formation of metastable nanodiamond, and other SuR phases, during serpentinization of the oceanic lithosphere at low-pressure and low-temperature conditions. Therefore, the presence of diamond in oceanic rocks, in particular chromitites, cannot be taken as a general indication of deep mantle recycling.En aquesta tesi doctoral s’investiguen en detall les cromitites ofiolítiques de Cuba Oriental i de Bou Azzer, Marroc, per tal d’identificar la presència de minerals exòtics d’ultra-alta pressió, formats en condicions superreduïdes o derivats de l’escorça continental, i interpretar-ne la formació. Els resultats representen la primera descripció de minerals exòtics en aquestes ofiolites i les respectives discussions han permès descartar condicions d’ultra alta pressió per les cromitites i les roques associades i proposar models de formació simples relacionats amb la serpentinització de la litosfera oceànica pels minerals exòtics. S’ha investigat la interacció de líquids toleítics evolucionats amb cromitites preexistents a la zona de Potosí, Cuba, i es proposa un model de formació en dues etapes: primer la cristal·lització d’un magma de tipus MORB genera, mitjançant cristal·lització fraccionada, magmes residuals enriquits en elements incompatibles, i posteriorment alguns d’aquests magmes residuals s’escapen i reaccionen amb les cromitites. A les cromitites ofiolítiques de Cuba Oriental s’ha pogut identificar diamant, lamel·les orientades de clinopiroxè i de rútil, fases superreduïdes (carboni amorf, moissanita, Si i Cu natiu, aliatges de Fe-Mn) i minerals derivats de l’escorça continental. Els grans de diamant són de mida nanomètrica, es troben en inclusions fluides juntament amb metà, serpentina i magnetita. Totes les evidències indiquen que els nanodiamants es van formar durant la serpentinització en ambients superreduïts en condicions de baixa pressió i temperatura, igual que la resta de minerals superreduïts. En canvi, les lamel·les de clinopiroxè es van formar com a exsolucions degut a la cristal·lització de la cromita i les lamel·les de rútil es van formar per la interacció de les cromitites amb gabres. Finalment, el zircó podria representar material de la placa subduint atrapat pels magmes dels quals va cristal·litzar posteriorment la cromita. La investigació de les cromitites neoproterozoiques de Bou Azzer ha permès determinar la seva formació en una zona d’avant-arc durant l’inici de subducció, diferenciant dos estadis de formació relacionats amb basalts d’avant-arc (FAB) i boninites. Aquestes cromitites contenen inclusions de minerals del grup del platí i de minerals exòtics com són lamel·les de clinopiroxè, moissanita, Cu natiu, diàspora i zircó, similar a les cromitites de Cuba.
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Hickey, Diane P. "Ion implantation induced defect formation and amorphization in the Group IV semiconductors: diamond, silicon, and germanium /." [Gainesville, Fla.] : University of Florida, 2007. http://purl.fcla.edu/fcla/etd/UFE0021224.
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Walsh, Carl. "Deep ultra-hot Archaean mantle dynamics; highly depleted residues as cradles for mantle diamond." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/235717/1/Carl%2BWalsh%2BThesis.pdf.
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This project investigated the origin of ancient continents (more than 2.5 billion years old) that are often thought to form by shallow melting in the Earth’s mantle. Here, modelling and analysis of rock chemistry show deep melting is much more likely to produce the rocks and minerals observed, including minerals trapped in diamonds. A new formation model for ancient continents is presented that can explain the hottest lavas to ever erupt on Earth, and the association of diamonds with very chemically depleted rocks.
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Ikeda, M., H. Ito, M. Hiramatsu, M. Hori, and T. Goto. "Effects of H, OH, and CH_3 radicals on diamond film formation in parallel-plate radio frequency plasma reactor." American Institute of Physics, 1997. http://hdl.handle.net/2237/7026.
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Kabbes, Jason E. "Diamond Formation under Lower Mantle Redox Conditions: Experimental Constraints on the Mineralogical Host of Carbon in Earth’s Mantle." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282152005.
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Mbayi, Letsema. "Turning rough dreams into a polished reality? : investigating the formation of human capital in Botswana's diamond cutting and polishing industry." Thesis, Open University, 2013. http://oro.open.ac.uk/37431/.
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This thesis investigates Botswana’s vision to become a downstream player in the global diamond industry by creating downstream capabilities that can continue to benefit the country when diamond mining is no longer profitable. Botswana is the largest producer of diamonds, accounting for a quarter of the world’s diamond production by value. The government has used diamond revenues to foster economic growth. The diamond-led growth has however resulted in a largely undiversified economy with limited job creation. Furthermore, the country’s diamond-led growth is not sustainable, with resource depletion expected to take place in the next two decades. In response to these economic challenges, the government used its supply dominance to force downstream linkages in the diamond industry. As a result the country has 21 diamond cutting and polishing firms that employ over 3000 workers, representing a tenth of employment in the manufacturing sector. The research examines how efficiently human capital formation in Botswana’s diamond cutting and polishing industry is taking place in order to create downstream capabilities that can foster the industry’s competitiveness. This is done by examining the role of the education and vocational training system, industry training institutes and the firms themselves in creating the human capital required in the diamond cutting and polishing industry. This research also considers the impact of technological change on the industry’s human capital requirements. The education and vocational training system was found to meet the industry’s basic general human capital requirements. But due to the 2embryotic institutional training in the industry, the firms were found to be making investments in both industry- and firm-specific human capital. The research argues that institutional industry training needs to be strengthened, particularly in light of technological changes that may result in more industry-specific human capital requirements in the Botswana’s diamond cutting and polishing industry.
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Wiest, Landon A. "Formation, Functionalization, Characterization, and Applications of a Mixed-Mode, Carbon/Diamond-Based, Core-Shell Phase for High Performance Liquid Chromatography." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4239.
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My work has focused on a variety of different types of diamond-based, core-shell particles. These particles are formed with inert cores and poly(allylamine)/nanodiamond shells. Their intended purpose is to form an LC stationary phase that is stable from pH 1 – 14 and at elevated temperatures. At the beginning of my studies, the particles that had been made in the Linford laboratory were pH stable, but irregular and had poor mechanical stability. Since that time, I have worked to improve the particles by using more spherical zirconia and carbon cores, and I have improved their mechanical stability via chemical crosslinking with epoxides. I have performed van Deemter and van’t Hoff analyses to understand the properties of these columns. Efficiencies greater than 100,000 N/m are routinely achieved with these carbon/nanodiamond-based phases. In addition I contributed to two patents that show innovations in diamond functionalization. My contributions involved reduction of an oxidized diamond surface with LiAlH4 prior to functionalization with isocyanates. I also wrote some application notes for the Flare mixed-mode column, which was recently introduced to the market and contains particles comprised of a carbon core and a polymer/nanodiamond shell. These application notes show the gradient separations of four essential oils (lavender, melaleuca, peppermint and eucalyptus), and the isocratic separations of various triazine herbicides and a mixture of β2-agonists and amphetamines.This dissertation contains the following sections. Chapter 1 is a review of liquid chromatographic history and theory. It also includes a history of the use of diamonds in liquid chromatography. Chapter 2 is a study on a glassy carbon core - polymer/nanodiamond shell particle made in our laboratory. Stability studies at pH 11.3 and 13 were performed and different analytes were retained and/or separated on the column. Chapter 3 is a study performed on the Flare mixed-mode column. Separations of tricyclic antidepressants, β2-andrenergic receptor agonists, and linear chain alkylbenzenes were demonstrated with this phase. Van Deemter and van’t Hoff studies were also performed to probe the efficiency and selectivity of this column with different classes of analytes. Chapter 4 chronicles, via SEM and van Deemter analysis, the improvements that have taken place in our column after many iterations of improved synthetic methods and new materials. These include better particle uniformity, particle stability, and column efficiency. Three different carbon cores were analyzed, each better than the previous one. Appendices 1 – 6 are application notes published by Diamond Analytics of β2-andrenergic receptor agonists and amphetamines, triazine herbicides, and lavender, melaleuca, eucalyptus and peppermint essential oils. Appendices 7 and 8 are patents that contain ideas and research contributed by the author.
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Cheviot, Maureen. "Chemins cinétiques de formation du diamant microcristallin sur couches minces de nitrure de tantale élaborées par pulvérisation cathodique réactive." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0377/document.
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L’allègement des structures pour l’aéronautique pose, entre autres, la problématique del’usinage des matériaux composites et multi-matériaux. Le challenge réside dans la conceptiond’outils répondant aux conditions spécifiques d’usinage de ces matériaux et à leur extrêmeabrasivité. Une solution est de faire appel aux performances du diamant comme revêtementrésistant à l’usure. Dans le cadre de ce manuscrit, nous proposons d’étudier les cinétiques deformation du diamant microcristallin, sur des couches minces de nitrure de tantale (TaN). Cenitrure cristallise sous deux structures distinctes : une phase stable, hexagonale, h-TaN, et unephase métastable, cubique faces centrées, fcc-TaN. Des paramètres d’élaborationméticuleusement optimisés ont rendu possible la synthèse de ces deux structures sous forme decouches minces monophasées et la proposition de mécanismes de stabilisation. Leur potentiel entant que couche de germination du diamant a été évalué et quantifié grâce à une méthodologieoriginale, alliant expériences et modélisation. La contribution de la modélisation a permis nonseulement d’interpréter précisément les résultats obtenus expérimentalement, mais aussid’identifier les grandeurs influentes. Les coefficients de diffusion du carbone et flux de carbonetransférés dans h-TaN et fcc-TaN ont ainsi été déterminés. Les résultats obtenus, en termesd’interactions entre le TaN et le carbone, au cours du procédé d’élaboration du diamant, ouvrentdes perspectives intéressantes en termes de contrôle de la formation du diamant par CVDWeight reduction of aeronautic devices raises composite and multi-materialsmachining issues. The challenge lies in designing cutting tools able to resist to the specificmachining conditions of these materials and their abrasivity. One solution is to use diamond as awear resistant coating. In this work, we propose to study the kinetic of formation ofmicrocrystalline diamond onto a tantalum nitride (TaN) thin film. TaN exhibits two crystallographicstructures: the hexagonal stable one, h-TaN, and the metastable one with a face centered cubiclattice, fcc-TaN. An accurate control of deposition conditions allows us to isolate both structuresas single-phased thin films and to propose two stabilization mechanism scenarios. The influenceof each TaN structure on diamond formation has been gauged thanks to the inventivemethodology we developed and which combines experiments and modeling. The contribution ofmodeling relies on an accurate interpretation of the experimental results and the identification ofthe key parameters. Thus, carbon diffusion coefficients and carbon transfers into h-TaN and fcc-TaN phases could be determined. Our results, in terms of TaN/carbon interactions, open up newhorizons for diamond nucleation and growth in CVD conditions
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Kolesnikov, Anton. "Experimental investigation of hydrocarbon formation and transformation under Earth´s upper mantle conditions." Doctoral thesis, KTH, Kraft- och värmeteknologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-27017.
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The theory of the abyssal abiotic petroleum origin considers oil and natural gas to begenerated in the Earth’s upper mantle. Hydrocarbons migrate further through the deep faults into the Earth’s crust, where they can form oil and gas deposits in any kind of rock in any kind of structural position. Until recently one of the main obstacles for further development of this theory has been the lack of the data covering processes of generation and transformations of hydrocarbons. Experimental data, presented in this thesis, confirms the possibility of hydrocarbons formation from mantle inorganic compounds (water, Fe, CaCO3 or graphite) at temperature and pressure of the upper mantle (1500 K and 5 GPa). Experiments were carried out in CONAC high pressure device and multianvil apparatus BARS. Compositions of received gas mixtures were similar to natural gas. Quantity of hydrocarbons depended on the cooling regime of reaction mixture under pressure. Slow cooling favored higher quantity. We found that donor of carbon (CaCO3 or graphite) determines formation of “dry” (methane-rich) gas or “wet” (light hydrocarbons-rich) gas. Experiments in laser-heated diamond anvil cells showed that methane and ethane partially react under upper mantle thermobaric conditions (2-5 GPa, 1000-1500 K) to form mixture of hydrocarbons: methane, ethane, propane and n-butane – main compounds of natural gas. Similarity of final product mixture obtained from methane and ethane means thermodynamic stability of hydrocarbons in the thermobaric conditions of the upper mantle and equilibrium character of the observed processes.QC 20101203
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Fousson, Eric. "Formation de diamants par voies dynamiques et leur caractérisation." Mulhouse, 2000. http://www.theses.fr/2000MULH0623.
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Des nanodiamants de 5-7 nm ont été obtenus par détonation d'explosifs avec une balance d'oxygène négative pour des pressions de 20-30 GPa et des températures de 3000-4000 K. Nous avons utilisé des compositions TNT/RDX et TNT/HMX, certaines avec des additifs réducteurs ou carbonés (Al, B, noir de carbone, composé organique). Elles ont été tirées dans divers confinements (CO2, N2, vide, eau, NaCl, C2Cl3F3) afin de préserver les diamants formés de l'oxydation et de la rétro-graphitation. Après élimination des impuretés métalliques par H2SO4, il reste le carbone condensé (∼45% en masse du carbone initial), constitué de diamant (∼65%) et de carbone turbostratique (sp2) qui peut être éliminé sélectivement par un traitement via un mélange H2O2/HNO3. Les suies de détonation ont été caractérisées par diverses techniques RX, MEB, MET, RMN13C. Du diamant a également été obtenu par compression sous choc de précurseurs carbonés (graphite, noir de carbone, fullerènes, composés organiques…) mélangés à des poudres métalliques (Cu, Co,…) qui agissent comme catalyseur et dissipateur thermique, limitant le phénomène de rétro-graphitation. Les chocs ont été générés par lancement d'un impacteur sur l'échantillon carboné grâce à un dispositif de relèvement de plaques ou des canons de 30 et 105 mm de calibre (pressions de ∼50 GPa et durées de choc de 0,37 à 1,15 μs). L'analyse RX montre la présence de diamant, et de carbone turbostratique, la MET celle de plaquettes mono-cristallines de carbynes pour les produits issus de la compression de fullerènes et noir N110. La coexistence des trois allotropes du carbone est due à l'hétérogénéité des pressions et des températures dans l'échantillon. La présence en RMN 13C d'intenses bandes de rotation sp3 révèle une forte anisotropie cristalline du diamant dont la formation passe par un mécanisme probablement mixte, à la fois reconstructif et martensitique.
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Censier, Claude. "Dynamique sédimentaire d'un système fluviatile diamantifère mésozoïque : la formation de Carnot, République centrafricaine /." Orléans : Ed. du BRGM, 1991. http://catalogue.bnf.fr/ark:/12148/cb35519227w.
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André, Bernard. "Formation de dépôts de carbone de type diamant sous bombardement ionique." Grenoble INPG, 1991. http://www.theses.fr/1991INPG0093.
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A l'aide de dispositifs de depot sous vide en phase vapeur, nous avons etudie l'effet d'un bombardement ionique sur des couches de carbone de type diamant en cours de croissance. Nous avons montre que cette assistance ionique a la croissance induit d'importantes modifications des caracteristiques des revetements (composition chimique, indice de refraction complexe, durete et contrainte mecanique) et de l'interface couche-substrat. L'evolution de la masse volumique des depots avec les parametres du bombardement ionique (densite de courant, energie et masse des ions) est presentee. Un modele de croissance des films issu de simulations numeriques et base sur des deplacements selectifs d'atomes de carbone en hybridation sp#2 explique ces resultats. Une representation de la microstructure des depots deduite d'analyses par microscopie electronique en transmission et spectroscopie raman est proposee. Ce modele est coherent avec une evolution du materiau sous bombardement ionique gouvernee par des deplacements selectifs d'atomes
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Ferroir, Tristan. "Formation et transformations de la matière extraterrestre : grains comètaires et météorites choquées." Lyon, École normale supérieure (sciences), 2009. http://www.theses.fr/2009ENSL0517.
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Au cours de cette thèse, nous avons pu participer à l'étude chimique et minéralogique des grains de la mission Stardust comètaires par des techniques basées sur le rayonnement synchrotron. L'importance de ces études tient au fait que les comètes sont parmi les objets les plus primitifs et les plus intacts de notre système solaire. Les météorites font aussi partie des premières briques du système solaire. Nous avons pu étudier les transformations qui se produisent au cours du choc dans ces roches. Nous avons notamment montré comment une partie de l'atmosphère martienne peut être capturée par les météorites lors de leur éjection mais aussi les différentes transformations qui peuvent se produire au cours du choc. Pour ceci, nous nous sommes intéressés à trois des grands systèmes minéralogiques qui existent : les olivines, les pyroxènes et le carbone. Nous avons ainsi pu mettre en évidence différents modes et mécanismes de transition de phase au sein de ces ensembles et montrer que le passage par un intermédiaire liquide dans deux des trois cas change la vision que nous avons des transitions de basse pression en polymorphe de haute pression dans les météorites. Par ailleurs, nous avons pu mettre en évidence l'existence d'un nouveau polytype du diamant et d'un nouvelle phase carbonée ultra dure dans les ureilites. Enfin, nous avons aussi étudié le comportement des feldspaths potassiques à haute pression par cellule à enclume de diamant couplée à la diffraction des rayons X et montré que la structure de haute pression, la hollandite, bien que subissant une transition de phase que nous avons découverte, semble stable jusqu'à la base du manteau terrestreDuring this Ph. D, we were member of the Preliminary Examination Team which studied the chemical ans mineralogical compositions of Stardust mission cometary grains using synchrotron radiation techniques. These studies are of great importance since comets are the most primitives and unmodified bodies of our Solar System. Apart from comets, meteorites are also part of the first solar system stones. Using a very wide range of analytical techniques, we studied the different transformations which take place during a shock event undergone by these rocks. We particulary studied how part of the martian atmosphere was trapped in martian meteorites during their ejection from their parental body. We also studied the different phase transformations during the shock events on three different mineralogical system : olivines, pyroxenes and carbon. We showed that different transformation mechanisms were active in these systems and that a melting step in two of the three cases greatly change our vision in the transformation mechanism from low pressure polymorphs to high pressure polymorphs in meteorites. Moreover, we described a new diamond polytype and a new ultra-hard phase of carbon in ureilites. Finally , we also made in situ studies of the behavior of K-feldspar at high pressure using diamond anvil cell coupled with X-ray diffraction techniques. We showed that the high pressure polymorph, K-hollandite, over goes a phase transition which we discovered and that it seems to be stable as deep as the bottom of the Earth mantle
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Martin, Audrey. "Recyclage du carbone et formation du diamant en zone de subduction : contraintes expérimentales." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2009. http://tel.archives-ouvertes.fr/tel-00725967.
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Afin d'évaluer les hypothèses de recyclage interne du carbone par la subduction et de formation de diamant dans la croûte subductée, des expériences ont été réalisées en presse multi-enclumes sur l'assemblage Fe-dolomite + quartz (présent dans les sédiments subductés ou formé par l'altération des basaltes) dans des conditions de pression-température de 4 à 14 GPa et de 800 à 1600°C. Deux études ont été menées : la stabilité de cet assemblage a d'abord été testée en conditions rédox intrinsèques puis en conditions réductrices ; ensuite, les interactions avec le coin mantellique ont été évaluées en étudiant, d'une part, les processus d'échange entre un cylindre de Fe-dolomite + quartz et un cylindre de péridotite à grenat, et d'autre part, les équilibres de phases dans des mélanges péridotite-sédiment. Cette étude montre qu'un sédiment (ou une éclogite) carbonaté est déstabilisé à plus faible profondeur en présence de fer. De plus, les conditions réductrices imposées par le manteau diminuent encore la stabilité de cet assemblage lors de la subduction. Une zone réactionnelle à clinopyroxène + Fe-magnésite se forme à l'interface slab/manteau. L'infiltration du carbone dans le coin mantellique est très rapide et de la magnésite s'y forme. Ainsi, un recyclage des carbonates à grande profondeur semble peu probable. Ces expériences montrent également que du graphite ou du diamant peut se former au sommet de la croûte océanique subductée par réduction des carbonates à basse température.
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Lucazeau, Emmanuelle. "Contribution à l'étude de la formation du carbure de molybdène sur le diamant." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0110.
Full textAbstract:
En vue de la realisation de contacts electriques ohmiques sur le diamant compatibles avec les proprietes physiques et chimiques uniques du diamant et qui soient capables de resister aux operations prolongees dans les environnements hostiles pour lesquels ces dispositifs sont destines, nous avons etudie la formation du carbure de molybdene sur le diamant par reaction en phase solide. Ce travail s'articule autour de l'etude de la formation du carbure de molybdene sur les diamants intrinseques ou dopes polycristallins et monocristallins homoepitaxies elabores au laboratoire par pulverisation catholique magnetron de molybdene sur la surface du diamant suivie de recuits sous atmosphere d'argon. La formation du carbure est suivie par diffraction des rayons x, par analyse par retrodiffusion de rutherford ou rbs, ou par spectroscopie de photo-electrons induits par rayons x ou xps. Nous avons mis au point une procedure d'elaboration du carbure de molybdene hexagonal -mo#2c sur le diamant polycristallin conduisant a la formation d'un contact ohmique stable a haute temperature. Sur les films monocristallins homoepitaxies, la formation du -mo#2c se trouve ralentie par une incorporation importante d'oxygene dans la couche metallique durant le depot. La presence de bore ralentit la formation du carbure et sa cristallisation.
20
Censier, Claude. "Dynamique sédimentaire d'un système fluviatile diamantifère mésozoïque : la formation de Carnot (République centrafricaine)." Dijon, 1989. http://www.theses.fr/1989DIJOS036.
Full textAbstract:
On étudie les formations du socle et la formation glaciaire de la Mambéré, sur lesquelles repose la formation de Carnot, dans le but de préciser l'histoire géologique et le cadre paléogéographique ante-mésozoïque de l'ouest de la Republique centrafricaine. La formation glaciaire de la Mambéré fait l'objet d'une étude détaillée; sa place dans l'évolution géologique de l'Afrique au paléozoïque, est discutée. Une étude géologique détaillée de la formation de Carnot est abordée: le matériel détritique, à dominante gréseuse, est issu du démantèlement des formations du complexe schisto-quartzitique et de la formation glaciaire de la mambere; il est donc recyclé. Les processus d'érosion sont liés à l'ouverture de l'Atlantique sud et à la distension du golfe de la Bénoué. Le milieu de sédimentation est typiquement fluviatile, très rarement palustro-lacustre. L'âge de la formation, compris entre la fin du crétacé inférieur et le crétacé supérieur, est argumenté sur des données paléoclimatiques et sur l'évolution géodynamique de l'Afrique centrale. Le soulèvement de la dorsale oubanguienne, post-crétacé, a entraine un léger mouvement de bascule de la formation de Carnot vers le SSE, à l'origine de la mise en place du réseau hydrographique actuel. La géologie du diamant de l'ouest de la R. C. A. Est étudiée. Les différents types de gites diamantifères, replacés dans leur contexte géologique, sont décrits. L'origine du diamant est abordée grâce aux résultats de l'étude de ses accompagnateurs alluvionnaires, de l'étude morpho-exoscopique des formes cristallines les plus fréquentes, et de l'étude comparée avec les autres gisements diamantifères de l'Afrique centrale. La formation de Carnot est la roche magasin du diamant exploité dans l'ouest de la R. C. A.
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Benyahia-Bentadjine, Sonia. "Mécanismes de formation et propriétés physico-chimiques et mécaniques des interphases epoxy-diamine/métal." Lyon, INSA, 2000. http://www.theses.fr/2000ISAL0025.
Full textAbstract:
Ce travail concerne l'étude de la réactivité interfaciale des monomères époxy (DGEBA) et diamine (IPD), avec des surfaces métalliques (titane, aluminium et or) à l'aide de différentes techniques d'analyses. Après avoir déterminer les propriétés physico-chimiques et mécaniques du polymère en volume, nous avons comparé ces dernières à celles obtenues dans le cas de films d'épaisseur variable. Nous avons mis en évidence la formation d'une interphase ayant des propriétés spécifiques différentes de celles du polymère en volume. Les propriétés de cette interphase dépendent de la nature du substrat et de son traitement de surface, de la nature de la diamine et du rapport schoechiométrique du mélange. Nous avons également déterminer les mécanismes réactionnels responsables de la formation de cette interphase en étudiant des systèmes " modifiés " par les oxydes plus ou moins hydratés recouvrant la surface de nos substrats métalliques. La diamine se chimisorbe à la surface des oxydes métalliques et simultanément, une attaque chimique de ces derniers par la diamine est observée. La diffusion des ions métalliques au sein des monomères induit la formation de complexes entre les ions métalliques et les groupements amines des monomères. Lorsqu'un seuil de saturation est atteint ces complexes précipitent sous forme de cristaux insolubles dans les monomères. Par ailleurs, ces complexes sont également responsables d'une séparation de phase qui traduit la formation d'un nouveau réseau. La compréhension de l'ensemble de ces phénomènes nous permet de réaliser des matériaux volumiques possédant les propriétés de films minces et donc de l'interphaseThe interfacial reactivity between epoxy (DGEBA) and diamine (IPD) monomers and metallic substrates (titanium, aluminum and gold) has been studied using various analytical techniques. Chemical, physical and mechanical properties of organic coatings were determined as a function of their thickness and compared to bulk values. An interphase having specific properties and quite different to polymer bulks ones was underlined. Interphase properties were found to be affected by the substrate nature, metallic surface treatments, the diamine nature (whether aromatic, aliphatic or cycloaliphatic) and the stoechiometric ratio of epoxy-amine mixture. Reaction mechanisms leading to the interphase formation were determined by studying "modified" monomers by hydrated oxide layer. It was found that the diamine monomer reacts with the metallic surface and induces a chemical etching. Then metallic ions then diffuse through the organic layer to form metal-amine complexes. When a saturation threshold was reached, crystals of modified monomers were observed at room temperature. These complexes induce phase separation during the cure cycle of the epoxydiamine mixture leading to a new network formation. The understanding of these phenomena, allows us to produce bulk materials having the same properties than thin films or interphase
22
Charrier, Gaëlle. "Etude de la formation de terminaisons oxygénées et azotées sur diamant par des traitements électrochimiques en milieux aqueux et ammoniac liquide." Versailles-St Quentin en Yvelines, 2013. http://www.theses.fr/2013VERS0009.
Full textAbstract:
Le diamant semi-conducteur présente des propriétés remarquables qui en font un très bon candidat pour toutes sortes d'applications, notamment en électrochimie ou pour l'immobilisation de molécules d'intérêt biologique. La nature des terminaisons de surface joue un rôle essentiel sur ses propriétés physiques et chimiques. Ainsi, de nombreux travaux sont consacrés au passage de groupements hydrogénés sur les films de diamant bruts de fabrication à des groupements oxygénés ou azotés plus réactifs. C'est dans ce contexte que nous avons développé une nouvelle méthode d'oxydation des surfaces de diamant, au potentiel de repos et en présence d'un oxydant puissant. Cette méthode est efficace et peu contraignante, elle permet de former un grand nombre de groupements "C-O" à la surface des électrodes sans en altérer les propriétés électrochimiques. Afin de générer des groupements azotés en surface, de nouvelles méthodes ont également été développées grâce à des traitements électrochimiques dans l'ammoniac liquide. Ces traitements ont conduit à la formation de groupements amines C-NH2 à la surface des films de diamant, ouvrant ainsi la voie à de nombreuses applications, notamment dans le domaine de la post-fonctionnalisation de surface par des molécules organiques. L'évolution de la chimie superficielle et des propriétés électrochimiques des électrodes de diamant au cours des différents traitements ont été suivies grâce à une approche combinée de mesures de mouillabilité, d’analyses de surfaces (XPS, MEB) et de caractérisations électrochimiques (C-V et I-V en présence d'un couple redox)Semiconductive diamond presents outstanding properties attractive for numerous applications, from electrochemistry to the immobilization of biomolecules. The nature of the surface terminations strongly influences its chemical and physical properties. Thus, many works are devoted to the modification of the hydrogenated surface groups of as-grown diamond into more reactive oxygenated or nitrogenated ones. In this context, we developped a new method for the oxidation of diamond surfaces at open circuit potential conditions and in the presence of a strong oxidizing specie. This efficient method is easy to perform and leads to the formation of a great amount of “C-O” groups at diamond surfaces without any degradation of the electrochemical properties of the electrodes. New direct amination methods have also been developped using electrochemical treatments in liquid ammonia, leading to the formation of C-NH2 groups and opening the way for many applications, for instance surface post-functionalization with organic molecules. The evolution of the surface chemistry and electrochemical properties of the electrodes during the different treatments has been followed by contact angle measurements, surface analyses (XPS, SEM) and electrochemical characterizations (C-V and I-V with a redox couple)
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Sesay, Mohamed Kanja. "La gouvernance sans Etat : une étude de cas sur les territoires contrôlés par le front révolutionnaire uni en Sierra Leone." Thesis, Bordeaux 4, 2013. http://www.theses.fr/2013BOR40043/document.
Full textAbstract:
La guerre civile en Sierra Leone débute en 1991 et dure jusqu’en 2002.Encore aujourd’hui, les analystes sont assez partagés sur ses causes, notamment lesmotivations des rebelles du Front Révolutionnaire Uni (RUF), mouvement àl’origine des hostilités. De son entrée en Sierra Leone à nos jours, le RUF a étél’objet de plusieurs débats et critiques, tant sur son organisation que sur sesméthodes guerrières. En questionnant d’abord la capacité organisationnelle de cemouvement, la thèse a pour objet de contextualiser les arguments souvent associésavec des guerres civiles de ce type. Ils insistent sur l’absence de sens : ces conflitsillustreraient d’abord une situation de chaos total. Elles seraient aussi laconséquence de l’absence ou de la défaillance d’un État.Cette présente étude s’inscrit dans le prolongement des débats sur le RUF.Elle démontre que ce dernier n’était pas si désorganisé que ce que racontent lescommentateurs, avertis ou non. Cette opinion répandue résulte notamment d’unemédiatisation intense de son usage intensif de la violence extrême, très réellecependant. Le RUF n’était pas qu’un groupe de voleurs de diamants sanguinairesmais aussi une force assez structurée avec une logique hiérarchique claire, voireune idéologie. Grâce à ces facteurs, il a mis en place des structures lui permettantd’établir les relations de gouvernant à gouvernés avec les populations urbainessous son contrôle. Cette force rebelle a instauré un mode de gestion de lacollectivité. Cela a modifié la nature de ce groupe armé, devenu, dans les zonessous son contrôle, un « appareil administratif » civil, loin d’être toujoursperformant mais bien identifiable comme tel.En juxtaposant les interactions complexes d’une gouvernance quotidienne,la thèse met en lumière les méthodes de gouvernance du RUF et les aspects dits« normaux » de la vie dans ces villes en guerre. Elle analyse les variables de larelation entre les membres du mouvement rebelle occupant ces communes et lapopulation locale. Une fois une ville conquise, les rebelles sont obligés d’y fairequelque chose. Le RUF impose un « système administratif » instaurant un ordre devie en commun dans toute cette zone.L’étude analyse donc ces outils de la gouvernance civile, mobilisés entemps de guerre. Au cours de cet étude, plusieurs recherches de terrain en SierraLeone, ont été menées. Ces séjours sur place ont permis la réalisation de plusieursentretiens, individuels et collectifs. Ils soutiennent les idées générales exposéesdans cette thèseThe war in Sierra Leone began in 1991 and ended in 2002. Analysts remaindivided on the question of its cause, particularly on the issue of the motivations ofthe rebel Revolutionary United Front (RUF), the armed group which started thehostilities. From its entry into Sierra Leone to date; the RUF has been the subjectof much debate and criticism, both on its organization and its methods of wagingwar. By asking questions relating to the organizational capacity of the RUF, thisstudy aims to contextualize the central arguments often associated with civil warsof the Sierra Leonean kind: they insist on the absence of meaning; these conflictsillustrate a situation of chaos and/or are devoid of political reflections. They arealso the consequence of the absence or failure of a State.This present study continues these discussions in relation to the RUF, bydemonstrating that this guerilla force was not as disorganized as often portrayed,despite increased media coverage on its use of violence. The RUF was not a groupof murderous diamond thieves but also quite structured with a clear hierarchicallogic or ideology. Through this internal organisation, it set up structures toestablish governor/governed relations with urban populations under its control.The rebel force thus established a system to manage these local communities. Suchconsiderations changed the nature of the armed group in the areas under itscontrol, where it established a civil "administrative unit", far from being efficientbut identifiable as such.By juxtaposing the complex interactions of daily governance, the thesishighlights the governance practices of the RUF and the aspects that characterise"normal" life in these « war torn » towns. It analyzes the variables of therelationship between members of the rebel movement occupying these towns andthe local population. Once a town is conquered, the rebels are forced to dosomething there, an "administrative system" establishing an order of coexistence inthe whole area is imposed.The study therefore analyzes the tools of civil governance, mobilized intime of war. During this study, several field research trips to Sierra Leone, wereconducted. These trips have allowed the realization of several interviews,individual and collective. They support the general ideas presented in this thesis
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Reich, Blair Jesse Ellyn. "Cyanide-catalyzed C-C bond formation: synthesis of novel compounds, materials and ligands for homogeneous catalysis." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4987.
Full textAbstract:
Cyanide-catalyzed aldimine coupling was employed to synthesize compounds
with 1,2-ene-diamine and ñ-imine-amine structural motifs: 1,2,N,N'-
tetraphenyletheylene-1,2-diamine (13) and (+/-)-2,3-di-(2-hydroxyphenyl)-1,2-
dihydroquinoxaline (17), respectively. Single crystal X-ray diffraction provided solidstate
structures and density functional theory calculations were used to probe isomeric
preferences within this and the related hydroxy-ketone/ene-diol system. The enediamine
and imine-amine core structures were calculated to be essentially identical in
energy. However, additional effects-such as ÃÂ conjugation-in 13 render an enediamine
structure that is slightly more stable than the imine-amine tautomer (14). In
contrast, the intramolecular hydrogen bonding present in 17 significantly favors the
imine-amine isomer over the ene-diamine tautomer (18).
Aldimine coupling (AIC) is the nitrogen analogue of the benzoin condensation
and has been applied to dialdimines, providing the first examples of cyclizations effected
by cyanide-catalyzed AIC. Sodium cyanide promoted the facile, intramolecular
cyclization of several dialdimines in N,N-dimethylformamide, methanol, or
dichloromethane/water (phase-transfer conditions) yielding a variety of six-membered
heterocycles. Under aerobic conditions, an oxidative cyclization occurs to provide the
diimine heterocycle.
Cyanide-catalyzed aldimine coupling was employed as a new synthetic method
for oligomerization. Nine rigidly spaced dialdimines were oxidatively coupled under
aerobic conditions to yield conjugated oligoketimines and polyketimines with
unprecedented structure and molecular weight (DP = 2 - 23, ~700 -8200 g/mol). The ñ- diimine linkage was established based on IR spectroscopy, NMR spectroscopy, size
exclusion chromatography, and X-ray crystallographic characterization of the model
oxidized dimer of N-benzylidene-(p-phenoxy)-aniline. Cyclic voltammetry indicates ptype
electrical conductivity, suggesting they are promising candidates for plastic
electronic devices.
The cyanide-catalyzed benzoin condensation reaction of 4-substituted
benzaldehydes followed by oxidation to the diketone, and the Schiff Base condensation
of two equivalents of o-aminophenol provides 2,3-(4-X-phenyl)2-1,4-(2-
hydroxyphenyl)2-1,4-diazabutadiene. The ligand is given the moniker X-dabphol.
These ligands are readily metallated to form M-X-dabphol complexes. The copper
complexes catalytically fix CO2 with propylene oxide to yield propylene carbonate. DFT
studies along with a comparison with Hammet parameters help validate and elaborate on
the catalytic cycle and the catalytic results obtained. The nickel complex is competent
for olefin epoxidation. Synthesis, characterization, X-ray structure, DFT analysis, and
catalytic activity of the parent nickel dabphol complex are reported.
25
Naamoun, Mehdi. "Mécanisme de formation et de propagation des dislocations au sein de diamant CVD monocristallin et développement de stratégies visant à réduire leur densité." Paris 13, 2013. http://scbd-sto.univ-paris13.fr/secure/edgalilee_th_2013_naamoun.pdf.
Full textAbstract:
L’objectif principal de ce travail de thèse est l’obtention de films de diamant monocristallin à faible densité de dislocations, condition sine qua none à leur utilisation dans le domaine de l’électronique de puissance. Dans un premier temps, la formation et la propagation de ces défauts étendus au sein des monocristaux de diamant ont été étudiées. Deux sources principales de dislocations ont été mises en évidence : (i) les dislocations provenant du coeur du substrat germe (diamant naturel ou HPHT) qui se propagent à travers la couche CVD épitaxiée, (ii) les dislocations provenant de l’interface HPHT-CVD. Pour éliminer les défauts de la seconde origine, un traitement de surface combinant le procédé ICP-RIE (réalisée sur la face supérieure) et une gravure par plasma H2/O2 (sur les faces latérales de l’échantillon) a été proposé. Des monocristaux CVD épais (> 300 μm) présentant une densité de défauts réduite (de l’ordre de 104 par cm2) ont ainsi été obtenus. Afin d’éliminer les défauts de coeur, des techniques innovantes fondées d’une part sur le masquage sélectif des défauts par des particules métalliques et d’autre part sur la macro et sur la micro-structuration de surface, ont été développées. La macro-structuration de surface a démontré la possibilité de modifier la direction de propagation des dislocations vers les bords du cristal. La technique de micro-structuration ainsi que le masquage sélectif (développée et brevetée lors de cette thèse) ont montré la possibilité de faire se rencontrer les dislocations et de les annihiler, conduisant à l’inhibition de leur progression au sein du cristal CVD épitaxiéThe main objective of this PhD thesis is to obtain single crystal diamond films with low dislocation density, prerequisite to their use in the field of power electronics. At first, the formation and propagation of these extended defects into single crystal diamond were studied. Two main sources of dislocations have been identified: (i) dislocations directly originating from the substrate (natural or HPHT diamond) that thread through the CVD layer, (ii) and dislocations formed at the HPHT-CVD interface. To eliminate defects of the second origin, surface treatments combining the ICP- RIE process (carried on the upper side) and H2/O2 plasma etching (on the back side and on the lateral faces of the sample) were proposed. Thus, thick CVD layers (> 300 μm) with a reduced defect density (around 104 per cm2) were obtained. To eliminate dislocations directly originating from the substrate, innovative techniques based on the one hand on selective masking of defects by metal particles and on the other hand by the macro and micro-structuration, were developed. Surface macro-structuration demonstrated the ability to change the direction of dislocation’s propagation towards the crystal edges. Selective masking (developed and patented during this PhD thesis) and micro-structuration techniques have shown the ability to reduce dislocation density by preventing them from propagating through the CVD crystal
26
LUCET, DENIS. "Synthese de substrats et d'inhibiteurs potentiels de la biosynthese de la biotine. Nouvelle methodologie de formation stereoselective du motif diamino vicinal." Paris 11, 1997. http://www.theses.fr/1997PA112033.
Full textAbstract:
Dans l'objectif de developper de nouveaux herbicides sans action sur les especes animales, nous nous sommes interesses a la biosynthese d'une vitamine (la biotine) puisque celle-ci est specifiquement produite par les micro-organismes et par les plantes. Dans ce cadre, nous avons realise la premiere synthese chimique des enantiomeres de l'acide 8-amino-7-oxononanoique (kapa) et montre que c'est l'enantiomere s qui est le bioprecurseur de la biotine d'apres la croissance qu'il induit chez saccharomyces cerevisiae. Plusieurs analogues structuraux de ce vitamere de la biotine ont ete synthetises mais aucun d'entre eux ni l'enantiomere non naturel du kapa ne presente d'activite inhibitrice significative vis-a-vis de la biosynthese de la biotine sur organisme entier (levure de boulanger ou lentille d'eau). La premiere synthese totale stereoselective de la dethiobiotine (bioprecurseur direct de la biotine) ainsi que de plusieurs de ses stereoisomeres a egalement ete realisee. Pour cela, nous avons developpe une methode originale permettant la formation de precurseurs de composes comportant le motif 1,2-diamino. Cette methodologie repose sur l'addition conjuguee stereoselective d'un equivalent chiral de l'ammoniac sur un nitroalcene. Apres l'evaluation de differents nucleophiles azotes sans succes, nous avons montre que le sel potassique de la 4-phenyloxazolidin-2-one s'additionne de facon totalement stereoselective et avec de bons rendements sur divers nitroalcenes. Outres leur transformation en derives de diamines vicinales dont l'interet et les methodes de syntheses ont ete presentes au cours d'une revue bibliographique, certains de ces produits d'addition ont egalement ete convertis en precurseurs directs d'alpha-aminocetones ou d'acides alpha-amines optiquement actifs.
27
Michau, Dominique. "Etude de l'influence du substrat sur la formation de films de diamant : application au développement de couches minces de nitrure de bore cubique." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1995. http://tel.archives-ouvertes.fr/tel-00143406.
Full textAbstract:
En utilisant une démarche de type "Chimie du Solide", le rôle des principaux facteurs caractérisant la surface du substrat (composition chimique, structure et liaisons chimiques) sur la germination de cristallites de diamant, ainsi que leur morphologie, a ete mis en évidence. La densité de nucléation et le rapport Csp2/Csp3 ont pu notamment etre corrélés a la diffusion du carbone dans le substrat. Afin de contrôler celle-ci, des couches superficielles de composes covalents tels que les nitrures et les borures ont été utilisées. Elles ont permis d'atteindre des densités très importantes de nucléi de diamant pour des temps de dépôt relativement courts. L'ensemble des résultats concernant le dépôt par hétéroépitaxie du diamant a permis de proposer une méthodologie au niveau du choix du substrat et des espèces réactives pour l'obtention de couches minces de nitrure de bore cubique.
28
Wu, Jian-Haur, and 吳健豪. "Diamond Formation By Thermal Activation And HFCVD." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/39611766076840246013.
Full textAbstract:
碩士國立東華大學
材料科學與工程研究所
89
This study on diamond synthesis has been carried out in two ways to achieve methods of high growth rate and of scalable high-volume production. One is by thermal activation of graphite, the other based on hot-filament CVD method. Diamond formation by thermal activation of graphite is a novel technique that synthesize diamond particles at the highest reported growth rate of 100~500 µm/s. We tried to follow the growth method reported by A. V. Palnichenko et al. in Nature 1999. Diamond formation at such a high growth rate is shown in this report. Our samples were analyzed by X-ray, SEM, EDS and Raman spectroscopy. The results show that the main products are diamond-like carbon and graphite, and they are different from the report mentioned previously. We classify the synthesis of diamond by hot-filament CVD into two series. The first one is the influence of hydrogen-storage alloy for diamond formation. The second is observing diamond growth in three-dimensional packing of Ni or Cu net. But the results show no effectively increasing of the diamond growth rate in both ways.
29
黃弼鑫. "Cold flow analysis of a microwave PECVD for diamond-like thin-film formation." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/09464809373478639660.
Full text
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Fernandes, Joana Cristina Taveira. "Water treatment with boron-doped diamond electrodes – A review on by-products formation." Master's thesis, 2021. http://hdl.handle.net/10362/118283.
Full textAbstract:
The formation and identification of by-products is crucial for understanding the possible
environmental and public health risks of applying electrochemical advanced oxidation processes
(EAOPs) in water treatment, involving boron-doped diamond (BDD) anodes. Despite the
substantial research work concerning the use of BDD technology in water treatment review
articles with a specific focus on by-products formation and their hazardous effects in the major
environmental fields of application in water treatment are not available. This comprehensive
review provides the current knowledge on the reactive species and by-products formed during
electrochemical oxidation with BDD in municipal landfill leachate treatment, industrial wastewater
treatment, disinfection of drinking water, municipal wastewater treatment, and removal of
micropollutants. The reactive species electrogenerated in EAOPs with BDD, including the reactive
oxygen species (ROS), reactive sulfate species (RSS), reactive chlorine species (RCS) and other
oxidant species, are systematically discussed. In general, halogenated and perhalogenated
compounds are the common by-products identified in the different fields of application. The
concentration and type of by-products were influenced by process conditions and the BDD anode
material itself. Recommended conditions to minimize the formation of halogenated and
perhalogenated compounds are acidic pH, low current densities, high chloride concentrations,
NaNO3 as a supporting electrolyte and avoiding active cooling temperatures (e.g., 5ºC). The few
available toxicological studies reported that BDD lowered the toxicity. However, in terms of toxic
effects in mammalian’s (i.e., rats and humans) health, there is a considerable number of by products classified as possible carcinogenic, endocrine disruptive and mutagenic. This review
paper provides better understanding of the by-products formed during electrochemical oxidation
with BDD anodes and raises awareness of the improvements that still need to be made when
applying this technology in water treatment plants.A formação e identificação de sub-produtos resultantes da utilização de processos eletroquímicos avançados de oxidação de diamante dopado com boro (BDD), para o tratamento de água, é essencial para a compreensão dos respetivos riscos para a saúde pública e o ambiente. Contudo, apesar da considerável bibliografia relativa à utilização desta tecnologia em tratamento de água, um estado da arte sobre a formação de sub-produtos e respetivos efeitos nocivos nas principais áreas de tratamento de água, ainda não foi elaborado. Esta dissertação tem como objetivo apresentar o conhecimento atual sobre as espécies reativas e sub-produtos formados durante a oxidação eletroquímica com BDD no tratamento de lixiviados de aterro municipal, água residual industrial, água potável, água residual municipal e remoção de micropoluentes. Foram abordadas as principais espécies reativas, nomeadamente, de oxigénio (ROS), de sulfato (RSS), de cloro (RCS) e, outras espécies oxidantes. Relativamente aos sub- produtos identificados, a presença de compostos halogenados e per-halogenados é recorrente nas diferentes áreas de tratamento de água. A concentração dos mesmos foi influenciada por condições experimentais e pelo material do BDD. Consequentemente, para minimizar a formação destes compostos, é recomendável a utilização de um pH ácido, baixa densidade de corrente, concentrações elevadas de cloretos, NaNO3 como eletrólito e evitar o uso de temperaturas baixas (e.g., 5oC). A diminuição da toxicidade com esta tecnologia foi verificada em alguns dos estudos. No entanto, em termos de efeitos tóxicos em mamíferos (i.e., roedores e humanos), existe um número considerável de sub-produtos classificados como possíveis carcinogénicos, disruptor endócrinos e mutagénicos. Esta dissertação contribui para uma melhor compreensão dos sub-produtos formados durante a oxidação eletroquímica com BDD, e proporciona um aumento da consciencialização sobre os progressos a realizar na implementação desta tecnologia em estações de tratamento de água.
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Vasilyev, Prokopiy. "The oxidation state of deeply subducted, altered oceanic crust: an experimental study and the evidence from natural samples." Phd thesis, 2016. http://hdl.handle.net/1885/101931.
Full textAbstract:
Eclogitic xenoliths from kimberlites are occasionally
diamond-bearing, and are often interpreted as having an origin as
subducted oceanic crust. The existence of diamonds in these rocks
constrains equilibrium temperatures and pressures of some
eclogites to the upper mantle. However the additional critical
parameter controlling the stability of diamonds, oxygen fugacity
(fO₂), is poorly constrained in eclogitic assemblages.
A series of piston-cylinder experiments were conducted using
model carbonate and kyanite bearing eclogite assemblages to
determine the oxygen fugacity of the limiting reaction for
carbonate vs. graphite/diamond:
Dolomite + 2Coesite = Diopside + 2Graphite/Diamond + 2Oxygen
as a function of pressure (P=3.5-6 GPa) and temperature
(T=900-1300 degree C).
The oxygen fugacity in the experiments was determined using Fe-Ir
alloy ƒO₂ sensors and a newly developed Fe-Pd-based redox sensor
for high-pressure experiments. The experimental data allowed
calibration of two redox reactions (involving
garnet-clinopyroxene and garnet-kyanite) as oxybarometers to
determine ƒO₂ of eclogitic rocks. Both reactions can be used to
evaluate the ƒO₂ of UHP metamorphic eclogites and eclogite
xenoliths from kimberlites.
The accuracy of the calculated ƒO₂ is highly dependent on
precision of the garnet Fe³⁺/ΣFe measurements, which were
obtained using the flank method and the synchrotron based Fe
K-edge XANES method. Both reactions were calibrated and used to
estimate ƒO₂ of diamond, kyanite and coesite bearing eclogite
xenoliths from Udachnaya kimberlite pipe, Yakutia, Russia. The
relatively high ƒO₂ of diamond stability in eclogite relative to
peridotite at the upper mantle PT conditions may explain the
higher abundance of diamonds in eclogite xenoliths and constrains
the mechanism of transport of carbon to the deep mantle.
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Makgato, Thuto Nelson. "Formation of surface diamond-like nanostructures on graphite induced by highly charged ion irradiation." Thesis, 2011. http://hdl.handle.net/10539/9249.
Full textAbstract:
The interaction of Antimony Slow Highly Charged Ions (SHCIs) of different charge states with Highly Oriented Pyrolitic Graphite (HOPG) is studied in terms of morphology and electronic modification of single-ion impact induced nanodefects. Results are presented in terms of non-contact Atomic Force Microscopy (NC-AFM) analysis, Raman spectroscopy, Photoluminescence and Scanning and Tunneling Spectroscopy (STS). A charge state dependence of radiation damage and nanodefect dimensions is observed using Raman spectroscopy and NC-AFM analysis respectively. Surface treatment of the nanodefects by annealing in a hydrogen atmosphere, induce modification of nanodefect dimensions and the corresponding electronic states as observed from NC-AFM analysis and STS. STS conducted on the treated nanodefects shows significant modification of the electronic energy band gap in Sb18+ and Sb22+ impact regions. The materials produced in this work by SHCI impact and surface treatment are believed to be diamond-like carbon (DLC) with electronic energy band gaps of approximately 2.05 eV and 2.33 eV corresponding to Sb18+ and Sb22+ impact regions respectively. DLC nanostructures observed in the present study could provide a host matrix for N-V luminant centers which can be used as single photon sources to fabricate patterned qubits using the Electron Beam Ion Trap (EBIT) for purposes of demonstrating scalable room temperature quantum information devices.
33
Wang, Han-Pei, and 王漢培. "The formation of diamond-like carbon (DLC) film in plasma assisted pulsed laser deposition method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/37557927972738024141.
Full textAbstract:
碩士國立成功大學
機械工程學系碩博士班
96
In this study a technique of deposition by plasma assisted pulsed laser in atmospheric pressure is proposed. The formation of diamond-like carbon (DLC) film has been investigated. This approach is made to accelerate the ablated carbon particles by a high temperature plasma torch, then the kinetic energy of the carbon particle can be increased to form the sp3 atomic structure of the carbon by the plasma flow. The influences of the plasma flow have been examined by numerical analysis and experimental observation. In the numerical analysis, the electromagnetic fields and the distribution of velocity and temperature on plasma flow have been solved by a set of magnetohydrodynamics (MHD) equations with the software FLUENT. The effects on the plasma flow at various parameters, such as electric current and inlet pressure, are discussed in this study. The plasma assisted pulsed laser deposition method was used to deposit DLC film on the steel substrate at atmospheric pressure with the argon gas flow in experiment. According to the results of the carbon film inspected by the Raman spectroscopy, it reveals that the intensity ratio of the D-band to G-band (Id/Ig) of the carbon film can be reduce to 0.513 by the implementation of plasma flow, therefore the DLC film was solidly formed. The adhesive strength of the DLC film was characterized by the scratch test, it can be seen that the critical load of the film is about 19 N, which is acceptable in comparison with other approaches.
34
Yu, Wen-Hung, and 游文宏. "Influence of tool wear and cutting parameters on the chip and burr formation in diamond turning." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/62372382203760442002.
Full textAbstract:
碩士淡江大學
機械與機電工程學系碩士班
101
Owing to the rapid development in the optical and opto-electronic industries, components/molds with micro patterns are in great demands. Although many approaches can be adopted to generate those micro-structures, precision diamond turning is by far the most commonly used method. However, diamond turning has its own problems to resolve. Micro-burr produced during the micro-cutting process is one of these drawbacks needing further investigation and, a feasible solution. Efforts have been made in this study to analyze the burr formation process in diamond turning by FEM simulation, micro-scratching and diamond turning. Influence of tool wear and cutting parameters such as rake angle, included angle and inclined angle on the chip and burr formation in diamond turning were systematically investigated. The results showed that (i) tool cutting edge sharpness together with tool rake angle and included angle have profound effect on burr formation and achievable surface finish, (ii) simulation can supply very useful information for setting the machining parameters to suppress the burr formation during micro-cutting process.
35
Barry, Travis. "Genetic Pore Types and Their Relationship to Reservoir Quality: Canyon Formation (Pennsylvanian), Diamond M Field, Scurry County, Texas." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10536.
Full textAbstract:
Carbonate reservoirs may have a variety of porosity types created by depositional, diagenetic, and fracture processes. This leads to the formation of complex pore systems, and in turn creates heterogeneities in reservoir performance and quality. In carbonate reservoirs affected by diagenesis and fracturing, porosity and peremeability can be independent of depositional facies or formation boundaries; consequently, conventional reservoir characterization methods are unreliable for predicting reservoir flow characteristics.
This thesis provides an integrated petrographic, stratigraphic, and petrophysical study of the 'Canyon Reef' reservoir, a Pennsylvanian phylloid algal mound complex in the Horseshoe atoll. Core descriptions on three full-diameter cores led to the identification of 5 distinct depositional facies based on fundamental rock properties and biota. Fifty-four thin sections taken from the core were described are pores were classified using the Humbolt modification of the Ahr porosity classification.
In order to rank reservoir quality, flow units were established on the basis of combined porosity and permeability values from core analysis. A cut off criterion for porosity and permeability was established to separate good and poor flow units. Ultimately cross sections were created to show the spatial distribution of flow units in the field.
36
Liu, Tao [Verfasser]. "High resolution investigation of texture formation process in diamond films and the related macro-stresses / von Tao Liu." 2009. http://d-nb.info/993966063/34.
Full text
37
Ko, Jui-Ling, and 葛瑞齡. "Simulation and experimental analysis of chip and burr formation mechanisms involved in diamond micro-cutting of ductile metals." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/24729019702128623467.
Full textAbstract:
碩士淡江大學
機械與機電工程學系碩士班
100
As the demand for micro-patterned parts getting bigger, the need for molds with micro/nano scaled patterns to duplicate these parts effectively and economically is increasing ever so rapidly. Over the years, numerous attempts have been made to fabricate these molds using various approaches such as lithography, FIB, and precision diamond turning. Amongst these approaches, diamond turning is by far the most commonly used method to generate the micro-patterned rollers for roll-to-roll fabricating of precision optical parts such as BEF and 3D films. However, micro-burrs are frequently producedduring the micro-cutting process which not only makes the mold un-usable but also increases the cost of machining. Since the micro-patterns/burrs are normally in micrometer-scale and the mold is usually too big to put into SEM for close examination, experimentally observation of the micro-cutting process and burr formation is rather difficult and costly.This research aimed to study the chip/burr formationprocess during the micro-cutting by simulation and micro-scratching approaches. Influences of the cutting parameters such as rake angle, inclination angle, tip radius, included angle, cutting speed and cut depthon the chip/burr formation were systematically investigated. The results showed good agreement with the scratching experiments. This means that simulation can supply very useful information for setting the machining parameters to suppress the burr formation during micro-cutting process.
38
Chen, Wen-Hao, and 陳玟豪. "Influence of tool shape/wear and cutting parameters on the burr formation mechanisms in precision diamond turning of micro-optical structure." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/98070489586825037174.
Full textAbstract:
碩士淡江大學
機械與機電工程學系碩士班
104
As the demand for micro-patterned parts getting bigger, the need for molds with micro/nano scaled patterns to duplicate these parts effectively and economically is increasing ever so rapidly. Over the years, numerous attempts have been made to fabricate these molds using various approaches such as lithography, FIB, laser ablation, and precision diamond turning. Amongst these approaches, diamond turning is by far the most commonly used method to generate the micro-patterned rollers for roll-to-roll fabricating of precision optical parts such as BEF and 3D films. However, micro-burrs are frequently produced during the micro-cutting process which not only makes the mold un-usable but also increases the cost of machining. Efforts have been made to study the burr formation process during the micro-cutting by finite element method based simulation and diamond turning experiments. Influences of the machining parameters such as cutting edge radius, included angle, depth of cut, cutting speed and spiral/plunge-cut approaches on the burr formation were systematically investigated. The results show that (i) cutting edge radius and depth of cut have profound effect on burr formation and (ii) plunge-cut approach performs better than spiral-cut in suppressing the burr formation during micro-cutting process.
39
CHA, R. Z., and 張仁宗. "The study of phenyl-naphthol diamine formation and its." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/78933963540579900897.
Full textAbstract:
碩士國立中央大學
化學工程研究所
83
4-(3-取代基-4-胺基苯)-2-羥基-奈胺類可以由以下的方法合成、此方法 是將1-(鄰-取代苯)-偶氮-2-奈酚、還原成胼類化合物、然後在溫度為0℃ 時、以鹽酸進行酸重排反應。以4-(4-胺基苯)-2-羥基-奈胺為例:首先由 苯胺經重氮化形成苯胺偶氮鹽於低溫及鹼性條件下、與β-奈酚形成苯-偶 氮-2-奈酚然後再經由鋅粉及醋酸在熱乙醇中還原為 苯-2-奈酚胼、苯-2- 奈酚胼在常溫的空氣中極為不穩定。 4-(4-胺基苯)-2-羥基-奈胺鹽酸鹽( 雙胺Ⅰ)、可以由苯-2-奈酚胼在鹽酸溶液中溫度為0℃時進行酸重排反應 、得到聯苯奈二胺鹽酸鹽、收率為40%、融點大於3000℃。類似的方法、 鄰-甲基苯胺可得到1-胺-4-(3'-甲基-4'-胺基苯)-2奈酚鹽酸鹽、簡稱雙 胺Ⅱ、收率37.5%、融點大於300℃。鄰-甲氧基苯胺、可得到1-胺-4-(3'- 甲氧基-4'-胺基苯)-2-奈酚鹽酸鹽、簡稱雙胺Ⅲ、收率35.6%、融點大 於300℃。合成之聯苯奈二胺之鹽酸鹽與2-奈酚、1-胺基-8-羥奈-3,6-雙 磺酸( H-酸)、6-胺基-1-羥奈-3-磺酸(J-酸)、7-胺基-10-羥奈-3-磺酸( γ-酸)之雙重氮鹽於低溫及鹼性偶合條件下、 得到雙偶氮染料、其水溶 液可視光最大吸收波長為530-641nm、為紅色到藍色溶液。很成功的合成 了非聯苯型之不對稱苯-奈雙胺及其雙偶氮染料。 4-(ortho-substituted-4-amino-phenyl)-2-hydroxy-1-napthyl- amine may be prepared by the following method, which consists in reducing 1-(ortho-substitutued-phenyl)-azo-2-naphthol to the hydrazo compound, and then acid rearrangement with hydrochloric acid at 0℃。 phenyl-azo-2-naphthol was at first prepared by copling dia- zotised aniline with β-naphthol, and reducing by means of zinc dust and acetic acid in hot ethanol solution gave N-phenyl-N'-1 -(2-naphthol)-hydrazine, which obtained by this means were uns- table when exposed to air at room temperature. 4-(4-amino-phenyl)-2-hydroxy-1-naphthylamine hydrochloride ( diamine Ⅰ) is formed by phenyl-hydrazo-2-naphthol with the acid rearrangement by treatment of the hydroazo compound with hydroc- hloric acid at 0℃. yield 41.9%. mp>300 0℃. Analogously, o-Toluidine yielded-4-amino-phenyl) -2-hydroxy-1- naphthol amine hydrochloride(Ⅱ), mp>300 0℃. in37.5 %. o- Anisidine yielded 4-(ortho-anisyl-4-amino-phenyl)-2-hydroxy- 1-naphthyl amine hydrochloride(Ⅲ), mp>300 0℃, in 35.6%. 1-amino-8-naphthol-3,6-disulfonic acid (H-acid) orβ-naphthol or 6-amino-1-naphthol-3-sulfonic acid (J-acid) or 7-amino- napht- hol or 6-amino-1-naphthol-3-sulfonic acid (r-acid) was coupled with those diamine diazonium slats in low temperature and strong basic sloution,to give dyes.The maximum absorption were between 530-641 nm. Successfully synthesized the unsymmetric benzidine type of phenyl-naphthol diamine derivatives and their diazo dyes.
40
Rajakumari, P. Maria Nirmal. "Network Formation In Amine Curing Of Higher Functional Epoxy Resins." Thesis, 1996. http://etd.iisc.ernet.in/handle/2005/1872.
Full text
41
Hui, Hsin-Yi, and 許欣怡. "The effect of cubic SiC on formation of oriented diamonds on Si(100) substrates." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/57031210340225400820.
Full textAbstract:
碩士國立交通大學
材料科學與工程系所
95
This dissertation focuses on the study of formation of cubic SiC (β-SiC) and oriented diamond film by microwave plasma chemical vapor deposition (MPCVD). In the first part of the dissertation, the main focus is on formation of β-SiC buffer layer using various deposition parameters including precursors, microwave power, and bias time. In the second part, the fabricated β-SiC was used as the substrate for the study of growth of oriented diamonds. Before SiC growth, carburization MPCVD had been performed using propane and methane as carbon sources. The <100> β-SiC layers on Si(100) substrates were synthesized by MPCVD using a mixture of propane and hydrogen gases as precursors with the application of a negative bias on the specimen. The morphology, crystallinity and chemical bonding after β-SiC formation on Si substrates were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). It is found that the microwave power and the bias time have great influence on the formation of α-SiC and β-SiC phases, their sizes and the density. The β-SiC islands exhibit a stripe morphology with width and length of 0.2μm and 0.1μm, respectively. In the diamond thin film growth process, only methane in hydrogen was used as reacted gases. Temperature and methane concentration are the major factors affecting oriented diamond growth based on the results of SEM, XRD, and Raman spectroscopy. It is demonstrated that <100>textured β-SiC in the first process can be used to fabricate high-quality diamond films with the <100>texture in which the epitaxial ratio approaches 38% for one hour growth under proper deposition conditions of 1% CH4 and growth temperature at 700℃.