Teses / dissertações sobre o tema "Chimie des défauts"
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Ehrlacher, Virginie. "Quelques modèles mathématiques en chimie quantique et propagation d'incertitudes". Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1073/document.
Texto completo da fonteThe contributions of this thesis work are two fold. The first part deals with the study of local defects in crystalline materials. Chapter 1 gives a brief overview of the main models used in quantum chemistry for electronic structure calculations. In Chapter 2, an exact variational model for the description of local defects in a periodic crystal in the framework of the Thomas-Fermi-von Weisz"acker theory is presented. It is justified by means of thermodynamic limit arguments. In particular, it is proved that the defects modeled within this theory are necessarily neutrally charged. Chapters 3 and 4 are concerned with the so-called spectral pollution phenomenon. Indeed, when an operator is discretized, spurious eigenvalues which do not belong to the spectrum of the initial operator may appear. In Chapter 3, we prove that standard Galerkin methods with finite elements discretization for the approximation of perturbed periodic Schrödinger operators are prone to spectral pollution. Besides, the eigenvectors associated with spurious eigenvalues can be characterized as surface states. It is possible to circumvent this problem by using augmented finite element spaces, constructed with the Wannier functions of the periodic unperturbed Schr"odinger operator. We also prove that the supercell method, which consists in imposing periodic boundary conditions on a large simulation domain containing the defect, does not produce spectral pollution. In Chapter 4, we give a priori error estimates for the supercell method. It is proved in particular that the rate of convergence of the method scales exponentiall with respect to the size of the supercell. The second part of this thesis is devoted to the study of greedy algorithms for the resolution of high-dimensional uncertainty quantification problems. Chapter 5 presents the most classical numerical methods used in the field of uncertainty quantification and an introduction to greedy algorithms. In Chapter 6, we prove that these algorithms can be applied to the minimization of strongly convex nonlinear energy functionals and that their convergence rate is exponential in the finite-dimensional case. We illustrate these results on obstacle problems with uncertainty via penalized formulations
Gasca, Petrica. "Zirconium – modélisation ab initio de la diffusion des défauts ponctuels". Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10111/document.
Texto completo da fonteZirconium is the main element of the cladding found in pressurized water reactors, under an alloy form. Under irradiation, the cladding elongate significantly, phenomena attributed to the vacancy dislocation loops growth in the basal planes of the hexagonal compact structure. The understanding of the atomic scale mechanisms originating this process motivated this work. Using the ab initio atomic modeling technique we studied the structure and mobility of point defects in Zirconium. This led us to find four interstitial point defects with formation energies in an interval of 0.11 eV. The migration paths study allowed the discovery of activation energies, used as entry parameters for a kinetic Monte Carlo code. This code was developed for calculating the diffusion coefficient of the interstitial point defect. Our results suggest a migration parallel to the basal plane twice as fast as one parallel to the c direction, with an activation energy of 0.08 eV, independent of the direction. The vacancy diffusion coefficient, estimated with a two-jump model, is also anisotropic, with a faster process in the basal planes than perpendicular to them. Hydrogen influence on the vacancy dislocation loops nucleation was also studied, due to recent experimental observations of cladding growth acceleration in the presence of this element
Colder, Alban. "Contribution à la compréhension des effets d'irradiation dans les semi-conducteurs germanium, silicium et arséniure de gallium". Caen, 2001. http://www.theses.fr/2001CAEN2015.
Texto completo da fonteAmzallag, Emilie. "Approche quantique des défauts ponctuels dans les systèmes cristallins : identification et influence sur les propriétés d’optique non linéaire". Pau, 2007. http://www.theses.fr/2007PAUU3030.
Texto completo da fonteCurrent researches on real material require a thorough analysis of their properties on an atomic scale because of the presence of defects (point defect, linear, of surface or volume). For the identification and the characterization of these defects, the difficulty of modeling lies in the system size and the rupture of periodicity due to the presence of the defect. During this work, two main themes were approached starting from DFT monodéterminantal approaches. The first one deals with the modelling of different point defects in titanium disulphide (TiS2) to help the interpretation of scanning tunneling microscopy images (STM). The second one is relating to the theoretical study of optical properties of crystalline systems with defects in sesponse to an external electric field. In TiS2 case, identification of various surface defects of this compound is based on the Tersoff and Hamman theory. The defects which we considered, according to experimental studies, are associated with the migration of a titanium atom towards a vacant site of the compact hexagonal structure of sulphur atoms with in parallel the formation of a vacancy. In complement of this work, we tried to simulate the local field created by the tip on the surface. Concerning the optical properties, it is a question of assessing the capacity of our methods to reproduce properly the linear optical response of periodic systems. We made a study on the energy loss function which enabled us to confront the theoretical results with experimental spectra, while trying to identify the detected electronic transitions. Finally, we studied the influence of substitutional defects on the nonlinear optic properties of silica starting from the -cristobalite which is considered as a model system
Deramond, Eric. "Valences mixtes dans les bronzes de vanadium MxV205(M=Li, Al, Cu, Ag) et non stoechiométrie par insertion et défauts étendus". Toulouse 3, 1993. http://www.theses.fr/1993TOU30211.
Texto completo da fonteLorrain, Yves. "Etude du défaut de sélectivité des membranes échangeuses d'anions au contact de solutions acides. Contribution à la réduction de ce défaut de sélectivité par modification de surface". Montpellier 2, 1995. http://www.theses.fr/1995MON20256.
Texto completo da fonteVentura, Aude. "Polymères sous rayonnements ionisants : étude des transferts d'énergie vers les défauts d'irradiation". Phd thesis, Université de Caen, 2013. http://tel.archives-ouvertes.fr/tel-00950232.
Texto completo da fonteEhrlacher, Virginie, e Virginie Ehrlacher. "Quelques modèles mathématiques en chimie quantique et propagation d'incertitudes". Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00719466.
Texto completo da fonteBelhabib, Tayeb. "Comportement thermique des défauts lacunaires induits par l'hélium et les gaz de fission dans le dioxyde d'uranium". Phd thesis, Université d'Orléans, 2012. http://tel.archives-ouvertes.fr/tel-00831705.
Texto completo da fonteMeslin, Estelle. "Mécanismes de fragilisation sous irradiation aux neutrons d'alliages modèles ferritiques et d'un acier de cuve : amas de défauts". Rouen, 2007. http://www.theses.fr/2007ROUES077.
Texto completo da fonteMtimet, Habib. "Analyse fréquentielle d'image pour une résolution subpixel : Etude d'un système nanolidar appliqué à la localisation des défauts dans les composants III-V". Montpellier 2, 1994. http://www.theses.fr/1994MON20018.
Texto completo da fonteTchandjou, Nkeuna. "Etude des surfaces physiques des semiconducteurs III-V pour l'élaboration de circuits IC ou OEIC". Montpellier 2, 1991. http://www.theses.fr/1991MON20216.
Texto completo da fontePizzi, Elisabetta. "Influence de la pression partielle d'oxygene sur les concentrations en defauts et sur la diffusion de l'oxygene dans l'UO2+x". Phd thesis, Ecole Centrale Paris, 2013. http://tel.archives-ouvertes.fr/tel-00969106.
Texto completo da fonteLiang, Liang. "Simulation ab initio des défauts étendus du Ti & en présence d'interstitiels H et O". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX009/document.
Texto completo da fonteABSTRACT: The aim of this thesis is to study the influence of hydrogen or oxygen solutes on extended defects in alpha titanium by ab initio calculation. Results are divided into three parts. In a first part the octahedral interstitial site of alpha-Ti is found energetically more favorable for a H or an O atom. The presence of H increases the volume while O has the opposite effect. The presence of H slightly decreases the elastic constants of alpha-Ti while O has an opposite effect. In a second part two new SFs are found: 0.57·(c+a) on π2 and 0.215·[1-102] on π1 plane. The second one is related to the low formation energy of the {10-11} twin boundary. A c+a screw dislocation 3-part dissociation mechanism is proposed. However the c+a screw core tends to spread differently according to the initial core position and a complete 3-part dissociation is not found, which may mean that such a dissociation is not easily obtainable from an initially perfect dislocation core. As segregation to SF means a decrease of the SF energy, the presence of O may make the SF formation energetically more difficult, contrary to H case. H strongly segregates to the a screw dislocation core region with segregation energies varing from 0.06 to 0.3 eV while O hardly segregates to it. Both H and O in core sites change the meta-stable gliding prismatic dissociation to π1 plane or a prism-π1 plane mixed configuration. According to our measurements of Peierls energy barriers with H or O in different sites and concentrations, H makes the gliding more difficult, thus increasing the CRSS in prismatic plane, in agreement with experimental measurements. The effect of H is not big enough to induce a cross-slip of the gliding a-screw dislocation to the π1 plane and that screw will prefer to keep on gliding in its same prismatic plane. The Peierls energy barrier is extremely increased when an O is present in the core position, much higher than the barrier for π1 plane glide or a glide in the nearest prismatic plane. A cross-slip could happen in this case. In the last part, three different deformations are applied to TBs. Their structural stabilities depend not only on their intrinsic characters at the atomistic level but also on the deformation mode applied. {10-12}, {11-22} TB structures fail for deformations as low as 1% or 2% along the c-axis. The {11-21} and the {10-11} TBs are much more resistant. The presence of segregated H and O enhances the {10-12} and {11-22} TB limited stability. A twinning disconnection dipole model is proposed which allows the simulation of a TD in a size limited supercell. Segregation energy calculations with the {10-12} TB and its TD validate the model at the TB level and show that H and O should distribute more or less homogeneously to the TD core and the TB, with only a slight preference to the TD core although not at the interstitial sites of the atomic layer related to the disconnection step itself
Colin-Gouillou, Marie. "Etude théorique de l'échange isotopique H/D et 16-O/18-O sur la surface (001) de MgO". Poitiers, 1999. http://www.theses.fr/1999POIT2294.
Texto completo da fonteGupta, Florence. "Etude du comportement du produit de fission césium dans le dioxyde d’uranium par méthode ab initio". Paris 11, 2008. http://www.theses.fr/2008PA112129.
Texto completo da fonteThe knowledge of the behaviour of fission products in the nuclear fuel is very important for safety considerations and for understanding the evolution of the fuel properties under irradiation. In this work, we focussed mainly on the behaviour of caesium in UO2 through ab initio studies of its solubility at point defects in the matrix, its diffusion and its contribution to the formation of solid phases in the fuel. The role of electronic correlation effects of the f electrons of uranium on these properties and on the description of the defect free crystal, is assessed. The formation energies of the main point defects are calculated and their concentration as a function of fuel stoichiometry and temperature is estimated. The migration barriers and migration paths for the self-diffusion of oxygen and uranium vacancies and oxygen interstitials in UO2 are discussed. The solubility of Cs is found to be very low in UO2 in agreement with experimental findings. The most favourable trapping sites are determined as a function of oxygen concentration in the fuel. Our results show that in the hyper-stoichiometric regime, the diffusion of Cs from its most favourable trapping site is limited by the uranium vacancy diffusion mechanism. We also considered the formation of the main solid phases of caesium resulting from its oxidation (Cs2O, Cs2O2, CsO2) and from its interaction with the fuel (Cs2UO4), with molybdenum (Cs2MoO4) and with the zirconium of the clad (Cs2ZrO3), since the formation of such phases, their solubility and their interdependence will affect the release of caesium
Toorabally, Milad. "Development of negative TiO2-based electrodes by soft chemistry for aqueous proton ions batteries". Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS496.
Texto completo da fonteGreen batteries that are safe, made of readily available and ethically sourced resources, cost-effective and easy to manufacture are needed. Lithium-ion technology, which uses Li-based materials and toxic flammable solvents, does not currently meet all of these criteria. With this in mind, we propose a complementary solution to Li-ion batteries in the form of an aqueous proton-ion battery. The primary challenges posed by aqueous batteries stem from their low energy density, which is the result of the restricted electrochemical stability window of water. This limitation narrows the field of candidates capable of intercalating protons without triggering parasitic reactions such as the hydrogen evolution reaction (HER). TiO2 materials present an intriguing option for use as a negative electrode for proton insertion. The chemical structure synthesized in solvothermal condition has been modified to achieve three distinct compounds: a layered, amorphous lepidocrocite type titanate sample further optimized with zinc ions chemically incorporated into its interlayer, a cationic defective anatase, and a stoichiometric anatase. The electrochemical analysis of the zinc-optimized layered titanate and defective anatase samples, and their integration as negative electrodes in full-cell conditions, demonstrates promising characteristics with notably, an extended potential window and heightened reversible proton capacity. These results were correlated to the materials characterization and the effect on proton transport
Robert, Donatien. "Etude multi-échelle des mécanismes de (dé)lithiation et de dégradation d'électrodes à base de LiFePO4 et de Silicium pour accumulateurs Li-ion". Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00924945.
Texto completo da fonteKaddissy, Josiane. "Hydrogen production from irradiated aluminum hydroxide and oxyhydroxide". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS253/document.
Texto completo da fonteDihydrogen production is a critical issue for the current management of nuclear wastes. One potential source of hydrogen generation is the radiolysis of hydrated mineral phases encountered in the nuclear waste transportation and storage casks. We chose to study aluminum hydroxide (Al(OH)3) (Bayerite) and oxyhydroxides (AlOOH) (Boehmite) as model compounds. The determination of molecular hydrogen production was evaluated with respect to structure and particle size at room temperature and after annealing. In order to have a better understanding of the mechanisms and to identify the precursors of molecular hydrogen, we studied the irradiation defects and their stabilities using Electron Paramagnetic Resonance (EPR). The effect of adsorbed water and structural water on the molecular hydrogen production was studied. Different radiation sources were used such as Gamma radiation, electron beam radiations and heavy ions. In the last part, preliminary results related to the impact of impurities on hydrogen production are presented
Laghdir, Abdelouahed. "Etude énergétique des polarons et bipolarons dans le polythiophène : importance des effets coulombiens". Montpellier 2, 1990. http://www.theses.fr/1990MON20194.
Texto completo da fonteAlexander, Rebecca. "Energy landscape of defects in body-centered cubic metals". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX072/document.
Texto completo da fonteThe structural materials in nuclear reactors are subjected to severe irradiation conditions,leading to changes in their mechanical properties. The aging of these materials raises important issuessuch as those related to the safety of existing plants and future reactors. In many cases, materials withbody-centered cubic bcc crystal structure are used with iron, tungsten, vanadium and tantalum as basemetal. Collisions between irradiating particles and atoms constituting materials generate point defectswhose migration leads to the formation of clusters responsible for aging. In this thesis, we studied theenergetic properties of point defects in the bcc metals mentioned above at the atomic scale. Modelingpoint defects at the atomic scale can be achieved with different methods that differ only in the quality ofthe description of the interaction between atoms. Studies using accurate atomic interactions such ab initiocalculations are computationally costly making it impossible to directly study clusters of large sizes. Themodeling of atomic interactions using semi-empirical potentials reduces the reliability of predictivecalculations but allow calculations for large-sized clusters. In this thesis we have developed a uniqueenergy model for dislocation loops as well as for three-dimensional interstitial cluster of type C15. Theresulting model has no size limit and can be set entirely by ab initio calculations. To test its robustness forlarge sizes of clusters we also set this model with semi-empirical potentials calculations and comparedthe predictions of the model to atomic simulations. With our development we have determined: (i) Therelative stability of interstitial dislocation loops according to their Burgers vectors. (ii) The stability of theclusters C15 compared to the type of cluster loop. We showed that the C15 type clusters are more stablewhen they involve less than 41 interstitials in iron. (iii) In Ta we were able to show the same stability till20 interstitials. The experiments involving iron show that depending on the irradiation temperature,highly mobile dislocation loops of Burgers vector ½ <111> or loops with Burgers vector <100> areformed. Considering formation mechanisms under irradiation as a function of temperature, formation ofthe <100>-type clusters lacked an acceptable theoretical explanation for about 50 years. In this thesis, theaccuracy of our energy model enabled validation of several theories proposed in the last 50 years. Inparticular we have shown that the formation of loops <100> at high temperatures can be formed fromC15 clusters which may be created directly in the irradiation process. These clusters are immobile andcan grow. Beyond a certain size, the C15 clusters dissociate into loops ½ <111> or <100>. We haveextended our model to free energy calculation of defect formation allowing for finite temperaturepredictions which is further compared to atomic simulations. The laws established in this thesis using ourmodel to calculate the free energy of formation of the cluster size functions were then used in a clusterdynamics simulation. On comparison with experiments involving post-irradiation Oswald ripening in asample of iron exposed to an atmosphere of helium, our energy model showed significant improvementsover older energy laws, such as the capillary law widely-used in multiscale computation cluster dynamicsor Monte Carlo kinetics. We conclude that the new laws established from our calculations are essential topredict the concentration of dislocation loop under irradiation, depending on their sizes. The success ofsuch an approach encourages extension of a similar study in more complex materials
Kwon, Jaeyoung. "Origine et nature des composés intermétalliques métastables engendrés par les procédés thermomécaniques d'assemblage entre métaux : cas du broyage du système Al-Cu". Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10139.
Texto completo da fonteThe γ1−Al4Cu9 compound is often observed at Al rich composition, as the main product by mechanical alloying (MA). To understand the conditions and the persistence of γ1−Al4Cu9 at Al rich composition, Al−25 at.% Cu mixtures were milled and investigated by various characterization methods. This experimental study confirms the preferential formation of γ1. In an effort to elucidate this surprising feature, first-principles DFT calculations were performed for bulk and point defect enthalpies in γ1−Al4Cu9. Based on the independent-point-defect-approximation (IPDA) and statistical thermodynamics, the concentrations of the various antisites, vacancies and interstitials were obtained as functions of temperature and deviation from stoichiometry, together with the free energy of γ1−Al4Cu9. These first-principles DFT calculations results revealed that the off−stoichiometry behavior of γ1−Al4Cu9 may provide a plausible explanation for its unusual stability. In a second step, the validity of IPDA and point defect interactions were investigated by (i) Monte-Carlo simulations with empirical potentials for Al−Cu, (ii) ab initio simulations of complex point defects in Al-rich off-stoichiometric γ1 compounds. The last step of this study on the formation of γ1−Al4Cu9 was concerned with the possibility of athermal mechanisms, investigated by first-principles DFT calculations and an original (M2BCE) cluster expansion approach including a reciprocal-space treatment. In conclusion, this study brings significant elements to interpret the preferential formation of complex γ1−Al4Cu9 phases in various a priori unfavourable environments. It evidences key-results regarding the origin and nature of metastable phases produced by MA in Al−Cu
Sorriaux, Maxime. "Réactivité électrochimique et chimique des matériaux à base d'oxyde de titane avec un liquide ionique chloroaluminé pour batteries à l'aluminium". Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS076.
Texto completo da fonteSocietal changes drive the need for new energy storage systems. Forecasts consider that lithium-ion batteries will cease to meet the demand within the next decade. In this regard, the development of new battery technologies is mandatory. That is why, in this work, the aluminium battery system is explored. Investigations are performed on both the electrolyte and the electrode materials. In this study, the aluminium ion intercalation in the electrode material is achieved, using the defect chemistry. Indeed, cationic vacancies within a titanium oxide structure offer favourable insertion sites for a wide variety of ions. However, the battery lifespan is observed to be greatly shortened due to interactions between the electrode material and the ionic liquid used as the electrolyte
Durinck, Julien. "Modélisation de la plasticité de la forsterite par calculs à l'échelle atomique et par dynamique des dislocations". Lille 1, 2005. https://ori-nuxeo.univ-lille1.fr/nuxeo/site/esupversions/9fd43a9a-26ef-450b-93e3-5ad8c43033b0.
Texto completo da fonteNgayam, Happy Raoul. "Prévisions de l’évolution microstructurale sous irradiation d’alliages ferritiques par simulations numériques à l’échelle atomique". Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10173/document.
Texto completo da fonteIn this work, we have improved a diffusion model for point defects (vacancies and self-interstitials) by introducing hetero-interstitials. The model has been used to simulate by Kinetic Monte Carlo (KMC) the formation of solute rich clusters that are observed experimentally in irradiated ferritic model alloys of type Fe – CuMnNiSiP – C.Electronic structure calculations have been used to characterize the interactions between self-interstitials and all solute atoms, and also carbon. P interacts with vacancies and strongly with self-interstitials. Mn also interacts with self-interstitials to form mixed dumbbells. C, with occupies octahedral sites, interacts strongly with vacancies and less with self-interstitials. Binding and migration energies, as well as others atomic scale properties, obtained by ab initio calculations, have been used as parameters for the KMC code. Firstly, these parameters have been optimized over isochronal annealing experiments, in the literature, of binary alloys that have been electron-irradiated. Isochronal annealing simulations, by reproducing experimental results, have allowed us to link each mechanism to a single evolution of the resistivity during annealing. Moreover, solubility limits of all the elements have been determined by Metropolis Monte Carlo. Secondly, we have simulated the evolution at 300 °C of the microstructure under irradiation of different alloys of increasing complexity: pure Fe, binary alloys, ternaries, quaternaries, and finally complex alloys which compositions are close to those of pressure vessel steels. The results show that the model globally reproduces all the experimental tendencies, what has led us to propose mechanisms to explain the behaviours observed
Alam, Giri Wahyu. "Influence of seeding and growth conditions on grain selection, defects, and properties of high-performance multi-crystalline silicon (HPmc-Si)". Electronic Thesis or Diss., Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0711.
Texto completo da fonteAmong new bulk silicon PV materials, HPmc-Si is one to be considered due its higher conversion efficiency compared to mc-Si solar PV. This research work aims at understanding the influence of the seeding materials and growth conditions on HPmc-Si ingots (dislocations and impurities). Five ingots were grown, and two types of seeding materials are compared to study the grain structure, the electrical properties and the conversion efficiency of solar cells. The initial growth region up to 50 mm is directly linked to the seed layer properties which are dependent on the melting segment parameters. The growth parameters take control on the grain structure after the seed affected region. The growth parameters studied modify little the characteristics of HPmc-Si ingots and the solar cell conversion efficiency. Low carrier lifetimeareas determine the conversion efficiency and they can mainly be associated to the grain size, besides metallic impurities. The grain competition is very dynamic to suppress defective grains and to maintain smaller grain size variation, homogeneous grain size and properties being the most important characteristic of HPmc-Si ingots
Metsue, Arnaud. "Modélisation des structures de coeurs des dislocations dans les minéraux du manteau terrestre à l’aide du modèle de Peierls-Nabarro". Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10001/document.
Texto completo da fontePlastic deformation of minerals in rocks plays an important role in the global convection of the Earth’s mantle. However, the deformation mechanisms of minerals are not well-known. In general, plastic deformation is due to the dislocation motion. The dislocations are linear defects of the crystal. The mobility of the dislocation is governed by the dislocation core structure.Here, we used the Peierls-Nabarro model that is a theoretical model to address the issue of dislocation core modelling. This model provides also the lattice friction of the crystal against the dislocation motion through the calculation of the Peierls stress. Developed more than 50 years, the model has a great interest since the 70’s with the introduction of the generalized stacking fault (GSF) concept that provides a general description of the dislocation core. The determination of the GSF consists in the calculations of energy barriers associated with the shearing of the crystal in a crystallographic plane in one or more directions. In this study, we have determined the dislocation core structures of the post-perovskite phase present at the core-mantle boundary and of the wadsleyite, diopside and forsterite, major minerals from the crust to 510Km deep. We used the one-dimension formulation of the Peierls-Nabarro model in a first time that has been extended to three dimensions in order to model much more complex dislocation cores
Alam, Giri Wahyu. "Influence of seeding and growth conditions on grain selection, defects, and properties of high-performance multi-crystalline silicon (HPmc-Si)". Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0711/document.
Texto completo da fonteAmong new bulk silicon PV materials, HPmc-Si is one to be considered due its higher conversion efficiency compared to mc-Si solar PV. This research work aims at understanding the influence of the seeding materials and growth conditions on HPmc-Si ingots (dislocations and impurities). Five ingots were grown, and two types of seeding materials are compared to study the grain structure, the electrical properties and the conversion efficiency of solar cells. The initial growth region up to 50 mm is directly linked to the seed layer properties which are dependent on the melting segment parameters. The growth parameters take control on the grain structure after the seed affected region. The growth parameters studied modify little the characteristics of HPmc-Si ingots and the solar cell conversion efficiency. Low carrier lifetimeareas determine the conversion efficiency and they can mainly be associated to the grain size, besides metallic impurities. The grain competition is very dynamic to suppress defective grains and to maintain smaller grain size variation, homogeneous grain size and properties being the most important characteristic of HPmc-Si ingots
Song, Xi. "Activation des dopants implantés dans le carbure de silicium (3C-SiC et 4H-SiC)". Thesis, Tours, 2012. http://www.theses.fr/2012TOUR4019/document.
Texto completo da fonteThis work was dedicated to the activation of implanted dopants in 3C-SiC and 4H-SiC. The goal is to propose optimized process conditions for n-type implantation in 3C-SiC and for p-type in 4H-SiC.We have first studied the n-type implantation in 3C-SiC. To do so, N, P implantations, N&P co-implantation and the associated annealings were performed. The nitrogen implanted sample, annealed at 1400°C-30 min evidences a dopant activation rate close to 100% while maintaining a good crystal quality. Furthermore, the electrical properties of extended defects in 3C-SiC have been studied. Using the SSRM measurements, we have evidenced for the first time that these defects have a very high electrical activity and as a consequence on future devices.Then, we have realized a study on p-type doping by Al implantation in 4H-SiC with different implantation and annealing temperatures. Al implantation at 200°C followed by an annealing at 1850°C-30min lead to the best results in terms of physical and electrical properties
Yin, Chengying. "Hydrogen production from irradiated calcium silicate hydrate". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS355/document.
Texto completo da fonteIn France, cementitious materials are used as conditioning matrix of low level and intermediate level nuclear wastes. Water radiolysis occurs due to the nuclear wastes stored in the materials. The formation of its radiolytic products such as H₂ gas must be evaluated for safety reasons. Calcium silicate hydrate (C-S-H) is the main product (50%) of hydration of Portland Cement (PC). The aim of this study is to understand the radiolytic mechanisms of the hydrogen production in C-S-H, to investigate the effect of impurities (such as alkali ions, additional hydroxides or nitrates ions) on H₂ gas production in C-S-H and to examine if interactions exist between different main phases (C-S-H and portlandite) in cement matrix. After using various characterization techniques, samples were submitted to different types of irradiation (gamma rays and electrons and heavy ions (HI) beams) to determine their H₂ radiolytic yield, G(H₂). In C-S-H system, it has been shown, under gamma irradiation, that G(H₂) does not depend on water content, moreover, C-S-H system itself produce efficiently H₂ gas. The comparison between the results obtained under gamma rays and that obtained under HI implies: there is no/ low LET effect in C-S-H. While with nitrate ions in C-S-H, a large decrease of G(H₂) is observed. Irradiation of C2S and C3S hydrates mainly composed of C-S-H and portlandite shows that here is no energy transfer phenomena between these two phases. Finally, the electron paramagnetic resonance (EPR) spectroscopy experiments have enabled proposing radiolytic mechanisms. All these results help us to understand the radiation effects in cements
Vincent, Edwige. "Simulations numériques à l'échelle atomique de l'évolution microstructurale sous irradiation d'alliages ferritiques". Lille 1, 2006. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2006/50376-2006-Vincent.pdf.
Texto completo da fonteKharouf, Riad. "Caractérisation des défauts par attaque chimique dans les couches minces épitaxiales de silicium". Paris 11, 1985. http://www.theses.fr/1985PA112023.
Texto completo da fonteAllart, Marion. "Ségrégation interfaciale dans les métaux en cours de déformation à chaud : cas du système nickel - soufre". Phd thesis, Université de Nantes, 2012. http://tel.archives-ouvertes.fr/tel-00757072.
Texto completo da fontePerrin, Hugo. "Lignes de contact dynamiques à l'échelle microscopique". Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC287/document.
Texto completo da fonteThis thesis reveals two dissipative microscopic phenomena close to the contact line in the fields of capillarity and adhesion. The study is based on dynamic experiments and theoretical predictions. Experimental measurement of macroscopic quantities and the hydrodynamic theory give access to dynamic information located close to the contact line. The different dissipative phenomena, located close to the contact line, originate from the properties of the substrates on which the contact line moves. For a heterogeneous rigid surface, we have developed a rheological model of the contact line based on hydrodynamics, in order to theoretically establish the temporal evolution of the contact line and its deformations. A modal decomposition based on the reduction of the energy by the reaction path theory allows a quantitative prediction of the thermally activated dynamics of the contact line, in agreements with the experiment carried out. For a deformable substrate, based on the analysis of two different experiments of wetting dynamics and on the estimation of the dissipation in the substrate founded on its viscoelasticity, a general understanding of the dynamical behavior of contact lines on viscoelastic substrates is achieve. Finally, this viscoelastic model is applied to the case of weak adhesion, where experimentally we measured the peeling dynamics from a viscoelastic substrate. This extension to adhesion bridge the gap between different interfacial phenomena into a general understanding
Goudreau, Karine. "Une étude des défauts d'homocouplage dans la polymérisation par (hétéro)arylation directe à l'aide de polymères modèles". Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/34035.
Texto completo da fonteMaalouf, Azar. "Contribution à l'étude des procédés de réalisation de circuits intégrés optiques en matériaux polymères". Phd thesis, Université Rennes 1, 2007. http://tel.archives-ouvertes.fr/tel-00456179.
Texto completo da fonteJanvier, Catherine. "Solutions solides de zirconium dans la cérine : modèle thermodynamique et stabilité thermique à haute température". Grenoble INPG, 1998. http://tel.archives-ouvertes.fr/tel-00841807.
Texto completo da fonteMortazavi, Amiri Narjes Beigom. "Relations entre motifs structuraux et dynamique de réseau dans les cristaux mixtes Cu-Zn-Sn-Se : études premiers principes". Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0333/document.
Texto completo da fonteThe works addresses vibrational properties of novel semiconductors, specifically the Cu2ZnSnSe4 and Cu2ZnSnS4 compounds of the kesterite structure, which, in the domain of photovoltaics, become competitive with leading materials of chalcopyrite type, notably Cu(In,Ga)Se2. The anticipated immediate practical interest of such study is that the vibration spectra are likely to make possible a distinction between different structural phases, possible for a given composition. The vibration modes are accessed by using a first-principle theory approach. The manuscript is divided into five chapters, with the following contents: (1) A brief introduction into the work principle and the problematics of photovoltaics, specifically of the solar cells based on multinary semiconductors; the chapter closes by the description of the phase diagram of the Cu-Zn-Sn-Se system. (2) An overview of the density functional theory (DFT) and of the technics of numerical simulations using the SIESTA code. (3) The vibrational properties of Cu2ZnSnSe4 in its two phases, kesterite and stannite, as studied by first-principles method, with a detailed comparison being done along with a thorough mode-by-mode analysis. (4) Vibrational properties of a secondary phase Cu2SnSe3, which often competes with the Cu2ZnSnSe4 phase in the process of sample growth. (5) Calculation of phonons in the Cu2ZnSnS4 structure containing intrinsic defects (vacances; anti sites), with the objective of estimating vibrational contributions to entropy and the correction of the composition - temperature phase diagram in this multi nary system. The general conclusion summarises the results which are published in 5 articles
Christien, Frédéric. "Ségrégation interfaciale dans les métaux". Habilitation à diriger des recherches, Université de Nantes, 2013. http://tel.archives-ouvertes.fr/tel-00912930.
Texto completo da fonteGheeraert, Etienne. "Défauts de structure et impuretés dans les couches minces de diamant élaborées par dépôt chimique en phase vapeur". Grenoble 1, 1992. http://www.theses.fr/1992GRE10030.
Texto completo da fonteHenault, Bastien. "Identification des processus physico-chimiques à l’origine des défauts locaux des surfaces polies optique et superpolies". Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC090.
Texto completo da fonteThis PhD work focuses on the study of the physicochemical mechanisms involved in the chemical-mechanical polishing of Zerodur® (glass-ceramics) with an abrasive based on cerium oxides. The defects observed after polishing were characterized by optical microscopy and atomic force microscopy (AFM). Two main populations were observed, namely "fine" (longitudinal and continuous stripes) caused by debris of polished material. The second is called "scratch" (perpendicular fractures) caused by abrasive agglomerates. RX spectroscopic analyzes of the abrasive showed an increase in the Ce3+/ Ce4+ ratio after the polishing phase. This point confirms the chemical part of Zerodur® polishing. Zeta potential analyzes were carried out on these same abrasives and show an evolution of the abrasive surface charge. AFM observations show that the higher the Ce4+ concentration, the better the final polished surface quality. The polished surface was also probed with ToF-SIMS analyzes. This shows the presence of a cerium-enriched layer of several tens of nanometers, which may be a site for the chemical-mechanical polishing reaction. More precisely, this reaction seems to take place in the glassy phase of Zerodur®
Ouazzani, Jamil Abdelali. "Influence de la température de dissociation thermique du gypse sur la cinétique de réhydratation de l'anhydrite orthorhombique". Lyon, INSA, 1987. http://www.theses.fr/1987ISAL0055.
Texto completo da fontePhysico-chemical characterisation and chemical reactivity of pure orthorhombic anhydrite (CaSo4) obtained by thermal dissociation of pure synthetic calcium sulfate dehydrate were studied by the mean of either classical technico used to determine the structural and mineralogical parameters of the studied solids or the conversion rate of the hydratation reaction, or more specific technico i. E. : infrared absorption spectroscopy and thermo stimulated exo electronic emission (TEE) in order to detect the short-distance distorters and the presence of superficial defects. It was shown that the anhydrite prepared at 800°C ^resented a, optimum od reactivity for the process of dissolution-nucleation-growth, which is associated to its reaction of hydration by liquid water. Further more it was been observed that the concentration in superficial defect detected by TEE reaches a maximum precisely when the solid is prepared at this temperature the superficial defect are involved at the beginning of the reaction : (0 < α <0. 03, in which α is the conversion rate of anhydrite into dehydrate) as potential sites, which implies an heterogeneous nucleation process of the relation product. A model of this process was proposed and the phenomenon of heterogeneous nucleation was clearly pointes out by scanning electron microscopy. On the other hand the short-distance distorter studied by infrared absorption spectroscopy has only a limited rôle in comparison to that of superficial defects, whether or not the solid be preliminarily mechanically activated by grinding
Poupon, Laurent. "Étude des mécanismes de conduction électrique dans le dioxyde d'étain polycristallin en relation avec les défauts ponctuels". Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1998. http://tel.archives-ouvertes.fr/tel-00841348.
Texto completo da fonteLaouti, Nassim. "Diagnostic de défauts par les Machines à Vecteurs Supports : application à différents systèmes mutivariables nonlinéaires". Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00985437.
Texto completo da fonteTigeras, Menendez Maria Aranzazu. "Fuel failure detection, characterization and modelling : effect on radionuclide behaviour in PWR primary coolant". Paris 11, 2009. http://www.theses.fr/2009PA112063.
Texto completo da fonteThis thesis aims to study the fission product behavior and actinides in the PWR primary coolant. From fuel pellet to plant wastes it is extremely important to monitor the radionuclide behavior in order to know as precisely as possible the radionuclide inventory which can have a radiological impact. The presence of fuel cladding defects involves the increase of fission product activity and a possible dissemination of fissile material. These both consequences have to be limited in order to ensure safe operating, to limit environmental impact and to optimize the NPP worker operations. This study has permitted : - the verification of theoretical assumptions and models, concerning the fission product, actinide release, with the power plant feedback; - the proposition of a global methodology permitting to detect and characterize the fuel failures; - the verification of operating conditions influence according to simulations results ; - the Review of thermodynamic database and determination of actinide/iodine speciation adapted to the primary coolant. The main contributions of the works are the proposition of criteria and tools to improve the fuel failure diagnosis, the primary coolant chemical program and the operating conditions of degassing and purification in order to control the fission product and actinide impact in the PWR primary coolant
Buis, Camille. "Etude des corrélations entre les défauts structuraux et les inhomogénéités spatiales des détecteurs de rayons X à base de CdTe pour l'imagerie médicale". Phd thesis, Université Jean Monnet - Saint-Etienne, 2013. http://tel.archives-ouvertes.fr/tel-01056544.
Texto completo da fonteBen, Kaddour Najat. "Propriétés thermodynamiques et non-stoechiométrie du composé YBa2Cu3O7-x". Tours, 1991. http://www.theses.fr/1991TOUR4004.
Texto completo da fonteKimouche, Amina. "Vers de nouveaux matériaux hybrides basés sur le graphène épitaxié : contrôle de la formation de défauts et leur rôle dans l’intercalation". Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY027/document.
Texto completo da fonteEpitaxial graphene grown on metal substrates is a promising platform for developing new hybrid systems, in which interface effects can be exploited to engineer novel properties. The insertion of foreign species between graphene and its substrate, referred to as “intercalation”, was shown very powerful in this respect. With the help of surface science tools, we have studied three graphene/metal systems, two of which are intercalated hybrid systems, and the other is a candidate for such a system: (i) graphene/Ir(111) intercalated with an ultrathin oxide, (ii) graphene/Ir(111) intercalated with cobalt (sub) atomic layers, and (iii) graphene on Re(0001). We found that some defects, especially wrinkles (linear delaminations of graphene from its substrate) and other curve graphene regions, play a crucial, yet unanticipated role in the intercalation process. We also found that the intercalation proceeds in a markedly different fashion under ultra-high vacuum and under atmospheric pressure. In the first system, oxygen-containing species were found to intercalate via the open end of wrinkles, to diffuse along then, and to form oxide nanoribbons along wrinkles accordingly. These ribbons modify the charge density of graphene, which also translates into substantial changes in the inelastic (Raman) optical response of graphene. In the second system, the efficiency of intercalation proved to be dependent on the graphene-metal interaction, which varies between differently oriented graphene domains on Ir(111). In this systems the entry sites for intercalated species could be identified, thanks to in operando observation of the process, as curved regions in graphene. Finally, graphene growth in a third system, graphene on Re(0001), was addressed in order to enable the future development of graphene/Re superconducting hybrids. In this system, we proposed two growth routes, one being a surface-confined process, on bulk single-crystal Re(0001), and the other being a temperature-induced segregation of carbon dissolved at high temperature in thin Re(0001) films on sapphire
Bozzolo, Nathalie. "Contribution de la microscopie électronique en transmission analytique à la caractérisation du diamant CVD". Vandoeuvre-les-Nancy, INPL, 1996. http://docnum.univ-lorraine.fr/public/INPL_T_1996_BOZZOLO_N.pdf.
Texto completo da fonteBerrada, Sara. "Synthèse de dérivés génotoxiques permettant la quantification des pontages interbrins et l’identification de défaut de réparation chez le patient atteint de l’anémie de Fanconi". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0145.
Texto completo da fonteInter-strand crosslink (ICL) are formed by covalent link between two nucleotides located on opposite strands of DNA. This physical link blocks the replication and transcription mechanisms. Because of this mode of action, BIPs-inducing agents are highly toxic to abnormally proliferating cells, which makes them very effective drugs for the treatment of cancers. However, their use is limited by the occurrence of severe side effects resulting in organ failure due to excessive accumulation of ICLs. This may be caused by insufficient repair capacity which will result in healthy cell death upon exposure to ICLs and organ failure.In order to identify the origin of insufficient repair in these patients, a comprehensive knowledge of ICLs repair is required. To date, many repair pathways have been described, but steps in the repair process are still unknown. A direct detection of ICLs would allow to answer these questions. However, the currently available techniques suffer from various limitations and a direct detection of ICLs, at the cellular level and/or in organs, is challenging.During my thesis, I modified two ICLs inducing agents. One is currently used in chemotherapy and the second one has completed a phase II clinical trial. I demonstrated that these modified agents show unchanged cytotoxicity and ability to induce ICLs compared to unmodified agents. I validated their detectability by microscopy as well as by FACS and demonstrated that they could be used to measure ICL repair in different cell lines