This study concerns four high performance structural alloys designed to withstand the extreme temperature and irradiation environment inside fusion and fission fast breeder reactors: two Reduced Activation Ferritic Martensitic (RAFM) steels (Fe-14wt%Cr and a European standard alloy EUROFER97) and two equivalent Oxide Dispersion Strengthened (ODS) steels (Fe-14wt%Cr ODS (CEA ODS) and EUROFER ODS). Neutron irradiation of the samples was impractical due to timescale and specific handling requirements for radioactive samples. Instead, ion implantation was used to simulate the helium and damage of neutron irradiation. Samples of each alloy were subjected to a range of ion implantations: 75appm He, 2000appm He, 2000appm He + 4.5dpa Fe and 2000appm Ne. The matrix of four materials and five implantation conditions was analysed using the following experimental techniques: nanohardness indentation, Vickers hardness testing, micropillar compression, microcantilever bending, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). These techniques were used to compare the properties of the unimplanted materials and their response to implantation. Yield stress (σ_y) was comparable across hardness testing and microcantilever bending, and consistently showed σ_y Fe-14wt%Cr < EUROFER < EUROFER ODS < CEA ODS. When subject to helium implantation, 75appm He caused insignificant changes in σy while 2000appm He increased σ_y in all materials. This increase was most significant in Fe-14wt%Cr due to its low grain boundary density and lack of oxide/carbide particles. The particle dispersions in the other materials act as helium traps, preventing the formation of TEM visible bubbles and reducing the hardening effects of the helium. Across all results it becomes clear that, although not to the degree of the ODS materials, EUROFER is more radiation resistant than Fe-14wt%Cr. It therefore appears that it is the presence of a complex microstructure including small grains and a distribution of oxide or carbide particles, rather than the specific inclusion of oxide nanoparticles, that provides RAFM steels with superior irradiation resistance properties.

O efeito bactericida de íons cobre é bem conhecido; no entanto a atividade inibitória depende diretamente da concentração desses íons no material base. Contudo, essa concentração deve ser controlada, pois o excesso destes íons pode ser tóxico e além disso, a implantação de cobre pode comprometer a resistência a corrosão do substrato metálico. A propriedade bactericida é desejável para aplicação em ligas metálicas empregadas em diversos setores, na assepsia de materiais que tenham contato direto com subprodutos que necessitam alta pureza e com baixíssimos índices de contaminação. O aço inoxidável austenítico AISI 304 é amplamente utilizado devido às suas propriedades mecânicas e de resistência à corrosão. Considerando isso, o aço AISI 304 é o foco do presente estudo, mesclando as características anticorrosivas naturais com a assepsia oligodinâmica proveniente da dopagem com íons de cobre. Nesse sentido, avaliou a resistência à corrosão do aço inoxidável AISI 304 com diferentes doses de cobre implantado (1015 íons.cm-2 e 1016 íons.cm-2) por monitoramento do potencial de circuito aberto e voltametria cíclica em uma solução eletrolítica de NaCl 3,5 % em peso. Através de simulações computacionais, previu-se que nos parâmetros escolhidos, a profundidade de implantação dos íons no substrato atingiu até 40 nm da superfície, com uma concentração de pico, maior teor de cobre, na profundidade de 12 nm. As amostras com doses de 1015 íons.cm-2 de cobre apresentaram o potencial de pites semelhante ao aço inoxidável austenítico AISI 304 sem implantação de Cu. Na análise de EDS observou-se que as áreas que não sofreram corrosão, apresentaram melhor distribuição dos elementos de liga e do cobre implantado em comparação com as regiões com maior incidência de pites. A maior intensidade de pites foi encontrada para a amostra com maior dose de cobre implantado (1016 íons.cm-2 de cobre). / The bactericidal effect of copper ions is well known; however, the inhibitory activity depends directly on the concentration of these ions in the base material. However, this concentration should be controlled because the excess of these ions can be toxic and the implantation of copper may compromise the corrosion resistance of the metal substrate. The bactericidal property is desirable for application in metal alloys used in the several sectors, in the asepsis of materials that have direct contact with by-products that require high purity and with very low contamination rates. The AISI 304 austenitic stainless steel is widely used because of its mechanical properties and corrosion resistance. Considering this, the AISI 304 is the focus of the present study, mixing the natural anticorrosive characteristics with the oligodynamic aseptic from the copper ions doping. The corrosion resistance of AISI 304 stainless steel with different doses of implanted copper (1015 ions.cm-2 and 1016 ions.cm-2) was evaluated by monitoring the open circuit potential and cyclic voltammetry in an electrolytic solution of NaCl 3,5% by weight. Through computational simulations, it was predicted that in the chosen parameters, the implantation depth of the ions in the substrate reached up to 40 nm from the surface, with a peak concentration, higher copper content, at the depth of 12 nm. The samples with doses of 1015 ions.cm-2 of copper had the pit potential similar to the austenitic stainless steel AISI 304 without implantation of Cu. In EDS analysis, it was observed that the areas that did not undergo corrosion had better distribution of the alloying elements and of the implanted copper compared to the regions with a higher incidence of pitting. The highest pitting intensity was found for the sample with the highest dose of implanted copper (1016 ions.cm-2 copper).

abstract: Thin films have been widely used in various applications. This research focuses on the characterization of novel thin films in the integrated circuits and photovoltaic techniques. The ion implanted layer in silicon can be treated as ion implanted thin film, which plays an essential role in the integrated circuits fabrication. Novel rapid annealing methods, i.e. microwave annealing and laser annealing, are conducted to activate ion dopants and repair the damages, and then are compared with the conventional rapid thermal annealing (RTA). In terms of As+ and P+ implanted Si, the electrical and structural characterization confirms that the microwave and laser annealing can achieve more efficient dopant activation and recrystallization than conventional RTA. The efficient dopant activation in microwave annealing is attributed to ion hopping under microwave field, while the liquid phase growth in laser annealing provides its efficient dopant activation. The characterization of dopants diffusion shows no visible diffusion after microwave annealing, some extent of end range of diffusion after RTA, and significant dopant diffusion after laser annealing. For photovoltaic applications, an indium-free novel three-layer thin-film structure (transparent composited electrode (TCE)) is demonstrated as a promising transparent conductive electrode for solar cells. The characterization of TCE mainly focuses on its optical and electrical properties. Transfer matrix method for optical transmittance calculation is validated and proved to be a desirable method for predicting transmittance of TCE containing continuous metal layer, and can estimate the trend of transmittance as the layer thickness changes. TiO2/Ag/TiO2 (TAgT) electrode for organic solar cells (OSCs) is then designed using numerical simulation and shows much higher Haacke figure of merit than indium tin oxide (ITO). In addition, TAgT based OSC shows better performance than ITO based OSC when compatible hole transfer layer is employed. The electrical and structural characterization of hole transfer layers (HTLs) in OSCs reveals MoO3 is the compatible HTL for TAgT anode. In the end, the reactive ink printed Ag film for solar cell contact application is studied by characterizing its electromigration lifetime. A percolative model is proposed and validated for predicting the resistivity and lifetime of printed Ag thin films containing porous structure. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2017

Cette thèse est centrée sur le développement de modèles numériques pour simuler le comportement physique des plasmas présents dans un réacteur d'implantation ionique à immersion plasma. Ces modèles ont pour but d'estimer l'impact des réglages opérationnels du réacteur sur les paramètres plasma pertinents pour l'implantation, comme le flux ionique sur le substrat et la distribution en énergie des ions. La géométrie complexe du réacteur rend difficile sa modélisation d'un seul tenant, du fait des importants gradients temporels et spatiaux attendus pour les densités ioniques et la température électronique. Une stratégie de simulation en deux étapes a donc été adoptée : - Un modèle quasi-homogène, couplé à un module de chimie en volume élaboré, permet de représenter des deux portions de la source plasma et d'obtenir l'évolution de la composition du plasma en fonction de la puissance radiofréquence injectée. - Un modèle unidimensionnel de type PIC-MC permet de décrire la dynamique de la gaine ionique qui se forme près du substrat du fait du potentiel imposé, ainsi que de déterminer la distribution de l'énergie d'impact des ions et les flux d'implantation correspondants. Au final, ces travaux de recherche ont permis d'aboutir à une meilleure compréhension de l'impact des paramètres opérationnels du réacteur sur le flux ionique et la distribution en énergie des ions arrivant sur le substrat. La connaissance des couplages physiques entre la source plasma et la chambre d'implantation autorise l'optimisation du processus de dopage, puisque les paramètres opérationnels peuvent être réglés de manière à minimiser la profondeur de dopage après implantation. / Numerical models have been developped to simulate the plasma present inside a plasma immersion ion implantation reactor. Their goal is to estimate the impact of the reactor’s settings on the plasma parameters relevant for ion implan-tation. The complex geometry of the reactor renders its modelling difficult, because of the stiff spatial and temporal gradients expected, so a two-step simulation stra-tegy was adopted : – A global model of the plasma source, coupled to a detailed volume chemistry module, allows to determine the time evolution of the plasma composition according to the radio-frequency power injected in the source.– A 1D PIC-MC model of the sheath facing the substrate describes the dyna-mics of the expanding sheath and allows to determine the ion impact energy distribution function and corresponding implantation profiles. Determination of the couplings between the plasma source and the implantation chamber makes possible to optimize the doping process, since the reactor’s opera-tional settings can then be adjusted to minimize the doping depth after implanta-tion.

abstract: Rapid processing and reduced end-of-range diffusion effects demonstrate that susceptor-assisted microwave annealing is an efficient processing alternative for electrically activating dopants and removing ion-implantation damage in ion-implanted semiconductors. Sheet resistance and Hall measurements provide evidence of electrical activation. Raman spectroscopy and ion channeling analysis monitor the extent of ion implantation damage and recrystallization. The presence of damage and defects in ion implanted silicon, and the reduction of the defects as a result of annealing, is observed by Rutherford backscattering spectrometry, moreover, the boron implanted silicon is further investigated by cross-section transmission electron microscopy. When annealing B+ implanted silicon, the dissolution of small extended defects and growth of large extended defects result in reduced crystalline quality that hinders the electrical activation process. Compared to B+ implanted silicon, phosphorus implanted samples experience more effective activation and achieve better crystalline quality. Comparison of end-of-range dopants diffusion resulting from microwave annealing and rapid thermal annealing (RTA) is done using secondary ion mass spectroscopy. Results from microwave annealed P+ implanted samples show that almost no diffusion occurs during time periods required for complete dopant activation and silicon recrystallization. The relative contributions to heating of the sample, by a SiC susceptor, and by Si self-heating in the microwave anneal, were also investigated. At first 20s, the main contributor to the sample's temperature rise is Si self-heating by microwave absorption. / Dissertation/Thesis / M.S. Materials Science and Engineering 2013

O presente estudo verificou o aumento da resistência à perda de corte de instrumentos produzidos em liga de níquel-titânio, após tratamento de implantação iônica de nitrogênio. Para tal, foram utilizados vinte e um instrumentos da marca K3 ?ENDO, de n° 25.02, com 21 mm, divididos em dois grupos. O grupo 1 foi constituído por onze instrumentos submetidos à ação de uma câmara de implantação iônica de nitrogênio, servindo um deles como controle para a determinação da quantidade de íons implantados. O grupo 2 foi composto por dez instrumentos não submetidos ao processo de implantação iônica. Cada lima instrumentou 20 blocos de canais simulados 20.02 de 21 mm, previamente lavados em cuba ultra-sônica com detergente a 40°C por 10 minutos e depois com água bidestilada por mais 10 minutos. Os mesmos foram secos com jato de ar, voltaram para estufa a 40°C por 2 dias e finalmente pesados em balança analítica. Após cada instrumentação os blocos foram lavados em cuba ultra-sônica com detergente a 40°C por 20 minutos e pesados novamente. O ensaio de resistência à perda de corte foi realizado mediante a instrumentação de cada bloco com auxílio de um simulador de ação da instrumentação endodôntica, sendo a amplitude percorrida pelo contra-ângulo padronizada em 2,5 mm a cada penetração por 8 vezes atingindo um total de 2,0 cm para dentro do canal simulado, com força de penetração de 1,5 N. Quanto a resistência à perda de corte os resultados mostraram que os instrumentos implantados não apresentaram diferença estatisticamente significante em nível de 5 % (? = 0,5 %) até 20 usos. Porém, os instrumentos não implantados mostraram diferença estatisticamente significante (? = 0,5 %) entre 5 e 15 usos, 5 e 20 usos, bem como entre 10 e 20 usos. Ao compararem-se instrumentos implantados e não implantados, observou-se que em 5 e 10 usos não houve diferença estatisticamente significante (p>5%). Já na comparação entre ambos com 15 e 20 usos a diferença foi estatisticamente significante (? = 0,5 %). Lícito foi concluir, portanto, que o processo de implantação de íons de nitrogênio manteve a resistência à perda de corte de instrumentos produzidos em liga de níquel-titânio até 20 usos. Os instrumentos não implantados mostraram perda progressiva do poder de corte significativamente entre 5 e 15 usos, 5 e 20 usos, bem como entre 10 e 20 usos. Comparando-se instrumentos implantados e não implantados, observou-se que até 10 usos ambos comportaram-se igualmente no que respeita à perda de corte. Já na comparação entre ambos com 15 e 20 usos a diferença foi significativa. / The present study investigated the cutting ability resistance in nickel-titanium instruments after nitrogen ion implantation treatment. Twenty-one instruments of K3 ?ENDO brand, number 20.02, with 21 mm, were divided in two groups. The group 1 submitted 11 instruments to nitrogen ion implantation chamber, while on served as positive control for the determination of the ion implantation quantity. In group 2, the 10 instruments were not submitted to ion implantation treatment. Each file instrumented 20 acrylic blocks 20.02 with 21 mm, previously washed in ultrasonic container with detergent in 40°C for 10 minutes and then with bidestiled water for 10 minutes. They were dried and put in a 40°C stove for 2 days and finally weighed in analytic balance. After instrumentation the blocks were washed for 20 minutes and weighed again. The usage essay was realized through the instrumentation of each block using an endodontic instrumentation simulated action, with a 2,5 mm standardized distance for 8 times, getting a total of 2,0 cm inside the simulated canal with a strong penetration of 1,5 N. The results showed that there was no statistical difference in cutting resistance of instruments treated with ionic implantation process until 20 uses. Although in the non treated instruments there was a gradual reduce in cutting ability resistance from 5 to 20 uses. The conclusion was that the nitrogen ion implantation process increases the cutting resistance of nickel-titanium instruments.

Orientador: Cecília Amélia de Carvalho Zavaglia / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T19:02:52Z (GMT). No. of bitstreams: 1 RodriguesJunior_Roberio_M.pdf: 3328140 bytes, checksum: d0f2014c71eeb448ae530ee5df6b8479 (MD5) Previous issue date: 2010 / Resumo: Com o intuito de avaliar a eficiência de diferentes recobrimentos superficiais aplicados a tuchos de válvulas - um componente utilizado em motores à combustão - foram propostos alguns recobrimentos que foram comparados a um recobrimento já utilizado pela indústria. Para as avaliações foram realizados ensaios de microdureza, ensaios de desgaste micro-abrasivo e avaliações da microestrutura dos recobrimentos. Os recobrimentos estudados foram: nitretação a gás convencional, esta já utilizada pela indústria; implantação iônica por imersão em plasma (IIIP) de nitrogênio; IIIP de nitrogênio sobre a camada já existente de nitretação a gás convencional; e confrontada com uma amostra sem nenhuma camada de recobrimento superficial aplicada. Os ensaios de desgaste micro-abrasivo foram realizados em um equipamento do tipo esfera contra bloco, utilizando solução abrasiva de carboneto de silício (SiC), e variando a carga normal aplicada, sendo elas de 1, 2 e 3N. Os resultados mostram que a nitretação a gás convencional obteve o mais elevado nível de microdureza na superfície e também o mais elevado nível de desgaste por micro-abrasão; este resultado prevaleceu nesta amostra para todas as cargas normais aplicadas. Em geral, a amostra que obteve o melhor nível de desgaste, ou seja, o menor volume desgastado foi a amostra que não tinha nenhum tipo de recobrimento / Abstract: With the intention to evaluate the efficiency of different coatings applied to valve tappets - a component used in combustion engines - was proposed some coatings that was compared to an coating already known by the industry. For the evaluations were performed micro hardness tests, micro abrasive wear tests and studies of the microstructure of the coatings. The coatings studied were: conventional gas nitriding, this one already used by the industry; ionic implantation by plasma immersion (IIPI) of nitrogen; IIPI of nitrogen over the layer already existing of conventional gas nitriding; against a sample that was tested without any layer of coating. The micro abrasive tests were performed in an equipment named ball-on-block, using abrasive solution of silicon carbide (SiC), and varying the normal load from 1, 2 and 3N. The results showed that the conventional gas nitriding performed the highest level of micro hardness on the surface, and also the highest level of micro abrasion wear; this result prevailed in this sample in all the normal load applied. Generally, the sample that obtained the best level of wear, in other words, the lowest worn volume was the sample whithout any coating / Mestrado / Materiais / Mestre em Engenharia Automobilistica

D.Ing. (Electrical and Electronic Engineering) / Please refer to full text to view abstract

The original work presented in this thesis describes research into Si-based luminescent materials, prepared specifically by ion implantation and rapid thermal processing of thermal oxide films. An in-depth optical characterisation, employing photoluminescence (PL) and Raman spectroscopy was complimented with electron microscopy, revealing the source of efficient room temperature PL as nano-scale silicon inclusions (Si-NCs). The evolution of the Si-NC size and density with isothermal and isochronal annealing may be described using classical thermodynamics according to a diffusion limited, Ostwald ripening process. Values for the coarsening rate and activation energy, extracted from the evolution of the Si-NC size with annealing indicate that the transport of Si atoms and precipitate formation are enhanced in ion implanted films, attributable to the presence of vacancy and interstitial defects generated during ion irradiation. The PL and Raman spectra are well correlated with the evolving Si-NC size and density according to the quantum confinement (QC) model in which samples containing larger clusters emit at longer wavelengths. However, the formation of bound exciton states within the band gap of small clusters (< 2nm), as a result of specific surface chemistries, suppresses higher energy emissions. The increase in PL intensity with annealing was exactly correlated with the increase in PL lifetime, characteristic of the removal of non-radiative defects. A dependence of the PL dynamics on emission energy, with higher energies exhibiting shorter lifetimes, further evidences the QC effect. Blue shifted emission at high excitation flux and/or low temperature is correspondent with the slower PL dynamics and preferential saturation at longer wavelengths. Raman spectra were fit using a phonon confinement model, from which Si-NC size distributions were extracted and found to compare favourably with those obtained from TEM images. Stresses in the films, determined from the Raman peak position, were used as an independent method for calculating the Si surface energy, which is very close to the literature values. A single, high temperature anneal of Si and erbium (Er) co-doped films revealed a preferential aggregation of Er at the Si-NC formation site, which is of particular importance for the photo-sensitization of Er PL around 1.5μm. The Er PL was enhanced in the presence of Si-NCs by several orders of magnitude compared with a reference SiO2:Er. Whilst broadband pumping of the Er via Si-NCs evidences a non-resonant energy transfer mechanism with an efficiency which depends on the Si-NC size, the process is limited at high excitation flux by a combination of low sensitizer (Si-NC) density and non-radiative losses. Finally the Si-NC PL intensity in phosphorus (P) co-doped films was studied and found to depend strongly on the annealing conditions and P concentration. For lower temperature treatments, a factor 2 PL enhancement, relative to an un-doped reference was obtained, attributed to the passivation of Si-NC surface defects. Higher temperature treatments resulted in the monotonic quenching of the PL with increasing P concentration, attributed to the introduction of an efficient Augerre combination channel as a result of the ionization of P-donors inside large Si-NCs. A simple statistical model predicts this behaviour and provides an incidental estimate of the Si-NC size.

A new understanding of the damage formation mechanisms in Si is developed and investigated over an extended range of ion energy, dose, and irradiation temperature. A simple model for dealing with ion-induced damage is proposed, which is shown to be applicable over the range of implantation conditions. In particular the concept of defect "excesses" will be discussed. An excess exists in the lattice when there is a local surplus of one particular type of defect, such as an interstitial, over its complimentary defect (i.e., a vacancy). Mechanisms for producing such excesses by implantation will be discussed. The basis of this model specifies that accumulation of stable lattice damage during implantation depends upon the excess defects and not the total number of defects. The excess defect model is validated by fundamental damage studies involving ion implantation over a range of conditions. Confirmation of the model is provided by comparing damage profiles after implantation with computer simulation results. It will be shown that transport of ions in matter (TRIM) can be used effectively to model the ion-induced damage profile, i.e. excess defect distributions, by a simple subtraction process in which the spatially correlated defects are removed, thereby simulating recombination. Classic defect studies illuminate defect interactions from concomitant implantation of high- and medium-energy Si+-self ions. Also, the predictive quality of the excess defect model was tested by applying the model to develop several experiments to engineer excess defect concentrations to substantially change the nature and distribution of the defects. Not only are the excess defects shown to play a dominant role in defect-related processing issues, but their manipulation is demonstrated to be a powerful tool in tailoring the implantation process to achieve design goals. Pre-amorphization and dual implantation of different energetic ions are two primary investigative tools used in this work. Various analyses, including XTEM, RBS/channeling, PAS, and SIMS, provided experimental verification of the excess defect model disseminated within this dissertation.