Tesis sobre el tema "Supraconducteurs – Matériaux"
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Alloui, Lotfi. "Modélisation tridimensionnelle des matériaux supraconducteurs". Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112215.
Texto completoWe present a contribution for three-dimensional modeling of coupled electromagnetic and thermal phenomena in high temperature superconductor. The control volume method is used for the resolution of the partial derivative equations characterising of the treated physical phenomena. The electromagnetic and thermal coupling is ensured by an alternate algorithm. All mathematical and numerical models thus developed and implemented in Matlab software, are used for the simulation. The results in magnetic term and those in thermal term are largely presented. The validity of the suggested work is reached by the comparison of the results so obtained to those given by the experiment
Villaume, Alain. "Imagerie Magnéto Optique pour les matériaux supraconducteurs". Phd thesis, Université Joseph Fourier (Grenoble), 2006. http://tel.archives-ouvertes.fr/tel-00087773.
Texto completoLes études MO ont notamment porté sur les matériaux supraconducteurs à haute température critique élaborés ou étudiés au CNRS-CRETA et laboratoire de Cristallographie. En particulier, un dispositif de texturation par défilement sous champ magnétique de rubans multifilamentaires de Bi2212 a été mis au point. Connaître précisément les conditions de texturation pour chaque échantillon permet en effet de mieux interpréter les données issues des caractérisations, et notamment les images MO. Nous avons pu mettre en évidence par des obervations MO que la texturation sous champ magnétique améliore le piégeage et la texture des filaments, notamment ceux situés au centre des rubans. Par ailleurs le courant critique mesuré à 4,2K est augmenté de 30 à 40\% grâce à la texturation sous champ magnétique.
Dans les massifs YBCO, nous avons mis en évidence grâce aux images MO que l'adaptation du taux d'oxygène dans l'atmosphère du four lors des phases de montée et descente en température est cruciale pour l'obtention d'un dopage homogène en oxygène. L'étude effectuée grâce à l'imagerie MO a par ailleurs révélé que le perçage d'un réseau de trous permet une amélioration significative de la qualité de la texture et de la densité locale de courant critique.
Les Coated Conductors fournis par Theva$^{\copyright}$ ont également fait l'objet d'études MO. Des défauts spécifiques, en forme d'étoiles et dus à la délamination de la couche tampon de MgO ont pu être observés. Les observations MO sous contrainte axiale in situ ont révélé que le courant critique était limité par l'apparition de bandes de contraction (Lüders Bands) dans le substrat, induisant des fissures dans les couches tampon et supraconductrice. Ces fissures ont été observées pour la première fois en MO au cours de cette thèse. L'imagerie MO a également permis de mettre en évidence la présence de fissures horizontales dues à la compression latérale de la couche MgO.
Enfin des mesures en courant de transport de films minces ont été effectuées en parallèle avec des observations MO. Il apparaît que les défauts créés artificiellement par lithographie n'entraînent pas une différence mesurable sur la densité de courant critique (bien que la densité de courant locale dépasse le Jc), mais plutôt une augmentation de la résistivité de flux flow ou de flux creep. Ce travail a été consacré à la réalisation et l'utilisation d'un dispositif d'imagerie Magnéto-Optique (MO) pour l'étude des matériaux supraconducteurs. La principale originalité de ce dispositif est de permettre des mesures sous courant de transport (30A), sous champ magnétique (jusqu'à 100mT), et/ou sous contrainte axiale (80kg maximum).
Les études MO ont notamment porté sur les matériaux supraconducteurs à haute température critique élaborés ou étudiés au CNRS-CRETA et laboratoire de Cristallographie. En particulier, un dispositif de texturation par défilement sous champ magnétique de rubans multifilamentaires de Bi2212 a été mis au point. Connaître précisément les conditions de texturation pour chaque échantillon permet en effet de mieux interpréter les données issues des caractérisations, et notamment les images MO. Nous avons pu mettre en évidence par des obervations MO que la texturation sous champ magnétique améliore le piégeage et la texture des filaments, notamment ceux situés au centre des rubans. Par ailleurs le courant critique mesuré à 4,2K est augmenté de 30 à 40\% grâce à la texturation sous champ magnétique.
Dans les massifs YBCO, nous avons mis en évidence grâce aux images MO que l'adaptation du taux d'oxygène dans l'atmosphère du four lors des phases de montée et descente en température est cruciale pour l'obtention d'un dopage homogène en oxygène. L'étude effectuée grâce à l'imagerie MO a par ailleurs révélé que le perçage d'un réseau de trous permet une amélioration significative de la qualité de la texture et de la densité locale de courant critique.
Les Coated Conductors fournis par Theva$^{\copyright}$ ont également fait l'objet d'études MO. Des défauts spécifiques, en forme d'étoiles et dus à la délamination de la couche tampon de MgO ont pu être observés. Les observations MO sous contrainte axiale in situ ont révélé que le courant critique était limité par l'apparition de bandes de contraction (Lüders Bands) dans le substrat, induisant des fissures dans les couches tampon et supraconductrice. Ces fissures ont été observées pour la première fois en MO au cours de cette thèse. L'imagerie MO a également permis de mettre en évidence la présence de fissures horizontales dues à la compression latérale de la couche MgO.
Enfin des mesures en courant de transport de films minces ont été effectuées en parallèle avec des observations MO. Il apparaît que les défauts créés artificiellement par lithographie n'entraînent pas une différence mesurable sur la densité de courant critique (bien que la densité de courant locale dépasse le Jc), mais plutôt une augmentation de la résistivité de flux flow ou de flux creep.
Lecrevisse, Thibaud. "Contribution à l'Etude des aimants supraconducteurs utilisant des matériaux supraconducteurs à haute température de transition". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00904070.
Texto completoLecrevisse, Thibault. "Contribution à l'étude des aimants supraconducteurs utilisant des matériaux supraconducteurs à haute température de transition". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00875176.
Texto completoLenoir, Gilles. "Caractérisation et modélisation du comportement mécanique de matériaux supraconducteurs". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLC044/document.
Texto completoSuperconducting cables are widely used in high field magnets and have recently been extended to electricity transport. Cables are composed of a complex assembly of superconducting strands, themselves composed of superconducting filaments twisted in a metallic matrix and surrounded by an outerlayer. The electrical-strain dependence of individual strands is known to be responsible for the degradation of the electrical performance of cables. Thus, it is necessary to understand and predict the mechanical behavior at the strand scale to predict the electrical properties and optimize the manufacturing process of cables to achieve higher fields and better transport capabilities.A multi-scale mechanical characterization of Nb3Sn and MgB2 strands was carried out through tests on complete strands and strands without an outer-layer. A specific device was developed for uniaxial tests on small brittle wire. Nano-indentation tests were also carried out to access to the local properties of each material in the strand.A strategy for the modeling and identification of the mechanical behavior of strands was developed. The model is based on a simplified representation of the structure built from the component volume fractions and the nanoindentation tests. The identification of the parameters is carried out using the experimental database previously developed. The model is intended to be subsequently used to simulate the coupled mechanical and electrical behavior of cables.Discussion about damage phenomenon in strands is carried out through the study of strain localization observed in strands, observations and analyses after interrupted tests, and tensile tests performed in an X-ray tomograph
Buzon, Didier. "Limitation de courant à partir de matériaux supraconducteurs HTc". Grenoble INPG, 2002. http://www.theses.fr/2002INPG0067.
Texto completoElbaa, Mohamed. "Caractérisation et modélisation des matériaux supraconducteurs à haute température critique". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0196.
Texto completoThe aim of this thesis is to optimize the process of magnetization of superconducting pellets at high critical temperature (SHTC) by pulsed field magnetization (PFM) in order to use them in applications in the field of electrical engineering. In the design phase of the inductor necessary to magnetize these SHTC pellets, modeling and simulation are strongly recommended to perform the necessary calculations of the various electrical characteristics of the magnetization system. Therefore, we have developed an analytical model to study the influence of the presence of a superconducting bulk on the value of the inductance of an induction coil in a ferromagnetic circuit. The aim is to solve the Laplace and Poisson equations in different regions of interest through the magnetic vector potential. The analytical resolution was performed (carried out) using a computer code developed under MATLAB where the results obtained were in good agreement with those obtained by numerical simulation under COMSOL. The inhomogeneity of YBaCuO type SHTC pellets in terms of critical current density Jc was also investigated. To do this, we carried out experiments on the magnetization of these bulks by the PFM method. We have shown that the flat surface containing the crystallization germ (seed) of these pellets is characterized by a higher Jc than the other surface. Also, we studied the influence of the position of the seed crystallization in the two-pellet characterization method
Delabie, Christophe. "Elaboration d'un simulateur de dispositifs planaires microondes : Application à la caractérisation de matériaux supraconducteurs". Lille 1, 1994. http://www.theses.fr/1994LIL10146.
Texto completoPuigsegur, Alexandre. "Isolation céramique pour câbles supraconducteurs en Nb3Sn". Montpellier 2, 2005. http://www.theses.fr/2005MON20167.
Texto completoAlhasan, Rada. "Étude et réalisation d'une nouvelle structure d'un moteur synchrone supraconducteur". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0009/document.
Texto completoIn this work, we have achieved and validated a new superconductor motor structure, consisting of a superconducting inductor and of an armature of copper. The original structure of this motor is based on the principle of flux modulation by the use of a bulk superconductor screen. After modeling the machine by finite elements, the construction of the engine has been achieved successfully, a very delicate stage with many difficulties. The results show not only the technical feasibility of the machinery, but also its good operation. The experiments with and without load, and the one under short circuit, allowed to determine the elements of the Ben-Eschenburg model for this machine. As conclusion, the aim of the project was successfully achieved
Ropers, Bruno. "Synthèse et propriétés physiques de matériaux composites désordonnés supraconducteurs YBaCuO-argent". Bordeaux 1, 1992. http://www.theses.fr/1992BOR10523.
Texto completoAlhasan, Rada. "Étude et réalisation d'une nouvelle structure d'un moteur synchrone supraconducteur". Electronic Thesis or Diss., Université de Lorraine, 2015. http://www.theses.fr/2015LORR0009.
Texto completoIn this work, we have achieved and validated a new superconductor motor structure, consisting of a superconducting inductor and of an armature of copper. The original structure of this motor is based on the principle of flux modulation by the use of a bulk superconductor screen. After modeling the machine by finite elements, the construction of the engine has been achieved successfully, a very delicate stage with many difficulties. The results show not only the technical feasibility of the machinery, but also its good operation. The experiments with and without load, and the one under short circuit, allowed to determine the elements of the Ben-Eschenburg model for this machine. As conclusion, the aim of the project was successfully achieved
Kopia, Agnieszka. "Étude expérimentale et modélisation de la réactivité chimique au sein de matériaux multiphasés ferrite - supraconducteurs". Toulon, 2000. http://www.theses.fr/2000TOUL0008.
Texto completoGranular composite systems made of ferrite NiFejO^ and superconducting phase Bi2Sr2Ca2Cu3Ox. (noted as F/S composites) have been elaborated and characterized. These multiphase systems depend on three parameters: the ferrite volume fractions (<£), the temperature (T) and the time (t) of thermal treatment- The chemical degradation of the solid composite was controlled by determining the evolution of each phase using various techniques: X-ray diffraction analyses, scanning electron microscopy including X-ray local analyses, magnetic susceptibility and electrical resistance measurements at low temperature. High temperature electrical impedance spectroscopy analyses has been performed to better understand the chemical evolution of the system during a thermal treatment. Using the X-ray diffraction analyses, a kinetics study led to a modeling of the reaction kinetics in this composite system. Two types of reactions were considered: a S/F inter-grain reaction and a S/S self-degradation reaction. Using scanning electron microscopy and ED AX equipment, the concentration profiles of the elements of each phase S and F have been determined: diffusion coefficients have been defined using a simplified Pick law. High temperature electrical impedance spectroscopy analyses have delivered new kinetics data: two types of evolutions forthe resistance of the composite system are evidenced. New kinetics parameters are proposed through a mode! of evolution describing the degradation of a system. Finally the electrical resistances at low temperature of specific composites have been analyzed as a function of variable applied magnetic fields. Giant magnet oresi stive effects have been observed: they strongly depend on the thermal treatment parameters (temperature and time for a fixed composition)
Maccioni, Pierre. "Influence des matrices résistives sur la stabilité des composites supraconducteurs". Rennes, INSA, 1990. http://www.theses.fr/1990ISAR0001.
Texto completoCourrèges, Stanis. "Les matériaux ferroélectriques et supraconducteurs appliqués à la conception de dispositifs microondes". Limoges, 2007. https://aurore.unilim.fr/theses/nxfile/default/1310462e-e3ee-4477-9c6d-aa828a54b786/blobholder:0/2007LIMO4024.pdf.
Texto completoFirst of all, this manuscript deals with the input multiplexer channel superconductor band pass filters, with high selectivity, high Q and narrow bandwidth, for satellite applications. Tuning methods are developed with respect to the stringent specifications and limit the losses caused by the usual methods. The central frequencies of the superconductor filters are adjusted by taking into account the responsible and controllable physical parameters. An extra method is suggested to obtain a little frequency tuning after this first step and respect rigorously the specifications. Secondly, a 2D/3D static and electromagnetic analysis, based on the method of lines, of microwave planar tunable devices including ferroelectric thin-film is presented. This software can characterize the ferroelectric layers: determination of the permittivity versus the applied electric field
Roche, Cécile. "Étude de nouveaux matériaux thermoélectriques : cas des phases de Chevrel". Vandoeuvre-les-Nancy, INPL, 2000. http://www.theses.fr/2000INPL050N.
Texto completoNguyen, Nhat Tung. "Mise en oeuvre et intégration des matériaux supraconducteurs dans les dispositifs de puissance". Grenoble INPG, 2009. http://www.theses.fr/2009INPG0139.
Texto completoOur study focuses on the promising technology of deposited YBaCuO superconductor tape used as fault current limiter. Our main objective is to find an adapted YBaCuO coated conductor and the relevant parameters to improve its transition homogeneity. First of all, an inventory of superconducting fault current limiters and YBaCuO coated is proposed. Then, electrical measurements, as well as a new experimental setup created for an optical study of the first moments of transition are described. Three different deposited conductors (EHTS, AMSC and Super Power) have been tested in current limitation. The architexture of the AMSC conductor is very promising. Finally, modeling studies based on simulation and analytical approach, as well as simulation of SFCL use in the real network are presented. The results support the usage of deposited conductors to limit the fault current
Sow, Amadou Oumar. "Etude sous pression des nanotubes de carbone et des matériaux supraconducteurs à base de fer". Grenoble, 2010. http://www.theses.fr/2010GRENY004.
Texto completoIn this thesis, we have studied pressure effects on the electrical and structural properties of I- double wall carbon nanotubes (DWCNTs), ans II- iron-based superconductors. I- DWNCTs networkks exhibit, at low temperatures, a power law behavior of the conductance G, a signature of Luttinger liquid (LL). At high temperatures, G is linear, signalizing a crossover to a Fermi liquid (FL) state. The apparition of the linear behavior is shifted over room temperature by the application of a pressure. That is explained by the freeze of twist modes, responsible for the electron scattering and the high temperature linear behavior. II- We have studied newiron-based superconductors. On LaFeAsO1-xFx, our study was the first to investigate correllations between structural and superconducting properties under pressure. The analysis pointed out similarities with cuprates (compressibility) and conventional ssuperconductors. We showed in SrFeAsF and CaFeAsF the coexistence state between a spin density wave (SDW) and superconductivity. The appearance at P≥2GPa of the superconducting state is attributed to hole doping, following a interlayers charge transfer due to the pressure. Thus, this doping is less destructive for the SDW than the electron one. We then studied Sr4V2O6FeAs2. Its large perovskite layer has an important task, on one hand by maintaining the initial perfect values of the tetragonal angles until ~10GPa, on the other hand by rejecting any structural "tetragonal to orthorhombic" transition-type, preventing the SDW development and then allowing the compound to exhibit superconductivity at zero-pressure. We showed that the critical temperature TC is the highest when tetragonal angles have their perfect values. Our last study was focused on Fe Se. After analysing the structural and transport data, we discovered a new high pressure orthorhombic phase with TC~35K, the highest measured to date in this system
Saliou, Françoise. "Matériaux supraconducteurs en technologie couches épaisses pour applications aux circuits micro-ondes : analyse des comportements". Brest, 2003. http://www.theses.fr/2003BRES2011.
Texto completoThe aim of this work is the elaboration of YBCO superconducting thick film on substrates mainly YSZ. The technical deposit choice is screen-printing for its simplicty and because it is already overcome in industry. YBCO thick films were prepared by screen printing an ink, obtained by mixing YBCO powder in an organic binder, on the Y2O3-stabilized zirconia polycristalline substrates. The experimental study is based on the optimisation of the deposit technique,ink prepration, thermal treatments. We presented the results of a detailed invetsigation of the effects of two temperatures profiles on the properties (classical sintering and Melt Processed Technique). It was observed that these prpoerties are governed by the microstructure of YBCO ant the orientation factor (texturation). The peritectic mix of YBa2Cu3O7-8+BaCuO2+CuO gives interseting results for all tested YBCO compositions
Delerue, Johann. "Matrices de bolomètres supraconducteurs à haute température critique pour l'infrarouge : matériaux, technologies et caractérisations optiques". Paris 6, 2002. http://www.theses.fr/2002PA066098.
Texto completoLangerome, Benjamin. "Spectroscopie infrarouge de matériaux supraconducteurs dans des conditions extrêmes de haute pression ou basse température". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS343.
Texto completoSuperconductivity is highly studied in condensed matter physics for its potential applications. Indeed, this phenomenon is macroscopically characterized by remarkable properties, but generally occurs in materials at cryogenic temperature thus limitating their exploitation. Recently, renewed interest has appeared for conventional superconducting materials with the discovery of H₃S, whose transition temperature is at 200 K. For this compound, the coupling between electrons and phonons is at the origin of the electronic pairing, a necessary condition for superconductivity. The associated energy for this coupling belongs to the far infrared range, even THz, making infrared spectroscopy an ideal tool to study the mechanism. This thesis presents the studies of two superconducting materials in extreme experimental conditions of pressure and temperature, allowed by the high brilliance of synchrotron radiation. For the superconducting phase H₃S under pressures superior to 150 GPa, the environment of diamond anvil cell excludes most of the techniques to determine the nature of the mechanism but the optical studies remain adapted. The spectroscopic results presented here demonstrate a strong coupling between electrons and phonons, which explains the origin of such a high transition temperature. Complementary measurements aiming at characterizing NaCl under pressure is also described because this material is often used as a pressure transmitting medium in high pressure cells, in particular for the superconducting H₃S. The second study reports spectroscopic results in the THz on nanometric layers of Nb, whose superconducting transition temperatures are 4,5 K and 6,8 K. These measurements confirm that the conventional nature of the mechanism subsists within these quasi-bidimensional thin films. For this work, an instrumental ensemble allowing the spectroscopic measurements of materials down to 200 mK has been entirely developed based on an adiabatic demagnetization cryostat
Nouailhetas, Quentin. "Synthesis, Characterization and Comparison of New Bulk Superconductors". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0269.
Texto completoSuperconducting materials have already been used in my applications such as MRI, particle accelerators TOKAMAKS or superconducting cables. With this, new projects are under development, such as superconducting electrical motors or magnetic shielding which could involve superconducting bulks as permanent magnets or magnetic shields. In this way, this Ph.D. is focused on the synthesis, characterization and comparison of the different superconducting bulks such as Iron-based or cuprates. Classic furnace sintering and Spark Plasma Sintering processes have been used on Iron-Selenide superconductors to optimize their superconducting properties and phase purity. Characterizations of the superconducting and material properties of the synthesized superconductors have been carried out as well as on other materials like REBaCuO (Rare Earth, Barium, Copper oxide) superconductors. Different characterization techniques are presented like magnetometry with a MPMS-SQUID (Magnetic Property Measurement System, Superconducting Quantum Interference Device), trapped field cartography, X-ray diffraction and Scanning electron or optical microscopy. I also had the occasion to characterize the superconducting properties of Infiltration Growth YBaCuO bulks using cantilever magnetometry with magnetic fields up to 33 T. With this, a comparison of the measured properties with other superconducting materials is done to determine the readiness of those materials concerning electrical engineering and their competitiveness compared to other well-developed materials such as Melt Growth YBaCUO bulks
Belguerras, Lamia. "Études théoriques et expérimentales d'accouplements magnétiques supraconducteurs". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0040/document.
Texto completoMagnetic couplings (or couplers) are used to transmit torque from a prime mover to its load without mechanical contact. This contactless transmission allows to reduce noise and vibration, to increase reliability and ensure hermetic isolation in severe environments. When the prime mover is a superconducting motor, a coupler which uses superconducting materials has more torque transmission capabilities and enables to transmit torque between a cryogenic media (cryostat) and the ambient temperature. This work focuses on the study of magnetic couplers using high temperature superconductors (HTS) and permanent magnets. Radial and axial field magnetic couplings, for which we developed analytical and numerical design tools, are proposed. A 2D analytical model for calculating the magnetic field distribution in a flux focusing HTS coupling is developed and validated by finite element computations. This model is then embedded in a genetic algorithms optimization procedure. The aim is to find the dimensions of the coupling that maximize torque and minimize the overall length of the HTS wires. A prototype axial field HTS coupler has been also designed, constructed and tested. Several tests have been conducted to characterize the HTS coils. Results of magnetic field, critical current and torque measurements are presented
El, Khokh Norddine. "Synthèse, réactivité et caractérisation de précurseurs moléculaires de matériaux de haute pureté : alcoxydes des terres rares (lanthane, cérium) et du cuivre (II)". Nice, 1990. http://www.theses.fr/1990NICE4392.
Texto completoCarcel, Carole. "Synthèse d'oligoTTF à lien saturé, fonctionnalisé et conjugué : Caractérisation électrochimique et formation de matériaux". Montpellier 2, 2001. http://www.theses.fr/2001MON20163.
Texto completoBelguerras, Lamia. "Études théoriques et expérimentales d'accouplements magnétiques supraconducteurs". Electronic Thesis or Diss., Université de Lorraine, 2014. http://www.theses.fr/2014LORR0040.
Texto completoMagnetic couplings (or couplers) are used to transmit torque from a prime mover to its load without mechanical contact. This contactless transmission allows to reduce noise and vibration, to increase reliability and ensure hermetic isolation in severe environments. When the prime mover is a superconducting motor, a coupler which uses superconducting materials has more torque transmission capabilities and enables to transmit torque between a cryogenic media (cryostat) and the ambient temperature. This work focuses on the study of magnetic couplers using high temperature superconductors (HTS) and permanent magnets. Radial and axial field magnetic couplings, for which we developed analytical and numerical design tools, are proposed. A 2D analytical model for calculating the magnetic field distribution in a flux focusing HTS coupling is developed and validated by finite element computations. This model is then embedded in a genetic algorithms optimization procedure. The aim is to find the dimensions of the coupling that maximize torque and minimize the overall length of the HTS wires. A prototype axial field HTS coupler has been also designed, constructed and tested. Several tests have been conducted to characterize the HTS coils. Results of magnetic field, critical current and torque measurements are presented
Park, Jung-Chul. "Oxydation électrochimique d'oxydes en milieu alcalin : application aux matériaux supraconducteurs La₂CuO₄ et YBa₂Cu₃O₇-δ". Bordeaux 1, 1990. http://www.theses.fr/1990BOR10630.
Texto completoSchoenstein, Frédéric. "Elaboration et caractérisation de composites à base de couches minces ferromagnétiques pour les applications hyperfréquences". Orléans, 2003. http://www.theses.fr/2003ORLE2021.
Texto completoCocuaud, Nadine. "Synthèse et étude de céramiques supraconductrices à haute température critique : caractérisation chimique et approche moléculaire". Toulouse 3, 1990. http://www.theses.fr/1990TOU30056.
Texto completoAntunes, Laurent. "Caractérisation de composites supraconducteurs aléatoires - phases au bismuth/argent : contribution à l'étude des jonctions faibles dans ces matériaux". Phd thesis, Université Sciences et Technologies - Bordeaux I, 1998. http://tel.archives-ouvertes.fr/tel-00163366.
Texto completoJondo, Koffi. "Equilibres entre phases dans le système Tl-Ba-Ca-Cu-O : application à la préparation de matériaux supraconducteurs". Lyon 1, 1994. http://www.theses.fr/1994LYO10070.
Texto completoGourieux, Thierry. "Structures électroniques des céramiques supraconductrices YBa2Cu3O7-[delta] et des interfaces terres rares-palladium. Etudes par photoémission, absorption et spectroscopie Auger". Nancy 1, 1990. http://docnum.univ-lorraine.fr/public/SCD_T_1990_0009_GOURIEUX.pdf.
Texto completoYan, Yong. "Non-stoechiométrie et défauts structuraux dans les supraconducteurs de type "123" à haute température critique". Lyon 1, 1992. http://www.theses.fr/1992LYO10303.
Texto completoBaudron, Stéphane. "Liaisons hydrogène à l'interface organique-inorganique comme outils de construction de matériaux moléculaires cristallins : 0". Angers, 2002. http://www.theses.fr/2002ANGE0030.
Texto completoLeboulanger, Christine. "Analyse technométrique des relations ago-antagonistes entre le Japon et les Etats-Unis : cas de l'industrie des matériaux supraconducteurs". Caen, 1993. http://www.theses.fr/1993CAEN0549.
Texto completoThe "technometric" study focusing on supraconductor materials significantly shows the more and more international nature of the phenomenon of patent. Great industrial nations such as the United-States and Japan get more and more inclined to project their techniques and new products overseas in order to create broader markets. The globalisation of technology - thus appearing with superconductivity - espresses multiple and complex realities which seemingly have to be managed. Apparently the Japanese industrial strategy is to cover the whole industrial field while focusing the means of action on some essential poles. The american indutrial strategy aims keeping a worldwide leadership, which she thinks is on the way to escape her. Japan appears like a country where technology originates while a very creative country such the United-States loses ground. This expresses a tendency to a levelling between both countries. This research shows that ago-antagonism approach prevails in the supraconductor materials industry. In fact the actors are seeking for a balance between competition and cooperation to cope with the specificities of the field concerned
Badèche, Belkacem-Toufik. "Etude des propriétés de transport de supraconducteurs de la famille BiSrCaCuO : fils et céramiques inhomogènes et cristaux à température critique supérieure à la valeur standard et présentant des anomalies de résistivité entre 200 et 300 K". Aix-Marseille 3, 1994. http://www.theses.fr/1994AIX30049.
Texto completoAmrani, Idrissi Hassan Radi. "Relations entre les variations de stoechiométrie en oxygène, la présence d'oxyde de cuivre libre et les transitions supraconductrices dans les céramiques Nd-Ce-Cu-o". Perpignan, 1996. http://www.theses.fr/1996PERP0234.
Texto completoZhang, Chaowu. "Étude de l'optimisation et de la cinétique de formation de conducteurs supraconducteurs Nb3Sn obtenus par la méthode de l'étain interne". Grenoble 1, 2007. http://www.theses.fr/2007GRE10112.
Texto completoSuperconductors Nb3Sn wires are one of the most applicable cryogenic superconducting materials and the best choice for high-field magnets exceeding 10T. One of the most significant utilization is the ITER project which is regarded as the hope of future energy source. The high-Cu composite designs with smaller number of sub-element and non-reactive diffusion barrier, and the RRP (Restacked Rod Process) internal-Sn technology are usually applied for the wire manufacturing. Such designed and processed wires were supplied by MSA/Alstom and WST/NIN in this research. The systematic investigation on internal-Sn superconducting wires includes the optimization of HT conditions, phase formation and its relation with superconductivity, microstructure analysis, and the phase formation kinetics. Because of the anfractuosity of the configuration design and metallurgical processing, the MF wires are not sufficient for studying a sole factor effect on superconductivity. Therefore, four sets of ME wires with different Sn ratios and different third-element addition were designed and fabricated in order to explore the relationship between phase formation and superconducting performances, particularly the A15 layer growth kinetics. Different characterization technics have been used (magnetization measurements, neutron diffraction and SEM/TEM/EDX analysis)The A15 layer thicknesses of various ME samples were measured and carried out linear and non-linear fits by means of two model equations. The results have clearly demonstrated that the phase formation kinetics of Nb3Sn solid-state reaction is in accordance with an n power relation and the n value is increased with the increase of HT temperature and the Sn ratio in the wire composite
Giovannelli, Fabien. "Synthèse, texturation et caractérisation de céramiques supraconductrices (TR)Ba2Cu3Oy (TR = Nd, Sm, Eu, Gd)". Caen, 2002. http://www.theses.fr/2002CAEN2027.
Texto completoDelorme, Fabian. "Influence de la microstructure et de la texture sur les propriétés supraconductrices de céramiques (RE,Y)Ba2Cu3O7-delta texturées : Synthèse et caractérisation". Caen, 2002. http://www.theses.fr/2002CAEN2012.
Texto completoLebbou, Kheirreddine. "Matériaux supraconducteurs à température critique élevée Tl1-x(Pb-Bi)x(Sr1-yBay)2Ca2Cu3Oz et Tl1-xPbx(Sr1-yBay)2Ca2Cu3Oz : élaboration et caractérisation de phases de pureté crontôlée". Lyon 1, 1996. http://www.theses.fr/1996LYO10061.
Texto completoFrachet, Mehdi. "Etudes ultrasonores de l'état normal des cuprates supraconducteurs à haute température critique". Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAY063.
Texto completoIn cuprates, copper oxides, an unconventionnal superconductivity appears by chemical doping between a Mott insulator and a correlated Fermi liquid. Beyond superconductivity, the phase diagram includes multiple broken symmetry phases, including spin and charge density waves. All these phases interact together and with superconductivity, in a complex way. A deeper knowledge of this phase diagram is without doubt a necessary step toward the resolution of the high-Tc enigma. In this aim, we propose in this experimental thesis to measure velocity and attenuation of sound in the low temperature normal state of cuprates, using high magnetic fields.The first (main) part of this thesis focus on the magnetism of La2-xSrxCuO4 (LSCO). In this compound, an antiferromagnetic glass competes with superconductivity. By applying high magnetic fields of the order of 90 T we show that, when superconductivity is weakened enough, the antiferromagnetic glass disappears together with the pseudogap. The persistence of this order up to p*, and the associated ordered magnetic moment, could explain recent observations at p* without necessarily implying that the pseudogap is an ordered phase. Among them are the fall of the Hall number and quantum criticality signatures observed in different cuprates.The shorter second part deals with a related topic: the two distinct charge density waves (CDW, 2D and 3D) of YBa2Cu3O6+_ (Y-123). By performing sound velocity measurements in high magnetic fields we constrain the doping range of the 3D CDW and show that the latter is unlikely at the origin of the Fermi surface reconstruction. Sound velocity measurements also allow the determination of dTc/dεi, the Tc's susceptibility to a given elastic deformation. The complex and anisotropic doping dependence of dTc/dεi cannot be easily reconcile alone with a scenario of competition between CDW(s) and superconductivity
Coiffard, Grégoire. "Détecteurs à inductance cinétique pour l'astronomie millimétrique : étude des matériaux et des procédés de fabrication". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI077/document.
Texto completoFor 10 years, kinetic inductance detectors are developed for millimeter radioastronomy and they now reach photon-noise sensitivities. A kinetic inductance detector (KID) is a resonator, equivalent to an RLC circuit whose resonant frequency is f_0, structured in a superconducting metal. Incoming photons, with energy greater than the superconducting gap, are absorbed in the metal and change its surface impedance leading to a shift Df_0 of the resonant frequency of the resonator. KID arrays are made with hundred of resonators with different resonant frequencies. We study the fabrication of aluminum-KID arrays of 1932 pixels on 4 inch substrate with homogeneous superconducting properties over this area. Various ways to electrically and optically optimize these arrays are proposed. These optimization allow us to choose arrays that have the required performances. These arrays are now installed in the NIKA-2 (New Instrument of KID Array) instrument in IRAM's 30 m telescope located on the Pico Veleta in Spain. We also analyze reactive sputtered titanium nitride thin films and we present a rapid and non-destructive measurement to characterize the nitrogen content in these films. We describe upgrades of the deposition chamber that allow more uniform thin films to be deposited. TiN KID arrays are fabricated and characterized from these optimized thin films. The performances of these TiN prototype arrays are surprisingly good and encourage future work
Faqir, Hakim. "Synthèse, croissance cristalline et caractérisations de quelques phases, supraconductrices ou non, dans le système (Bi,Pb)-Sr-Ca-Cu-O". Aix-Marseille 1, 1995. http://www.theses.fr/1995AIX11042.
Texto completoZhang, Chaowu. "Etude de l'optimisation et de la cinétique de formation de conducteurs supraconducteurs Nb3Sn obtenus par la méthode de l'étain interne". Phd thesis, Université Joseph Fourier (Grenoble), 2007. http://tel.archives-ouvertes.fr/tel-00178091.
Texto completoL'épaisseur de la couche de la phase A15 mesurée dans différents monofilaments a permis de déterminer la loi de cinétique de formation selon deux modèles. Les résultats ont clairement montré que le modèle de diffusion en phase solide est en accord avec une loi de puissance n et que la valeur de n augmente avec la température de traitement et le taux d'étain dans le fil composite.
Bujnowski, Bogusz. "Propriétés d'équilibre et de transport électronique dans des jonctions hybrides entre supraconducteurs et matériaux ferromagnétiques et/ou à fort couplage spin-orbite". Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0242.
Texto completoWe investigate the interplay of the pairing state in conventional superconductors (S) and spin-active fields. In conventional S electrons with opposite momenta and spins bind into so-called Cooper pairs. The pair correlations penetrate normal conducting materials (N) on the length scale of the superconducting coherence length, what is known as the proximity effect. The proximity effect gives rise to interesting phase coherent phenomena that are strongly modified in the presence of spin active fields. For example it is strongly suppressed in a ferromagnet (F), which prefers a parallel spins of the electrons and counters the conventional pairing mechanism. A prominent manifestation of the proximity effect is the Josephson effect, where the phase difference between the macroscopic wavefunctions of two spatially separated S leads to a non dissipative current at zero voltage.We consider the Josephson effect in a junctions involving spin splitted S, where the orientation of the exchange field can be controlled individually in both S. In such junctions, when the fields are oriented antiparallely, it is possible to increase the critical current by increasing the magnitude of the exchange fields. This is a counter intuitive result considering the pair breaking nature of the fields. The formation of the Andreev bound states (ABS) has not been investigated so far. We analyze the spectral properties of this junction and show that for collinear orientations of the fields, any deviation from the case of equal fields leads to finite intervals of phases without ABS. In general the spectral composition of the current is found to be a superposition of the contributions from the ABS and the continuous spectrum and strongly depends on the transmissivity of the junction.The suppression of the proximity effect in magnetic heterostructures can be avoided by generating triplet components of the pair correlations with spin projections perpendicular to the field, so-called long range triplet correlations (LRTC). LRTCs can be generated due to the presence of spin-orbit coupling (SOC) and a homogeneous exchange field, what has not been confirmed experimentally yet. We propose favorable junction setups to observe the LRTCs and calculate the Josephson current considering two common types of SOC, that result in spin precession and anisotropic spin relaxation effects. The contributions to the current from the effects depend on the orientation of the exchange field and their competition leads to current reversal scenarios which represent a signature of the LRTCs.We then turn to another equilibrium phenomenon, namely equilibrium spin currents (ESC). We show that in a nanowire with SOC, breaking the time-reversal symmetry by a Zeeman field leads to a bulk equilibrium spin current which manifests itself in a sizable edge spin polarization, transverse to the Zeeman field. This property occurs in both, the normal and superconducting state, independently of the degree of disorder. The transverse edge spin polarization is strongly enhanced in the superconducting state when the Zeeman energy is of the order of the induced superconducting gap. This leads to a unknown transverse magnetic susceptibility that can be much larger than the known longitudinal one.At the end of the thesis, we investigate electronic transport in heterostructures of the recently discovered Weyl semimetals (WSM). This material class exhibits a pseudo-relativistic dispersion around so-called Weyl points in the Brillouin zone, that are characterized by their chirality in the low-energy limit. We discovered a interesting chiral filtering effect when interfacing two distinct WSMs, if the Weyl nodes on each side of the interface are separated in energy and momentum space. We calculate the differential conductance across the interface and identify the regimes where it is possible to achieve transport of one, none, or both chiralities
Millet, Patrice. "Supraconducteurs à haute température critique (Familles 1 2 3 et 2 2 1 2) : influence de la substitution de terres rares : synthèses, structures (R.X), microstructures (M.E.) et propriétés physiques". Toulouse 3, 1990. http://www.theses.fr/1990TOU30012.
Texto completoSeaux, Jean-François. "Conception, optimisation et test de dispositifs intégrant des matériaux en couche mince supraconducteurs ou ferroélectriques pour des applications de filtrage dans le domaine spatial". Limoges, 2005. http://aurore.unilim.fr/theses/nxfile/default/41920dfd-a8ee-4cd3-8ed9-7dcfa9d61606/blobholder:0/2005LIMO0048.pdf.
Texto completoThe research work presented in this memory relates to the realization of innovating microwave filtering devices from thin layer superconductors or ferroelectrics for space applications. The high-temperature superconductor planar technology makes it possible to obtain at the same time compact circuits and excellent electric performances. C-band eight-pole self-equalized quasi-elliptic filters for an input multiplexer (IMUX) have been designed. Moreover, a Ka-band preselect filter has been studied. We have also searched to tune the superconductive filters after their manufacture using ferroelectric materials. An electromagnetic method has been developed to characterize BST deposits on adapted substrates. The goal was to realize reconfigurable or tunable devices
Cazy, Evelyne. "Intéractions d'YBaCuO avec la vapeur d'eau, le gaz carbonique et l'oxygène : application à l'optimisation des céramiques à petits grains". Limoges, 1996. http://www.theses.fr/1996LIMO0006.
Texto completoEssoumhi, Abdellatif. "Céramiques conductrices ioniques de type NaSICON : élaboration par chimie douce et caractérisations physico-chimiques". Toulon, 2005. http://www.theses.fr/2005TOUL0018.
Texto completoThis work deals with the synthesis and characterizations of NaSICON-type ionic conducting ceramics of general formula Na1^xM2->Six. 4,P:. X__. 0:: \vith 1. 8 < x < 2. 2 and 0 < y < x/4. New compositions have been synthesized Tvv:;h complete substitution of zirconium by hathium. Syntheses were made using the sci-gei method; the synthesized precursors have been characterized by coupled TDA-TGA technique. The oxides obtained after precursors pyrolysis were identified using XRD technique. A study of sintering was carried out using dilatometry in order to select the most adapted thermal cycle to these ceramics. After sintering the oxides, the obtained ceramics have been characterized from their electric conductivity point of view. The complex impedance spectroscopy enabled us to differentiate the conductivity related to the grains from the conductivity related to grain boundaries and to reveal the influence of porosity towards total conductivity. The results highlight that these new ceramics conductivity is remarkable, compare to the values of total conductivity at 300K (about 10~4 S. Cm"!) published in the literature for other NaSICON-type materials