Master´s thesis is focus on the proces of mechanical alloying. It is the proces of modifying a hetegeneous mixture of powder materials into a homogeneous composite powder. Experiments are focus on three types of composite materials. A magnetic soft alloy Permalloy, ODS steel based on commercially available powder steel 434 LHC and low-activation high-chrome ODS steel 14Cr-2W. On composite powders are made a series of mechanical tests and chemicel analysis. Based on this tests and analysis it was possible to confirm the milling time needed to create fully homogeneous composite powder. Next step is compaction of composite powder into compact volume and another mechanical tests ana analysis of microstructure. In these analyzes to determine whether i tis necessary to use protective atmosphere during mechanical alloying. All three type of materials succesfull prepared by mechanical alloying. It was found that for created of a fully homogeneous composite powder is necessary to perform mechanical alloying for 24 hours. When processing of corrosion resistant materials, i tis possible to perform mechanical alloying in an air atmosphere. During mechanical alloying materials which are subject to oxidation, i tis necessary to use protective atmosphere.

Este trabalho utilizou pulsos laser ultracurtos para modificar, de forma controlada, as características dimensionais de nanopartículas de prata em solução aquosa. Para atingir este objetivo foram empregados algoritmos genéticos e circuitos microfluídicos. Utilizou-se um conformador temporal de pulsos ultracurtos para criar diversos perfis temporais de pulsos que irradiaram soluções de nanopartículas de prata. Estes perfis temporais foram ajustados em tempo real, visando otimizar o resultado do experimento, quantificada pela diminuição do diâmetro médio das nanopartículas nas soluções irradiadas. Uma vez que cada experimento de minimização do diâmetro das nanopartículas exigiu centenas de medidas, sua realização foi possível em decorrência da utilização de um circuito microfluídico construído especialmente para este trabalho. Neste circuito é possível utilizar pequenas quantidades de amostra, levando a curtos tempos de irradiação e medição, além da evidente economia de amostras. Para a realização deste trabalho foi elaborado e testado um algoritmo genético interfaceado a diversos equipamentos, incluindo um filtro acustóptico dispersivo programável que modifica as características temporais dos pulsos ultracurtos, através da introdução de componentes de fases espectrais nestes pulsos. Utilizando o algoritmo genético e o filtro acustóptico dispersivo programável foram realizados experimentos de encurtamento da duração temporal dos pulsos ultracurtos provenientes do sistema laser, resultando na obtenção de pulsos com durações próximas às limitadas por transformada de Fourier. Além disso, foram realizados experimentos para a otimização do processo evolutivo do algoritmo genético escrito em Labview. Os experimentos de irradiação de soluções de nanopartículas de prata mostraram que, ao conformar a duração dos pulsos utilizados nas irradiações, pôde-se controlar as dimensões destas nanopartículas, diminuindo seu tamanho médio por um fator 2. Esses experimentos caracterizam a irradiação de nanopartículas por lasers de pulsos ultracurtos como uma importante técnica de controle de características de nanopartículas. / This work used ultrashort laser pulses to modify, in a controlled way, the dimensional characteristics of silver nanoparticles in aqueous solution. To reach this goal, genetic algorithm and microfluidic circuits were used. A pulse shaper was used to create different temporal profiles for the ultrashort pulses used to irradiate the silver nanoparticle solutions. These temporal profiles were conformed in real time, aiming to optimize the experiment result, quantified by the decrease of the average diameter of the nanoparticles in the irradiated solutions. Since each nanoparticle diameter minimization experiment demanded hundreds of measurements, its achievement was possible by the use of a microfluidic circuit specially built for this work. This circuit enables the use of small sample quantities, leading to short irradiation and measurement intervals, besides evident sample savings. To make this work possible, a genetic algorithm was created and tested. This genetic algorithm was interfaced to several equipments, including an acustooptic programmable dispersive filter that modifies the ultrashort pulses temporal characteristics by the introduction of spectral phases in the pulses. The genetic algorithm and the acustooptic programmable dispersive filter were used in conjunction in experiments to temporally shorten the ultrashort pulses from the laser system, generating pulses durations close to the Fourier transform limited ones. Besides, experiments were performed with the Labview coded genetic algorithm to optimize its evolutionary process. The silver nanoparticles irradiation experiments showed that the ultrashort pulses temporal conformation allowed the control of these particles dimensions, decreasing its mean size by a factor of 2. These experiments characterize the nanoparticles irradiation by ultrashort pulses as an important technique to control the nanoparticles characteristics.

Ligas metálicas não nobres são amplamente utilizadas em odontologia desde a segunda metade do século XX. Várias ligas metálicas para utilização em próteses sobre o implante dentário têm sido propostas nos últimos anos, visando uma melhor interação metal-cerâmica e maior resistência eletroquímica ao ambiente bucal. O objetivo deste trabalho é avaliar e comparar o comportamento eletroquímico in vitro de ligas à base de cobalto-cromo e níquel-cromo, utilizadas em supra estruturas de implantes dentários. Estas ligas foram estudadas em meios de solução aquosa de NaCl 0,15 mol L-1, saliva artificial e NaCl 0,15 mol L-1 com adição de caseína, fluoreto de sódio ou ácido acético, a partir de técnicas eletroquímicas e não eletroquímicas. Como técnicas eletroquímicas foram empregadas: medidas de potencial de circuito aberto, curvas de polarização anódica, cronoamperometria, voltametria cíclica e espectroscopia de impedância eletroquímica. As técnicas não eletroquímicas utilizadas foram: espectroscopia de absorção atômica com atomização eletrotérmica (EAA-FG), espectroscopia de fotoelétrons excitados por raios-X (XPS), microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva (EDS). Foram realizados testes de citotoxicidade utilizando a metodologia de incorporação do vermelho neutro. Uma boa correlação foi estabelecida entre os resultados obtidos pelas diferentes técnicas. Em solução de NaCl e saliva artificial as ligas apresentaram a seguinte ordem de resistência à oxidação: CoCrW < NiCrMo < CoCrMo. O filme formado em meio de saliva artificial se mostrou mais protetor do que o formado em meio de NaCl para todas as ligas, indicando que componentes presentes na saliva ao se adsorverem na superfície conferem uma maior proteção à mesma. As análises por XPS confirmaram a existência de um filme rico em Cr(III) com pequena concentração de cobalto e de níquel no filme passivo. As análises por EAA-FG a potenciais mais positivos mostraram que nesta região há oxidação generalizada, com a total dissolução do filme passivo e formação de Cr(VI), Ni(IV) e Co(II). As análises por MEV-EDS, para a superfície das ligas CoCrW e NiCrMo, apresentaram uma superfície quase homogênea e composições semelhantes antes e após 8h de imersão em meio de NaCl e em saliva artificial. A caseína atuou inibindo os processos de oxidação sobre a liga CoCrW e NiCrMo e sua atuação se tornou mais intensa com o aumento do potencial. A liga NiCrMo apresentou maior resistência à corrosão em meio de caseína quando comparada com a liga CoCrW. Os íons fluoreto atuam melhorando as características passivantes do filme, mas este efeito decresce com o aumento do potencial; a presença de ácido acético causa um aumento do efeito passivante do filme, à medida que cresce o potencial. As ligas CoCrW e NiCrMo não apresentaram efeito citotóxico, de acordo com a metodologia utilizada. / No noble metallic alloys are largely employed in odontology since the second part of the XX centrury. Different alloys have been proposed in order to be used in prosthesis on dental implants at last years, with the objective to obtain electrochemical resistance to oral environment. The aim of this work is to evaluate and to compare the electrochemical behavior \"in vitro\" of Co-Cr and Ni-Cr based alloys, used on dental implants structures. These alloys were studied in 0.15 mol L-1 NaCl aqueous in the absence and presence of casein, artificial saliva, sodium fluoride and acetic acid, using electrochemical and non-electrochemical techniques. Open circuit potencial measurements, anodic polarization curves, cronoamperometry, cyclic voltametry and electrochemical impedance spectroscopy were used as electrochemical techniques. Atomic absorption spectroscopy with graphite furnace (EAA-GF), X-ray photoelectron spectroscopy (XPS), scaning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used as non electrochemical techniques. Cytotoxicity tests using the neutral red incorporation methodology were performed. A good correlation between the different techniques it was obtained. The alloys presented the following corrosion resistance order: CoCrW < NiCrMo < CoCrMo. The film formed in artificial saliva has been showed a better protective action than the observed in NaCl medium for the three studied materials as an indicative of the adsorption of substances present on saliva and the consequent inhibitive effect. XPS analysis have confirmed the presence of a Cr2O3 film with low Co(II) and Ni(II) concentrations. EAA-GF analysis at more positive potentials have shown the presence of generalized oxidation with total dissolution of the passive film resulting in Cr(VI), Ni(IV) and Co(II) ions as soluble products. MEV and EDS analysis have shown a quasi homogeneous and similar surface before and after 8h immersion in NaCl and artificial saliva. Casein has acted as inhibitor for oxidation process of CoCrW and NiCrMo in NaCl medium and its effects increases as the potential becomes more positive. The alloy NiCrMo presented a higher corrosion resistance in NaCl solution containing casein when compared to the CoCrW alloy. Ions fluoride has promoted a better performance of the film at Ecorr but its effects decreases at more positive potentials.The presence of acetic acid increases the passivating effect as potencial becomes more positive. Cytotoxicity was not observed for the alloys studied, using the described methodology

Ligas metálicas não nobres são amplamente utilizadas em odontologia desde a segunda metade do século XX. Várias ligas metálicas para utilização em próteses sobre o implante dentário têm sido propostas nos últimos anos, visando uma melhor interação metal-cerâmica e maior resistência eletroquímica ao ambiente bucal. O objetivo deste trabalho é avaliar e comparar o comportamento eletroquímico in vitro de ligas à base de cobalto-cromo e níquel-cromo, utilizadas em supra estruturas de implantes dentários. Estas ligas foram estudadas em meios de solução aquosa de NaCl 0,15 mol L-1, saliva artificial e NaCl 0,15 mol L-1 com adição de caseína, fluoreto de sódio ou ácido acético, a partir de técnicas eletroquímicas e não eletroquímicas. Como técnicas eletroquímicas foram empregadas: medidas de potencial de circuito aberto, curvas de polarização anódica, cronoamperometria, voltametria cíclica e espectroscopia de impedância eletroquímica. As técnicas não eletroquímicas utilizadas foram: espectroscopia de absorção atômica com atomização eletrotérmica (EAA-FG), espectroscopia de fotoelétrons excitados por raios-X (XPS), microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva (EDS). Foram realizados testes de citotoxicidade utilizando a metodologia de incorporação do vermelho neutro. Uma boa correlação foi estabelecida entre os resultados obtidos pelas diferentes técnicas. Em solução de NaCl e saliva artificial as ligas apresentaram a seguinte ordem de resistência à oxidação: CoCrW < NiCrMo < CoCrMo. O filme formado em meio de saliva artificial se mostrou mais protetor do que o formado em meio de NaCl para todas as ligas, indicando que componentes presentes na saliva ao se adsorverem na superfície conferem uma maior proteção à mesma. As análises por XPS confirmaram a existência de um filme rico em Cr(III) com pequena concentração de cobalto e de níquel no filme passivo. As análises por EAA-FG a potenciais mais positivos mostraram que nesta região há oxidação generalizada, com a total dissolução do filme passivo e formação de Cr(VI), Ni(IV) e Co(II). As análises por MEV-EDS, para a superfície das ligas CoCrW e NiCrMo, apresentaram uma superfície quase homogênea e composições semelhantes antes e após 8h de imersão em meio de NaCl e em saliva artificial. A caseína atuou inibindo os processos de oxidação sobre a liga CoCrW e NiCrMo e sua atuação se tornou mais intensa com o aumento do potencial. A liga NiCrMo apresentou maior resistência à corrosão em meio de caseína quando comparada com a liga CoCrW. Os íons fluoreto atuam melhorando as características passivantes do filme, mas este efeito decresce com o aumento do potencial; a presença de ácido acético causa um aumento do efeito passivante do filme, à medida que cresce o potencial. As ligas CoCrW e NiCrMo não apresentaram efeito citotóxico, de acordo com a metodologia utilizada. / No noble metallic alloys are largely employed in odontology since the second part of the XX centrury. Different alloys have been proposed in order to be used in prosthesis on dental implants at last years, with the objective to obtain electrochemical resistance to oral environment. The aim of this work is to evaluate and to compare the electrochemical behavior \"in vitro\" of Co-Cr and Ni-Cr based alloys, used on dental implants structures. These alloys were studied in 0.15 mol L-1 NaCl aqueous in the absence and presence of casein, artificial saliva, sodium fluoride and acetic acid, using electrochemical and non-electrochemical techniques. Open circuit potencial measurements, anodic polarization curves, cronoamperometry, cyclic voltametry and electrochemical impedance spectroscopy were used as electrochemical techniques. Atomic absorption spectroscopy with graphite furnace (EAA-GF), X-ray photoelectron spectroscopy (XPS), scaning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used as non electrochemical techniques. Cytotoxicity tests using the neutral red incorporation methodology were performed. A good correlation between the different techniques it was obtained. The alloys presented the following corrosion resistance order: CoCrW < NiCrMo < CoCrMo. The film formed in artificial saliva has been showed a better protective action than the observed in NaCl medium for the three studied materials as an indicative of the adsorption of substances present on saliva and the consequent inhibitive effect. XPS analysis have confirmed the presence of a Cr2O3 film with low Co(II) and Ni(II) concentrations. EAA-GF analysis at more positive potentials have shown the presence of generalized oxidation with total dissolution of the passive film resulting in Cr(VI), Ni(IV) and Co(II) ions as soluble products. MEV and EDS analysis have shown a quasi homogeneous and similar surface before and after 8h immersion in NaCl and artificial saliva. Casein has acted as inhibitor for oxidation process of CoCrW and NiCrMo in NaCl medium and its effects increases as the potential becomes more positive. The alloy NiCrMo presented a higher corrosion resistance in NaCl solution containing casein when compared to the CoCrW alloy. Ions fluoride has promoted a better performance of the film at Ecorr but its effects decreases at more positive potentials.The presence of acetic acid increases the passivating effect as potencial becomes more positive. Cytotoxicity was not observed for the alloys studied, using the described methodology

Este trabalho utilizou pulsos laser ultracurtos para modificar, de forma controlada, as características dimensionais de nanopartículas de prata em solução aquosa. Para atingir este objetivo foram empregados algoritmos genéticos e circuitos microfluídicos. Utilizou-se um conformador temporal de pulsos ultracurtos para criar diversos perfis temporais de pulsos que irradiaram soluções de nanopartículas de prata. Estes perfis temporais foram ajustados em tempo real, visando otimizar o resultado do experimento, quantificada pela diminuição do diâmetro médio das nanopartículas nas soluções irradiadas. Uma vez que cada experimento de minimização do diâmetro das nanopartículas exigiu centenas de medidas, sua realização foi possível em decorrência da utilização de um circuito microfluídico construído especialmente para este trabalho. Neste circuito é possível utilizar pequenas quantidades de amostra, levando a curtos tempos de irradiação e medição, além da evidente economia de amostras. Para a realização deste trabalho foi elaborado e testado um algoritmo genético interfaceado a diversos equipamentos, incluindo um filtro acustóptico dispersivo programável que modifica as características temporais dos pulsos ultracurtos, através da introdução de componentes de fases espectrais nestes pulsos. Utilizando o algoritmo genético e o filtro acustóptico dispersivo programável foram realizados experimentos de encurtamento da duração temporal dos pulsos ultracurtos provenientes do sistema laser, resultando na obtenção de pulsos com durações próximas às limitadas por transformada de Fourier. Além disso, foram realizados experimentos para a otimização do processo evolutivo do algoritmo genético escrito em Labview. Os experimentos de irradiação de soluções de nanopartículas de prata mostraram que, ao conformar a duração dos pulsos utilizados nas irradiações, pôde-se controlar as dimensões destas nanopartículas, diminuindo seu tamanho médio por um fator 2. Esses experimentos caracterizam a irradiação de nanopartículas por lasers de pulsos ultracurtos como uma importante técnica de controle de características de nanopartículas. / This work used ultrashort laser pulses to modify, in a controlled way, the dimensional characteristics of silver nanoparticles in aqueous solution. To reach this goal, genetic algorithm and microfluidic circuits were used. A pulse shaper was used to create different temporal profiles for the ultrashort pulses used to irradiate the silver nanoparticle solutions. These temporal profiles were conformed in real time, aiming to optimize the experiment result, quantified by the decrease of the average diameter of the nanoparticles in the irradiated solutions. Since each nanoparticle diameter minimization experiment demanded hundreds of measurements, its achievement was possible by the use of a microfluidic circuit specially built for this work. This circuit enables the use of small sample quantities, leading to short irradiation and measurement intervals, besides evident sample savings. To make this work possible, a genetic algorithm was created and tested. This genetic algorithm was interfaced to several equipments, including an acustooptic programmable dispersive filter that modifies the ultrashort pulses temporal characteristics by the introduction of spectral phases in the pulses. The genetic algorithm and the acustooptic programmable dispersive filter were used in conjunction in experiments to temporally shorten the ultrashort pulses from the laser system, generating pulses durations close to the Fourier transform limited ones. Besides, experiments were performed with the Labview coded genetic algorithm to optimize its evolutionary process. The silver nanoparticles irradiation experiments showed that the ultrashort pulses temporal conformation allowed the control of these particles dimensions, decreasing its mean size by a factor of 2. These experiments characterize the nanoparticles irradiation by ultrashort pulses as an important technique to control the nanoparticles characteristics.

Les Plasmons de surface à l’interface d’un métal et d’un diélectrique sont des oscillations collectives des électrons libres. Pour une interface plane, les plasmons se manifestent comme des champs électromagnétiques évanescents, confinée à quelques centaines de nanomètres de la surface métallique et se propagent le long de l'interface. Ce mode plasmonique, appelé plasmon propagatif de surface (PSP), est un mode fondamental. D’autres modes fondamentaux, non-propagatifs, sont appelé plasmons localisés (LSP) et apparaissent dans les nano-particules métalliques. Dans ce travail, nous avons calculé analytiquement la polarisabilité de géométries métalliques complexes et les résultats obtenus permettent d’expliquer les conditions de résonance des différents modes plasmoniques.Parmi les divers modes plasmoniques, plusieurs modes fondamentaux ont été étudiés en détail et décrits par une formulation analytique. Tout d’abord, dans un réseau binaire de lignes métalliques, des plasmons propagatifs confinés par la dimension finie des lignes sont générés. Ce mode plasmonique est appelé plasmons propagatifs confinée (CPP). D’autre part, dans des réseaux périodiques de nano-particules métalliques, déposées sur un film métallique, des modes de Bragg (BM) sont excités par la diffraction des PSP. De plus, dans de telles structures, un couplage harmonique entre les LSP des nano-particules et le PSP du film métallique sous-jacent se traduit par l’apparition d’un mode hybride (HLP). Les caractéristiques de ce mode hybride pour un réseau de nano-cylindres métalliques sur un film métallique sont présentées en détails, en particulier son intérêt en bio-détection.L'effet du milieu diélectrique environnant sur les modes plasmoniques est utilisé dans les détecteurs basés sur la résonance des plasmons de surface (SPR). Ces systèmes mesurent le décalage de la résonance d’un mode plasmonique, qui est fonction de l’indice de réfraction du milieu diélectrique. L’un des buts de ce travail est d'optimiser les détecteurs SPR pour des expériences typiques sondes – cibles où les molécules sonde sont greffées à la surface du capteur. Nous avons montré que par une fonctionnalisation sélective de la surface métallique, une amélioration de la performance de détection peut être obtenue en terme de quantité de molécules cibles détectable. L'amélioration de champ proche joue aussi un rôle majeur dans les techniques de diffusion Raman exaltée de surface (SERS). La présence de certains des modes plasmoniques étudiés dans les substrats nano-structurés permet d’augmenter significativement l'intensité du signal SERS.Pour réaliser ce travail, des méthodes numériques adaptées à la géométrie particulière des structures étudiées ont été développés pour calculer les distributions des champs proches et lointains dans ces structures. Les caractéristiques de ces modes plasmoniques ont été mesurés expérimentalement et leurs performances en détection SPR ont été démontrées en utilisant une configuration basée sur une interrogation angulo-spectrale en configuration de Kretschmann. Des expériences de SERS ont également été réalisées en collaboration avec le CSPBAT à Paris 13. Les différentes structures ont été fabriquées par lithographie électronique à l’IEF à Paris 11. Les résultats expérimentaux concordent avec les résultats numériques et analytiques.Cette description détaillée des modes plasmoniques offre une compréhension plus complète du phénomène de résonance des plasmons de surface dans les nanostructures métalliques et permet d’optimiser les structures selon l’application souhaitée. Le modèle présenté dans ce travail est relativement général et peut être utilisé pour décrire les propriétés électromagnétiques de différentes géométries et configurations expérimentales. De la représentation complète des modes plasmoniques, différents aspects des interactions photons-plasmons peuvent ainsi être étudiés. / The surface plasmons on metallic surfaces are excited by the collective oscillations of free electrons. They satisfy certain resonance conditions and their dispersion can be considered as modes of the system. The plasmons at uniform metal-dielectric interfaces manifest as evanescent electromagnetic (EM) fields confined to a few hundreds of nanometers from the metallic surface and propagate along the interface. This mode is called the Propagating surface plasmon (PSP) and is a fundamental plasmonic mode. The other fundamental modes, which are non-propagative, results from collective oscillations of free electrons on curved surfaces of metallic nano-particles. They are called localized surface plasmon (LSP) modes. We have shown that the polarizability of complex geometries with an underlying substrate can be calculated analytically and the results obtained closely approximate the resonance conditions for such geometries.In this work, various other plasmonic modes originating from the two fundamental modes were studied in details and described by their corresponding analytical formulation. In a binary metallic arrays on glass substrate, plasmonic modes are excited by diffraction orders, called the Wood-Rayleigh modes (WRM). In metallic strips the PSP is confined by the finite edges of the strips and propagate along the length of the strips, called the confined propagating plasmons (CPP).For arrays of metallic nano-particles on a metallic film, the Bragg modes (BM) are excited by diffraction of the PSP. In such structures the LSP of the nano-particles and the PSP of the film can undergo a harmonic coupling to give rise to the hybrid lattice plasmon (HLP). The characteristics of the HLP mode for an array of metallic nano-cylinders on a metallic film is presented in details.The effect of the surrounding medium on the plasmonic modes is used in surface plasmon resonance (SPR) detectors which probe the shift in resonance condition of the modes. Such shift is dependent on the intrinsic dispersion of the modes. The aim of this work is to optimize the SPR detectors for affinity biosensing where probe and analyte molecules are bound to the metallic surface. We have shown that by selective functionalization of the metallic biochip surface, an enhancement of the performance of such detection can be achieved in terms of the amount of analyte used. Also the near field enhancement plays a major role in surface enhanced Raman scattering (SERS). We have shown that the presence of certain modes in the system can enhance the recorded SERS intensity.Rigorous numerical methods, adapted to the particular geometry under study, were developed to compute the near and far field characteristics of different structures. The experimental excitation of the modes and their application in SPR detection was demonstrated using a setup based on a spectral scanning modality operating in the Kretschmann configuration. The various structures were fabricated on a biochip using e-beam lithography at IEF, University Paris Sud and the reflectivity dispersion from the biochip was recorded. Such experimental results were shown to be in close agreement with the theoretical results. SERS experiments were carried out in collaboration with CSPBAT at University Paris 13 and the results were seen to fit closely the theoretically predicted trends.Such detailed description of plasmonic modes can offer a complete understanding of the surface plasmon resonance phenomenon in metallic structures and be optimized as per required for various applications. The theories presented in this work can be used to effectively describe the EM properties of different geometries and experimental configurations. From a comprehensive representation of plasmonic modes, different aspects of the photon-plasmon interactions can thus be elucidated.

Les travaux expérimentaux présentés dans cette thèse associent deux pans de la physique de la matière condensée, avec d'un côté la physique des verres de spins et de l'autre la physique mésoscopique. Le verre de spins est un exemple emblématique de système désordonné et frustré, il se caractérise à basse température par un ordre magnétique non conventionnel, où le désordre magnétique apparaît gelé. De plus, celui-ci est considéré comme un système modèle pour étudier les verres en général et de ce fait, il a fait l'objet de nombreuses études expérimentales et théoriques. Après d'importants efforts de recherche, la description de l'état fondamental de ce système a abouti à deux approches très différentes. La première, donnée par la résolution non triviale du problème en champ moyen, met en avant un état fondamental composé d'une multitude d'états organisés et hiérarchisés. La deuxième approche, dite des "gouttelettes", se base quant à elle sur la dynamique hors équilibre d'un unique état. Cependant, en dépit de ces contributions, la compréhension de cette phase est loin d'être complète et la nature de l'état fondamental reste encore un débat ouvert. Dans un conducteur mésoscopique, le transport se fait de manière cohérente : les électrons gardent la mémoire de leur phase, ce qui permet d'observer des effets d'interférences électroniques. La motivation à la base de ce travail est d'utiliser ces effets d'interférences comme outil pour étudier le verre de spins. En effet, étant donné que les interférences électroniques dépendent intiment de la disposition du désordre statique du conducteur, le transport cohérent peut se révéler être une sonde microscopique très efficace pour étudier la configuration du désordre dans un conducteur. Bien que quelques expériences pionnières de transport cohérent existent dans des verres de spins, ce domaine de recherche n'a que très peu été exploré. Néanmoins, il a connu un récent renouveau grâce à des travaux théoriques qui montrent de quelle manière cette sonde est sensible au désordre magnétique gelé et comment elle peut fournir des informations sur la nature de l'état fondamental du verre de spins. Ainsi, ce travail de thèse expérimental présente l'implémentation de mesure de transport dans des verres de spins mésoscopiques. La première partie de l'étude est consacrée aux caractéristiques générales de transport classique et quantique de ces systèmes. Nous avons examiné les propriétés de la résistivité en fonction de la température et du champ magnétique et nous montrons que ces systèmes mésoscopiques possèdent bien des comportements attendus pour des verres de spins. Dans une deuxième partie, nous nous sommes intéressés au comportement de la magnétorésistance à bas. Nous avons mis en avant que celle-ci présente une forte hystérésis dont l'amplitude dépend fortement, de la température dans la phase vitreuse et de la vitesse de balayage du champ magnétique. Nous avons argumenté que ce comportement particulier traduit la mise hors équilibre du système et montrons comment la température et la vitesse de balayage du champ magnétique pilotent l'écart à l'équilibre. Dans cette partie, nous avons aussi examiné par des mesures de transport la relaxation du système vers l'équilibre, après l'avoir excité. Nous présentons également les propriétés de transport étonnantes que nous avons observées à bas champ, résultant de protocoles en températures et en champs magnétiques plus complexes. / The experiments presented in this thesis associate two fields of condensed matter physic, on the one hand with the spin glass physic and the other hand with the mesoscopic physic. The spin glass state is one of the most emblematic of disordered and frustred system and at low temperature, it is caracterized by an unconventionel order where the magnetic disorder is quenched. Moroever, it is considered as a model system for glasses in general and thereby it has been extensively studied, both experimentally and theoreticlly. After extensive research efforts, the description of fundamental state of the system has lead towards two well different approaches. The first, given by the mean field solution, highlights a fundamental composed of mulitple states organised and hierarchical. The second, called droplet model is based on the off--equilibrium dynamic of a unique ground state. However, despite these contributions, the understanding ot this phase is far from being complete and the nature of the ground state still remains an open question. In a mesoscopic conductor, the transport of electron is coherent: electrons keep the memory of their phase, so that one can observe interference effects. The main motivation of this work is to use these interference effects in order to to probe the spin glass state. Indeed, as electronic interference depends of the position of the static disorder, coherent transport can be a useful tool to study the configuration of the microscopic disorder. Althought few coherent transport experiments exist to probe the spin glass, this field of research has very little explored. Nevertheless, this area has been a revival thanks to theoritical work, showing how coherent transport is sensitived to the quenched disorder and how it may provide informations of the nature of fundamental state of spin glass. So, this experimental work deals with the implementation of transport measurements in mesoscopic spin glasses. The first part of the study is focused on the general charateristics of classical and quatum transport of these system. We have examined the resistivity as a function of the temperature and magnetic field and we show that these mesoscopic systems have a spin glass-like behaviour. In a second part, we have focused on the low field magnetoresistivity. We show that it presents a strong hysteresis, whose the amplitude is strongly depends, both of the temperature in the glassy phase and sweeping rate of the magnetic field. We argue that this particular behaviour is related to the out off-equilibrium of the system and we show how the temperature and the sweeping rate control the deviation to the equilibrium. In this part, we also examine by transport measurements how the system relaxes towards the equilibrium just after its excitation. In addition, we present surprinsing transport propreties that we observed, resulting of experimental protocols more sophisticated in temperatures and magnetic fields.

Les interactions entre le fer métal et l'argilite du Callovo-Oxfordien choisie comme roche hôte pour le stockage des déchets radioactifs, a été étudiée expérimentalement. Le rôle des paramètres clés des transformations (rapports fer/argile, et liquide/roche) ont été étudiés à 90°C, et afin d'accélérer la cinétique des réactions à 150°C et 300°C. Les interstratifiés illite-smectite et les illites sont dissous et remplacés par de nouvelles phases argileuses. Les analyses au MET ont permis de déterminer des Fe-serpentines (phases à 7 Å, groupe de la berthiérine) à 90°C, des phases gonflantes de type smectite tri-octaédrique à 150°C, et des chlorites et des interstratifiés chlorite/smectite à 300°C. Quelle que soit la température, la transformation des feuillets illitiques (I et I/S) n'est pas complète et il reste toujours des feuillets à garniture interfoliaire sodi-calcique, interprétés comme des smectites résiduelles ou néoformées. En comparaison avec le système fer-smectite (bentonite), les différences portent sur la cinétique de réaction, beaucoup plus rapide dans le cas de l'argilite, et l'instabilité du quartz qui comme l'illite contribue à libérer le silicium nécessaire à la formation des silicates de fer. Les transformations observées trouvent des analogies avec les altérations hydrothermales et métasomatoses Fe-Mg des systèmes naturels / The interactions between the iron metal and the argillite from the Callovo-Oxfordian formation chosen as host for the disposal of the radioactive wastes, was experimentally studied. The role of the key parameters of the transformations (iron / clay, and liquid / rock ratios) was studied at 90°C, and, to accelerate reaction kinetics, at 150°C and 300°C. Mixed layered illite-smectite and illites are dissolved and replaced by new clay phases. TEM analyses show that Fe-serpentines (7 Å phases, group of the berthierine) predominates in run products at 90°C, tri-octaedral Fe-rich smectites at 150°C, and chlorites and probably smectite chlorite mixed layered at 300°C. Whatever the temperature, the illite and I/S replacement is not complete and trun products are always accompanied by sodi-calcic residual and/ or newly formed smectites. In comparison with the iron-smectite (bentonite) system, the differences concern the reaction kinetics which are much faster in the case of the argillite, and the instability of the quartz which, as the illite, contributes to release the silicium necessary for the formation of iron silicates. The observed process find analogies with the hydrothermal changes described in natural hydrothermal alterations and Fe-Mg metasomatism

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Les terrains ultramafiques de Nouvelle-Calédonie, riches en Ni, Co, Mn et Cr sont exploités par des mines à ciel ouvert, ce qui génère l'émission de poussières riches en métaux. L'objectif de ce travail est de développer des approches pour estimer le risque environnemental lié aux poussières émises par les mines à ciel ouvert et les usines de traitement du minerai de nickel. L'estimation de la fraction biodisponible des métaux contenus dans deux fractions granulométriques de poussières, celle inférieure à 100 ~m mobilisable par le vent (F<1 OO~m.) et celle susceptible de pénétrer le système respiratoire (PM1 0), a été réalisée par extractions cinétiques à I'EDTA. L'obtention des PM10 a nécessité la mise au point d'une technique de tri par transport des particules dans un tube horizontal grâce à un flux d'azote. Les extractions cinétiques ont permis de discrimtner trois fractions de métaux: rapidement extraite, lentement extraite et non biodisponibles. Les concentrations en métaux potentiellement biodisponibles sont toujours très élevées et la fraction lentement extraite est toujours la plus concentrée. Pour F<1 00 ~m. les constantes cinétiques de la fraction lentement extraite sont plus faibles pour les poussières de sols miniers que celles de sols forestiers. Les poussières issues de sols miniers seraient alors un réservoir en éléments métalliques biodisponibles à plus long terme. La bioindication lichénique avec traitement en données compositionnelles des concentrations en métaux permet de définir un indice de dispersion des poussières. Cette méthodologie pourrait appuyer les réseaux de surveillance de la qualité de l'air en Nouvelle-Calédonie. / Bioavailability estimation of nickel, cobalt and manganese in dust from ultramafic soils likely to be mobilized by wind and~eve lopment of a bioindication tool using lichen for dust emitted by mining activities in New Caledonia New Caledonian altered ultramafic soils, particularly rich in Ni, Co, Mn and Cr, are extracted by opencast mines which generale dust rich in metals. The objective of th is work is to develop approaches for environmental risk assessment of dust emitted by opencast mines and nickel ore metallurgical plants. The assessmentof metals' bioavailable fraction from two dust granulometrie size fractions, one less than 100 IJm which is mobilizable by wind (F<1001Jm,) and another one able to penetrate the respiratory system (PM 1 0), has been determined by kinetic extraction with EDT A. The development of a new separation deviee based on particle transport subjected to a nitrogen flux in a horizontal tube has been necessary for PM1 0 segregation. Kinetic extractions le ad to the distinction of th ree metal pools: rapidly labile, less rapidly labile and non-bioavailable. Trace metal potentially bioavailable concentrations were always high and the less rapidly labile pool is always the most concentrated pool. Concerning F<1 001Jm, the less rapidly kinetic constant of the less rapidly labile pool is weaker for mining soils than forest soils. F<1001Jm fractions from mining soils representa more durable reserve in trace metal than the same fraction from forest soils. Bioindication using lichens with compositional data analysis of their metal concentration allow defining an indicator of emission dispersion. This methodology could support air quality monitoring networks in New Caledonia.