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Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-08-26Bitstream added on 2014-06-13T19:29:33Z : No. of bitstreams: 1 simoes_rd_me_bauru.pdf: 3082806 bytes, checksum: b44fcfd386ae934a75a9814336462470 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O principal objetivo deste trabalho de mestrado foi a obtenção e caracterização estrutural de um material com propriedades físico-químicas compatíveis com aquelas requeridas por um biomaterial. Filmes contendo diferentes volumes de látex de borracha natural em uma massa fixa de poli(fluoreto de vinilideno) (PVDF), na forma de pó foram fabricados por compressão/aquecimento de uma mistura de ambos os materiais sem o uso de qualquer solvente. Este é um fator importante considerando o uso destes filmes no futuro próximo como biomateriais em diferentes aplicações (indução do crescimento do tecido ósseo, por exemplo), uma vez que os solventes convencionais usados para dissolver o PVDF têm se mostrado tóxicos ao organismo humano. Os filmes foram submetidos a um tratamento via descarga corona de forma que amostras com e sem tal tratamento foram caracterizadas através das técnicas de espectroscopia vibracional via espalhamento Raman e absorção no infravermelho (FTIR), análise térmica via termogravimetria (TG), calorimetria exploratória diferencial (DSC) e análise dinâmico-mecânica (DMA) e microscopias ótica e eletrônica (MEV). As medidas termomecânicas mostraram que os filmes obtidos possuem características mecânicas similares àquelas encontradas no osso humano e boa estabilidade térmica considerando-se a aplicação desejada. As medidas via espectroscopia vibracional indicaram que o PVDF e o látex não interagem quimicamente, compondo uma blenda polimérica. Além disto, os resultados obtidos via micro-Raman mostraram que o aumento da quantidade de látex na blenda permite uma melhor dispersão deste látex na matriz de PVDF quando da produção dos filmes... / The main goal of this work was to obtain and characterize structurally a material with physical-chemical properties compatible with those required for a biomaterial. Films containing different volumes of latex of natural rubber in a fixed mass of poly (vinylidene fluoride) (PVDF) powder were fabricated by compressing/annealing a mixture of both materials without using any solvent. This is an important issue having in mind to use these films in the future as biomaterials in different applications (growing of the bone tissue, for instance) once the solvents used to dissolve the PVDF are toxic to human being. The films were submitted to a corona discharge treatment in a way that samples with and without such treatment were characterized using micro-Raman scattering and Fourier transform infrared absorption (FTIR) spectroscopies, thermo-mechanical techniques using thermogravimetry (TG), differential scanning calorimetry (DSC) and dynamical-mechanical analysis (DMA) and optical and scanning electron microscopies (SEM). The thermo-mechanical measurements revealed that the films present mechanical properties close to that found for the human bone and high thermal stability considering the desired applications. The vibrational spectroscopies showed that the latex and PVDF do not interact chemically leading to the formation of a polymeric blend. Besides, the results recorded using the micro-Raman technique revealed that the higher the amount of latex in the blend, the better the miscibility between both materials. In terms of morphology, the blend surface is formed by two domains: one is rougher and contains the latex well dispersed into the PVDF matrix while the other is smoother and contains both materials as well but in a less homogeneous dispersion. However, as the volume of latex is increased from 0.3 to 1.0 mL, the smoother domains become rarer to be found... (Complete abstract, click electronic address below)

Orientador: Carlos José Leopoldo Constantino / Banca: Neri Alves / Banca: Osvaldo Novais de Oliveira Júnior / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: O principal objetivo deste trabalho de mestrado foi a obtenção e caracterização estrutural de um material com propriedades físico-químicas compatíveis com aquelas requeridas por um biomaterial. Filmes contendo diferentes volumes de látex de borracha natural em uma massa fixa de poli(fluoreto de vinilideno) (PVDF), na forma de pó foram fabricados por compressão/aquecimento de uma mistura de ambos os materiais sem o uso de qualquer solvente. Este é um fator importante considerando o uso destes filmes no futuro próximo como biomateriais em diferentes aplicações (indução do crescimento do tecido ósseo, por exemplo), uma vez que os solventes convencionais usados para dissolver o PVDF têm se mostrado tóxicos ao organismo humano. Os filmes foram submetidos a um tratamento via descarga corona de forma que amostras com e sem tal tratamento foram caracterizadas através das técnicas de espectroscopia vibracional via espalhamento Raman e absorção no infravermelho (FTIR), análise térmica via termogravimetria (TG), calorimetria exploratória diferencial (DSC) e análise dinâmico-mecânica (DMA) e microscopias ótica e eletrônica (MEV). As medidas termomecânicas mostraram que os filmes obtidos possuem características mecânicas similares àquelas encontradas no osso humano e boa estabilidade térmica considerando-se a aplicação desejada. As medidas via espectroscopia vibracional indicaram que o PVDF e o látex não interagem quimicamente, compondo uma blenda polimérica. Além disto, os resultados obtidos via micro-Raman mostraram que o aumento da quantidade de látex na blenda permite uma melhor dispersão deste látex na matriz de PVDF quando da produção dos filmes... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The main goal of this work was to obtain and characterize structurally a material with physical-chemical properties compatible with those required for a biomaterial. Films containing different volumes of latex of natural rubber in a fixed mass of poly (vinylidene fluoride) (PVDF) powder were fabricated by compressing/annealing a mixture of both materials without using any solvent. This is an important issue having in mind to use these films in the future as biomaterials in different applications (growing of the bone tissue, for instance) once the solvents used to dissolve the PVDF are toxic to human being. The films were submitted to a corona discharge treatment in a way that samples with and without such treatment were characterized using micro-Raman scattering and Fourier transform infrared absorption (FTIR) spectroscopies, thermo-mechanical techniques using thermogravimetry (TG), differential scanning calorimetry (DSC) and dynamical-mechanical analysis (DMA) and optical and scanning electron microscopies (SEM). The thermo-mechanical measurements revealed that the films present mechanical properties close to that found for the human bone and high thermal stability considering the desired applications. The vibrational spectroscopies showed that the latex and PVDF do not interact chemically leading to the formation of a polymeric blend. Besides, the results recorded using the micro-Raman technique revealed that the higher the amount of latex in the blend, the better the miscibility between both materials. In terms of morphology, the blend surface is formed by two domains: one is rougher and contains the latex well dispersed into the PVDF matrix while the other is smoother and contains both materials as well but in a less homogeneous dispersion. However, as the volume of latex is increased from 0.3 to 1.0 mL, the smoother domains become rarer to be found... (Complete abstract, click electronic address below) / Mestre

Made available in DSpace on 2014-06-11T19:30:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-19Bitstream added on 2014-06-13T19:39:43Z : No. of bitstreams: 1 kitagawa_il_me_bauru.pdf: 1240008 bytes, checksum: 9ebbdde64d8ef13b31f5e5e5f9a075cc (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Esta dissertação apresenta o estudo do crescimento (em escala nanométrica) e morfológica (em escala micrométrica) de filmes finos fabricados segundo a técnica Layer-by-Layer (LbL) contendo ftalocianina tetrasulfonada de níquel, polímeros condutores, o polímero poli(alilamina hidroclorada) (PAH), e gomas naturais. Três sistemas foram investigados: i) filmes LbL de NiTsPc e PAH; ii) filme LbL de NiTsPc, PAH e gomas naturais e iii) filmes LbL dos polímeros condutores polianilina (PANI) e poli(o-metoxianilina) (POMA) com gomas naturais. As gomas utilizadas neste trabalho foram extraídas das árvores cajueiro (Anacardium occidentale), chichá (Sterculia striata), caraia (Sterculia urens) e angico (Anadenanthera macrocarpa Benth). As caracterizações destes filmes foram realizadas por meio das técnicas de espectroscopia eletrônica utilizando absorção na região do ultravioleta-visível (UV-vis), espectroscopia vibracional por espalhamento micro-Raman e por absorção na região do infravermelho (IV) com transformada de Fourier (FTIR). Os resultados deste trabalho mostraram que, somente os filmes de NiTsPc e PAH em pH 8,5 e os filmes de NiTsPc, PAH e gomas naturais apresentaram crescimento controlado, uniformidade morfológica e química. / This dissertation presents the study of growth (in nano-scale thickness) and morphology (micrometric scale) of thin films produced using the Layer-by-Layer technique (LbL) containing nickel tetrasulfonated phthalocyanine, conducting polymers, the polymer poly(allylamine hydrochloride) (PAH), and natural gums. Three systems were investigated: i) LbL films of NiTsPc and PAH; ii) LbL films of NiTsPc, PAH and natural gums and iii) LbL films of the conducting polymers polyaniline (PANI) and poly (o-methoxyaniline) (POMA) with natural gums. The gums used in this work were obtained from the cashew (Anacardium occidentale), chicha (Sterculia striata), caraia (Sterculia urens) and angico (Anadenanthera macrocarpa Benth) trees. The characterizations of the LbL films were made using the ultraviolet-visible (UV-vis) absorption spectroscopy, vibrational spectroscopy through micro-Raman scattering and Fourier Transform infrared (FTIR) absorption. The results showed that only the LbL films of NiTsPc and PAH at pH 8.5 and the LbL films of NiTsPc, PAH and natural gums present controlled growth and morphological and chemical uniformity.

Compte tenu de leur bioactivité et de leur ostéoconduction, les revêtements d’hydroxyapatite (HA) favorisent le développement de tissu osseux et contribuent à l’adhérence et à la prolifération des cellules osseuses tout en préservant l’intégrité mécanique du dispositif métallique de l’implant. Toutefois, des signes de résorption de cette couche ont été constatés et l’introduction du procédé de projection plasma pour la réalisation de dépôts d’HA a donné lieu à plusieurs controverses. Certaines études ont montré que les dépôts d’HA par projection plasma présentent une mauvaise adhérence sur le titane, une dégradation et écaillage avec le temps. Ce phénomène est attribuable à la décomposition de l'HA au cours de la projection et à l'existence de phases secondaires cristallisées ou amorphes qui fragilisent le dépôt. A l’heure actuelle, les recherches de nouvelles apatites thermiquement plus stables se développent. Ainsi des dépôts à base de fluorapatite ou de fluorhydroxyapatite fournissent des dépôts plus stables et plus adhérents. Il existe d’autres formes d’apatites comme la chlorapatite (ClA) qui fond sans se décomposer ce qui permettrait d’éviter la formation des phases étrangères qui provoquent l’écaillage du dépôt. Ce travail porte sur la synthèse et la caractérisation de phosphates de calcium apatitiques destinés au recouvrement de prothèses ostéoarticulaires et/ou d’implants dentaires métalliques. L’élaboration des poudres d’apatite a été réalisée par réaction solide-solide, en solution aqueuse ou en sel fondu. Plusieurs apatites ont été étudiées : la fluorapatite, la fluorhydroxyapatite, la chlorapatite et l’apatite calcostrontique. On obtient des poudres pures, bien cristallisées et stoechiométriques. Nous avons ensuite étudié la stabilité thermique des poudres d’apatite par analyse thermogravimétrique. La stabilité thermique de la ClA et sa fusion sans décomposition permettent d’obtenir des dépôts sans phases secondaires avec un taux de cristallinité élevé. Parmi toutes les poudres étudiées, nous avons choisi de sélectionner la chlorapatite pour la suite de l’étude ainsi que l’hydroxyapatite comme référence. La poudre de ClA est déposée sur un substrat en titane via une mini-torche plasma mobile à basse énergie, conçue pour les implants dentaires ou orthopédiques de petites tailles et de géométries complexes. La projection par la mini-torche plasma permet de réaliser des dépôts fins et adhérents. Les propriétés structurales et microstructurales des dépôts de ClA et d’HA effectués dans les mêmes conditions ont été évaluées par diffraction des rayons X, spectroscopies FTIR et Raman. L’analyse des revêtements de ClA et d’HA par diffraction des rayons X atteste de la présence d’une seule phase cristalline. Néanmoins, le rapport de cristallinité des dépôts de ClA est largement supérieur à celui des dépôts d’HA, pour lesquels le rapport de cristallinité est supérieur à la norme requise. Ce résultat est du à la stabilité thermique de la ClA par rapport à l’HA. Les spectroscopies FTIR et Raman montrent la présence d’un faible taux de phase amorphe et d’oxyapatite. Nous avons également développé une nouvelle méthode semi-quantitative par cartographie Raman permettant de déterminer l’homogéneité de composition du dépôt. Enfin, nous avons montré que l’adhérence des dépôts de ClA au substrat déterminée suivant la norme ASTM C633 est équivalente à celle de l’HA. La réponse biologique des dépôts a été étudiée in vitro avec des cellules pré-ostéoblastes humaines sur les deux compositions ClA et HA. Les tests montrent que quelle que soit la composition du dépôt, la prolifération cellulaire augmente au cours du temps d’incubation. Une étude in vivo a été menée sur un modèle animal ovin en site fémur et humérus pour des durées de 2 et 6 mois afin d’évaluer le potentiel ostéoconducteur des dépôts d’HA et de ClA. Aucune réaction inflammatoire n’a été observée et l’interprétation des résultats d’analyses histologiques et physico-chimiques est en cours. / Plasma-sprayed hydroxyapatite (HA) has been shown to enhance bone apposition as compared with uncoated metal implants. In spite of their good clinical performances, implant bio-integration is still limited due to the poor adhesion of HA-coating on the titanium surface and the decomposition of HA into several foreign phases during plasma spray. The plasmaspray process was thus considered not to be optimum for HA coatings. To circumvent these disadvantages, other types of calcium phosphates have been proposed to replace HA, such as tricalcium phosphate or biphasic calcium phosphate with little improvement. Chlorapatite (ClA) however has never been tested despite its ability to melt without decomposition which could be a decisive advantage to avoid apatite decomposition and could increase coating crystallinity. This work concern the synthesis and the characterization of apatitic calcium phosphate as coating for endoprostheses and dental implants. The syntheses of the different apatite powders were performed by solid-solid reaction, in aqueous solution or by molten salt reaction. Several apatites were studied: fluorapatite, fluorhydroxyapatite, chlorapatite and strontium substituted apatite. The as-synthesized powders are pure, well crystallized and stoechiometric. The thermal properties of apatite powders were compared using thermogravimetric analysis. The thermal stability of ClA and its melting without decomposition allows to obtain deposits with no secondary phases and with a degree of crystallinity close to 100 %. We have therefore chosen ClA and HA as feedstock powders to achieve coatings. The as-synthesized ClA powder was deposited on a titanium substrate using a novel low energy plasma mini-gun characterized by a low power range (<13 kW) and portability allowing in-situ coating deposition designed for dental and orthopedic small implants with complex geometry. The plasma spray with the mini-gun gives thin and adherent coatings. It also provides economic benefits such as low energy and a higher yield of feedstock powder than conventional gun. The structural and microstructural properties of ClA and HA coatings performed under the same conditions were evaluated by X-ray diffraction, Raman and infrared spectroscopy. X-ray diffraction analyses on the ClA and HA coatings indicate the presence of crystalline apatite as the only crystalline phase. However, the crystallinity ratio of ClA coatings was much higher than that of HA coatings but superior to the required standard in both cases. This difference is due to the thermal stability of ClA powder. IR and Raman spectroscopy shows the presence of low levels of amorphous phase and oxyapatite. We have also developed a new semiquantitative method by Raman imaging in order to determine coating homogeneity. The mechanical properties of coatings were determined according to the standard test measurements ASTM C633. The adhesion of ClA coatings to the substrate is equivalent to HA coatings. The biological response of the coatings was studied in vitro with human preosteoblast cells on both ClA and HA coatings. Tests show that wathever the composition of coating, cell proliferation increases with time of incubation. The in vivo osteoconductive properties of coatings were studied in femur and humerus sites of an ovine animal model during 2 and 6 months. No inflammatory reaction has been observed and the interpretation of histological and physico-chemical results is in progress.

The Maya of Central America developed a complex society: among their many achievements they developed a writing system, complex calendar and were prolific builders. The buildings of their large urban centres, such as Copan in Honduras, were decorated with painted stucco, moulded masks, carving and elaborate murals, using a range of coloured pigments. In this study the paints used on the buildings of Copan and some ceramic sherds have been investigated, non-destructively, using micro-Raman spectroscopy, micro-ATR infrared spectroscopy, environmental scanning electron microscopy with energy dispersive X-ray analysis (ESEM-EDX) and FTIR-ATR imaging spectroscopy. The paint samples come from four buildings and one tomb covering three time periods in the four hundred year history of Copan. The main pigment used in the red paint on these samples was identified as haematite, and the stucco as a mixture of calcite particles dispersed throughout a calcite-based lime wash stucco. The composition and physical nature of the stucco changed through time, indicating a refining of production techniques over this period. A range of minor mineral components have been identified in each of the samples including rutile, quartz, clay and carbon. The presence and proportion of these and other minerals differed in each sample, leading to unique mineral signatures for the paint from each time period. Green and grey paints have also been identified on one of the buildings, the Rosalila Temple. The green pigment was identified as a celadonite-based green earth, and the grey pigment as a mixture of carbon and muscovite. The combination of carbon and mica to create a reflective paint is a novel finding in Maya archaeology. The high spatial resolution of the micro-FTIR-ATR spectral imaging system has been used to resolve individual particles in tomb wall paint and to identify their mineralogy from their spectra. This system has been used in combination with micro-Raman spectroscopy and ESEM-EDX mapping to characterize the paint, which was found to be a mixture of haematite and silicate particles, with minor amounts of calcite, carbon and magnetite particles, in a sub-micron haematite and calcite matrix. The blending of a high percentage of silicate particles into the haematite pigment is unique the tomb sample. The stucco in this tomb wall paint has finely ground carbon dispersed throughout the top layer providing a dark base for the paint layer. Changing paint mixtures and stucco composition were found to correlate with changes in paint processing techniques and building construction methods over the four hundred years of site occupation.

Solid Oxide Fuel Cells (SOFCs) are emerging as a potential breakthrough energy conversion technology for clean and efficient production of electricity and heat from hydrogen and hydrocarbon fuels. Sc0.1Ce0.01ZrO2 electrolytes for Solid Oxide Fuel Cells are very promising materials because their high ionic conductivity in the intermediate temperature range 700°C-800°C. The vibration response of cubic and rhombohedral (β) 10 mol%Sc2O3 - 1 mol%CeO2 - ZrO2(Sc0.1Ce0.01ZrO2 ) both at room and high-temperatures is reported. The in-situ heating experiments and ex-situ indentation experiments were performed to characterize the vibrational behavior of these important materials. A temperature and stress-assisted phase transition from cubic to rhombohedral phase was detected during in-situ Raman spectroscopy experiments. While heating and indentation experiments performed separately did not cause the transition of the cubic phase into the rhombohedral structure under the performed experimental conditions and only broadened or strained peaks of the cubic phase could be detected, the heating of the indented (strained) surface leaded to the formation of the rhombohedral Sc0.1Ce0.01ZrO2. Both temperature range and strained zone were estimated by in situ heating and 2D mapping, where a formation of rhombohedral or retention of cubic phase has been promoted. The mechanical properties, such as Young’s modulus, Vickers hardness, indentation fracture resistance, room and high temperature four point bending strength and SEVNB fracture toughness along with the stress – strain deformation behavior in compression, of 10 mol% Sc2O3 – 1 mol % CeO2 - ZrO2 (ScCeZrO2) ceramics have been studied. The chosen composition of the ScCeZrO2 has very high ionic conductivity and, therefore, is very promising oxygen ion conducting electrolyte for the intermediate temperature Solid Oxide Fuel Cells. Therefore, its mechanical behavior is of importance and is presented in this study.

Ce mémoire de thèse aborde la caractérisation expérimentale du transfert thermique à l’échelle nanométrique dans des matériaux compatibles avec les procédés de la micro-électronique. Pour cela deux techniques de caractérisation sont appliquées chacune à deux différents systèmes, le silicium mésoporeux irradié et les membranes de silicium suspendues. La première technique de caractérisation est la thermométrie micro-Raman. La puissance du laser chauffe l'échantillon exposé. La détermination de la conductivité thermique nécessite la modélisation de la source de chaleur par la méthode des éléments finis. Dans les cas considérés la modélisation de la source de chaleur repose sur différents paramètres qui doivent être soigneusement déterminés. La seconde technique de caractérisation est la microscopie à sonde locale (d’acronyme anglais SThM), basée sur le principe de la microscopie à force atomique (d’acronyme anglais AFM). Utilisée en mode actif, la sonde AFM est remplacée par une sonde résistive de type Wollaston qui est chauffée par effet Joule. Utilisée en mode AFM contact, cette technique permet une excitation thermique locale du matériau étudié. La détermination de la conductivité thermique nécessite l'analyse de la réponse thermique de la sonde au moyen d'échantillons d'étalonnage et également via la modélisation dans le cas des géométries complexes. L'effet de la position de la pointe sur le transfert de chaleur entre la pointe et l'échantillon est étudié. Une nouvelle méthode de découplage entre le transfert de chaleur entre la pointe et l'échantillon, respectivement à travers l'air et au contact, est proposée pour la détermination de la conductivité thermique des géométries complexes. Les résultats obtenus avec les deux techniques pour les échantillons de silicium mésoporeux irradiés à l’aide d’ions lourds dans le régime électronique sont en bon accord. Ils montrent la dégradation de la conductivité thermique du silicium mésoporeux suite à une augmentation dans la phase d’amorphe lorsque la dose d’irradiation croît. Les résultats obtenus sur les membranes de silicium suspendues montrent une réduction de la conductivité thermique de plus de 50 % par rapport au silicium massif. Lorsque la membrane est perforée périodiquement afin de réaliser une structure phononique de période inférieure à 100 nm, cette réduction est approximativement d’un ordre de grandeur. Un chapitre introduisant un matériau prometteur à base de silicium pour observer des effets de cohérence phononique conclut le manuscrit. / This PhD thesis deals with the experimental characterization of heat transfer at the nanoscale in materials compatible with microelectronic processes. Two characterization techniques are applied to two different systems, irradiated mesoporous silicon and suspended silicon membranes. The first characterization technique is micro-Raman thermometry. The laser power heats up the exposed sample. The determination of the thermal conductivity requires the modeling of the heat source using finite element simulations. The modeling of the heat source relies on different parameters that should be carefully determined. The second characterization technique is Scanning Thermal Microscopy (SThM), an Atomic Force Microscopy (AFM)-based technique. Operated in its active mode, the AFM probe is replaced by a resistive Wollaston probe that is heated by Joule heating. Used in AFM contact mode, this technique allows a local thermal excitation of the studied material. The determination of the thermal conductivity requires the analysis of the thermal response of the probe using calibration samples and modeling when dealing with complicated geometries. The effect of the tip position on heat transfer between the tip and the sample is studied. A new method decoupling the heat transfer between the tip and the sample, at the contact and through air, is proposed for determining the thermal conductivity of complicated geometries. The results obtained from the two techniques on irradiated mesoporous silicon samples using heavy ions in the electronic regime are in good agreement. They show a degradation of the thermal conductivity of mesoporous silicon due to the increase in the amorphous phase while increasing the ion fluence. The results obtained on suspended silicon membrane strips show a decrease in the thermal conductivity of more than 50 % in comparison to bulk silicon. When perforated into a phononic structure of sub-100 nm period, the membrane thermal conductivity is about one order of magnitude lower than the bulk. A chapter introducing a promising silicon-based material for the evidence of phonon coherence concludes the manuscript.

Si les traitements actuels de conservation restauration des objets métalliques du patrimoine permettent de ralentir les processus de corrosion, ils s'avèrent non optimisés dans bien des cas. Les limites des traitements sont dues en grande partie au fait que les produits de corrosions chlorés développés sur les objets archéologiques et les mécanismes à l'origine de leur formation, mettant en jeu le chlore, sont mal connus. <br />Dans le cadre de cette thèse, l'investigation des mécanismes de corrosion du fer dans les sols en présence de chlore s'est appuyée sur une grande partie analytique consistant en une caractérisation locale et structurale des produits de corrosion chlorés sur un corpus d'objets archéologiques. Pour ce faire, différentes techniques d'analyses de caractérisation micro structurales ont été mises en œuvre, notamment des investigations de diffraction et d'absorption des rayons X sous rayonnement synchrotron ont été menées. Ces travaux de recherche ont permis d'obtenir des résultats fondamentaux dans la caractérisation des phases chlorées. Principalement deux phases cristallines différentes ont été identifiées. L'oxyhydroxyde akaganeite beta–FeOOH, qui est un composé couramment présent dans les produits de corrosion d'objets exposés à un environnement chloré. Par ailleurs l'étude a révélé la présence d'une phase plus fortement chlorée, l'hydroxychlorure beta–Fe2(OH)3Cl. Ce résultat est des plus important car cette phase a rarement été observée auparavant sur les échantillons archéologiques or elle est présente en proportion non négligeable. Un certain nombre de mécanismes de formation de ces phases en fonction des conditions du milieu d'enfouissement ont été proposés. Ceci devra donc être pris en considération pour l'amélioration des méthodes de traitement des objets métalliques du patrimoine. Un second axe de l'étude a consisté à mieux comprendre la localisation du chlore dans l'akaganeite beta–FeOOH, qui est un composé considéré comme le principal responsable de la dégradation des objets archéologiques, car pouvant relâcher des chlorures. Seul le couplage de la caractérisation des produits de corrosion chlorés, à l'échelle microscopique, sur les échantillons archéologiques avec l'étude de phases synthétisées a permis de comprendre les systèmes complexes de corrosion à long terme du fer dans les sols en présence de chlore.

Ce travail de thèse porte sur l'organisation de nanoparticules sur des surfaces grâce à une approche originale basée sur le dépôt à faible énergie d'agrégats, préformés en phase gazeuse (approche Bottom-up), sur substrats de graphite HOPG, fonctionnalisés par des réseaux 2D de défauts créés par faisceau d'ions focalisés nano-FIB (approche Top-down). L'obtention de réseaux 2D d'amas d'agrégats est conditionnée par la diffusion des agrégats déposés et leur sensibilité aux défauts artificiels FIB. Le développement de cette approche passe tout d'abord par des simulations Monte-Carlo réalisées dans le cadre du modèle DDA (Dépôt-Diffusion-Agrégation). Ensuite, sa faisabilité expérimentale est testée avec succès en déposant des agrégats d'or. En particulier, cette étude montre la dépendance des propriétés morphologiques et structurales des défauts FIB en fonction de la dose d'ions. Par ailleurs, la sensibilité des agrégats aux défauts FIB, ainsi que la possibilité de contrôler la taille des amas, la période du réseau et sa géométrie sont analysées. Enfin, en se plaçant dans les conditions optimales permettant la meilleure organisation, notre approche est étendue aux agrégats magnétiques Co50Pt50, candidats potentiels au stockage d'information à ultra-haute densité. Une étude de l'influence du recuit sur les réseaux d'agrégats Co50Pt50 montre une amélioration de la qualité de l'organisation, et surtout une transition de phase des agrégats de la structure<br />A1 vers la structure L10.