Thèses sur le sujet « Matériaux de faible dimension »
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Al, Hokayem Karen. « Synthèse électrochimique de nanostructures à base de tellure pour la conversion thermoélectrique ». Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0315.
Texte intégralAmong the thermoelectric materials, tellurium has a high positive Seebeck coefficient (500 μV/K) at room temperature but with a relative high thermal conductivity (3 W/m.K). Nanostructuring is a solution to improve thermoelectric performances, as the lattice part of the thermal conductivity can be independently lowered. In this work, we synthesized self-standing Te nanostructures by electrodeposition technique, taking advantage of the templating properties of ionic liquids solvents. Single crystalline hexagonal nanostructures were systematically obtained with a preferential orientation along the [001] direction. By varying the conditions of electrodeposition, the size of nanostructures can be tuned. Finally, nanorods of 52 ± 11 nm in diameter and less than 300 nm long were grown by applying a small charge density. Tellurium nanorods were used as precursors of an additional synthesis step. Indeed, by simple redox reaction in Ag(I) or Cu(II) aqueous solution, Te nanostructures have been transformed into single crystalline nanorods Ag2+xTe and Cu1.75Te respectively. In the last part of the work, we tried to incorporate these nanostructures as well as graphene quantum dots in conductive polymer in order to realize flexible hybrid films. The latter should combine the interesting thermoelectric properties of the nanostructures and the low thermal conductivity as poly(3-hexylthiophene) (P3HT)
D'Andrea, Fabio. « La variabilite atmospherique a basse frequence comme probleme de faible dimension ». Paris 6, 1999. http://www.theses.fr/1999PA066012.
Texte intégralMokthari, Ilham. « Synthèse et caractérisation de polyimides poreux à faible constante diélectrique ». Chambéry, 2005. http://www.theses.fr/2005CHAMS049.
Texte intégralThis research work concerns the elaboration of low dielectric constant materials to be used as interlayer dielectrics in microelectronics. The strategy adopted for the generation of porosity relies on the thermal degradation of thermolabiles polycaprolactone sequences simply dispersed or covalently linked to thermostable polyimide matrices, slightly crosslinked by a photochemical process. The first part of this work is devoted to the synthesis and characterization of different polyimides matrices. In a second part, functionnalized polycaprolactone segments (amine-PCL or diamine-PCL) have been synthesized, characterized and involved in a polycondensation reaction in order to end up with controlled architecture copolymers. The last part of the work is related to the elaboration of porous materials. First, the experimental conditions suitable for a complete elimination of the thermolabile segments without any mage to the polyimide matrix have been determined. Therefore, a precise study of the influence of different parameters (polyimide structure, glass transition temperature, polycaprolactone proportion introduced. . . ) on the elaboration of porous structures have been realized. The results obtained suggest at two parameters are crucial for the elaboration of porosity : a high transition temperature of the matrix as well as a phase separation of the thermolabile segments in the themostable polymer
Cargnelli-Barral, Katia. « Elaboration et caractérisation d'aérogels organiques de très faible densité ». Montpellier 2, 1999. http://www.theses.fr/1999MON20023.
Texte intégralDupin, Christophe. « Etude du comportement mécanique des matériaux composites à matrice céramique de faible épaisseur ». Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00955585.
Texte intégralBoukraa, Djaber. « Sur la conception, la génération de trajectoires et la commande d'un avion autonome de faible dimension ». Evry-Val d'Essonne, 2006. http://www.biblio.univ-evry.fr/theses/2006/Interne/2006EVRY0027.pdf.
Texte intégralThis work deals with the fixed wings unmanned aerial vehicle (UAV) design, trajectories planning and control. The manuscript is organized as follows : The first part presents the process of design and the UAV modelling. In the second part we propose two algorithms. The first one allows to determining the trim configurations (state and control vectors) for different constraints and limitations to which it is subjected. The second algorithm is a trajectories planner; it uses like primitives a set of trim trajectories to reduce the complexity of the dynamical model. It generates the optimal trajectory by using bang-bang strategy. The last part of this manuscript presents a control technique based on output feedback linearization. This approach transforms the system into an equivalent linear system. This makes possible the use, after that, of any linear control approach
Boubidi, Pascal. « Caractérisation expérimentale et modélisation numérique de la fatigue à faible nombre de cycles d'un superalliage base ni monocristallin sous chargement multiaxial ». ENSMP, 2000. http://www.theses.fr/2000ENMP1001.
Texte intégralSène, Ndèye Awa. « Etudes expérimentales et numériques de la micro-formabilité des matériaux métalliques de faible épaisseur ». Chambéry, 2010. http://www.theses.fr/2010CHAMS010.
Texte intégralIn recent years, a growing demand on micro technical products is observed. Nowadays, the production of parts with small dimensions and thin thickness by the micro deep drawing process is not always well controlled. New difficulties encountered in the manufacture of such parts are often linked to scaling effects. The objective of this thesis is to characterize the micro-forming ability of aluminium of thin thickness for the determination of micro-forming limit diagrams. The starting point is the achievement of a specific micro deep drawing tool with a punch diameter 9 mm for materials of maximum thickness 0. 4 mm, coupled to an image analysis set-up. Using this experimental device allowed a series of tests on annealed aluminium 1050 A (99. 5%) of small thickness. Several micro-forming limit diagrams were determined by various methods and different criteria for the detection of necking. In order to obtain virtual micro-forming limit diagrams, a numerical modelling of micro deep drawing process has been established: a first simulation with the definition of the complete tool taking into account the surface roughness and a second simulation called "reduced" in which only in the central part of the sample is modelling. For this last, geometric imperfections and microstructure heterogeneities were respectively introduced. Finally, the potential of the micro deep drawing tool is used for the deformation of single crystals and multicrystals following different strain paths in order to validate later micro-mechanical models
Félix, Vincent. « Caractérisation thermique de matériaux isolants légers. Application à des aérogels de faible poids moléculaire ». Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL095N/document.
Texte intégralThe issue of preserving energy raises a number of challenges to science, particularly its efficiency. The conception and characterization of new more efficient thermal insulating materials prove fundamental in this regard. Aerogels appear as serious candidates in this area, their manufacturing process provides extreme characteristics such as high porosity and low density for some of them. Thermal characterization of such materials is tricky, their low sensitivity to heat flux makes well-known methods difficult to implement. Through the study of low molecular weight aerogel samples designed by the LCPM a characterization method suitable to these samples has been developed by the LEMTA. This “three-layers” method offers the advantages of being robust and to overcome the knowledge of parameters that are difficult to reach in such cases. Describing and validating this method is the main object of this work. In addition, thermal conductivity measurements under vacuum have been processed which allowed a deeper understanding of the structure of aerogels. The results obtained this study open perspectives for the optimization of new solutions for thermal insulation
Morandeau, Antoine. « Carbonatation atmosphérique des systèmes cimentaires à faible teneur en portlandite ». Phd thesis, Université Paris-Est, 2013. http://tel.archives-ouvertes.fr/tel-00932816.
Texte intégralTornay, Nathalie. « Vers des outils d'aide à la conception pour intégrer les dimensions techniques, écologiques et sensibles des matériaux de construction ». Thesis, Toulouse, INSA, 2011. http://www.theses.fr/2011ISAT0003/document.
Texte intégralThe choice of materials and way of implementation is known and will be known as a significant growth in the world of architecture. Actually, changes are largely induced by technical dimension, but also representations and precepts that appear with the emergence of the concept of sustainable development in our society.Design support tools about materials scale focus on the physical dimensions (thermal, life cycle, refreshments, etc.). Our work is questioning the integration of technical, environmental and sensible dimensions in a design support tool based on reference. The referential activity is a specific approach in the initial phases of designing on a project. These phases correspond to crucial choice, which remain poorly assisted by digital tools.Our work aims to highlight the different characteristics of materials, but also their interactions. This study differs from conventional approaches of materials, which generally, constructive solutions are presented material by material. Indeed, we rely on a data structure and interdisciplinary knowledge (architecture, urbanism, landscape, aesthetic, technical, cognitive, perception approach, environmental approach, etc.).This research tends to be a first proposal for a design support tool named DILEM'MAtériaux that takes into account materials in their contribution to origin of founding ideas and definition of concept, in the initial phases of designing on a project
Mur, Jacques. « Corrélations entre propriétés structurales et magnétiques : cas d'identités quasi-isolées à faible interaction d'échange intracluster ». Bordeaux 1, 1985. http://www.theses.fr/1985BOR10584.
Texte intégralCôté, Stéphane. « Critères de stabilité interne pour des matériaux de faible plasticité soumis à l'écoulement de l'eau ». Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27459/27459.pdf.
Texte intégralBoudjemaa, Nourredine. « Délaminage des matériaux composites stratifiés à faible et grande vitesse de sollicitation en mode I ». Compiègne, 1987. http://www.theses.fr/1987COMPD059.
Texte intégralBecker, Christian. « Systèmes polymérisables à faible retrait et études de matériaux pour la stéréolithographie à laser CO2 ». Vandoeuvre-les-Nancy, INPL, 1994. http://docnum.univ-lorraine.fr/public/INPL_T_1994_BECKER_C.pdf.
Texte intégralEl, Maiss Janwa. « Conception des matériaux à faible énergie de surface : une nouvelle étape pour la production durable ». Thesis, Nice, 2015. http://www.theses.fr/2015NICE4073.
Texte intégralTwo types of Low surface energy materials LSEMs can be recognized; those which are firstly applied on solid surfaces to elaborate superhydro/oleophobic surfaces that are micro and nano structured, and secondly at the water/air interface to synthesize new ecofriendly surfactants. LSEMs are essentially made from fluorinated compounds due to their unique properties of being both hydro and oleophobic as well as, their thermal and chemical stability in corrosive media. This project shows that the creation of superhydrophobic materials with high oleophobic properties does not necessarily require the utilization of long and bioaccumulative perfluorocarbon chains. Two approaches were adopted in this field. The first strategy was to develop ProDOT derivatives bearing short fluorinated chains to study the influence of the fluorinated chain length on the surface wettability. The proceeding part was to explore the effect of the introduction of a hydrocarbon tail and study the effect of their type and chain length on the surface properties. Another important aspect of this research involves the application of LSEMs on soft materials like surfactants as alternatives to toxic perfluorinated homologues. This study was done to explore the effect of the variant hydrocarbon chains with a short fluorinated tail of hybrid surfactants as well as the effect of the polar head. In this area, two families of hybrid sulfate and bisulfates were synthesized. Their physico-chemical properties were investigated and interesting results were obtained
Pelletant, Aurelien. « Elaboration de matériaux composites céramiques à faible coefficient de dilatation thermique pour des applications spatiales ». Thesis, Lyon, INSA, 2012. http://www.theses.fr/2012ISAL0018.
Texte intégralHigh resolution satellite imagery from space optical systems is mainly limited by the mirror size and the mass of structures supporting the mirror. Nowadays, the development of light athermal systems is the major challenge to improve these optical systems. So, light materials having good mechanical properties (E/ρ3 > 10, σf > 100 MPa) and thermal stability (< 2.0e-6/K) are required. Within this context, our project consists in processing new ceramic composites by combining positive thermal expansion coefficient (TEC) materials having good mechanical properties (alumina or ceria doped zirconia) and negative TEC materials (zirconium tungstate or β-eucryptite) The processing of zirconium tungstate-based materials showed several decomposition and chemical reactions with some oxide matrix leading to its giving up. In the case of β-eucryptite, vermicular phenomenon occurs during sintering leading to the formation of intragranular porosity. Sintering parameters optimization can limit this porosity. The study of the thermal behavior of pure β-eucryptite materials shows that the very negative TEC results from microcracking, generated by the TEC anisotropy of its crystal lattice. This microcracking depends on the grain size and the aggregate size in the case of powder materials. Despite the fact that the TEC of its lattice (called intrinsic TE C equals to -0.4e-6/K) is very low, its bulk (or extrinsic) TEC can reach values until -10.9e-6/K according to the processing conditions. In this work, two strategies for developing composites were studied. The first one consists in decreasing the matrix TEC using an uncracked β-eucryptite powder (-0.4e-6/K) while the second one consists in elaborating near zero TEC materials from a microcracked β-eucryptite powder (-3.0e-6/K). When ceria-doped zirconia is used, ceria content must be adjusted in order to limit zirconia phase transformation. This transformation is driven by tensile stresses induced by the β-eucryptite and modifies the composite thermal behavior linearity. In both studied cases, dense composites show a modification of the β-eucryptite intrinsic TEC from -0.4e-6/K to more than +3.2e-6/K as a consequence of compressive stresses applied by the oxide matrix. An uncompleted densification of composites is required to relax these stresses. Taking into account these observations, several very low TEC composites were elaborated. However, the uncompleted densification of composites and the β-eucryptite microcracking greatly decrease the mechanical properties of these materials
Tornay, Nathalie. « Vers des outils d'aide à la conception pour intégrer les dimensions techniques, écologiques et sensibles des matériaux de construction ». Electronic Thesis or Diss., Toulouse, INSA, 2011. http://www.theses.fr/2011ISAT0003.
Texte intégralThe choice of materials and way of implementation is known and will be known as a significant growth in the world of architecture. Actually, changes are largely induced by technical dimension, but also representations and precepts that appear with the emergence of the concept of sustainable development in our society.Design support tools about materials scale focus on the physical dimensions (thermal, life cycle, refreshments, etc.). Our work is questioning the integration of technical, environmental and sensible dimensions in a design support tool based on reference. The referential activity is a specific approach in the initial phases of designing on a project. These phases correspond to crucial choice, which remain poorly assisted by digital tools.Our work aims to highlight the different characteristics of materials, but also their interactions. This study differs from conventional approaches of materials, which generally, constructive solutions are presented material by material. Indeed, we rely on a data structure and interdisciplinary knowledge (architecture, urbanism, landscape, aesthetic, technical, cognitive, perception approach, environmental approach, etc.).This research tends to be a first proposal for a design support tool named DILEM'MAtériaux that takes into account materials in their contribution to origin of founding ideas and definition of concept, in the initial phases of designing on a project
Soni, Medha. « Investigation of exotic correlated states of matter in low dimension ». Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30381/document.
Texte intégralQuantum statistics is an important aspect of quantum mechanics and it lays down the rules for identifying dfferent classes of particles. In this thesis, we study two projects, one that surveys models of Fibonacci anyons and another that delves into fermions in optical lattices. We analyse the physics of mobile non-Abelian anyons beyond one-dimension by constructing the simplest possible model of 2D itinerant interacting anyons in close analogy to fermionic systems and inspired by the previous anyonic studies. In particular, we ask the question if spin-charge separation survives in the ladder model for non-Abelian anyons. Furthermore, in the study of this model, we have found a novel physical effective model that possibly hosts a topological gapped state. For fermions in one dimensional optical lattices, we survey the effects of non-adiabatic lattice loading on four different target states, and propose protocols to minimise heating of quantum gases. The evaporative cooling of a trapped atomic cloud, i.e. without the optical lattice potential, has been proven to be a very effective process. Current protocols are able to achieve temperatures as low as T/TF ≈ 0.08, which are lost in the presence of the optical lattice. We aim to understand if defects caused by poor distribution of particles during lattice loading are important for the fermionic case, forbidding the atoms to cool down to the desired level. We device improved ramp up schemes where we dynamically change one or more parameters of the system in order to reduce density defects
Liscio, Fabiola. « Nanostructures magnétiques auto-assemblées sur des surfaces à faible énergie par épitaxie par jets moléculaires ». Grenoble INPG, 2009. https://tel.archives-ouvertes.fr/tel-00391031.
Texte intégralNanostructures of MxPt1x (M=Co and Fe) alloys have perpendicular magnetic anisotropy which makes them good candidates as high density magnetic recording media. In this thesis work, the structural and magnetic properties of these nanostructures were studied as a function of the substrate (structure, symmetry and surface energy) and the co-deposition temperature. The nanostructures were prepared by co-deposition of transition metal atoms on low energy surfaces WSe2(0001) and NaCl(001) by molecular beam epitaxy. This led to the formation of stress-free nanostructures whose properties were characterized by techniques including X-ray diffaction, XAFS, GISAXS, TEM, STM and SQUID magnetometry. The chemical order effects at short- and long-range and the in uence of morphology and growth direction on magnetic properties were clearly shown
Salles, Alain. « Conception d'éléments passifs magnétiques pour convertisseurs de faible puissance ». Toulouse 3, 2008. http://thesesups.ups-tlse.fr/362/.
Texte intégralThis thesis is a contribution to integrated power supplies for portable systems working at low voltage and low current. Several teams have been working over 30 years on magnetic components integration on silicon. Our objective was a design of a 1µH inductor working within 1MHz to 10MHz frequency range for 1W applications with 1V output voltage. Numerical simulation tools have been developed on the basis of a geometrical normalization of planar spiral inductors and equations describing inductive and resistive behavior. Numerical results showed us that inductors with low DC resistance implied geometric dimensions difficult to realize with actual microelectronics techniques. To overcome these limitations, we considered series/parallel association of magnetically coupled planar inductors. As a consequence, MEMS based process (thick resist deposition, electrolytic growth) has been developed to validate numerical results. Finally, a test bench dedicated to impedance measurements, has been developed to define inductors working frequency range
Chattoraj, Joyjit. « Effet d'une faible température sur les mécanismes élémentaires de la déformation plastique dans les matériaux amorphes ». Phd thesis, Université Paris-Est, 2011. http://pastel.archives-ouvertes.fr/pastel-00664392.
Texte intégralBenhaboucha, Nadia. « Quelques problèmes mathématiques relatifs à la modélisation des conditions aux limites fluide-solide pour des écoulements de faible épaisseur ». Lyon 1, 2003. http://tel.archives-ouvertes.fr/docs/00/04/65/31/PDF/tel-00005482.pdf.
Texte intégralThe problem considered in this PhD work is the asymptotic study of thin thickness flows and the modeling of the boundary conditions to impose on the fluid-solid interface in various situations. The first chapter is dedicated to the asymptotic study of a coupling between a thin film of fluid and an adjacent thin porous medium. This situation appears in boundary lubrication problems. We show that there is a critical value between the size of the microstructure of the porous medium, the free fluid gap and the thickness of the porous medium. Moreover it is shown that an actual geometry can always be described by that critical case for which a modified Reynolds equation is proved. Numerical calculations show the difference between our model and two other models proposed in the mechanical literature. In chapter 2, one is interested in the study of a thin flow behavior when one of the surface is rough. This study can be related to the preceeding chapter by considering a porous medium with a single layer. We use the two scale convergence technique in homogenisation to obtain rigorously the convergence results. Moreover, the convergence of the normal and tangential constraints on the smooth and rough surfaces are studied. In the last chapter, we consider a micropolar fluid with new boundary conditions at the fluid-solid interface linking the velocity and the microrotation by introducing a so called ``boundary viscosity''. We prove the existence and uniqueness of the solution and we derive, by way of asymptotic analysis, a generalized micropolar Reynolds equation. Numerical results enhance the influence of the new boundary conditions on the load and the friction coefficient. Comparisons are made with other works retaining a no slip boundary condition
Melo, Moura Jorge Daniel de. « Utilisation en structures des résineux à faible densité : conséquences technologiques de scénarios sylvicoles extrêmes ». Nancy 1, 1996. http://docnum.univ-lorraine.fr/public/SCD_T_1996_0041_DE_MELO_MOURA.pdf.
Texte intégralPop-Piron, Flavia-Florina. « Nouvelles architectures fonctionnelles pour la reconnaissance moléculaire, systèmes conjugués à faible Gap et matériaux pour électrode avancés ». Phd thesis, Université d'Angers, 2009. http://tel.archives-ouvertes.fr/tel-01016464.
Texte intégralSidi, Ali Cherif Karim. « Matériaux à faible permittivité en interaction avec une solution : caractérisation par spectroscopie d’impédance et fonctionnalisation de surface ». Grenoble INPG, 2008. http://www.theses.fr/2008INPG0037.
Texte intégralWith the continuous downsizing of the interconnect structures, barriers against copper diffusion can no longer be deposited by physical techniques. Therefor, liquid phase deposition techniques are foreseen to achieve conformal coating of the features. However, such processes require an efficient initiation of the metal deposition onto insulating substrates. Also, the porous SiOCH dielectric materials can interact with the deposition solutions. An elegant way to address both issues is to functionalize the extreme surface of porous SiOCH materials in order to (i) seal the open pores to prevent diffusion of the deposition solution and (ii) activate the surface to promote subsequent barrier deposition. In this exploratory study, we first assess the use of impedance spectroscopy to characterize the interaction between an aqueous solution and porous SiOCH materials. This work allows us to validate the technique and propose an efficient methodology of study. Moreover, we demonstrate that water penetrates the porous SiOCH materials according to Fick’s law. Then, the functionalization process by superficial silanization of the porous materials is developed and the efficiency of the pore sealing treatment is demonstrated by ellipsometric porosimetry. Finally, the use of impedance spectroscopy to characterize the efficiency of a pore sealing treatment is discussed
Vidal-Dho, Matthias. « Mécanismes de vieillissement liés à la pénétration d’humidité dans les matériaux diélectriques à faible permittivité des interconnexions ». Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALT066.
Texte intégralOver the past decades, scaling of microelectronic chips, in particular transistors and memory cells, has allowed to increase substantially both the density of integrated circuit and integrate the umber of functions offered. Such scaling required the introduction oflow permittivity dielectrics, which are particularly sensitive to moisture pollution. This thesis details the dielectrics main properties and the consequences of moisture ingress insuch low-permittivity dielectrics, also referred as SiOC :H dielectrics. The fabrication of low-κ/copper-based interconnects is detailed. Then, the SiOC :H dielectric material is characterised to determine its chemical and molecular structure in order to understand underlying physical phenomenon leading to the material electrical performances degradation. Then, the conception and fabrication of electrical test structures required to evaluate the impact of moisture on the electrical properties and performances of integrated SiOC :H dielectric material is presented. Finally, the results of electrical characterisations carried out on these structures provide a better understanding of physical phenomenon leading to electrical performance degradation of SiOC :H dielectric material used in the semiconductor industry
Si, Ahmed Fariza. « Elaboration et caractérisation de matériaux de type pérovskite, à faible teneur en plomb ou dépourvus de plomb ». Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCK005.
Texte intégralMost of ferroelectric materials currently used in the industrial applications are lead-based ceramics. Such compounds are harmful to the environment due to the toxicity and volatility of lead oxide during the preparation process of these materials. Therefore, environmental friendly lead-free ceramics or low-lead content materials with equivalent properties has become one of the main topics as an alternative to lead-based ceramics. In this view, the present work focuses on investigating materials with formulas :Ba1-xPbx(Ti1-yZry)O3 (2.5% ≤ x ≤ 10%) and Ba1-xEr2x/3(Ti1-yZry)O3.Solid state route was used for materials elaboration. The experimental techniques used are thermogravimetric analysis, dilatometry, X-ray diffraction, scanning electron microscopy coupled to an EDX microanalysis system and impedance spectrometry. The use of these various processes allowed us to optimize the synthesis conditions and to obtain dense ceramics with density superior to 90%. In addition, the structural parameters were refined by the Rietveld method and then discussed. Furthermore, these ceramics exhibited normal and/or relaxor ferroelectric properties then some of them have very interesting dielectric characteristics in the vicinity of room temperature. Such lead-free ceramics or low-lead content materials reduce significantly the environmental pollution. Due to their good dielectric performances, they could be potential candidates for replacing lead-based materials currently used in various electronic equipments
Si, Ahmed Fariza. « Elaboration et caractérisation de matériaux de type pérovskite, à faible teneur en plomb ou dépourvus de plomb ». Electronic Thesis or Diss., Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCK005.
Texte intégralMost of ferroelectric materials currently used in the industrial applications are lead-based ceramics. Such compounds are harmful to the environment due to the toxicity and volatility of lead oxide during the preparation process of these materials. Therefore, environmental friendly lead-free ceramics or low-lead content materials with equivalent properties has become one of the main topics as an alternative to lead-based ceramics. In this view, the present work focuses on investigating materials with formulas :Ba1-xPbx(Ti1-yZry)O3 (2.5% ≤ x ≤ 10%) and Ba1-xEr2x/3(Ti1-yZry)O3.Solid state route was used for materials elaboration. The experimental techniques used are thermogravimetric analysis, dilatometry, X-ray diffraction, scanning electron microscopy coupled to an EDX microanalysis system and impedance spectrometry. The use of these various processes allowed us to optimize the synthesis conditions and to obtain dense ceramics with density superior to 90%. In addition, the structural parameters were refined by the Rietveld method and then discussed. Furthermore, these ceramics exhibited normal and/or relaxor ferroelectric properties then some of them have very interesting dielectric characteristics in the vicinity of room temperature. Such lead-free ceramics or low-lead content materials reduce significantly the environmental pollution. Due to their good dielectric performances, they could be potential candidates for replacing lead-based materials currently used in various electronic equipments
Choukroun, Johan. « Théorie de la résonance paramagnétique électronique des matériaux magnétiques de basse dimension. L'interaction de Dzyaloshinsky-Moriya ». Aix-Marseille 3, 2001. http://www.theses.fr/2001AIX30070.
Texte intégralThe Electron Paramagnetic Resonance (EPR) technique is a powerful tool for studying magnetic materials. A clear lack of a unified and rigourous EPR theory for low-dimensional antiferromagnets (intensively studied nowadays) led us to look at the theoretical side of this technique. The magnetic interactions are described by the isotropic exchange Hamiltonian (as the main interaction), the symmetric (or dipole-dipole) anisotropy, and the staggered Dzyaloshinsky-Moriya anisotropy. The EPR signal represents the energy absorbed by the magnetic compound under the effect of a microwave field. We have thus calculated this quantity within the Mori formalism. We obtain a perturbative expression describing the signal at finite temperatures. The EPR signal position comes from the anisotropy of the static susceptibility, the spin dynamics, and the asymmetric part of the lineshape. We show that the linewidth depends on a unique four-spin correlation function, up to second order in anisotropy. An exact expression for this function is obtained for the Dzyaloshinsky-Moriya interaction, showing that the scheme including both RPA (Random Phase Approximation) decoupling and spin diffusion leads to a wrong result. .
Poilâne, Christophe. « CARACTÉRISATION MÉCANIQUE DES MATÉRIAUX EN FAIBLE ÉPAISSEUR PAR INTERFÉROMÉTRIE NUMÉRIQUE. APPLICATION AUX ESSAIS DE GONFLEMENT ET DE TRACTION ». Phd thesis, Université de Franche-Comté, 1998. http://tel.archives-ouvertes.fr/tel-00326993.
Texte intégralLa projection de franges permet de mesurer la carte des déplacement hors-plan. Elle est adaptée à la mesure des contraintes résiduelles dans les films minces par analyses de courbure et/ou essais de gonflement. On montre suite à trois études expérimentales :
1. la précaution à prendre dans l'utilisation de la formule de Stoney même pour des bicouches libre-libre (SiO2/Si) ;
2. la présence de flambage dans les membranes bicouches comprimées encastré-encastré (SiO2/Si) ;
3. un parfait accord entre essais de gonflement et essais de nano-indentation pour des films tendus (polimiide).
La photographie numérique de speckle permet de mesurer la carte des déplacements dans le plan. Elle est adaptée avec succès à un banc d'essais de traction conçu durant la thèse et spécialement dédié aux films minces. Un algorithme original de calcul a été développé pour obtenir une résolution subpixel. Les performances de l'algorithme sont comparées par des simulations et des expériences aux algorithmes classiques de corrélation. Sa rapidité et sa haute résolution permettent de calculer les cartes de déplacements en temps réel. Les déformations dans le plan en sont déduites et permettent le tracé des courbes contrainte/déformation puis le calcul du module d'Young E et du coefficient de Poisson v. Les matériaux choisis pour valider le banc d'essai sont le cuivre électrodéposé, matériaux ductile, puis le silicium monocristallin, matériaux fragile.
Ayrault, Christophe. « Influence de la pression statique sur la caractérisation ultrasonore de matériaux poreux : étude du régime de faible diffusion ». Le Mans, 1999. http://www.theses.fr/1999LEMAA005.
Texte intégralFregard, Florence. « Rôle des interactions hydrophobes et électrostatiques dans l'adhésion de bactéries méthanogènes aux matériaux de faible énergie de surface ». Lille 1, 1991. http://www.theses.fr/1991LIL10047.
Texte intégralSabbagh, Fadi. « Modélisation des transferts hydriques sous faible potentiel matriciel, entre matériaux de propriétés contrastées : application à des ouvrages enterrés ». Grenoble 1, 1991. http://www.theses.fr/1991GRE10088.
Texte intégralPetrov, Branko. « Étude de matériaux photoconducteurs ultra rapides à faible gap et leurs applications dans les dispositifs et systèmes THz ». Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10619.
Texte intégralAugiseau, Vincent. « La dimension matérielle de l'urbanisation : flux et stocks de matériaux de construction en Ile-de-France ». Thesis, Paris 1, 2017. http://www.theses.fr/2017PA01H111.
Texte intégralConstruction materials are the largest flows entering urban areas after water, while they constitute the top waste deposit. The relation between these material flows and urbanization processes has receive little attention and it is the object of this study. Work was conducted in collaboration with the Regional and inter-departmental directorate for the environment and energy Ile-de-France, responsible of the quarries regulation plan, and the Regional council, which is in charge of the C&D waste management plan. This research contributed to methodological improvement for the quantification and localisation of contruction material flows and stocks at regional scale with the case study of Ile-de-France region. Il demonstrates that that the primary and secondary resources available and extracted are close in terms of quantity. However, the utilization rate of the secondary resources is significantly lower than those of primary resources due to normative and regulatory frameworks.In 2013, the mobilization of construction materials from Ile-de-France was mainly generated by the process of urban renewal. This renewal causes major demolition and reconstruction, but it is also carried by urban densification and requires the import of external materials. In addition, the renewal of built works is strongly related to spatial configuration. A projection of material flows up to 2032 shows that achieving the targets for housing construction defined in regional master plan (SDRIF) would lead to a sharp increase in the import rate of materials. This observation calls for alternative public actions aiming at better management of urban resources
Posseme, Nicolas. « Étude de l'intégration des matériaux à très faible permittivité diélectrique dans une structure damascène pour les filières technologiques CMOS ». Phd thesis, Université de Grenoble, 2005. http://tel.archives-ouvertes.fr/tel-00685803.
Texte intégralPossémé, Nicolas. « Étude de l'intégration des matériaux à très faible permittivité diélectrique dans une structure damascène pour les filières technologiques CMOS ». Université Joseph Fourier (Grenoble), 2005. http://www.theses.fr/2005GRE10081.
Texte intégralAs device dimensions continue to shrink, RC delay in interconnects becomes more significant. This delay can be reduced by the use oflow dielectric constant (k) materials and low resistivity metals (Cu). The low k compatibility with different integration steps needs to be investigated. This work focuses on etch mechanisms and impact of ash processes on SiOCH material (porous and non porous) for their integration in single damascene architecture. This architecture is characterized physically and electrically. SiOCH etching is driven by a fluorocarbon interaction layer formed on top of the dielectric under plasma exposure. The formation of this fluorocarbon layer is governed by the plasma operating conditions (power injected in the plasma source, pressure and gas flow in the etch chamber), nature of the chemistry used and the chemical composition of the material itself. For porous materials reactive species can diffuse through the pores inducing a film modification. These modifications are increased during the ash step. Ln this last case, a new ash chemistry needs to be developed allowing a trade off between the sidewall film modification required to prevent metal barrier diffusion and the increase in the dielectric constant
Noudeviwa, Albert M. D. « Etude et optimisation de dispositifs à base de matériaux faibles gap pour applications hautes fréquences et ultra faible consommation ». Thesis, Lille 1, 2011. http://www.theses.fr/2011LIL10132/document.
Texte intégralAdvent of itinerant technologies was done with the autonomy needs increase in the mobile electronics devices. In addition the high devices integration density leads to the thermal dissipation limits of the classic cooling systems. Thus in this thesis the low Vds operation mode is investigated in narrow band gap materials based HEMTs in order to reduce the power consumption. This study is done at room temperature (300K) and at cryogenic temperature (77K). Concerning antimonide based HEMTs, record performances was published at 300K (fT = 144GHz à 100mV for Lg=120nm). In terms of noise performances both of industrial studied HEMTs and antimonide based HEMTs present at 30GHz and Vds=100mV NFmin value around 1.6dB and Gass around 6dB for power dissipation lower than 10mW/mm. Finally low noise amplifier (LNA) design is done in order to evaluate the potential use of those devices in low power consumption electronics at room and cryogenic temperature. Those designs allowed to obtain at Vds=100mV NF value around 1.7dB and Gass around 6dB with power dissipation lower than 6mW/mm at room temperature and at cryogenic temperature NF value around 0,6dB for Gass value higher than 7dB
Wu, Jianxiong. « Développement de nouveaux matériaux catalytiques à faible teneur en métaux précieux pour le post-traitement des gaz d'échappement automobiles ». Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1R021/document.
Texte intégralThe current study aims to develop novel catalytic materials for the post-treatment of exhaust gas stemming from gasoline engines. The Three Way Catalyst (TWC) is generally considered as a mature and reliable technology capable of removing simultaneously the main pollutants present in the automobile exhaust gas: CO, HC and NOx. The existing TWC system relies heavily on the significant use of Platinum Group Metals (PGMs) and Rare Earth Elements (REEs). However, the high-cost and scarcity of the conventional PGM-based TWC system constitutes an obstacle for the cost reduction of exhaust gas treatment technology as well as a severe burden on natural resource. Another drawback of conventional TWC is associated with the sintering of precious metals in the process of catalyst operation and unsatisfactory N2 selectivity during NOx reduction. Therefore, alternative solutions are required which should ideally allow a substantial reduction of PGMs usage without sacrificing significantly the catalytic performance. Trois voiesThe goal of this study is to evaluate the feasibility of applying perovskite-type materials as an alternative to the replacement of conventional TWC system. The main approach employed is composition optimization of perovskite-type materials, including creation of non-stoichiometry in the chemical composition, partial substitution in A or B site and addition of small amount of PGMs. Influence of partial substitution in A or B site as well as the synergistic effect of dual substitutions in both A and B site were investigated. Results showed that Cu doping in B site could enhance oxidation of CO and C3H6 while Mn doping had a noticeable promoting impact on NO reduction under stoichiometric conditions. Small amount of PGM loading combined with doping of Cu or Mn could enhance remarkably the redox properties of the lanthanum ferrite perovskite. Ca doping in A site affected the dispersion and diffusion of precious metals across the perovskite substrate. The PGM-loaded perovskite catalysts outperformed the commercial benchmark catalyst in terms of higher NO conversion and N2 selectivity in stoichiometric condition in the operating temperature range of the TWC system but the deNOx activity during cold-start process remains a big challenge
Nos, Melodie. « Synthèse organique et auto-assemblage de métallo-polymères conjugués à faible gap pour la préparation de nouveaux matériaux organiques ». Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC259/document.
Texte intégralThis work is focused on the development of original low band gap metallo-polymers to generate potential candidates for solar cell devices. In order to decrease the band gap value of the metallo-polymers, the first part of this work explores the insertion of one or two charge transfer complexes (CTC) in the ligand structure, using diketopyrrolopyrrole (DPP) as acceptor and thiophene as donor in order to decrease the band gap. The second part of this work is interested in the improvement of charge carrier mobility. The development of strategies to promote chains self-organization in the material with the introduction of an organizing group on the ligand are studied in order to generate a π-type weak interactions network or hydrogen bonds. The targeted metallo-polymers are obtained using a dehydrohalogenation reaction between a dialkyne ligand and a platinium (II) complex. Electronic, optic and physic properties characterization of these original compounds confirm the interest for using them in organic solar cell devices
Millet, Céline. « Les applications des fluides supercritiques en microélectronique : Retrait de la résine photosensible et nettoyage de matériaux de très faible permittivité ». Montpellier 2, 2004. http://www.theses.fr/2004MON20187.
Texte intégralNamoulniara, Diatto Kevin. « Etude expérimentale de la diffusion du CO2 et des cinétiques de carbonatation de matériaux cimentaires à faible dosage en clinker ». Thesis, La Rochelle, 2015. http://www.theses.fr/2015LAROS008/document.
Texte intégralOne solution for reducing the environmental impact of concrete is to substitute a part of cement by mineral additions, such as granulated blast furnace slag. However, this substitution should not reduce the performances of concrete with respect to carbonation, one of the main ageing phenomena of reinforced concrete structures. Carbonation is a chemical reaction between the cement matrix and the carbon dioxide from the atmosphere. In addition to the formation of calcium carbonate, this reaction results in a pH reduction of the pore solution and a risk of corrosion. Laboratory accelerated tests show a wide disparity between the carbonation resistance of high mechanical performances concretes with low porosity and the resistance of more porous and more usual ones. The objective of this thesis is to better understand the phenomenon of carbonation of cementitious materials, including those containing blast furnace slags. This work was carried out by decoupling the phenomena involved in carbonation that are gaseous diffusion, chemical reactions and water transfers. First, an experimental device for measuring the CO2 diffusion coefficient was developed. After validation, the latter was used in a parametric study carried out on cement pastes showing the influence of composition and carbonation on the diffusion coefficient. The second part of the thesis work focused on studying the kinetics of carbonation of pastes with respect to the degree of water saturation. Prior to carbonation, the studied pastes were conserved during a long period at various RH to achieve hydric equilibrium. The carbonation kinetics of small size samples of pastes was studied by means of monitoring of weight changes and thermogravimetric analyzes for identification of residual hydrates and formed carbonates. We have thus shown differences in behavior of hydrates and binders during carbonation involving the material microstructure
Coulibaly, Mamadou. « Caractérisation des décharges électriques se propageant aux interfaces gaz/solide – Relation entre propriétés des matériaux et dimension fractale ». Phd thesis, Ecole Centrale de Lyon, 2009. http://tel.archives-ouvertes.fr/tel-00419967.
Texte intégralIl ressort des résultats obtenus que l'aspect morphologique des décharges varie selon les constituants de l'interface gaz/solide, l'amplitude et la polarité de la tension ainsi que la pression du gaz. En présence d'un gaz ou mélange donné, Lf augmente quasi-linéairement avec la tension et décroît lorsque la pression, l'épaisseur du solide diélectrique et/ou le taux de SF6 dans le mélange augmentent. Aussi, pour une tension et une pression données, Lf est plus élevé en polarité positive alors que la tension d'apparition des décharges est plus élevée en polarité négative. Les résultats obtenus avec l'azote et le mélange SF6 - N2 sont très aléatoires. Le calcul du champ par éléments finis (Flux 2D/3D) montre que le renforcement du champ au voisinage de la pointe est d'autant plus important que la différence entre la constante diélectrique du matériau solide et celle du gaz est grande. Les enregistrements de courants associés aux décharges ont révélé l'existence d'une décharge secondaire de signe opposé à la tension appliquée. Ce phénomène est dû à l'accumulation de charges sur la surface de l'isolant solide ; certains matériaux accumulent moins de charges surfaciques et la longueur finale des décharges qui s'y développent est plus courte. Une relation entre le type de gaz (mélange) et sa pression, la nature du diélectrique solide et son épaisseur, et la dimension fractale D des décharges a été établie. D diminue lorsque l'épaisseur e du solide et/ou la pression du gaz augmente et/ou la permittivité diélectrique du solide diminue.
Coulibaly, Mamadou Lamine. « Caractérisation des décharges électriques se propageant aux interfaces gaz/solide : Relation entre propriétés des matériaux et dimension fractale ». Ecully, Ecole centrale de Lyon, 2009. http://www.theses.fr/2009ECDL0013.
Texte intégralThis work deals with the study of morphology and final length Lf of creeping discharges propagating over different kinds of solid dielectrics (PTFE with various fillers, Epoxy resin and glass) in presence of SF6, N2 and CO2 gases as well as SF6 - N2 and SF6 - CO2 mixtures, under lightning impulse voltage (1. 2/50 μs) using a point - plane electrode arrangement. The materials we considered were selected for their wide use in high voltage apparatus such as GIS and circuit breakers. The characteristics of creeping discharges are analyzed in function of the amplitude and polarity of voltage, the kind and thickness of solid insulator, the type of gas (or mixtures) and pressure as well as the concentration of constituents of mixtures. It’s shown that the morphological of creeping discharges depends on the components of solid/gas interface, the amplitude and polarity of voltage as well as the gas pressure. In presence of a given gas (mixture), Lf increases quasi-linearly with the voltage and decreases when the pressure and/or the thickness of insulator and/or the rate of SF6 in a given mixture increase. And for given voltage and pressure, Lf is higher when the point electrode is positive whereas the initiation threshold voltage of discharges is higher with a negative point. The results obtained with nitrogen and SF6 - N2 gas mixture are very scattered. The computation of electric field using the finite elements method (Flux 2D/3D codes) shows that the electric field is enhanced in the vicinity of the point; it’s more important as the difference between the dielectric constants of gas and solid material is high. The recordings of currents associated to discharges revealed the existence of a secondary discharge of opposed sign to the applied voltage. This phenomenon is due to the accumulation of charges at the surface of solid insulator; some materials accumulate less surface charges and the final length of the discharges which develop over them is shorter. A relation between the type of gas (mixture) and its pressure, the kind of dielectric solid and its thickness, and the fractal dimension D of discharges was established. D decreases when the thickness e of solid and/or the pressure ofgas increase and/or the dielectric constant of insulator decreases
Gamet-Cauro, Lauren-Claire. « Synthèse et caractérisation de précurseurs du titane et de l'yttrium à ligands insaturés : application au dopage de matériaux microcellulaires de faible densité par des oxydes ». Lyon 1, 2001. http://www.theses.fr/2001LYO10140.
Texte intégralRaballand, Vanessa. « Gravure en plasma dense fluorocarboné de matériaux organosiliciés à faible constante diélectrique (SiOCH, SiOCH poreux). Etude d'un procédé de polarisation pulsée ». Phd thesis, Université de Nantes, 2006. http://tel.archives-ouvertes.fr/tel-00115585.
Texte intégralLa gravure des matériaux est réalisée en plasma fluorocarboné (CHF3) additionné ou non de H2 ou Ar, dans un réacteur à couplage inductif (ICP), dans lequel le substrat est polarisé négativement. Ce procédé a été modifié en appliquant une polarisation pulsée au substrat (1 Hz à 10 kHz). Dans cette configuration, l'énergie des ions est pulsée. L'influence des conditions de pulse (fréquence, et rapport cyclique rc=TON/T) sur la gravure des matériaux SiOCH poreux, SiOCH, SiCH, SiO2, et Si est étudiée. En particulier, en diminuant le rapport cyclique, ce procédé pulsé fournit d'excellents résultats concernant la gravure sélective de SiOCH poreux vis à vis de SiCH et SiO2.
Pour optimiser le procédé de gravure, une meilleure compréhension de l'interaction plasma-surface, et par suite des mécanismes de gravure, est indispensable. Pour cela, des analyses de surface (XPS, ellipsométrie spectroscopique, MEB) sont corrélées à des analyses du plasma (spectrométrie de masse, spectroscopie d'émission optique, sonde de Langmuir, sonde plane). En particulier, durant cette thèse, le diagnostic de sonde plane a été développé. Il permet une mesure précise du flux d'ions, qui peut alors être mesuré en temps réel en plasma polymérisant, électronégatif et instable. En comparant ces différents diagnostics, nous concluons que les mécanismes de gravure en polarisation pulsée sont similaires à ceux en polarisation continue. Toutefois, le procédé de gravure diffère. Aussi, pour comprendre ce procédé, un modèle décrivant les vitesses de gravure en fonction de la tension de polarisation a été développé. En résumé, lorsque aucune tension n'est appliquée (phase OFF), un film fluorocarboné se dépose à la surface des matériaux. Puis, à l'application d'une tension (phase ON), une énergie des ions supérieure à celle obtenue en polarisation continue est nécessaire pour graver ce dépôt puis graver le matériau. De plus, la gravure du matériau en polarisation pulsée s'opère à travers un film fluorocarboné plus riche en fluor par rapport au mode continu : La gravure des matériaux en est améliorée. Le modèle, tenant compte de cet état de surface, décrit alors correctement les seuils et vitesses de gravure des différents matériaux en polarisation pulsée.
Raballand, Vanessa. « Gravure en plasma dense fluorocarboné de matériaux organosiliciés à faible constante diélectrique (SiOCH, SiOCH poreux) : étude d'un procédé de polarisation pulsée ». Nantes, 2006. http://www.theses.fr/2006NANT2040.
Texte intégralThis study concerns the etching of low permittivity methylsilsesquioxane materials, SiOCH and porous SiOCH, used as intermetal dielectric in microelectronics devices, with fluorocarbon inductively coupled plasma. Etching of SiO2 and SiCH, used as hard mask or etch stop layer is also studied. The aim is to obtain a high porous SiOCH etch rate with a high selectivity versus SiCH and SiO2. To reach this goal, the etching process has been modified : the bias voltage, and so the ion energy, is pulsed. This process provides excellent results concerning both etch rate and selectivity. To understand etch mechanisms of Si, SiCH, SiO2, SiOCH, and porous SiOCH in continuous and pulsed modes, surface analyses (XPS, ellipsometry) are coupled to plasma analyses (mass spectrometry, optical emission spectroscopy, planar probe). A model describing etch rates when a pulsed bias voltage is applied has been developed
Hu, Yong. « Approximation faible et principe local-global pour certaines variétés rationnellement connexes ». Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00691513.
Texte intégralArgane, Rabei. « Valorisation des rejets miniers à faible teneur en sulfures comme granulats pour mortiers ». Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0039.
Texte intégralMine tailings represent the finely ground industrial by products generated throw beneficiation of ore minerals. During mine exploitation, these tailings are generally transported in slurry form to large storage facilities, called tailings ponds or impoundments. These facilities are, in most cases, difficult to manage and expensive to rehabilitate. They are responsible for the generation of important environmental impacts and significant ecological disruptions, depending on their pollution potential, management technique, physical stability and the climate conditions. In this context, numerous studies have been conducted to develop new techniques for a sustainable management of mine tailings. The feasibility of reusing some tailings in the construction sector as cementing materials and additives for mortars or concretes were successfully achieved. However, the majority of the conducted studies are still at laboratory stages. Moreover the reuse of tailings as construction material is yet subject of numerous difficulties in term of social acceptance. Various parameters are also of concern, especially the physical and chemical stability of tailings as well as their eco-compatibility. In parallel, the uncontrolled reuse of low sulfide tailings as construction material is increasing in some developing countries (e.g. Morocco). In fact, nearby some abandoned mine sites, these tailings are considered as natural sands and are used for the manufacture of surface finishing mortars. This traditional recycling may constitute mechanical and environmental risks, principally related to tailings mechanical unconformity and to their non-negligible residual metal concentrations. Therefore, the aim of the current research is to evaluate the actual impact of two Moroccan mine tailings (named Zeida and Mibladen), commonly used as aggregates in the Upper-Moulouya region, on the mechanical properties of mortars and on their long term environmental behavior. This work has also as specific aim, to study the technical feasibility of using low sulfide tailings as sand substitute for the manufacture of rendering and masonry mortars. To attain this aim, a thorough characterization of the physical, chemical and mineralogical properties as well as the geochemical behavior of mine tailings was carried out. Mechanical properties of tailings-based mortars were then measured and compared to reference samples (sand-based mortars) using different tests such as setting time, entrained air volume and compressive strength. In parallel, mortars durability and hydration products were evaluated by mean of durability tests (wetting drying cycles, sulfate attack and acid rain simulation) and analytical methods (scanning electron microscopy, X-ray diffraction and thermo-gravimetric analysis). Finally, mortar samples were submitted to various leaching tests to evaluate the pollution potential of these matrices