Teses / dissertações sobre o tema "Diffraction des rayons X sur monocristal"
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Kenfack, Tsobnang Patrice. "Synthèse, caractérisation et étude du comportement à la déshydratation par diffraction des rayon X sur monocristal et poudre, de quelques composés supramoléculaires à base de métallo-tectons ioniques". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0243/document.
Texto completo da fonteThis work, realized under the IUCr initiative, framework involves the structural study via X-ray diffraction, of some heteromolecular architectures formed by the association through non-covalent bonds, between the tris (oxalato) chromate (III) and tris (oxalato) ferrate (III) anions {[M(C2O4)3]3-, M = Cr, Fe} and the cationic complex of the 2-picolylamine (amp) and transition metal (Co2 +, Cu2 + and Mn2 +). Co2 + ion builds two-dimensional corrugated layers made of bimetallic chiral chains where the two different complex ions ([Cr(C2O4)3]3- and [Co(amp)3]3 +) are connected by hydrogen bonds. These layers, connected by weak hydrogen interactions, host between them, water molecules which build dodecameric clusters having new characteristics. The dehydrated compound has different structure and color and is able to quickly reabsorb water molecules from surrounding to regenerate the initial compound despite that it has no pores. Several cycles of this process do not seriously affect the crystalline quality of this compound. The compound obtained with the Cu2 + ion also has a two-dimensional framework. Their layers are formed between the dimeric cation [Cu2 (amp) 4Cl]3 + and the anion {[M(C2O4)3]3-,M = Cr, Fe}. Both compounds are iso-structural; their frameworks are formed via π - - - π interactions and build 1D channels which contain water molecules forming hexameric clusters. The compound undergoes a phase transition between 100 K and the dehydration temperature (341K). During this dehydration, a loss of symmetry of the compound is recorded and rehydration process is more difficult than for cobalt(III)-framework. The use of Mn2+ ions does not give the expected architecture but a new coordination polymer
Lebon, Alexandre. "Influence de la direction de polarisation sur la coexistence de phases et la structure en domaines du ferroélectrique - relaxeur Pb(Zn1/3Nb2/3)O3 : une étude sur monocristal par diffraction des rayons X et diffusion Raman". Châtenay-Malabry, Ecole centrale de Paris, 2001. http://www.theses.fr/2001ECAP0707.
Texto completo da fontePb(Zn1l3Nb2/3)03 (PZN) is a complex lead based perovskite. This ferroelectric relaxor exhibits remarkable electromechanical properties that make necessary a study as a function of the direction of polarisation. In fact, even though the spontaneous polarisation is parallel to a <111> direction, its piezoelectric properties are optimised when the crystal is polarised along [001]. Spontaneously, the cubic → rhombohedral phase transition that occurs at Tc = 385 ± 5 K is diffuse in temperature. Rhombohedral microdomains appear within the cubic phase, as their number increases, they occupy all the crystal around 330 K. Below Tc, the application of an electric field along [111] induces a complex structure of rhombohedral macrodomains. These macrodomains of a few tens of microns are separated by regions that diffuse light and that belongs to {11O} plans. As the [001] direction of the applied electric field is concerned, a Monoclinic tetragonal phase coexistence is induced. In a field cooling process, a structure of 4 monoclinic microdomains is ordered symmetrically with respect to the direction of the electric field. All , our data enabled to build an electric field - temperature diagram (E-T) along [001]. At last, on the basis of structural data, a tetragonal symmetry is proposed for the nanopolar regions that give way to dielectric relaxation
Morançais, Amélie. "Effet du grenaillage sur la durée de vie des aubes monocristallines de turbine". Thesis, Troyes, 2016. http://www.theses.fr/2016TROY0004/document.
Texto completo da fonteShot-peening is widely used on roots of high pressure turbine blade to postpone crack initiation in stress concentration area. This pre-stressing introduces compressive residual stress and strain hardening in a surface layer which will influence lifetime. The aim of this thesis is to propose a methodology which allows taking into account the impact of such pre-stressing and their evolution on the fatigue behaviour of a single crystal nickel-based superalloy (AM1) used for high pressure turbine blades. Firstly, the experimental work is devoted to the determination of the initial mechanical state (residual stresses and strain hardening). Residual stresses are namely determined using X-ray diffraction involving the use of a specific method developed by Ortner. This experimental initial mechanical state is then introduced as an input in structure calculation. The well-known method involving the direct introduction of eigenstrain profiles is used and improved to also introduce strain hardening variables and the complete anisotropic mechanical state in all the integration points of the structure. The next step consist in following experimentally and modeling the evolution of these quantities under thermal and mechanical loads under an uniform temperature (650°C). Finally, the complete lifetime assessment is carried out on representative shot-peened samples. Results are discussed with respect to experimental fatigue tests
Dutta, Rajesh. "Etude in situ, par diffraction des rayons X et diffusion neutronique sur monocristaux, de la complexité structurale de l'oxyde fortement corrélé Pr2-xSrxNiO4+δ". Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0754/document.
Texto completo da fonteNon-stoichiometric oxides from the Ruddlesden-Popper series, such as Pr2NiO4+δ, can be hole-doped by substituting strontium to praseodymium or by oxygen insertion. This leads to complex structural ordering involving oxygen-, charge- and spin ordering. The complex phase diagram of Pr2-xSrxNiO4+δ was explored using X-ray (laboratory and synchrotron) as well as neutron diffractions. For the doped phase of highest oxygen content (Pr2NiO4.25), we could evidence an incommensurate structure with satellite reflections of 6th order, yielding a very complex diffraction pattern of up to four twin-individuals and eight incommensurate domains. Checkerboard-type charge ordering was identified already at ambient temperature, while stripe charge ordering was observed below 170 K by synchrotron and neutron diffraction; incommensurate spin ordering appears below 99 K. This thesis reveals the existence of many complex oxygen and electronically ordered phases going along with small variations of the oxygen/strontium stoichiometry
Ahumada, Toro Guillermo. "Synthèses et caractérisations spectroscopiques, structurales et électrochimiques de nouveaux complexes bases de Schiff symétriques contenant le groupe 2-thiényle électropolymérisable". Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S075.
Texto completo da fonteThe one-pot double condensation reaction of 2-thenoyltrifluoroacetone (TTAH) with primary diamines does not lead to the formation of the expected symmetric Schiff bases, but in the case of ethylenediamine (en) to a mixture of bis(trifluoroacetamide)ethylene and 7-(thiophene-2-yl)-5-(trifluoromethyl)-2,3-dihydro-1H-1,4-diazepine derivatives, while only 4-trifluoromethyl-2-(thiophen-2-yl)-1,5-benzodiazepine was isolated starting from o-phenylenediamine. The templated condensation reaction between ethylenediamine and bis(β-diketonate)metal complexes [M(TTA)2(S)2] (M = Co, Ni, Cu) gave exclusively the corresponding octahedral compounds [M(TTA)2(en)], where the ethylenediamine ligand chelates the metal center. The symmetrical Schiff base ligands [H2N2O2] bearing the 2-thienyl and the trifluoromethyl groups were prepared in two steps by (i) double condensation of acetylthiophene and ethylenediamine to generate the expected diimine, and (ii) treatment of the diimine with trifluoroacetic acid. In their corresponding Schiff base complexes of Co(II), Ni(II) and Cu(II), the metal ion is tetracoordinated in a square-planar environment. The coordination sphere is formed by the nitrogen and oxygen atoms of the dianionic tetradentate [N2O2]2- ligand. Those complexes as well as their analogues in which the CF3 group has been substituted for the 4-fluorophenyl unit, are inert toward electropolymerization. By contrast, replacement of the CF3 group by the parent methyl one allows electrochemical oxydation of the respective complexes and formation of an isolating deposit with passivation of the electrode and inhibition of the propagation of the polymerization. Interestingly, insertion of a conjugated p-phenylene unit between the 2-thienyl group and the CF3-substituted [M(N2O2] core permits the generation of a polythienyl-containing square planar Schiff base complexes of Ni(II) and Cu(II) films, and their deposition on an electrode using an electrochemical oxidation process
Syamala, Vishnu Vijayakumar. "Molecular organization in solid-state using sigma-hole interactions : Exploring the effect of crystalline environment". Electronic Thesis or Diss., Université de Lorraine, 2022. https://docnum.univ-lorraine.fr/ulprive/DDOC_T_2022_0214_VIJAYAKUMAR_SYAMALA.pdf.
Texto completo da fonteUnderstanding the fundamentals of the formation and stabilization of non-covalent interactions is of paramount importance in the field of crystal engineering. In this direction, this thesis reports the crystallographic investigation of a sub-class of non-covalent interactions known as sigma-hole interactions. sigma-hole interactions are defined as those involving electrophilic sites (also called sigma-holes) associated to a covalently bonded atom belonging to either p-block (groups 13-18) or d-block (groups 8,11 and 12) of the periodic table, and nucleophilic sites coming from either the same or a different molecule. Depending upon the group of the atom on which the sigma-hole is present, the interaction can be further classified into various sub-classes. Out of these, we have focused on the cases of halogen bond (HaB) and chalcogen bond (ChB) interactions. As compared to the well-established case of hydrogen bonds (HB), the rationale behind the formation and stabilization of HaB and ChB are still less explored. This thesis is aimed exactly in such a direction, to provide a deeper insight into the characteristics of HaB and ChB interactions, mainly by understanding how the electron density is distributed among the interacting pair of atoms and how it eventually influences the molecular organization in solid-state. Two main stream topics of crystallography are covered during the course of this thesis: (i) high-pressure X-ray diffraction studies and (ii) charge density analysis. Structural and electronic investigations are carried out based on the data derived from single-crystal X-ray diffraction (SCXRD) experiments performed either at ambient or extreme conditions. The so-obtained crystal structures were used to derive the electron density distribution in the periodic phases. The electron distributions of the molecular systems extracted from their crystalline environments were used to calculate the electrostatic potential in molecular surfaces and to carry out the topological analyses of the electron density and its laplacian function within the framework of the Quantum Theory of Atoms in Molecules (QTAIM) methodology. The effect of crystalline environments in tuning the properties of sigma-hole interactions is also explored in detail. The information gathered from such analyses is not only helpful to better understand the molecules in hands, but also to design new molecular patterns with the aim to control the structure-properties relationship in molecular crystals
Diologent, Frédérics. "Comportement en fluage et en traction de superalliages monocristallins à base de nickel". Paris 11, 2002. http://www.theses.fr/2002PA112300.
Texto completo da fonteWe have study the different mechanical behaviour (creep test performed at 760ʿC/840 MPa, 950ʿC/300 MPa, 1050ʿC/150 MPa, 1150ʿC/100MPa, and tensile test performed between 20ʿC and 1100ʿC) between a first generation single-crystal superalloy (AM1) and a new generation single-crystal superalloy (MC-NG). Difference between the chemistries of the two superalloys lies in the fact that MC-NG contrary to AM1 contains, among others, rhenium and ruthenium. Influence of the γ\γ' microstructures had been taking into account. We have identified parameters who control the superalloys creep deformation at 760ʿC. The difference of behaviour that we encounter between AM1 and MC-NG had been attributed to the solid solution strengthening of the γphase of the MC-NG which is higher than in the AM1. During creep comparison at 950ʿC and 1150ʿC we have enlighten the beneficial effect due to rhenium in the MC-NG who inhibit plasticity in the γphase trough different mechanisms. We have push forward our investigations concerning creep behaviour at 1050ʿC on these two alloys. In fact, previous studies had been shown the particular nature of the MC-NG creep curve compare to other superalloys at this temperature. We have identify mechanisms driving the early onset of the tertiary creep in the MC-NG case as well as lamellar γ\γ' microstructure destabilisation causes. Concerning tensile test, the aim was to understand in which extent 0,2\% yield stress was higher in the AM1 than in the MC-NG at low temperatures. Study of this behaviour according to temperature as well as dislocations structures examination allow us to conclude. So, the fact that MC-NG γ' phase be less alloying in titanium and tantalum than the AM1 one is responsible of this difference
Boulle, Alexandre. "Diffraction des rayons X sur couches d'oxydes épitaxiées : Elaboration et analyse microstructurale". Limoges, 2002. http://www.theses.fr/2002LIMO0040.
Texto completo da fonteThis work deals with microstructural analysis in oxide epitaxial layers. Specific acquisition methods have been developed, such as the so-called reciprocal space mapping technique. Experiments have been carried out on a home made diffractometer devoted to the study of nanostructured materials. This set-up allows very fast reciprocal space map acquisitions (e. G. A few tens of minutes) in a high resolution mode. The two-dimensional instrumental profile has been calculated taking into account each optical element in the beam path : the X-ray source, the four-bounce monochromator, the sample and the curved position sensitive detector. This study showed that the instrumental broadening can be as low as a few thousandth of degrees in most of the scanning modes. Two oxide systems have been investigated. The first one is the ferroelectric material SrBi2Nb2O9 deposited onto SrTiO3 by sol-gel coating. Integral breadth as well as Fourier analysis of the diffraction profiles showed that the samples contain stacking faults located along the c-axis. The microstructural analysis of Y2O3 stabilized ZrO2 thin films deposited onto Al2O3 by sol-gel coating has been undertaken by profile modeling into several directions of reciprocal space taking into account physical parameters (the instrument and the microstructure). A peculiar epitaxial growth mechanism and a void/matter phase separation have been evidenced. Additionally it is shown that the layers are highly strained, and strain relaxation probably occurs by the introduction of misfit dislocations
Fajoui, Jamal. "Influence des hétérogénéités intragranulaires sur le comportement des matériaux métalliques sous sollicitations mécaniques". Nantes, 2008. http://www.theses.fr/2008NANT2105.
Texto completo da fonteMetal forming may often involve intense forming sequences, leading to large strains and severe strain path changes. These processes, very constraining for material, are limited by the appearance and the development of plastic instabilities and/or damage. Deductive methods based on strain mechanisms and scale transitions constitute relevant tools for a better comprehension. Two-level homogenization approaches are developed for the micromechanical modelling of the elastoplastic material behaviour. At the microscopic level, the mechanical behaviour is described by different scale transition models like self-consistent, Kröner or Mori-Tanaka. The grain is considered as a two-phase material : dislocations walls (with high density dislocation) and cells (with low density dislocation) and cells (with low density dislocation). The intragranular heterogeneities are highlighted by a non-local work-hardening, which is linked to the twophase description. Correct agreement is observed between simulations and experiments (X-ray diffraction, mechanical tests) results at the meso and macroscopic levels
Taiebi, Issam. "Etude de la conversion de l'isopropanol et de l'oxydation ménagée du propane sur hétéropolyanions déposés sur silice : nature des sites réactifs". Lille 1, 2001. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2001/50376-2001-265.pdf.
Texto completo da fonteRieutord, François. "Réflectivité et diffraction des rayons X appliquées aux films minces organiques". Paris 11, 1987. http://www.theses.fr/1987PA112384.
Texto completo da fonteFilal, Saïd. "Influence de la composition organique et minérale des eaux des réseaux sur les caractéristiques chimiques et structurales des biofilms". Poitiers, 2001. http://www.theses.fr/2001POIT2314.
Texto completo da fonteBenrabah, Abderrahim. "Influence des contraintes résiduelles sur le comportement en fretting des matériaux métalliques". Ecully, Ecole centrale de Lyon, 1995. http://www.theses.fr/1995ECDL0038.
Texto completo da fonteBernard, Frédéric. "Les contraintes résiduelles en réactivité des solides : détermination et rôle sur les mécanismes réactionnels". Dijon, 1993. http://www.theses.fr/1993DIJOS021.
Texto completo da fontePoussin, Lysiane. "Influence de traitements thermiques et d'irradiations sur le polypropylène". Poitiers, 1995. http://www.theses.fr/1995POIT2315.
Texto completo da fonteAbgrall, Serge. "Mesure des forces de frettage sur un cylindre métallique émaillé, par diffraction des rayons X et par indentations Vickers". Toulouse, INPT, 1996. http://www.theses.fr/1996INPT006G.
Texto completo da fonteGavilan, Elisabeth. "Cristallochimie de composés hybrides à base de poly-carboxylates et d'oxoanions : synthèse, caractérisation structurale par diffraction des rayons X par le monocristal et la poudre et réactivité thermique". Rennes 1, 2007. http://www.theses.fr/2007REN1S170.
Texto completo da fonteThe aim of this work was to build porous hybrid materials displaying original topologies in order to obtain zeolite-like properties. The retained strategy was the use of targeted inorganic and organic building units (BU). The selected inorganic BU are made of various metallic polyhedra MOn and two kinds of organic BU have been chosen, poly-carboxylates and oxocarbons. The crystal structures of the hybrid materials have been solved from powder or single-crystal X-ray diffraction data and the thermal behaviours have been studied by thermogravimetry and thermodiffractometry. A discussion is carried out about the role of the metal environment and the ligand coordination modes on the structures dimensionality. Likewise, the influence of the bond strength within the hydrogen-bonding network on both the structure stability and the zeolite-like properties has been evidenced within these architectures
Choubrac, Léo. "Cristallochimie de composés dérivés de Cu2ZnSnS4 pour des applications photovoltaïques". Nantes, 2014. https://archive.bu.univ-nantes.fr/pollux/show/show?id=67905501-3436-41fa-8cc8-7fbe0e136902.
Texto completo da fonteThe photovoltaic performances of Cu2ZnSnS4 derivatives (CZTS)-based thin film solar cells are strongly dependant of the crystallochemistry properties of this material. Particularly, the copper-poor zinc-rich compounds are widely known to be the most efficient, and the structural disorder as a brake on growth of the efficiencies. A large set of CZTS compounds have been synthesized by solid state route. The study of these compounds permits us to determine a phase diagram which reveals two distinct type of substitution. Then we lead a structural investigation, at the scale of the cell with XRD methods (on powders and single crystals, and on classical as well as on resonant conditions), and at the atomic scale with solid state NMR of 65Cu, 67Zn and 119Sn. The combination of these techniques allows describing these substitution mechanisms and finally a relationship between composition, synthesis conditions and structural disorder. Then, Raman spectroscopy – as a common and thin-film suitable method – has been use as a characterization tool. Finally, a large part of these results have been extended to the homologue selenide compounds (Cu2ZnSnSe4 derivatives)
Dionnet, Bernard. "Influence des contraintes sur l'oxydation dans l'air à haute température d'alliages réfractaires". Limoges, 1993. http://www.theses.fr/1993LIMO0237.
Texto completo da fonteBonnin, Anne. "Étude d'un système portable d'inspection par rayonnement X utilisant les effets combinés d'absorption multi-énergies, de diffusion et diffraction X sur la matière". Lyon, INSA, 2009. http://theses.insa-lyon.fr/publication/2009ISAL0112/these.pdf.
Texto completo da fonteThis thesis is focused on the discrimination between explosives and common materials by X-rays. Three X-ray based methods are described: multi-energy transmission, Compton scattering and diffraction. These three methods are discussed from a theoretical and experimental point of view. The memory consists of four parts. After describing the general context of the study, the physical phenomena and the properties of the involved materials are given. In a second part devoted to transmission, the principle of multi-energy 2D imaging is presented. Then, we develop an approach to dual-energy 3D imaging, which allows a representation of materials in a database of effective density and atomic number. This approach allows to discriminate a numbers of explosives. In the third part, the X-ray diffraction is discussed in order to identify materials by their spectral signature. The semi-crystalline and crystalline materials are recognized, but not amorphous ones. The fourth part focuses on Compton scattering. We tested different methods of acquisition: pinhole, coded masks and a X-rays scanning technique using a pencil beam. These techniques allow to obtain images of objects. The device is placed on the same side of the object, which is particularly interesting in practical field. In summary, we discuss the complementarity of information extracted from these differents techniques to specify the characteristics of a portable system for land analysis
Loubens, Audrey. "Champ de déformation induit dans un monocristal par un réseau de dimensions submicroniques : diffraction des rayons X en mode haute résolution et simulation par éléments finis". Saint-Etienne, EMSE, 2006. http://www.theses.fr/2006EMSE0001.
Texto completo da fonteMechanical stresses in thin films and nanostructures have a strong influence on the reliability of devices. We propose a non destructive method for local strain measurements, which relies on X-ray diffraction coupled with finite element modelling. Si3N4 line arrays (thickness:149nm, width:145nm, pitch:169nm) on silicon have been analysed. Reciprocal space maps obtained by High Resolution X-Ray Diffraction are compared with maps calculated from displacement fields derived from finite element modelling. The good agreement between experiment and simulation allows for a validation of the calculated displacement field. The second model is an array of SOI (Silicon On Insulator) lines (period:0. 6m, width: period/2, t=50nm). The strain fields in the silicon substrate as well as in the SOI lines have been analysed. There is a qualitative agreement between measurements and calculations. This method is a powerful way to investigate local strain fields in a non-destructive way
François, Manuel. "Determination de contraintes residuelles sur des fils d'acier eutectoide de faible diametre par diffraction des rayons x". Paris, ENSAM, 1991. http://www.theses.fr/1991ENAM0011.
Texto completo da fonteBaudot, Sophie. "MOSFETs contraints sur SOI : analyse des déformations par diffraction des rayons X et étude des propriétés électriques". Phd thesis, Grenoble, 2010. http://www.theses.fr/2010GRENY064.
Texto completo da fonteThe use of mechanical stress in the channel of MOSFETs on SOI is mandatory for sub-22 nm technological nodes. Its efficiency depends on the device geometry and design. The impact of different steps of the transistor fabrication process (active area patterning, metal gate formation, Source/Drain (S/D) implantation) on the strain in strained Silicon-On-Insulator (sSOI) materials has been measured by Grazing Incidence X-Ray Diffraction (GIXRD). The electrical performance enhancement of MOSFETs on sSOI has also been estimated with respect to SOI (100% mobility enhancement for long and wide nMOS (L=W=10 μm), 35% saturation drive current (IDsat) enhancement for short and narrow nMOS (L=25 nm, W=77 nm)). Innovative strained structures have then been studied. We demonstrate a 37% (18%) IDsat enhancement for pMOS on SOI (sSOI) with SiGe S/D compared to sSOI with Si S/D, for a 60 nm gate length and a 15 nm film thickness. GIXRD measurements, together with mechanical simulations, enabled the study and optimization of new structures using the stress transfer from an embedded and stressed layer (SiGe or nitride) toward the channel
Baudot, Sophie. "MOSFETs contraints sur SOI : analyse des déformations par diffraction des rayons X et étude des propriétés électriques". Phd thesis, Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00557963.
Texto completo da fonteLatrach, Abdelkhalek. "Affinement structural par ajustement du profil total obtenu par diffraction X ou neutronique sur poudres". Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37598978d.
Texto completo da fonteal, @Haddad Mostapha. "Théorie statistique de la diffraction des rayons X et des neutrons : [thèse soutenue sur un ensemble de travaux]". Grenoble 1, 1989. http://www.theses.fr/1989GRE10046.
Texto completo da fonteMartin, Franck. "Microstructure, contraintes des multicouches métalliques Mo (110) / Ni (111) élaborées par pulvérisation ionique : influence sur les propriétés élastiques". Poitiers, 2003. http://www.theses.fr/2003POIT2266.
Texto completo da fonteWe investigated interfacial effects on properties of Mo(110)/Ni(111) multilayers by X-ray diffraction techniques and Brillouin light scattering. We observe a large softening of the shear modulus up to 65% of the predicted value. The interplanar spacings evolution and numbers of planes in Mo sub-layers suggest a Ni interdiffusion. . Considering an elastically soft interfacial layer in determining the C44 modulus allow to estimate it's specific modulus and the chemical interdiffusion length. The epitaxied multilayers showed a "Nishiyama-Wassemann" orientation relationship and a decrease of the "stress free" parameter, in Mo sub-layers, with decreasing period confirming the Ni diffusion in Mo. MoxNi1-x solid solutions showed metastable phases, for solute concentration below 27%, with a large decrease of the shear modulus up to 50% of the predicted value and above 27% alloys are amorphous and the shear modulus is stabilized
Lorut, Frédéric. "Etude de monocristaux de KTiOPO4 sous champ électrique : mesures électriques, observations optiques et imagerie par diffraction aux rayons X". Université Joseph Fourier (Grenoble), 2000. http://www.theses.fr/2000GRE10211.
Texto completo da fonteMaity, Avishek. "Etude des mécanismes de diffusion de l’oxygène dans SrFeO3-x et Pr2NiO4+d, réalisée par diffraction du rayonnement synchrotron in situ sur monocristal". Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT188/document.
Texto completo da fonteUnderstanding fundamental aspects of oxygen diffusion in solid oxides at moderate temperatures, down to ambient, is an important issue for the development of a variety of technological devices in the near future. This concerns e.g. the progress and invention of next generation solid oxygen ion electrolytes and oxygen electrodes for solid oxide fuel cells (SOFC) as well as membrane based air separators, oxygen sensors and catalytic converters to transform e.g. NOx or CO from exhaust emissions into N2 and CO2. On the other hand oxygen intercalation reactions carried out at low temperatures present a powerful tool to control hole doping, i.e. the oxygen stoichiometry, in electronically correlated transition metal oxides. In this aspect oxides with Brownmillerite (A2BB’O5) and K2NiF4-type frameworks, have attracted much attention, as they surprisingly show oxygen mobility down to ambient temperature. In this thesis we investigated oxygen intercalation mechanisms in SrFeO2.5+x as well as Pr2NiO4+x by in situ diffraction methods, carried out on single crystals in especially designed electrochemical cell, mainly exploring synchrotron radiation. Following up oxygen intercalation reactions on single crystals is challenging, as it allows to scan the whole reciprocal lattice, enabling to obtain valuable information as diffuse scattering, weak superstructure reflections, as well as information of the volume fraction of different domains during the reaction, to highlight a few examples, difficult or impossible to access by powder diffraction. Both title systems are able to take up an important amount of oxygen on regular and interstitial lattice sites, inducing structural changes accompanied by long range oxygen ordering. For SrFeO2.5+x the uptake of oxygen carried out by electrochemical oxidation yields SrFeO3 as the final reaction product. The as grown SrFeO2.5 single crystals we found to show a complex defect structure, related to the stacking disorder of the octahedral and tetrahedral layers. During the oxygen intercalation we evidenced the formation of two reaction intermediates, SrFeO2.75 and SrFeO2.875, showing complex and instantly formed long range oxygen vacancies. Due to the specific twinning with up to totally twelve possible twin individuals, we directly follow up the formation and changes of the specific domain and related micro-structure. We thus observed a topotactic reaction mechanism from SrFeO2.5 to SrFeO2.75, while further oxidation lead to important rearrangements in the dimensionality of the oxygen defects in SrFeO2.75, implying the formation of an additional twin domain in course of the reaction. The electrochemical reduction of orthorhombic Pr2NiO4.25 yields stoichiometric Pr2NiO4.0 as the final reaction product with the same symmetry, while tetragonal Pr2NiO~4.12 appears as a non-stoichiometric intermediate phase. Using a single crystal with 50µm diameter, the reaction proceeded under equilibrium conditions in slightly less than 24h, implying an unusually high oxygen ion diffusion coefficient of > 10^-11cm2*s-1 at already ambient temperature. From the changes of the associated twin domain structure during the reduction reaction, the formation of macro twin domains was evidenced. Heating up Pr2NiO4.25 single crystals in air revealed a complex series of phase transition, evidencing the true symmetry of the starting phase to be in fact monoclinic. Beside exploring the complex phase diagrams of SrFeO2.5+x and Pr2NiO4+d we were able to investigate detailed changes in the micro-structure using in situ single crystal diffraction techniques, impossible to access by classical powder diffraction methods. The importance of changes in the domain structure goes far beyond the investigated title compounds and has utmost importance of the performance, stability and lifetime of e.g. battery materials
Allain, Laurent. "Etude des effets de la temperature sur la diffraction des rayons x par des composes semiconducteurs iii-v". Paris 6, 1988. http://www.theses.fr/1988PA066016.
Texto completo da fonteLI, ALICE. "Application de la diffraction des rayons x a l'etude de la rupture par fatigue sur un alliage d'aluminium". Paris, ENSAM, 1993. http://www.theses.fr/1993ENAM0023.
Texto completo da fonteAllain, Laurent. "Etude des effets de la température sur la diffraction des rayons X par des composés semiconducteurs III-V". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376112320.
Texto completo da fonteMasson, Olivier. "Etude des défauts de structure par diffraction des rayons X sur poudres : Utilisation d'un montage en réflexion asymétrique équipé d'un détecteur courbe à localisation". Limoges, 1998. http://www.theses.fr/1998LIMO0008.
Texto completo da fonteReguer, Solenn. "Phases chlorées sur les objets archéologiques ferreux corrodés dans les sols : caractérisations et mécanismes de formation". Paris 11, 2005. https://tel.archives-ouvertes.fr/tel-00011748v2.
Texto completo da fonteFor restoration and conservation of metallic artefacts of the cultural heritage, investigation of iron corrosion process in soil related to the presence of chloride was based on local and structural characterization of chlorinated corrosion products formed on archaeological artefacts. To unambiguously identify these corrosion products, some high-resolution techniques as µ-Raman spectroscopy and X Ray synchrotron radiation micro beam techniques, such as micro X-Ray Diffraction and micro X-Ray Absorption experiments, were used to obtain structural micro scale information. A second part of the study concern discussion on the exact location of chlorine anions in akaganeite beta-FeOOH structure. The fundamental results help to gain new insights concerning the influence of such phases in iron corrosion mechanism within their precise characterisation
Bruneseaux, Fabien. "Apport de la diffraction des rayons X à haute énergie sur les transformations de phases, application aux alliages de titanes". Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL019N/document.
Texto completo da fonteThe high energy X-rays diffraction is a powerful tool to characterize the phase transformation in metallic materials. Its use in the case of titanium alloys has allowed to study the phase transformation during heat treatments. We were able to characterize the different phases involved, to determine in situ the evolution of the mass fraction and the cell parameters of each phase. In the first time, we have studied the phase transformation a + ß ? ß during heating of Ti17, Ti64 and Ti6242 titanium alloys. The cell parameters evolutions have been compared to the chemical composition variations (determined by Thermocalc). Then, the transformation kinetics have been compared to calculated results obtained by a phase field approach. For the Ti17 alloy, we have characterized the phase transformation ß ? a + ß during the cooling. Different conditions were used: the anisothermal condition (during continuous cooling) and the isothermal condition (during dwells at different temperatures). The influence of the thermal path have been considered by means of tempering from a [bêta]-metastable state at room temperature. The evolution of the phase fraction has been compared to kinetics measured by electrical resistivity. The cell parameter and full width at half maximum (FWHM) variations and of each phase have allowed to highlight the changes of the chemical composition and the elastic strain during phase transformation
Humbert, Séverine. "Influence de la topologie moléculaire et de la microstructure sur les propriétés mécaniques des Polyéthylènes". Lyon, INSA, 2009. http://theses.insa-lyon.fr/publication/2009ISAL0101/these.pdf.
Texto completo da fonteThe semi-crystalline polymers are widely used in fields as various as packaging, automotive, aeronautics. . . Because of their specific properties. Thus, the need to predict their viscoelastic and plastic behaviours with microstructural parameters is quite obvious. Due to its relatively simple structure which makes it a model material for semi-crystalline polymers, the Polyethylene has been and remains the most studied. However, there remain many unresolved issues, including the mechanical coupling between the amorphous and crystalline phases. Our work has been undertaken with a view to advancing knowledge on micro-mechanisms of deformation. In this aim, we have selected five polyethylenes of various molecular architectures. Then different heat treatments were carried out to modify their initial microstructure. We have been able to decorrelate the microstructure and the molecular topology. A wide campaign of microstructural and mechanical characterization (tensile tests, DMA, AFM, RX. . . ) has allowed to demonstrate the roles of two different scales on the mechanical behaviour: the scale of the lamella and the scale of the spherulites. Particular attention was paid on the stress transmitters (tie molecules, entanglements, interphase) present between the amorphous and crystalline phase. We have thus demonstrated their significant influence on micro-mechanisms of deformation. They play a role on the elastic and plastic properties much significant than it is generally reported in the literature
BENSOUSSAN, SERGE. "Deformations dans les heterostructures epitaxiees sur des substrats semiconducteurs iii-v : etude experimentale par diffraction de rayons x et simulation sur ordinateur". Paris 6, 1986. http://www.theses.fr/1986PA066374.
Texto completo da fonteBen, Soussan Serge. "Déformations dans les hétérostructures épitaxiées sur des substrats semiconducteurs III-V étude expérimentale par diffraction de rayons X et simulation sur ordinateur". Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37595951n.
Texto completo da fontePalin, Luca. "Résolution des structures cristallines par diffraction des rayons X et neutrons sur poudres en utilisant les méthodes d'optimisation globale". Phd thesis, Université Joseph Fourier (Grenoble), 2005. http://tel.archives-ouvertes.fr/tel-00077233.
Texto completo da fonteMonnet, Ghiath. "Caractérisation de l'énergie stockée par diffraction des rayons X dans les multicristaux de cuivre : effet sur la recristallisation statique". Phd thesis, Université Paris-Nord - Paris XIII, 1999. http://tel.archives-ouvertes.fr/tel-00426731.
Texto completo da fonteARANDA, PABLO. "Etude de la fusion bidimensionnelle par diffraction de rayons x : application a la monocouche de tetrachloromethane physisorbe sur graphite". Paris 6, 1994. http://www.theses.fr/1994PA066302.
Texto completo da fonteMOHANGD, GHIATH. "Caractérisation de l’énergie stockée par diffraction des rayons X dans les multicristaux de cuivre : effet sur la recristallisation statique". Paris 13, 1999. http://www.theses.fr/1999PA132009.
Texto completo da fonteLaire, Odile. "Mise au point du procédé d'élaboration par M. O. V. P. E. De matériaux semiconducteurs et d'hétérostructures III-V basées sur GaAs, Ga(1-x)Al(x)As, Ga(1-x)In(x)As". Montpellier 2, 1995. http://www.theses.fr/1995MON20063.
Texto completo da fonteGîrleanu, Maria. "Etude de la structure de films minces de nitrure de titane et d'aluminium Ti1-xAlxN (0 ≤ x ≤ 1) et de son rôle sur l'indentation". Phd thesis, Université de Haute Alsace - Mulhouse, 2010. http://tel.archives-ouvertes.fr/tel-00604272.
Texto completo da fonteLegagneux, Nicolas. "Chimie organométallique de surface sur hétéropolyacides supportés et non supportés : application à l'oxydation partielle du méthane en méthanol". Lyon 1, 2009. http://www.theses.fr/2009LYO10033.
Texto completo da fonteThe aim of this work was the synthesis and characterization of organometallic complexes grafted on silica supported ans unsupported heteropolyanions. PtMe2(COD) react on silicotungstic acid (H4SiW12O40) in an homogeneous way to form [SiW12 O10 4-] [Pt+Me(COD)(DMSO]4. DMSO. This reaction allow the formation of ionic interactions between the metallic center and the heteropolyacid which keeps his Keggin structure. The reaction with tetramethyltin gives this species : [SiW10 O40 4-] [Sn+ Me3 (DMSO)2]4. 2 DMSO. The supported heteropolyacids keep their Keggins structure and, for silicotungstic acid, an acidic proton remains on the polyanion. This acidic proton reacts stoichiometrically with PtMe2(COD) with quantitative release of methane. In an other hand, the silica supported silicotungstic acid behaves as a catalyst for the grafting reaction of tetramethyltin over the silanols of the silica surface. [SiW12 O10 4-] [Pt+Me(COD)(DMSO]4. DMSO. And oleum allow us to increase the TON of the oxidation of methane into methyl bisulfacte to 69
Chaigneau, Julienne. "Compétitions cationiques dans les pérovskites au bismuth (Bi,Pb)(Sc,Ti,Fe)O3 : influence sur les ordres polaire et magnétique". Châtenay-Malabry, Ecole centrale de Paris, 2008. http://www.theses.fr/2008ECAP1104.
Texto completo da fonteComplex perovskite structures derivated from AB03 structure are mainly known for their electrical properties. They can be used in capacitors, Random Access Memories (FeRAM), actuators. . . The insertion of a magnetic cation on the B-site allows the creation of multiferroic materials in which polar and magnetic orders coexist. These multifunctional materials have all the potential applications of both their properties. In addition, a whole range of new applications can be envisaged via the coupling between these orders (if it exists). For instance, they can be used in multiplestate memory elements, ir which data is stored both in the electric and the magnetic polarizations, or novel memory media, which might allow the writing of a ferroelectric data bit and the reading of the magnetic field generated by association. Aside from the potential applications, the fundament" physics of multiferroic materials is rich and fascinating. From the study of solid solutions(1-x)BiSc03-xPbTi03, (1-x)BiFe03-xPbTi03 et Bi1-xPbxFe03, we tried to understand the effect of chemical substitution on structure and properties of these materials. X-ray and Neutron diffraction studies with respect to substitution x and temperature, associated to magnetic measurements, allowed us te bring to light the existence of an energitical competition between polar and magnetic orders affecting magnetoelectric properties. Moreover, we evidenced the role of the cation nature on long-range and short-range crystallographic structure of solid solutions studied and notably on the existence and stability of low-symmetry phases in drawn phase diagrams ("Morphotropic Phase Boundaries")
Cunin, Frédérique. "Synthèses, études structurales par spectroscopie de vibration, diffraction de rayons x sur poudre, analyse Rietveld de perchlorates covalents et ioniques". Montpellier 2, 2000. http://www.theses.fr/2000MON20016.
Texto completo da fonteMuzard, Sophie. "Morphologie de dépôts d'or d'épaisseur nanométrique obtenus par pulvérisation ionique sur un substrat de carbone amorphe - effets de l'assistance par des ions de forte énergie - influence de l'incorporation de nickel par copulvérisation". Poitiers, 1998. http://www.theses.fr/1998POIT2256.
Texto completo da fonteMatringe, Caroline. "Nanostructuration bidimensionnelle de surfaces vicinales de saphir : Etude quantitative par diffusion et diffraction des rayons x sur sources de lumière synchrotron". Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0032/document.
Texto completo da fonteNanostructured systems based on nanoparticles deposited onto oxide surfaces have both a fundamental and technological interests. Final properties of such systems depend mostly on the shape and size of the nanoparticles and also on their spatial organization on the surface. In this general context, the use of vicinal surfaces appears to be an interesting way of producing templates for ordering nanoparticles. This work is devoted to the study of two-dimension (2D) nanostructuration of sapphire vicinal surfaces obtained under specific experimental conditions (vicinal surface orientation and thermal treatment parameters). The main objectives of this study were to describe the surface morphology of the samples having the 2D ordering and also to propose a mechanism regarding the transition from the 1D to the 2D ordering.Morphology of sapphire vicinal surfaces, annealed at 1250 °C under pure oxygen atmosphere during various durations up to 380 h, was studied by complementary technics: atomic force microscopy (AFM), grazing-incidence small-angle X-rays scattering (GISAXS), and grazing-incidence X-rays diffraction (GIXD). Results allowed us to describe the 2D ordered surface by being an assembly of pyramids with an isosceles triangle base decorating a rectangular centered lattice. The shape of those irregular tetrahedrons has been precisely determined with the crystallographic characteristics of sapphire. It has also been shown that a meandering step-edge phenomenon is probably the starting point of the transition between 1D and 2D lattices obtained when initial step-edges are straight
Brunelli, Michela. "Etude par diffraction des rayons X sur poudres haute résolution de solides organiques moléculaires : molécules bicycliques et dérivés halogénés de l'éthane". Université Joseph Fourier (Grenoble), 2001. http://www.theses.fr/2001GRE10002.
Texto completo da fonte