Teses / dissertações sobre o tema "Synthèse des phases MAX"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 50 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Synthèse des phases MAX".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja as teses / dissertações das mais diversas áreas científicas e compile uma bibliografia correta.
Magné, Damien. "Synthèse et structure électronique de phases MAX et MXènes". Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2284/document.
Texto completo da fonteThe aim of this work is at first to study the electronic structure of bidimensional titanium carbide systems, belonging to the MXene family and also to synthesize thin films of such new materials to characterize their properties. The study of the electronic structure has been performed for the Ti3C2T2 MXene with a special attention to the T surface groups by using a combination of electron energy loss spectroscopy and ab initio calculations. This study, focused on both valence and core electrons excitations, enabled the identification of the surface group localization, their influence on the MXene electronic structure as well as their chemical nature. The limits of our TEM-based study is also discussed in view of irradiation phenomena which induce the loss of hydrogen atoms. The synthesis of a MXene thin film requires, beforehand, that of a MAX phase thin film: we opted for Ti2AlC, the precursor for the Ti2C MXene. The MAX phase thin film synthesis was carried out by ex-situ annealing of a multilayer layers. X-ray diffraction experiments and cross-sectional transmission electron microscopy observations show that a highly textured Ti2AlC thin film is obtained above 600°C after the formation, at 400°C, of a metastable solid solution. Finally, by using the same process for V2AlC, we demonstrate that the initial phase orientation plays a key role for the texture of the thin film so obtained
Shi, Lu. "Des phases MAX au MXenes : synthèse,caractérisation et propriétés électroniques". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI101/document.
Texto completo da fonteMAX phases are layered early transition metal ternary carbides and nitrides so called because they are composed of M, an early transition metal, A, a group A element and X is C and/or N. MAX phase structure is composed of near close-packed planes of M atoms with the X atoms occupying all the octahedral sites between them. Their physical properties (stiffness, damage and thermal shock resistance, high thermal and electrical conductivity) along with the fact they are readily machinable, make them extremely attractive in terms of the potential technological applications.In 2011, it was discovered that by immersing Al-containing MAX phases in HF acid, it was possible to selectively etch the Al, resulting in two-dimensional (2D) materials, that were labeled MXene to denote the removal of the A-group element and make the connection to another conducting 2D material, graphene. This new member of 2D materials family owns stronger, more chemically versatile, and have higher conductivity than other materials. As such they are highly interesting on new applications, e.g. specialized in vivo drug delivery systems, hydrogen storage, or as replacements of common materials in e.g. batteries, sewage treatment, and sensors.In this thesis, as its self-telling title indicated, we present our work on the synthesis, structural characterization and the electron transport in the MAX phases and their 2D derivatives, MXenes.For MAX phase: motivated by the theoretically expected anisotropic properties of these layered materials, producing bulk single crystals is a natural way to obtain samples where the anisotropy of the physical properties can be experimentally probed. Also, knowledge of low-temperature behavior of single crystal is vital because it can provide insight into MAX intrinsic physical properties. Using high temperature solution growth and slow cooling technique, several MAX phases single crystals have been successfully grown, including Cr2AlC, V2AlC, Ti3SiC2, etc. Structural characterization confirms the single crystalline character of the samples. Experimentally, a set of experimental data was obtained from single crystals of V2AlC and Cr2AlC as a function of temperature and magnetic field. In particular, we obtain a very high ratio between the in-plane and parallel to the c-axis resistivity, which is very substantial, in the range of a few hundreds to thousands. From MR and Hall effect measurement, in-plane transport behaviors of MAX phases have been studied. The extracted mobility is in the range from 50 to 120 cm2/V·s, which is the same order of magnitude of polycrystalline sample. Theoretically, a general, yet simple model was proposed for describing the weak field magneto-transport properties of nearly free electrons in two-dimensional hexagonal metals. It was then modified to be applicable for the transport properties of layered MAX phases.For MXene: Large scale V2CTx MXene flakes was successfully synthesized by conventional HF-etching of V2AlC single crystals. Mechanical delamination of multilayered V2CTx flakes into few layer flakes and transfer on Si/SiO2 substrate was also achieved. Structural characterization demonstrated an enlarged interplane distance, while prior DMSO intercalation seems to have no effect on this type of MXenes. From EDS results, we concluded that -OH terminations on V2CTx is the dominated, and the most energetically favorable, compared to -F and -O functional groups. We then detail the electrical device fabrication process and proceed with electrical measurements results, performed down to low temperature, with the aim to extract useful information on charge carrier behavior. We successfully obtained some first hand transport data on V2CTx MXenes, the average value for the resistivity of V2CTx MXenes is 2 × 10-5 Ω ∙m, which is in consistent with reported other MXene samples. The mobility, 22.7 cm2/V·s , which stays in the same order of magnitude as its parent MAX phase
Zhang, Shiqi. "Etude de la Réactivité chimique des monocristaux de phase MAX". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI042/document.
Texto completo da fonteMAX phases are a family of layered ternary carbides and nitrides with chemical formula Mn+1AXn, where M is an early transition element, A is an element of groups 13 to16 and X is either C, N or both. These phases combine the merits of ceramics and metals, such as chemical stability, machinability, shock resistance, good electrical and thermal conductivity, etc. However, the investigation of their intrinsic properties and anisotropies has heretofore been limited by a lack of availability of single crystals. This thesis mainly deals with the chemical reactivity of MAX phase single crystals. Owing to the large size single crystals grown at LMGP, it was possible to directly assess the anisotropy of the chemical reactivity and to obtain original data. We showed that the prominent role played by the A element for initiating chemical transformations could lead to the synthesis of original materials, and we focused on four different aspects. First, we tried to synthesize MXenes from MAX phase single crystals: The purpose was to obtain large-scale MXenes by taking advantage of the large size of the single crystals. Effort was put on describing the chemical reactivity of MAX phases dipped in different etchants, focusing on HF. Secondly, we studied the MAX phase reactivity with chlorination: the initial purpose was to obtain MXenes, but we finally developed a method for synthesizing porous chromium carbides which exhibit several interesting properties. Thirdly, we used large size single crystals in order to assess the anisotropy of the electrochemical properties. A significant anisotropy was found, either by measuring the current during electrochemical polarization or by frequency-dependent impedance measurements. Several mechanisms were proposed in order to explain this anisotropy of the corrosion properties. Eventually, we showed that the electrochemical results could be used to indirectly evidence the presence of structural defects recently identified in the literature. Such defects, called ripplocations, are specific to nano-lamellar materials
Bugnet, Matthieu. "Synthèse, structure électronique et comportement sous irradiation aux ions de films minces de phases MAX". Poitiers, 2011. http://theses.univ-poitiers.fr/23902/2011-Bugnet-Matthieu-These.pdf.
Texto completo da fonteThe aim of this work is to synthesize model materials (epitaxial thin films) of ternary ceramics called MAX phases, in order to study their behavior under ion irradiation. To follow the microstructural modifications induced by ion irradiation, we used electron energy loss spectroscopy and X-ray absorption spectroscopy in addition to X-ray diffraction and transmission electron microscopy techniques. The growth of Cr2AlC and Cr2GeC epitaxial thin films was achieved by magnetron sputtering whereas the synthesis of textured Ti2AlN layers was obtained by high temperature plasma nitriding of multilayers with an average stœchiometry Ti2:Al1:N1. The electronic structure of unirradiated films of de Cr2AlC, Cr2GeC, Ti2AlC, Ti3AlC2 and Ti2AlN was then characterized. Experimental spectra were interpreted from ab initio simulations. This study shows that structural information may be obtained from fine structures of core electron excitation edges. After irradiation, the study of the C-K and Al-K near-edge fine structures in Ti3AIC2 evidences that Ti6C octahedra layers are very resistant to irradiation damage and on the contrary, aluminium layers are strongly disordered. A similar behavior is suggested for Ti2AlC, Ti2AlN and also partly for Cr2AlC. Though titanium based materials are still crystalline after irradiation at high fluence, chronium based compounds rapidly amorphize. It is evidenced that the initial crystalline structure is recovered after post-irradiation annealing
Alkazaz, Malaz. "Synthèse de films minces de phases MAX par recuit thermique - Application à la formation de contacts ohmiques sur SiC". Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2328/document.
Texto completo da fonteMAX phases are a family of ternary carbides or nitrides which properties are generally described as an exceptional combination of the best properties of metals and ceramics. Thin films of MAX phases being considered as good candidates for ohmic contacts on SiC substrates for power microelectronics devices, thin films of Ti2AlN and Ti3(Si,Ge)C2 were synthesized by using original approaches. Highly textured Ti2AlN thin films were so obtained by thermal annealing at 750°C of (Ti+Al)/AlN multilayers whereas epitaxial thin films of Ti3SiC2 on 4H-SiC were achieved after an annealing at 1000°C of TixAly or TixGey layers. Good ohmic contact behaviors of Ti3SiC2 layers were confirmed in this work whereas Ti2AlN thin films behave as Schottky barriers
Khan, Abbas. "Tailored oxides and carbides as active materials for high power energy storage devices". Electronic Thesis or Diss., Nantes Université, 2024. http://www.theses.fr/2024NANU4025.
Texto completo da fonteDesign of tailored materials using innovative approaches that allow faster charging/discharging processes could be the key for advancement of electric mobility. This thesis investigates novel materials for Li-ion battery negative electrodes, focusing on niobium-based multicationic oxides and titanium-based transition metal carbides. This research work explores the synthesis, structure, and electrochemical properties of these materials, with particular emphasis on atomic-scale structural modifications and Li+ storage mechanisms. Key findings include the investigation of in-situ electrochemical activation and unique Li+ storage behavior in AgNbO 3 model perovskite and Ag 1-3xLa x□2xNbO 3 (with 0 ≤ x ≤ 0.40; □ is an A -site vacancy) tailored materials. Additionally, the study examines the effect of A-site deficiency on the structure and Li+ insertion properties of K1-3xLa x□2xNbO 3 (with 0 ≤ x ≤ 0.15; □ is an A -site vacancy). Furthermore, insights into the polyacrylamide synthesis route for Ti and Al-based MAX phases are provided. These work present approaches to atomically tailor the materials without sacrificing the pristine phase, suggesting the potential use of less common ABO 3-type perovskites as negative electrodes. Additionally, it offers mechanistic insights into the wet chemical synthesis of MAX phases for their use as battery electrodes
Humphrey, Caroline. "Deformation in MAX phases". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610553.
Texto completo da fonteLiu, Zhongsheng. "Magnetic MAX phases: Itinerant electron magnetism of pure and Mn-doped Cr-based MAX phases". 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199312.
Texto completo da fonteBououdina, Mohamed. "Étude d'alliages et d'hydrures dérivés des phases de laves ZrCr2(1-x)M2x (M=éléments 3d et molybdène) : Synthèse, études structurale et thermodynamique en relation avec les propriétés de stockage de l'hydrogène". Grenoble 1, 1995. http://www.theses.fr/1995GRE10056.
Texto completo da fonteGupta, Surojit Barsoum M. W. "Tribology of MAX phases and their composites /". Philadelphia, Pa. : Drexel University, 2006. http://dspace.library.drexel.edu/handle/1860%20/875.
Texto completo da fonteHoffman, Elizabeth N. Barsoum M. W. "Carbide derived carbon from MAX-phases and their separation applications /". Philadelphia, Pa. : Drexel University, 2006. http://hdl.handle.net/1860/1120.
Texto completo da fonteGertzen, Jonathan. "MAX phases as an electrocatalyst support material: a DFT study". Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31459.
Texto completo da fonteKozak, Karolina. "Influence of elaboration conditions on the thermomechanical behavior of MAX phases". Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0047/document.
Texto completo da fonteMAX phases are ternary carbide and/or nitride with a great potential in various application. This study concerned two MAX phase compounds, namely Ti3SiC2 and Ti2AlC, which are on the most studied among all known MAX phases. The first part dealt with materials elaboration which includes both synthesis and sintering stages. The objective was to obtain a variety of materials with different microstructural features, i.e. phase composition and grain size. For this purpose, both commercial and SHS-derived powders were densified with two pressure-assisted sintering technique, i.e. SPS and HP. The second part of work was devoted to deeper understanding of the influence of phase composition and grain size to thermomechanical behavior of MAX phases. More information was provided when two experimental techniques, four-point bending and AE monitoring, were coupled together with post-mortem SEM observations. The developed experimental approach based on comparison of mechanical responses of Ti3SiC2 (MAX phase and secondary phases) and Ti2AlC (containing only MAX phases) compounds, is implemented to investigate the induced deformation and damage mechanisms. It was shown that higher quantity of MAX phases in the material improves flexural strength with corresponding more pronounce nonlinear behavior and high dissipated energy. When MAX phase grains are coarser the mechanical strength lowers but the nonlinear part becomes more significative, which results in higher values of dissipated energy. It was also shown that the secondary phases and the grain size impact the way in which the damage is accumulated within the sample. AE data provided more information on possible damage mechanisms and their chronology leading to hysteretic behavior of MAX phases. The last part has shown that the BPTT for Ti3SiC2 is ≈1200˚C and the grain size of MAX phases lowers this BPTT
Guitton, Antoine. "Mécanismes de déformation des phases MAX : une approche expérimentale multi-échelle". Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2280/document.
Texto completo da fonteIt is commonly believed that plastic deformation mechanisms of MAX phases consistin basal dislocation glide, thus forming pile-ups and walls. The latter can form local disorientationareas, known as kink bands. Nevertheless, the elementary mechanisms and the exact role ofmicrostructural defects are not fully understood yet. This thesis report presents a multi-scale experimentalstudy of deformation mechanisms of the Ti2AlN MAX phase. At the macroscopic scale,two kinds of experiments were performed. In-situ compression tests at room temperature coupledwith neutron diffraction brought new insight into the deformation behavior of the different grainfamilies in the polycrystalline Ti2AlN. Compression tests from the room temperature to 900 °Cunder confining pressure were also performed. At the mesoscopic scale, deformed surface microstructureswere observed by SEM and AFM. These observations associated with nanoindentationtests showed that grain shape and orientation relative to the stress direction control formationof intra- and inter- granular strains and plasticity localization. Finally, at the microscopic scale,a detailed dislocation study of samples deformed under confining pressure revealed the presenceof dislocation configurations never observed before in MAX phases, such as dislocation reactions,dislocation dipoles and out-of-basal plane dislocations. In the light of these new results, mechanicalproperties of MAX phases are discussed
Rackl, Tobias [Verfasser], e Dirk [Akademischer Betreuer] Johrendt. "Increasing the chemical diversity of MAX phases / Tobias Rackl ; Betreuer: Dirk Johrendt". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/121324627X/34.
Texto completo da fonteAmini, Shahram Barsoum M. W. "On the effect of texture on kinking non-linear elasticity of MAX phases and MAX-reinforced Mg matrix composites /". Philadelphia, Pa. : Drexel University, 2009. http://hdl.handle.net/1860/3113.
Texto completo da fonteHamm, Christin Maria [Verfasser], Christina [Akademischer Betreuer] Birkel e Barbara [Akademischer Betreuer] Albert. "Synthese, Charakterisierung und magnetische Eigenschaften ausgewählter Laves- und MAX-Phasen / Christin Maria Hamm ; Christina Birkel, Barbara Albert". Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1136078789/34.
Texto completo da fonteHaddad, Noël. "Etude des propriétés diélectriques des phases MAX par spectroscopie de pertes d'énergies des électrons". Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00662325.
Texto completo da fonteBei, Guo-Ping. "Synthesis, microstructural characterization and mechanical properties of nanolaminated Ti3AlxSn(1-x)C2 MAX phases". Poitiers, 2011. http://nuxeo.edel.univ-poitiers.fr/nuxeo/site/esupversions/9a20805b-0e53-47c0-8b16-c1a4ac3c2042.
Texto completo da fonteThe work described in this thesis concerns the elaboration, the microstructural characterization and the mechanical properties of nanolaminated MAX phases solid solutions. The MAX phases represent a large class of ceramics. They are a family of ternary nitrides and carbides, with the general formula Mn+1AXn (n=1, 2 or 3), where M is an early transition metal, A is a metal of the groups IIIA or IVA, and X is either carbon or nitrogen. We performed at first the optimization of the synthesis, by powder metallurgy, of highly pure Ti3AlC2. Since a new MAX phase, Ti3SnC2, has been discovered in the laboratory in 2007, the study has been further focused on the synthesis of Ti3AlxSn(1-x)C2 solid solutions by hot isostatic pressing. In a second step, the microstructural characterization of these solid solutions has been carried out, by studying, in particular, the variation of the cell parameters, the distortion rates of [Ti6C] octahedrons and [Ti6AlxSn(1-x)] trigonal prisms. Finally, we have determined the intrinsic hardness and the elastic modulus of the various solid solutions as a function of the Al content by using the nanoindentation. Besides, uniaxial and gas confining compression tests were realized at room temperature, to study and compare the deformation mechanisms of Ti3AlC2 and Ti3Al0. 8Sn0. 2C2. The relationship between microstructural modifications and mechanical properties are discussed. We show in particular that Ti3AlC2 and Ti3Al0. 8Sn0. 2C2 can be considered as "Kinking Non-linear Elastic" materials
Lu, Chengjie. "Mécanisme de brasage de la céramique Ti2AIC utilisant un alliage d'apport à base de nickel". Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS053/document.
Texto completo da fonteIn the present work, the brazing experiments of Ti2AlC ceramics to Ni substrate have been successfully performed in the temperature range between 1000°C and 1100°C, with the holding time varying from 15 min to 60 min. The corresponding mechanisms have been disclosed by studying the microstructure of the Ti2AlC/Ni joint. It is found that the Ni element originating from the BNi-2 filler can diffuse into the Ti2AlC substrate during the brazing process, mainly along the grain boundary, or in some grains with special orientations. The interaction process induces some differences in the fluidity of the liquid filler; consequently, the thickness of the Ti2AlC/Ni joints achieved finally is different at different brazing parameters. The maximum shear strength is measured to be 193 MPa, achieved at 1100°C holding for 30 min. Afterwards, the interaction behavior between the filler elements (including Ni, Cr and Si) and the Ti2AlC substrate, has been explained by DFT simulation. It is found that the three kinds of filler elements have their own preferred substitution sites: Ni atoms are most likely to be found at Al site, Cr atoms at Ti site, and Si atoms at Al site. Then, the decomposition mechanisms of the defective Ti2AlC model have been illustrated as well, which might occur in two possible means: unstable vibrational behaviors, and lower Gibbs energy of competing phases
Ben, Romdhane Ferdaous. "Synthèse et caractérisation de nouvelles phases bidimensionnelles par microscopie électronique in-situ". Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE001/document.
Texto completo da fonteThe aim of this thesis is the synthesis and characterization of new two-dimensional phases in an in-situ transmission electron microscopy experiment. These studies concerned the nucleation and growth of three deferent materials: quasi-two-dimensional silica (SiO2), the smallest possible carbon cages with the size of C20, and two-dimensional chalcocite (β-Cu2S). The characterization of these structures has been performed using high resolution imaging (HRTEM) and electron energy-loss spectroscopy (EELS). The first part of this thesis is devoted to the study of the nucleation and growth of an ordered or disordered 2D crystalline phase of silica on different substrates (Co, Ru, Fe) and a 1D silica phase grown at atomic steps of a metal surface. The second part illustrates the in-situ growth of the smallest possible carbon cages with a diameter of about 0.36 nm on catalytically active metal surfaces such as Co, Fe, or Ru. The last part is devoted to the growth of the thinnest stable layer of β-Cu2S on a graphene surface. All these studies were accompanied by image simulations
Terrien, Isabelle. "Synthèse et étude de nouvelles phases stationnaires à base de cristaux liquides". Bordeaux 1, 1998. http://www.theses.fr/1998BOR10585.
Texto completo da fonteNavailles, Laurence. "Synthèse et études structurales de nouvelles phases smectiques hélicoi͏̈dales : TGBA et TGBC". Bordeaux 1, 1994. http://www.theses.fr/1994BOR10554.
Texto completo da fonteBaben, Moritz to [Verfasser]. "Oxygen incorporation in MAX phases and TiAlN and elastic properties of nanolaminates / Moritz to Baben". Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1033652709/34.
Texto completo da fonteThore, Andreas. "A theoretical investigation of Tin+1AlCn and Mn2GaC MAX phases : phase stability and materials properties". Licentiate thesis, Linköpings universitet, Tunnfilmsfysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-111955.
Texto completo da fonteThe series name of this thesis Linköping Studies in Science and Technology Licentiate Thesis is incorrect. The correct name is Linköping Studies in Science and Technology Thesis.
Drouelle, Elodie. "Relations microstructure, propriétés mécaniques et résistance à l'oxydation de la phase MAX Ti3AlC2". Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2277/document.
Texto completo da fonteThe lightening of structures has become a major challenge for transport industries. New materials with, at least, equivalent specific properties to currently used materials have been designed in order to cope with this challenge. In this regard, Ti3AlC2 MAX phase has been studied. The high temperature (800-1000°C) oxidation resistance and tension and tensile creep properties were assessed for Ti3AlC2 samples elaborated using a powder metallurgy process (pressureless sintering + spark plasma sintering). The various oxidation tests pointed out two different behaviors (protective oxidation or catastrophic one depending on the grown oxides nature) mainly controlled by samples microstructural features (grains size, elements on A site, roughness and porosity). The first tensile creep tests ever performed on Ti3AlC2 MAX phase indicates the high ductility of these materials whose specific properties reach or surpass those of polycrystalline superalloys and titanium aluminides. A multi-scale study highlights deformation mechanisms occurring through intergranular sliding at 900 and 1000°C and through dislocations glide at 800°C. Damage mechanisms occurring through cavitation supported by crack oxidation phenomena on gauge length surface were also underlined
Guerrouache, Mohamed. "Synthèse de nouvelles phases monolithes versatiles à base de N-acryloxysuccinimide pour l'électrochromatographie". Phd thesis, Université Paris-Est, 2009. http://tel.archives-ouvertes.fr/tel-00473572.
Texto completo da fonteLin, Jing. "Synthèse des cyclodextrines amphiphiles et étude de leur incorporation dans des phases phospholipidiques". Paris 6, 1995. http://www.theses.fr/1995PA066658.
Texto completo da fonteRoger, Jérôme. "Nouveaux borosiliciures de terres rares : synthèse, diagrammes de phases, études structurales et physiques". Rennes 1, 2005. https://hal.archives-ouvertes.fr/tel-01323661.
Texto completo da fonteAbou, Hamad Valdemar. "Elaboration et caractérisation de contacts électriques à base de phases MAX sur SiC pour l'électronique haute température". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI079.
Texto completo da fontePower applications in which the ambient temperature is high, cause the increase of temperature in electronic components. Therefore, it is important to develop electronic devices that are able to withstand high current and high-power densities. In this thesis, our objective is to lay the foundations of a new technology for the manufacture of a new generation of Ti3SiC2 MAX phase-based electrical contacts, stable, reliable and reproducible on Silicon Carbide for very high temperature applications (300 - 600ºC). To synthesize Ti3SiC2 on SiC, two elaboration methods were studied in this thesis. The first approach is a reaction method, and the second approach consists on using a Ti3SiC2 target via the Pulsed Laser Deposition (PLD) technique. Our goal is to develop a good quality ohmic contacts. Physico-chemical, electrical (TLM) and mechanical (W-H and RSM) characterizations were performed on the Ti3SiC2 contacts. These samples underwent a thermal aging test at 600°C for 1500 hours under Argon, in order to study the stability and reliability of the electrical contacts at high temperatures. The obtained results showed that the reliability and the chemical stability between Ti3SiC2 and SiC allowed the contacts to keep an ohmic behavior with low electrical resistivity, in addition to a good mechanical behavior, even after 1500 hours of aging at 600ºC. Furthermore, the thermomechanical simulations performed were used to determine the effects of Interfacial Thermal Resistances on the heat dissipation and the mechanical stresses exerted on a high power PN diode. In this thesis, we have shown that an ohmic contact, based on Ti3SiC2, can remain stable and reliable on a 4H-SiC substrate, in temperatures up to 600ºC
Zhang, Tong. "Synthèse et étude de phases stationnaires chirales pour CLHP à base de dérivés d'amidon". Bordeaux 1, 1992. http://www.theses.fr/1992BOR10603.
Texto completo da fonteEl, Harrak Amin. "Synthèse, stabilité et propriétés électriques de phases conductrices anioniques du système Bi2O3-CaO-PbO". Lille 1, 1990. http://www.theses.fr/1990LIL10106.
Texto completo da fonteAlves-Weill, Isabelle. "Synthèse et caractérisations physico-chimiques de nouvelles phases du système Cs-V-Te-O". Bordeaux 1, 2000. http://www.theses.fr/2000BOR10547.
Texto completo da fonteBouyrie, Yohan. "Identification, synthèse et caractérisation de phases tétraédrites pour la conversion d’énergie par effets thermoélectriques". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0089/document.
Texto completo da fonteTetrahedrite with general chemical formula [(Cu,Ag)10(Zn,Fe)2(Sb,As)4S13] are a family of natural minerals, widely spread on Earth, which belongs to the sulfosalt class of compounds. Discovered in the 19th century and extensively studied by mineralogists over the last 60 years from both structural and chemical points of view, it is not until recently however that they have focused attention in thermoelectricity due to their very low thermal conductivity. In order to study the performance of these materials in terms of energy conversion by thermoelectric effect, this thesis consisted in synthesizing tetrahedrite materials by powder metallurgy method and in determining their transport properties both at low (2-300 K) and high temperatures (300-700 K). This wide temperature range enabled us to identify the microscopic mechanisms that govern the transport properties and to assess their thermoelectric performances. The study of their chemical homogeneity and thermal stability has confirmed the existence of a structural transition for certain compositions leading to phase separation upon cooling, a mechanism known in mineralogy and geology as an exsolution process. This mechanism is responsible for a modification of the transport properties and especially an impressive decrease in the thermal conductivity of the order of 50%. Numerous substitutions have been undertaken in an attempt to optimize the thermoelectric performances of these compounds. Tetrahedrite materials exhibit a metallic character that evolves into a semiconductor state depending on the chemical nature of the substituting element and on its concentration. Moreover, a detailed study of the thermal properties of these materials by inelastic neutron scattering has unveiled the microscopic origin of the very low thermal conductivity values observed in these materials
Puy, Guillaume. "Synthèse et caractérisation de phases stationnaires monolithiques de silice pour les techniques séparatives miniaturisées". Lyon 1, 2006. http://www.theses.fr/2006LYO10282.
Texto completo da fonteAlbarello, Nicolas. "Model-based trade studies in systems architectures design phases". Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2012. http://www.theses.fr/2012ECAP0052/document.
Texto completo da fonteThe design of system architectures is a complex task which involves major stakes. During this activity, system designers must create design alternatives and compare them in order to select the most relevant system architecture given a set of criteria. In order to investigate different alternatives, designers must generally limit their trade studies to a small portion of the design-space which can be composed of a huge amount of solutions. Traditionally, the architecture design process is mainly driven by engineering judgment and designers' experiences and the selected alternatives are often adapted versions of known solutions. The risk is then to select a pertinent but yet under optimal solution. In order to increase the confidence in the optimality of the selected solution, the coverage of the design-space must be increased. The use of computational design synthesis methods proved to be an efficient way to support designers in the design of engineering artifacts (structures, electrical circuits...). In order to assist system designers during the architecture design process, a computational method for complex systems is defined. This method uses an evolutionary approach (genetic algorithms) to guide the design-space exploration process toward optimal zones. The initial population of the genetic algorithm is created thanks to a computational design synthesis technique which permits to create different physical architectures and allocation mappings for a given functional architecture. The method permits to obtain the optimal solutions of the stated design problem. These solutions can be then used by designers for more detailed trade studies or for technical negotiations with system suppliers
Flämig, Max [Verfasser], e Ernst [Akademischer Betreuer] Rössler. "A Field Cycling NMR Relaxometry Study on Molecular Liquids and Plastically Crystalline Phases / Max Flämig ; Betreuer: Ernst Rössler". Bayreuth : Universität Bayreuth, 2020. http://d-nb.info/1222101726/34.
Texto completo da fonteDuclos, Françoise. "Synthèse et étude de phases stationnaires chirales obtenues par polymérisation ou greffage de réactifs chiraux". Rouen, 1992. http://www.theses.fr/1992ROUES029.
Texto completo da fonteFredenucci-Caillod, Lise. "Synthèse directe des méthylchlorosilanes : étude du processus de cuivrage, de phases actives modèles, du rôle des additifs". Lyon 1, 2006. http://www.theses.fr/2006LYO10051.
Texto completo da fonteMockute, Aurelija. "Characterization of Oxygen-rich Ti2AlC Thin Films". Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15059.
Texto completo da fonteIn this Thesis Ti-Al-C thin films deposited by cathodic arc at 700, 800 and 900 °C were investigated with respect to composition, structure and mechanical properties. The highest growth temperature resulted in close to single crystalline Ti2AlC MAX phase.
A high oxygen incorporation of 7-12 at.% was detected in all the films, likely originating from residual gas and the Al2O3 substrate. It was evident that the characteristic nanolaminated MAX phase structure was retained upon deflection from the ideal MAX phase stoichiometry.
Hardness and elastic modulus of the sample grown at 900 °C were 16 and 259 GPa, respectively, as determined by nanoindentation using a Berkovich tip. Nanoindentation measurements with a cube corner tip were also performed on all three samples in order to extract elastic moduli.
Analysis of loading-unloading curves and SPM images revealed no relation between pop-in events and pile-ups around the residual imprints, indicating that other mechanisms than formation of kink bands may be responsible for formation of pile-ups. This was also confirmed by cross-sectional TEM investigation of an indent: Ti2AlC MAX phase deformed without kinking and delamination, as opposed to the observations in single crystalline Ti3SiC2 films. Several possible reasons for the different deformation mechanism observed are discussed.
These results are of importance for the fundamental understanding of the origin of material characteristics, and serve as an initial study initiating further investigations of the influence of defects on MAX phase properties.
Mockute, Aurelija. "Characterization of Oxygen-rich Ti2AlC Thin Films". Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15059.
Texto completo da fontePopescu, Cristina. "Essai de modélisation de la discrimination d'atropoisomères hétérocycliques sur phases stationnaires chirales dérivées de polysccharides". Aix-Marseille 3, 1994. http://www.theses.fr/1994AIX30092.
Texto completo da fonteLhommeau, Mehdi. "Etude de systèmes à événements discrets dans l'algèbre (max,+) : synthèse de correcteurs robustes dans un dioi͏̈de d'intervalles : synthèse de correcteurs en présence de perturbations". Angers, 2003. http://www.theses.fr/2003ANGE0017.
Texto completo da fonteDiscrete event dynamic systems involving synchronization phenomena can be modelled by linear equa-tions in some dioids. This property justified the development of what one commonly calls linear system theory in dioids. This theory presents many analogies with the classical linear system theory and allows to tackle control problems. The first contribution concerns the robustness analysis of control laws for (max,+)-linear systems. The objective is to characterize the set of systems preserving the desired performances at the time of the synthesis. In other words, we try to characterize the acceptable variation margins or drifts for the system with respect to the imposed performances criteria. Then, the robust control problem is addressed. This time we suppose known, in the form of intervals, the amplitude of parameter variations of the system to be control and we seek the controller set allowing to achieve â given objective. As a preliminary a dioid of intervals is introduced, it makes possible to model the uncertain systems in the form of interval matrices including the set of all possible system behaviors. The controller synthesis presented in the deterministic case spreads then naturally to the uncertain context. The last part of this report, deals with the problem of control in the presence of disturbances. Following the literature on classical continuous systems, we show that this problem presents strong analogies with the classical problem of disturbance decoupling. In particular it is shown that it is possible to synthesize optimal controllers preserving the system state trajectories in the kemel of the output matrix
Chassaing, Christophe. "Synthèse et étude de phases stationnaires chirales pour la CLHP, à base de dérivés de polysaccharides". Bordeaux 1, 1996. http://www.theses.fr/1996BOR10556.
Texto completo da fonteASSABAA-BOULTIF, RACHIDA. "Synthèse et caractérisation de nouvelles phases oxynitrures de type Pérovskite, K₂NiF₄, NaCl et bronze quadratique". Rennes 1, 1993. http://www.theses.fr/1993REN10016.
Texto completo da fonteCorbel, Gwenaël. "Etude de phases à charpente anionique mixte : borate-fluorure et borate-oxyde : synthèse, cristallochimie, caractérisations physiques". Le Mans, 1999. http://www.theses.fr/1999LEMA1009.
Texto completo da fonteKurakevych, Oleksandr O. "Synthèse de nouvelles phases binaires ultra-dures dans le système B C N O sous très haute pression". Paris 13, 2007. http://www.theses.fr/2007PA132034.
Texto completo da fonteLepage, Éric. "Synthèse, caractérisation, fractionnement et étude des phases cristallines liquides du tricarbanilate de cellulose dans quatre solvants éthérés". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq25650.pdf.
Texto completo da fonteCachau, Christine. "Synthèse et étude chromatographique de phases stationnaires chirales pour CLHP à base de cyclodextrines natives et dérivées". Bordeaux 1, 1996. http://www.theses.fr/1996BOR10552.
Texto completo da fonteJacobsoone, Virginie. "Synthèse et caractérisation de phases oxyfluorées de type BIMEVOX et de verres oxyfluorés à base de Bi2O3". Lille 1, 1999. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1999/50376-1999-15.pdf.
Texto completo da fonteCompte tenu de la formule chimique des échantillons appartenant à ce domaine, un excès de Zn est nécessairement présent, mais aucune trace d’oxyde de zinc n’a pu être détectée sur les clichés de idffraction des rayons X sur poudre. La spectroscopie de diffusion Raman a permis de mettre en évidence une continuité entre les phases cristallisée et vitreuse. En accord avec l’évolution progressive et continue des spectres lorsque l’on passe de la phase cristallisée à la phase vitreuse, l’hypothèse la plus problable conduit à la délocalisation des ions Zn2+ à la périphérie du feuillet pérovskite. Cette hypothèse est en accord avec la forte augmentation du paramètre c. Par recuit, la phase G se transforme progressivement en phase de type C. Les échantillons de la phase G partiellement recristallisée présentent en mesures électriques une augmentation importante des valeurs de Sigma sont 50 fois supérieures à celles des échantillons vitreux correspondants (Sigma=4. 10-4 S. Cm-1 à 260 °C pour Bi0,65Zn1,215V0,135O1,313F2,43). Une étude des systèmes Bi3O3-PbO-PbF2 et Bi2O3-PbO-CdF2 a également été réalisée. Les synthèses ont été effectuées en creusets de quartz et ont permis d’isoler un large domaine vitreux s’étendant vers le binaire Bi2O3-PbO. Les analyses par fluorescence X ont montré que tous les échantillons incorporent une grande quantité de silice durant la synthèse. Les mesures de conductivité réalisées par spectroscopie d’impédance ont révélé une augmentation de Sigma avec le nombre d’ions F-