Nos dias atuais, grande parte das intervenções cirúrgicas inclui o implante de materiais. Os grandes obstáculos na implantação de próteses em organismos humanos são a coagulação sanguínea em contato com o material devido ao alto grau de ativação plaquetária e a compatibilidade dos tecidos biológicos ao material implantado. Agregando melhorias de propriedades mecânicas a superfícies biocompatíveis, materiais poliméricos apresentam grandes tendências a serem excelentes candidatos a biomateriais para tais aplicações. O objetivo deste trabalho foi realizar modificações superficiais em polímeros através do método de implantação por feixe iônico a fim de se investigar mudanças induzidas em suas propriedades superficiais e estudar possíveis mudanças em sua biocompatibilidade, em específico, sua hemocompatibilidade. Amostras de policarbonato foram irradiadas com feixes de íons de argônio com energia 23 keV e cinco diferentes doses. As superfícies das amostras foram analisadas com medidas de ângulo de contato, microscopia de força atômica, espectroscopia de massa de íons secundários, espectroscopia de fotoelétrons, espectroscopia de retroespalhamento Rutherford, deteção de recuo elástico, espectroscopia de raios-X induzidos por partículas e testes de adesão plaquetária. Os resultados das diferentes técnicas apontaram de forma consistente a uma série de alterações químicas e físicas induzidas nas superfícies das amostras, dentre elas: a perda significativa de hidrogênio nas amostras irradiadas, aumento do grau de reticulação entre as cadeias poliméricas que levou ao aumento de elétron deslocalizados e mudança de coloração, remoção de aditivos, migração à superfície de átomos de argônio implantados e alteração de hidrofilicidade. Ao confrontar todos os resultados obtidos com os resultados dos testes de adesão plaquetária, constatou-se que os efeitos observados aumentam o caráter trombogênico da superfície do policarbonato e que a remoção de aditivos com grupos sulfato e sulfonato após irradiação com argônio teve grande influência em tal aumento. / In the current days, a big part of the surgical interventions includes the implant of materials. The great obstacles for prosthesis implantation in living organisms are the blood clotting when in contact to the material due to a high level of platelet activation and the biological tissues compatibility to the implanted material. By joining improvements on mechanical properties to biocompatible surfaces, polymer materials present high tendencies to be excellent biomaterials candidates for such applications. The objective of this work was to perform surface modification in polymers through the ion beam implantation method in order to investigate changes induced in their surface properties and study possible biocompatibility changes. Samples of polycarbonate were irradiated with argon ion beam with 23 keV energy and different doses. The surfaces of the samples were analyzed by contact angle measurements, atomic force microscopy, secondary ion mass spectroscopy, x-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, elastic recoil detection, particle induced x-ray spectroscopy and platelet adhesion tests. The results from the different techniques pointed consistently to a series of chemical and physical changes induced on the samples\' surfaces, such as: significant loss of hydrogen for the irradiated samples, increase of cross-linking between polymer chains which led to the increase of delocalized electrons and color change, removal of additives, migration of argon atoms to the surface and hydrophilicity changes. By comparing all the obtained results to the platelet adhesion tests results, it was found that the observed effects increase the thrombogenic characteristic of the polycarbonate surface and that the removal of additives with sulfate and sulfonate groups after the argon irradiation had great influence on such increase.

Este trabalho tem por objetivo a caracterização de filmes finos de óxido de alumínio produzidos por deposição assistida por feixe de íons Ar+. Tal caracterização consiste em estabelecer a relação entre os parâmetros de produção (energia do feixe e uxo relativo de Ar), a composição e a estrutura dos lmes. Para tanto, utiliza-se técnicas de microscopia de força atômica, difração de raios-x, reetividade de raios-x e análise por feixe iônico. Resultados mostram que amostras produzidas à temperatura ambiente e à 450 oC são amorfas independentemente da energia do feixe iônico. Filmes formados com assistência de feixe possuem qualidade superior àqueles formados por deposição física de vapor. O bombardeamento de íons Ar+ mostra-se capaz de controlar a concentração de hidrogênio, a estequiometria, a rugosidade, o tamanho dos grãos e a densidade dos lmes nos. Amostras com excelente qualidade baixa rugosidade, estequiometria próxima da ideal e boa densidade foram produzidas utilizando íons com energia dentre 300 eV e 600 eV. / The scope of this work is the characterization of aluminum oxide thin films produced by Ar+ ion beam assisted deposition. This characterization consists in establishing the relationship between production parameters (ion beam energy and argon relative ux), structure and composition of these lms. In order to undertake this task, the following techniques were used: atomic force microscopy, x-ray diraction, x-ray reectivity and ion beam analysis. Results show that samples produced at room temperature and at 450 oC are amorphous regardless the ion beam energy. Films grown under ion assistance have better characteristics than the ones deposited by physical vapor deposition. The ion beam bombardment is capable of controlling hydrogen concentration, stoichiometry, roughness, grain size and density of alumina samples. High quality lms at surface and increased density lms with near ideal stoichiometry were produced with 300 eV and 600 eV ion beam energy.

O carbeto de silício (SiC) é um semicondutor com propriedades adequadas para substituir o silício em dispositivos eletrônicos em aplicações que exijam alta potência, alta frequência e/ou alta temperatura. Além disso, é possível crescer termicamente um filme de dióxido de silício (SiO2) sobre o SiC de maneira análoga ao silício. Porém, esses filmes apresentam maior densidade de defeitos eletricamente ativos na região interfacial SiO2/SiC que no caso do SiO2/Si, o que limita a qualidade dos dispositivos formados. Assim, compreender a origem da degradação elétrica e desenvolver métodos para passivar os defeitos na região interfacial SiO2/SiC são importantes passos para o desenvolvimento da tecnologia do SiC. Buscando uma melhor compreensão da natureza dos defeitos presentes na região interfacial SiO2/SiC, a interação de estruturas SiO2/SiC com vapor d’água enriquecido isotopicamente (D2 18O) e a interação com monóxido de carbono (CO), um dos subprodutos da oxidação térmica do SiC, foram investigadas. Observou-se que a interação com CO gera cargas positivas na estrutura e que a incorporação de deutério proveniente da água é fortemente dependente da rota de formação do filme de SiO2. Sabendo que a incorporação de nitrogênio e de fósforo na região interfacial SiO2/SiC são eficientes métodos para reduzir o número de defeitos eletricamente ativos nessa região, investigou-se a incorporação de nitrogênio em estruturas de SiC através de tratamentos térmicos em amônia enriquecida isotopicamente (15NH3) e desenvolveu-se um novo método de incorporação de fósforo, fazendo sua deposição por pulverização catódica (sputtering) Os métodos de incorporação propostos resultaram em maiores quantidades de nitrogênio e de fósforo na região interfacial SiO2/SiC do que os encontrados na literatura, tornando-os promissores candidatos na passivação elétrica do SiC. Além da caracterização físico-química utilizando diferentes técnicas, também foi feita a caracterização elétrica de capacitores Metal-Óxido-Semicondutor (MOS) testando filmes de SiO2 obtidos por sputtering ou por crescimento térmico. Adicionalmente, desenvolveu-se uma rota de síntese de padrões de 18O mais estáveis ao longo do tempo para serem utilizados em análises por reação nuclear. Também foi proposta uma metodologia de quantificação de fósforo via análise por reação nuclear. Dos resultados obtidos neste doutorado, uma melhor compreensão da natureza e da origem dos defeitos presentes na região interfacial SiO2/SiC foi alcançada. Também obteve-se uma melhor compreensão de como os elementos passivadores nitrogênio e fósforo interagem nessa região. / Silicon carbide (SiC) is a semiconductor with adequate properties to substitute silicon in electronic devices in applications that require high power, high frequency, and/or high temperature. Besides, a silicon dioxide (SiO2) film can be thermally grown on SiC in a similar way to that on Si. However, these films present higher density of electrical defects in the SiO2/SiC interfacial region when compared to the SiO2/Si interface, which limits the quality of the fabricated devices. Thus, it is important to understand the origin of the electrical degradation and to develop methods to passivate the defects in the SiO2/SiC interfacial region in order to develop the SiC technology. Aiming at a better understanding of the nature of defects at the SiO2/SiC interfacial region, the interaction of SiO2/SiC structures with water vapor isotopically enriched (D2 18O) and the interaction with carbon monoxide (CO), one of the SiC thermal oxidation by-products, were investigated. It was observed that the interaction with CO generates positive charges in the structure and that the deuterium incorporation from the water vapor is strongly dependent on the formation route of the SiO2 film. Knowing that nitrogen and phosphorous incorporation in the SiO2/SiC interfacial region are efficient methods to reduce the number of electrical defects in this region, the nitrogen incorporation in SiC structures by isotopically enriched ammonia (15NH3) annealings was investigated and a new method to incorporate phosphorous, by sputtering deposition was developed The proposed incorporation methods resulted in higher amounts of nitrogen and phosphorous then those found in literature, making them promising candidates to the electrical passivation of SiC. Besides the physico-chemical characterization using different techniques, the electrical characterization of Metal-Oxide-Semiconductor (MOS) capacitors was also performed, testing SiO2 films obtained by sputtering deposition or thermally grown. Additionally, a route to synthesize 18O standards for nuclear reaction analyses that are more stable over time was developed. Besides, a methodology to quantify phosphorous by nuclear reaction analysis was proposed. From the results obtained in this PhD thesis, a better understanding of the nature and the origin of defects present in the SiO2/SiC interfacial region was obtained, as well as a better understanding on how the passivating elements nitrogen and phosphorous interact in this region.

Environmentally-assisted cracking (EAC) phenomena affect the in-service behaviour of austenitic stainless steels in nuclear power plants. EAC includes such degradation phenomena as Stress Corrosion Cracking (SCC) and Corrosion Fatigue (CF). Factors affecting EAC include the material type, microstructure, environment, and stress. This is an important degradation issue for both current and Gen III+ light water reactors, particularly as nuclear power plant lifetimes are extended ( > 60 years). Thus, it is important to understand the behaviour of the alloys used in light water reactors, and phenomena such as SCC to avoid failures. Although there is no agreement on the mechanism(s) of SCC, the importance of localized electrochemical reactions at the material surface is widely recognised. Considerable research has been performed on SCC and CF crack growth, but the initiation phenomena are not fully understood. In this project, novel in situ analytical TEM techniques have been developed and applied to explore localised reactions in Type 304 austenitic stainless steel. In situ transmission electron microscopy has become an increasingly important and dynamic research area in materials science with the advent of unique microscope platforms and a range of specialized in situ specimen holders. In metals research, the ability to image and perform X-ray energy dispersive spectroscopy (XED) analyses of metals in liquids are particularly important for detailed study of the metal-environment interactions with specific microstructural features. To further facilitate such studies a special hybrid specimen preparation technique involving electropolishing and FIB extraction has been developed in this thesis to enable metal specimens to be examined in the liquid cell TEM specimen holder using both distilled H2O and H2SO4 solutions. Furthermore, a novel electrode configuration has been designed to permit the localized electrochemical measurement of electron-transparent specimens in the TEM. These novel approaches have been benchmarked by extensive ex situ experiments, including both conventional electrochemical measurements and microcell measurements. The results are discussed in terms of validation of in situ test data as well as the role of the electron beam in the experiments. In situ liquid cell TEM experiments have also explored the localized dissolution of MnS inclusions in H2O, and correlated the behaviour with ex situ experiments. Based on the research performed in this thesis, in situ liquid cell and in situ electrochemical cell experiments can be used to study nanoscale reactions pertaining to corrosion and localized dissolution leading to "precursor" events for subsequent EAC phenomena.

O carbeto de silício (SiC) é um semicondutor com propriedades adequadas para substituir o silício em dispositivos eletrônicos em aplicações que exijam alta potência, alta freqüência e/ou temperatura. Além disso, um filme de dióxido de silício (SiO2) pode ser crescido termicamente sobre o SiC de maneira análoga a sobre silício, permitindo que a tecnologia já existente para a fabricação de dispositivos utilizando Si possa ser adaptada para o caso do SiC. No entanto, filmes crescidos termicamente sobre SiC apresentam maior densidade de defeitos eletricamente ativos na região interfacial SiO2/SiC que no SiO2/Si. Assim, compreender a origem e os parâmetros que afetam essa degradação elétrica é um importante passo para a tecnologia do SiC. A primeira parte deste trabalho teve como objetivo compreender o efeito de parâmetros de oxidação (pressão de oxigênio e tempo de oxidação) no crescimento térmico de filmes de dióxido de silício sobre substratos de carbeto de silício. As oxidações foram realizadas em ambiente rico em 18O2 e a influência na taxa de crescimento térmico dos filmes de Si18O2 e nas espessuras das regiões interfaciais formadas entre o filme dielétrico e o substrato foram investigadas utilizando análises por reação nuclear. Para correlacionar as modificações nas propriedades investigadas com as propriedades elétricas das amostras, estruturas metal-óxidosemicondutor foram fabricadas e levantamento de curvas corrente-voltagem e capacitânciavoltagem foi realizado. Com isso, pretendeu-se melhor compreender a origem da degradação elétrica gerada pela oxidação térmica no SiC. Observou-se que a taxa de crescimento térmico dos filmes de SiO2 depende de um parâmetro dado pelo produto do tempo de oxidação e da pressão de oxigênio, para as condições testadas. O deslocamento da tensão de banda plana com relação ao valor ideal mostrou-se igualmente dependente desse parâmetro, indicando que uma maior degradação elétrica na região interfacial SiO2/SiC ocorrerá conforme o filme fica mais espesso devido ao aumento dos parâmetros investigados. Não observaram-se modificações nas espessuras da região interfacial SiO2/SiC e na tensão de ruptura dielétrica dos filmes de SiO2 atribuídas aos parâmetros de oxidação testados. Na segunda parte deste trabalho, visando minimizar a degradação elétrica da região interfacial SiO2/SiC gerada pela oxidação térmica do SiC, propôs-se crescer termicamente, em uma condição mínima de oxidação, um filme muito fino e estequiométrico de SiO2, monitorado por espectroscopia de fotoelétrons induzidos por raios X. Para formar filmes mais espessos de SiO2 e poder fabricar estruturas MOS, depositaram-se filmes de SiO2 por sputtering. As espessuras e estequiometria dos filmes depositados foram determinadas por espectrometria de retroespalhamento Rutherford com ou sem canalização. As estruturas MOS em que o filme fino de SiO2 foi crescido termicamente antes da deposição apresentaram menor deslocamento da tensão de banda plana com relação ao valor ideal e maior tensão de ruptura dielétrica do que as amostras em que o filme foi apenas crescido termicamente ou apenas depositado, confirmando a minimização da degradação elétrica da região interfacial SiO2/SiC pela rota proposta. O efeito de um tratamento térmico em ambiente inerte de Ar nas estruturas também foi investigado. Observou-se uma degradação elétrica na região interfacial SiO2/SiC devido a esse tratamento. Análises por reação nuclear indicaram que o filme fino crescido termicamente não permaneceu estável durante o tratamento térmico, perdendo oxigênio para o ambiente gasoso e misturando os isótopos de oxigênio do filme crescido termicamente com o do filme depositado. / Silicon carbide (SiC) is a semiconductor with adequate properties to substitute silicon in electronic devices in applications that requires high power, high frequency, and/or high temperature. Besides, a silicon dioxide (SiO2) film can be thermally grown on SiC in a similar way to that on Si, allowing that technology already used to fabricate devices based on Si to be adapted to the SiC case. However, the oxide films thermally grown on SiC present higher density of electrical defects at the SiO2/SiC interfacial region when compared to the SiO2/Si. Thus, the understanding of the origin and what parameters affect the electrical degradation is an important step to the SiC technology. The first part of this work aimed to understand the effect of oxidation parameters (oxygen pressure and oxidation time) in the thermal growth of silicon dioxide films on silicon carbide substrates. The oxidations were performed in an 18O2 rich ambient and the influence on the growth rate of the Si18O2 films and on the interfacial region thickness formed between the dielectric film and the substrate were investigated using nuclear reaction analyses. To correlate the modifications observed in these properties with modifications in the electrical properties, metal-oxide-semiconductors structures were fabricated and current-voltage and capacitancevoltage curves were obtained. The aim was to understand the origin of the electrical degradation due to the thermal oxidation of silicon carbide. It was observed that the growth rate of the Si18O2 films depends on the parameter given by the product of the oxygen pressure and the oxidation time, under the conditions tested. The flatband voltage shift with respect to the ideal value was also influenced by the same parameter, indicating that a larger electrical degradation in the SiO2/SiC interfacial region will occur as the film becomes thicker due to the increase of the values of the investigated parameters. No modifications were observed in the SiO2/SiC interfacial region thickness and in the dielectric breakdown voltage of the SiO2 films that could be attributed to the oxidation parameters tested. In the second part of this work, in order to minimize electrical degradation due to thermal oxidation of silicon carbide, a stoichiometric SiO2 film with minimal thickness was thermally grown, monitored by X-ray photoelectron spectroscopy. To obtain thicker films and to fabricate MOS structures, a SiO2 film was deposited by sputtering. The thicknesses and stoichiometries of the deposited films were determined by Rutherford backscattering spectrometry using or not the channeling geometry. The MOS structures in which a thin film was thermally grown before the deposition presented smaller flatband voltage shift and higher breakdown voltage when compared to SiO2 films only thermally grown or only deposited directly on SiC, confirming that the electrical degradation in the SiO2/SiC interfacial region was minimized using the proposed route. The effect of one thermal treatment in argon in the structures was also investigated. An electrical degradation in the SiO2/4H-SiC interface was observed. Nuclear reaction analyses indicated that the thin film thermally grown was not stable during the annealing, loosing O to the gaseous ambient and mixing O isotopes of the thermally grown film with those of the deposited film.

Patch antennas are fundamental elements in many microwave communications systems. However, patch antennas receive/transmit signals over a very narrow bandwidth (typically a maximum of 3% bandwidth). Design modifications directed toward bandwidth expansion generally yield 10% to 40% bandwidth. The series varactor tuned patch antenna configuration was the bandwidth enhancement method explored in this research; this configuration is implemented by dividing a patch antenna into multiple sections and placing varactors across the resultant gaps. In addition to yielding a large bandwidth, the configuration has a number of ancillary benefits, including straightforward integration and design flexibility. Through the research represented by this work, the properties of the series varactor tuned patch antenna, herein referred to as the Fragmented Patch Antenna (or FPA), were explored and optimized. As a result, an innovative patch antenna was produced that yielded 63.4% frequency tuning bandwidth and covered a frequency range between 2.8 and 5.4 GHz. The wide bandwidth was achieved through a detailed parametric study. The products of this study were the discovery of multiple tuning resonances that were used to expand the tuning bandwidth and the understanding/documentation of the significance of specific antenna dimensions. Measurement results were obtained through the fabrication of a prototype antenna using semiconductor varactors. In the second research phase, the construction of capacitors using the tunable permittivity material Barium Strontium Titanate (BST) was investigated. Using this material in conjunction with nano-fabrication techniques, varactors were developed that had good estimated performance characteristics and were considered appropriate for integration into adaptive microwave circuitry, such as the tunable antenna system. The varactors were constructed by using Focused Ion Beam (FIB) milling to create a nano-scale capacitive gap in a transmission line. A combination of end-point current detection (EPD) and cross-section scanning electron (SEM) and ion beam (FIB) microscope images were used to optimize the milling procedure. The future extensions of this work include the integration of the BST varactors with the antenna design; the configuration of the developed BST varactors lends itself to a straightforward integration with the FPA antenna.

L'objectif de cette thèse est de développer et de valider une méthode de calcul de dose indépendante afin de soutenir le travail de mise en service intense d'une installation de traitement par faisceaux d'ions légers (LIBT) et de valider le calcul de dose du système de planification de traitement (SP). Le travail porte sur les traitements de protonthérapie et est organisé en collaboration entre le laboratoire CREATIS (Lyon, France) et le centre de thérapie ionique MedAustron - Vienna - Austria (Wiener Neustadt, Autriche). Chez MedAustron - Vienna - Austria, afin d’exploiter une pénombre latérale aiguë du faisceau de protons et d’améliorer la précision des algorithmes de calcul de la dose TPS, l’intervalle entre la fenêtre de la tête de traitement et le patient est réduit en déplaçant le patient vers la tête de traitement. Par conséquent, les traitements non isocentriques doivent être pris en compte avec précision lors de la modélisation ainsi que lors de la phase de validation, car l'éloignement de la cible de l'isocentre de la pièce peut réduire la précision du traitement. Dans cette étude, la paramétrisation du faisceau de crayons à protons suit les recommandations de Grevillot et al. (2011), mais comprenant une description complète de la buse. Un soin particulier est apporté à la modélisation des propriétés du faisceau de crayon dans des conditions non isocentriques, y compris l'utilisation d'un Range Shifter (RaShi). La caractérisation du faisceau de crayon est basée uniquement sur les profils de fluence mesurés dans le profil de dose d’air et de profondeur acquis dans l’eau. De plus, le modèle présenté est calibré en dose absolue sur la base d'un nouveau formalisme produit-zone-dose présenté dans Palmans et Vatnitsky (2016). Finalement, une validation détaillée est effectuée dans l'eau, pour les distributions de doses tridimensionnelles de forme régulière. Plusieurs paramètres couramment exploités en dosimétrie des protons, tels que la distance parcourue, la pénombre distale, la modulation, la taille des champs et la pénombre latérale pour la dosimétrie protonique sont évalués à des fins de validation. Le modèle optique à faisceau de crayon a atteint une précision de l'exigence clinique de 1 mm / 10% et il n'est pas affecté par la complexité des traitements non isocentriques ni par l'utilisation d'un RaShi. Les plages sont reproduites entre 0,2 et 0,35 mm (déviation maximale) sans et avec le décaleur de plage, respectivement. La différence de dose dans les conditions de référence est de 0,5%. La validation de l'administration de la dose en 3D dans l'eau était à 1,2% maximum. La concordance des paramètres distaux et longitudinaux est généralement meilleure que 1 mm. Les résultats obtenus serviront de référence pour la future mise en œuvre clinique du système de calcul de dose indépendant MedAustron - Vienna - Austria. / The goal of this PhD is to develop and validate an independent dose calculation method in order to support the intense commissioning work of a Light Ion Beam Therapy (LIBT) facility, and to validate the Treatment Planning System (TPS) dose calculation. The work focuses on proton therapy treatments and is held as a collaboration between the CREATIS laboratory (Lyon, France) and the MedAustron - Vienna - Austria Ion Therapy Center (Wiener Neustadt, Austria). At MedAustron - Vienna - Austria, in order to exploit a sharp lateral penumbra for the proton beam as well as to improve the accuracy of the TPS dose calculation algorithms, the air gap between the treatment head window and the patient is reduced by moving the patient towards the treatment head. Therefore, non-isocentric treatments have to be accurately taken into consideration during modeling as well as validation phase as moving the target away from the room isocenter may lead to reduced treatment accuracy. In this study, the parametrization of the proton pencil beam follows the recommendations provided in Grevillot et al. (2011), but including a full nozzle description. Special care is taken to model the pencil beam properties in non-isocentric conditions, including the use of a Range Shifter (RaShi). The characterization of the pencil beam is based solely on fluence profiles measured in air and depth dose profile acquired in water. In addition, the presented model is calibrated in absolute dose based on a newly formalism in dose-area-product presented in Palmans and Vatnitsky (2016). Eventually, a detailed validation is performed in water, for three-dimensional regular-shaped dose distributions. Several parameters commonly exploited in proton dosimetry such as range, distal penumbra, modulation, field sizes and lateral penumbra for proton dosimetry are evaluated for validation purposes. The pencil beam optics model reached an accuracy within the clinical requirement of 1mm/10% and it is not affected by the complexity of non-isocentric treatments and the use of a RaShi. Ranges are reproduced within 0.2 and 0.35 mm (max deviation) without and with range shifter, respectively. The dose difference in reference conditions is within 0.5%. The 3D dose delivery validation in water was within 1.2% at maximum. The agreement of distal and longitudinal parameters is mostly better than 1 mm. The obtained results will be used as a reference for the future clinical implementation of the MedAustron - Vienna - Austria independent dose calculation system. As an example of the potential clinical outcome of the presented work, the patient specific quality assurance measurements performed in water have been successfully reproduced within the clinical requirement of 5% accuracy for a few patients.

La zircone 3Y-TZP présente un grand intérêt pour les applications dentaires, en implantologie orale, elle semble être un matériau extrêmement prometteur: elle allie une biocompatibilité à un aspect esthétique satisfaisant et présente aussi des propriétés mécaniques très supérieures aux autres céramiques. Ces bonnes propriétés mécaniques sont intimement liées à la microstructure du matériau, elle-même directement liée aux procédés d’élaboration comme nous l’a rappelé l’alarmante série de ruptures de plus de 800 têtes de prothèses de hanche en zircone au début des années 2000, due au phénomène de vieillissement de ce matériau. Cependant, les études cliniques menées à ce jour ne font toujours pas état des interrelations existant entre la microstructure, les propriétés mécaniques et la sensibilité au vieillissement. Il était donc primordial de valider et d’appliquer les connaissances acquises dans le domaine des sciences des matériaux pour l’application de la zircone 3Y-TZP en implantologie oral. C’est l’objectif de notre première publication. Nous avons également développé, dans notre deuxième publication, un protocole d’évaluation permettant dans un premier temps, d’évaluer l’effet de l’état de surface et de la microstructure sur la résistance mécanique d’implants neufs, puis de suivre leurs cinétiques de vieillissement tout en analysant l’évolution de la microstructure et son influence sur la résistance mécanique au cours du vieillissement. Tout cela permettant in fine, de prédire la durabilité d’un type d’implant. Nous avons par la suite, développé un programme informatique permettant la détection et la quantification du vieillissement pour un volume donné. Cette détection de la zone vieillie ou transformée est basée sur des modifications microstructurales caractéristiques engendrées lors du vieillissement. Enfin, nous avons pu mettre en évidence l’occurrence du phénomène de vieillissement in vivo, par l’analyse d’explants issus d’une étude clinique et démontrer leur probable implication dans ces cas d’échec. Le logiciel informatique de traitement d’image développé a été également, appliqué aux explants dans le but de mettre en lumière et d’expliciter l’occurrence du phénomène de vieillissement in vivo, afin de sensibiliser les acteurs de ce marcher aux problématiques rencontrées et d’optimiser de ce dispositif médical, à la lumière des connaissances actuelles. / 3Y-TZP zirconia is gaining interest in oral implantology, it seems to be a promising material with good biocompatibility, esthetic appearance and also the highest mechanical properties for a ceramic. These mechanical properties are closely related to the microstructure of the material itself directly related to production processes as we recalled the alarming series of breaks of more than 800 heads of zirconia hip replacements in the early 2000, due to the aging phenomenon of the material. However, clinical studies to date are still not state of the interrelationships between microstructure, mechanical properties and sensitivity to aging. It was therefore important to validate and apply the knowledge gained in the field of materials science for the application of 3Y-TZP zirconia oral implantology. This is the goal of our first publication. We also have developed in our second publication, a protocol to assess the effect of the surface modification and microstructure on the mechanical strength of new implants and follow their kinetics of aging and also, the evolution of the microstructure and its influence on the mechanical strength during aging, to predict the durability of a type of implant. We have subsequently developed a computer program for the detection and quantification of the aging for a given volume. This detection of the aged or transformed area is based on microstructural modifications produced during aging. Finally, we have been able to demonstrate the occurrence of the phenomenon of aging in vivo, by analyzing explants from a clinical study and demonstrate their involvement in the case of dental implant failure. The image processing developed was also applied to the explants in order to highlight and explain the occurrence of in vivo aging phenomenon. The objective is to optimize this medical device, in the light of current knowledge.

Photonic crystals (PhCs) are structures periodic in thedielectric constant. They exhibit a photonic bandgap, i.e., arange of wavelengths for which light propagation is forbidden.Engineering of defects in the PhC lattice offers new ways toconfine and guide light. PhCs have been manufactured usingsemiconductors and other material technologies. This thesisfocuses on two-dimensional PhCs etched in InP-based materials.Only recently, such structures were identified as promisingcandidates for the realization of novel and advanced functionsfor optical communication applications. The primary focus was on fabrication and characterization ofPhC structures in the InP/GaInAsP/InP material system. Thedemands on fabrication are very high: holes as small as100-300nm in diameter have to be etched at least as deep as 2µm. Thus, different etch processes had to be explored andspecifically developed for InP. We have implemented an etchingprocess based on Ar/Cl2chemically assisted ion beam etching (CAIBE), thatrepresents the state of the art PhC etching in InP. Different building blocks were manufactured using thisprocess. A transmission loss of 10dB/mm for a PhC waveguide, areflection of 96.5% for a 4-row mirror and a record qualityfactor of 310 for a 1D cavity were achieved for this materialsystem. With an etch depth of 4.5 µm, optical loss wasfound to be close to the intrinsic limit. PhC-based opticalfilters were demonstrated using (a) a Fabry-Pérot cavityinserted in a PhC waveguide and (b) a contra-directionalcoupler. Lag effect in CAIBE was utilized positively to realizehigh quality PhC taper sections. Using a PhC taper, a couplingefficiency of 70% was demonstrated from a standard ridgewaveguide to a single line defect PhC waveguide. During the course of this work, InP membrane technology wasdeveloped and a Fabry-Pérot cavity with a quality factorof 3200 was demonstrated. Keywords:photonic crystals, photonic bandgap materials,indium phosphide, dry etching, chemically assisted ion beametching, reactive ion etching, electron beam lithography,photonic integrated circuits, optical waveguides, resonantcavities, optical filtering, finite difference time domain,plane wave expansion.

Transmission Electron Microscopy (TEM) on light element materials and soft matters is problematic due to electron irradiation damage and low contrast. In this doctoral thesis techniques were developed to address some of those issues and successfully characterize these materials at high resolution. These techniques were demonstrated on graphene flakes, DNA/magnetic beads and a number of water containing biomaterials. The details of these studies are given below. A TEM based method was presented for thickness characterization of graphene flakes. For the thickness characterization, the dynamical theory of electron diffraction is used to obtain an analytical expression for the intensity of the transmitted electron beam as a function of thickness. From JEMS simulations (experiments) the absorption constant λ in a low symmetry orientation was found to be ~ 208 nm (225 ± 9 nm). When compared to standard techniques for thickness determination of graphene/graphite, the method has the advantage of being relatively simple, fast and requiring only the acquisition of bright-field (BF) images. Using the proposed method, it is possible to measure the thickness change due to one monolayer of graphene if the flake has uniform thickness over a larger area. A real-space TEM study on magnetic bead-DNA coil interaction was conducted and a statistical analysis of the number of beads attached to the DNA-coils was performed. The average number of beads per DNA coil was calculated around 6 and slightly above 2 for samples with 40 nm and 130 nm beads, respectively. These results are in good agreement with magnetic measurements. In addition, the TEM analysis supported an earlier hypothesis that 40 nm beads are preferably attached interior of the DNA-coils while 130 nm beads closer to the exterior of the coils. A focused ion-beam in-situ lift-out technique for hydrated biological specimens was developed for cryo-TEM. The technique was demonstrated on frozen Aspergillus niger spores which were frozen with liquid nitrogen to preserve their cellular structures. A thin lamella was prepared, lifted out and welded to a TEM grid. Once the lamella was thinned to electron transparency, the grid was cryogenically transferred to the TEM using a cryo-transfer bath. The structure of the cells was revealed by BF imaging. Also, a series of energy filtered images was acquired and C, N and Mn elemental maps were produced. Furthermore, 3 Å lattice fringes of the underlying Al support were successfully resolved by high resolution imaging, confirming that the technique has the potential to extract structural information down to the atomic scale. The experimental protocol is ready now to be employed on a large variety of samples e.g. soft/hard matter interfaces.