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Dai, Congxia. "An advanced data acquisition system & noise analysis on the aluminum reduction process." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=2850.
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Thesis (M.S.)--West Virginia University, 2003.Title from document title page. Document formatted into pages; contains ix, 82 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 75-78).
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Venzant, Kenneth L. "Analysis of residual stresses in laser trimmed alumina microelectronic substrates." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-07102009-040540/.
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Walker, Justin I. "Spectroscopic Analysis of Materials for Orthopaedic and Energy Conversion Applications." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1226948982.
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Gignac, Lynne Marie. "Processing and characterization of RF sputtered alumina thin films." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184611.
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Thin films of alumina were deposited on ferrite (NiₓZn₍₁₋ₓ₎Fe₂O₄), glass, single crystal silicon and graphite substrates by RF sputtering. Though standard, amorphous Al₂O₃ films are readily soluble in hot phosphoric acid, these sputtered films exhibited only reluctant etchability by the acid. Experiments were initially performed to understand the parameters in the sputtering process which were influential in the formation of unetchable films. The results showed that a high concentration of water vapor or oxygen molecules in the sputtering chamber during deposition was the most significant variable controlling the growth of unetchable films. The films were categorized according to their degree of solubility in H₃PO₄ and were examined using various microanalytical characterization techniques. TEM analysis directly showed the existence of crystalline γ-Al₂O₃ in the film at the film-substrate interface. The γ-Al₂O₃ phase grew with a preferred orientation coincident with the substrate orientation--as in heteroepitaxial growth. The occurrence of this film phase was related to the oxygen partial pressure, the substrate material, and the substrate temperature and was believed to be the cause of the film's incomplete etching behavior.
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Johnson, Brian Ivins. "Preparation and Detailed X-Ray Photoelectron Spectroscopy and Spectroscopic EllipsometryAnalysis of Ultrathin Protective Coatings." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8119.
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Ultra-thin films (UTFs) are important in many applications, seen in the semiconductor industry, in chromatography, in sensing, in microfluidics, in aerospace, and in robotics. They also protect materials from corrosion, change surface energies, limit water intrusion into materials, allow material self-cleaning and self-healing, provide scratch resistance, and impart other specific chemical properties. In many cases, UTFs drastically alter surface properties and therefore their applications. It is imperative that proper and consistent characterization be performed on coatings to confirm and understand their desired properties. In Chapter two, Al oxidation under MgF2 protective layers is studied using real time X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). These tools allowed me to monitor Al oxidation for both short (hours) and long (months) periods of time. XPS revealed the chemical changes that took place in these materials as a function of time, and these changes were verified with SE. These studies help increase an understanding of aluminum changes under MgF2 protective layers. The third chapter demonstrates ab initio calculations guided X-ray photoelectron spectroscopy (XPS) analysis of surfaces functionalized with fluorinated silanes. This study addresses deficiencies in the literature where CF2:CF3 ratios from experimental XPS data do not match theoretical CF2:CF3 ratios. In a systematic approach, I developed semi-empirical models directed both by ab initio calculations and adjustable, empirical parameters. These models were effective in describing the raw data and exceeded fitting methods used in literature. In Chapter four, SiO2 UTFs with variable thicknesses deposited on Eagle XG® glass substrates are characterized. Challenges associated with this work consisted of similar optical functions of the film and substrate as well as backside reflections from the substrate. These obstacles were met using a multi-sample analysis (MSA), a variable angle spectroscopic ellipsometric approach, and mechanical abrasion/roughening of the substrate backside. With these approaches, I developed a model that precisely fit the data collected from all the samples and gave the correct optical function of the material along with thickness values for each film. Surface characterization represents a commitment of resources. It takes time to make measurements, and it takes time to analyze and understand the results. As presented in this work, I increase understanding of ultra-thin films at interfaces using both a multi-tool approach as well as using multiple analytical methods on data collected from each tool.
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Bedin, Flávia Caroline. "Coprecipitados de alumínio e cério com 8-hidroxiquinolina: obtenção e comportamento térmico." Universidade Tecnológica Federal do Paraná, 2014. http://repositorio.utfpr.edu.br/jspui/handle/1/1114.
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O presente estudo teve como foco avaliar a influência das variáveis pH, temperatura e tempo de agitação na obtenção e no comportamento térmico dos coprecipitados de alumínio e cério com 8-hidroxiquinolina. O processo de síntese foi realizado através da metodologia de coprecipitação, utilizando como agente precipitante a 8-hidroxiquinolina. Para um melhor controle das variáveis influentes no sistema de precipitação, pH, temperatura e tempo de agitação, elaborou-se um planejamento experimental, semelhante ao planejamento estatístico, visando a otimização do processo. Foram utilizados, pH: 5, 10 e 7,5; temperatura: 25, 60 e 42,5 °C; tempo de agitação de 1, 2 e 3 h. Foram obtidos coprecipitados de todas as combinações das variáveis possíveis, esperando ter como resposta a influência de cada uma das variáveis no comportamento térmico dos complexos obtidos. Após síntese dos complexos os mesmos foram submetidos à análise de espectroscopia no infravermelho, onde se constatou a presença dos mesmos compostos para todas as condições. Foi realizada a análise térmica a fim de determinar a influência de cada um dos fatores sob o comportamento térmico dos complexos obtidos. A análise foi efetuada em atmosfera oxidativa, variando a taxa de aquecimento em 5, 10 e 20 °C min-1. Com o auxílio das curvas de análise térmica, observou-se que todas as variáveis tiveram influência no comportamento térmico dos materiais, sendo o pH, a variável que apresentou a diferença mais significativa entre os processos. A fim de determinar as fases dos óxidos obtidos após o tratamento térmico, utilizou-se a análise de difratometria de raios-X e, por meio desta, constatou-se que apesar as diferenças dos comportamentos térmicos dos materiais, as fases obtidas para todas as condições foram as mesmas, ou seja, uma mistura de óxido de alumínio e óxido de cério.The present study had as focus to evaluate the influence of the PH variables, temperature and time of agitation to obtain and the thermal behavior of co-precipitation of aluminum and cerium with 8-hidroxiquinolina. The process of syntheses was accomplished through the methodology of co-precipitation, using as precipitant agent the 8-hidroxiquinolina. For a better control of the variables that influence the precipitation system, pH, temperature and agitation time, it was elaborated an experimental planning, similar to the static planning, having as goal the optimization of the process. It was utilized, pH: 5, 10 and 7.5; temperature: 25, 60 and 42.5 ºC; agitation periods of 1, 2 and 3 h. It was obtained co-precipitation of all the variables possible combinations, hoping to have the influence of each variable on the thermal behavior of the complexes obtained. After syntheses of the complex the same were submitted to the spectroscopy analysis on the infrared where it was established the presence of the same compounds for all the conditions. The thermal analysis was done with the goal to determinate the influence of each one of the factors of the thermal behavior of the obtained complexes. The analysis was done in an oxidative atmosphere, varying the heating rate in 5, 10 and 20 º C min. With the aid of the thermal analysis curves, it was observed that all the variables had influence in the thermal behaviors of the materials, being the pH, the variable that presented the most significant difference between the processes. To determine the phases of the oxides obtained after the thermal treatment, it was used the x-ray diffraction analysis and, by that, it was established that despite the differences in the thermal behavior of the materials, the phases obtained to all the conditions were the same, meaning, a mixture of oxide of aluminum and cerium oxide.
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Poduri, Shripriya Darshini. "THEORETICAL MODELING AND ANALYSIS OF AMMONIA GAS SENSING PROPERTIES OF VERTICALLY ALIGNED MULTIWALLED CARBON NANOTUBE RESISTIVE SENSORS AND ENHANCING THEIR SENSITIVITY." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/51.
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Vertically aligned Multiwalled Carbon Nanotubes (MWCNTs) were grown in the pores of Anodized Aluminum Oxide (AAO) templates and investigated for resistive sensor applications. High Sensitivity of 23% to low concentration (100 ppm) of ammonia was observed. An equivalent circuit model was developed to understand the current flow path in the resistive sensor. This helped us in achieving high sensitivities through amorphous carbon (a-C) layer thickness tailoring by employing post-growth processing techniques like plasma etching.
A simulation model in MATLAB was developed to calculate the device resistance and the change in the sensitivity as a function of device parameters. The steady state response and transient response of the model to the number of ammonia molecules and its adsorption rate were studied. Effects of oxygen plasma, argon plasma and water plasma etch on thinning of the a-C layer were studied.
In order to enhance the sensitivity, the top and bottom a-C layers were replaced by a more conductive metal layer. This also helped in understanding the current flow in the device and in the estimation of the resistivity of the a-C layer.
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Santos, Thales Borrely dos. "Controle de propriedades de filmes finos de óxido de alumínio através da assistência de feixe iônico." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-03062017-212721/.
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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.
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Carossi, Lory Cantelli. "Propriedades ópticas da alumina anódica porosa e o efeito do guia de onda." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/9003.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Nanoporous anodic alumina films (NAA) may present different behavior to reflectance and photoluminescence techniques, with Fabry-Pérot interferences and waveguide properties. This phenomenon makes possible the use of NAA as transducer signal in optical sensors. In this work, we investigated how the pre-treatment, the number of steps of anodizing, the anodizing electrolyte mode and temperature affect electrochemical characteristics, morphological and optical mainly NAA. As a result, it was noticeable that the realization of electropolishing is necessary for both the NAA with good regularity as to make it possible to obtain a spectrum with the Fabry-Pérot interference. If the fabrication of NAA is done in two steps, it is possible to obtain reflectance spectra and luminescence fringed with better amplitudes, areas and heights. Regarding the anodizing mode, both the NAA anodized in galvanostatic how potentiostatic showed similar morphologies and spectra with fringes, but the interferences were better defined when the galvanostatic mode was performed. Regarding the temperature, it was noticeable that the change of this parameter leads influences the porous oxide thickness. The spectrum of the luminescence and reflectance increasing the electrolyte temperature caused an increase in interference. However, the range and resolution of interference decreased with increasing temperature. The oxide thicknesses were estimated by energy variation (?E), graph slope between order and 1/? and fast Fourier transform (FFT) techniques. The ratio of film thickness and pore diameter (L/dp) was performed to validate the NAA films with better waveguides property. Moreover, the surface composition analysis of NAA films anodized in phosphoric acid, oxalic acid and mixtures thereof by backscattering spectroscopy Rutherford (RBS) was performed. From simulations it was possible to note that the amount of carbon in the porous oxide structure is practically zero, which may indicate that the origin of the luminescence is related to the presence of more centers F.
Filmes de alumina anódica porosa (AAP) podem apresentar, espectros de reflectância e luminescência com interferências de Fabry-Pérot e propriedades de guias de onda. Esse fenômeno possibilita que a AAP possa ser utilizada como plataforma em sensores ópticos. Neste trabalho, foi investigado como o pré-tratamento, o número de etapas de anodização, o modo de anodização e a temperatura do eletrólito afetam características eletroquímicas, morfológicas e principalmente ópticas da AAP. Como resultado, foi possível notar que a realização do eletropolimento é necessário para obter tanto a AAP com boa regularidade como para que seja possível obter um espectro com as interferências Fabry-Pérot. Se a fabricação da AAP for feita em duas etapas, é possível obter espectros de reflectância e luminescência com franjas com melhores amplitudes, áreas e alturas. Com relação ao modo de anodização, tanto as AAPs anodizadas em modo galvanostático como potenciostático apresentaram morfologias semelhantes e espectros com franjas, mas as interferências foram melhor definidas quando o modo galvanostático foi realizado. Com relação à temperatura, foi possível notar que a mudança desse parâmetro ocasiona influencia na espessura do óxido poroso. Quanto aos espectros de luminescência e reflectância, o aumento da temperatura do eletrólito ocasionou um aumento no número de interferências. Entretanto, a amplitude e a resolução das interferências diminuíram com o aumento da temperatura. A espessura do filme poroso foi estimada pelas técnicas de variação de energia (?E), coeficiente angular do gráfico entre ordem da interferência e 1/? e através da transformada rápida de Fourier (FFT). E foi utilizada a razão entre a espessura do filme e diâmetro do poro (Esp/Dp) para averiguar os filmes de AAP com guias de onda que pudessem ser utilizadas como substratos para sensores ópticos. Além disso, foi realizada a análise de composição superficial dos filmes de AAP anodizados em ácido fosfórico, oxálico e mistura destes ácidos pela técnica de espectroscopia de retroespalhamento de Rutherford (RBS). A partir das simulações realizadas foi possível notar que a quantidade que carbono na estrutura do oxido poroso é praticamente nula, o que pode indicar que a origem da luminescência está relacionada à presença dos centros F.
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Dias, Marcio Soares. "Desenvolvimento de modelos analiticos para propriedades termicas e condução de calor transiente em varetas combustiveis nucleares." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266280.
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Orientadores: Elizabete Jordão, Vanderley de VasconcelosTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: A dependência com a temperatura das propriedades térmicas dos materiais faz com que a análise do transiente térmico em varetas combustíveis de reatores nucleares seja não-linear. Tradicionalmente, métodos de diferenças finitas ou de elementos finitos são utilizados para resolver este problema. A remoção efetiva do calor gerado nas varetas combustíveis constitui uma das considerações primárias no projeto de reatores nucleares. Os fabricantes de combustíveis nucleares e as geradoras de energia elétrica de fonte nuclear devem demonstrar a segurança do reator através da análise dos resultados de situações transientes diversas. Estes transientes podem ocorrer tanto em operação normal, quanto em situações de acidentes e devem ser analisados para assegurar que a vareta combustível manterá sua integridade para todas estas condições. A equação de transferência de calor para o combustível é não-linear. Esta equação não-linear de diferenciais parciais pode ser convertida em uma forma linear por meio da transformação baseada nas propriedades térmicas. Este trabalho apresenta a análise teórica aplicada no desenvolvimento de um modelo analítico, aqui chamado de variacionais relativos e direcionado para a modelagem de propriedades térmicas de materiais cerâmicos de aplicação nuclear, em particular o dióxido de urânio, UO2, e o óxido de alumínio, Al2O3. As propriedades térmicas modeladas são aquelas envolvidas no processo de condução de calor em materiais cristalinos: expansão térmica, calor específico, condutividade térmica e as suas formas integrais. No processo de avaliação de dados foram utilizados cerca de 5500 medidas de propriedades físicas e térmicas disponíveis na literatura aberta. Com base neste desenvolvimento é estabelecida a relação linear entre a variação de entalpia e a integral de condutividade térmica do UO2. Esta relação permite resolver, analiticamente, as distribuições espacial e temporal de temperaturas no combustível nuclear para as condições de estado estacionário e de transiente. A solução encontrada aplica-se igualmente outros sistemas onde o balanço de energia seja determinado pelo equilíbrio entre calor armazenado e calor transportado. A modelagem analítica desenvolvida amplia as possibilidades de avaliação crítica da consistência de propriedades térmicas e físicas dos materiais
Abstract: The temperature dependence of the material thermal properties makes the transient thermal analysis of reactor fuel pins to be non-linear. Traditionally, finite difference or finite element methods have been used to solve this problem. Effective heat removal from the fuel pins of a nuclear reactor poses one of the primary considerations in reactor design. Nuclear fuel vendors and nuclear electricity utilities must demonstrate the safety of the reactor by thorough examination of the outcome of various transient situations. These transient effects may occur in normal operation as well as in accident situations and must be analysed to insure the fuel pin maintains its integrity. The governing heat transfer equation for the fuel is non-linear. This non-linear, partial differential equation can be recast into a linear form by introducing a transformation based on material property. This work presents the theoretical analyses to develop a analytical model, here named model of relative variationals, for modelling of thermal properties of nuclear ceramic materials, in matter uranium dioxide, UO2, and aluminium oxide, Al2O3. The modeled thermal properties are those involved in the process of heat transport in crystalline materials: thermal expansion, specific heat, thermal conductivity and their integral forms. In the data evaluation process were used about 5500 measures of physical and thermal properties available in the open literature. Based on this development, the linear relationship has been established between the UO2 enthalpy and thermal conductivity integral. This relationship enables the heat conduction equation to be solved analytically for steady state and transient conditions. The solution is also applied in other systems where the balance of energy is determined by the equilibrium between stored heat and transported heat. The developed analytical modelling enlarges the possibilities for critical evaluation of the thermal and physical properties of the materials
Doutorado
Sistemas de Processos Quimicos e Informatica
Doutor em Engenharia Química
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Alibhai, Awla Amirali. "Strategies for the analysis of alumina oxides using SIMS." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404913.
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Potier, Louis. "DFT-MD simulations of aluminium oxide/liquid water interfaces for heterogeneous catalysis." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLE032.
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Cette thèse, financée par l'ANR SLIMCAT (Solid-Liquid Interface at Molecular Scale for Catalysis), a pour but de caractériser la structure des interfaces alumine/eau liquide, tant du point de vue du solide que du liquide en contact. Au-delà des propriétés structurales, nous apportons des informations supplémentaires sur la chimie se produisant à l'interface, et tentons de comprendre/démontrer dans quelles mesures les modèles de surfaces d'α-alumine sont pertinents pour les surfaces de γ-alumine qui sont utilisés expérimentalement dans la catalyse hétérogène. La DFT-MD (Dynamique Moléculaire basée sur la Théorie de la Fonctionnelle de la Densité) a été utilisée pour les simulations, plusieurs codes informatiques ont été développés afin de calculer toutes les propriétés structurales et spectroscopiques pertinentes à partir des données de simulations. La spectroscopie SFG (Sum Frequency Generation) a été aussi utilisée dans nos calculs théoriques pour attribuer de façon définitive la composition, la spéciation et la structure des surfaces aqueuses α-(0001)-C et α-(1102)-R. Plusieurs surfaces ont été présentées dans la littérature comme étant la plus stables pour l'orientation (1102)-R de l'α-alumine. En simulant toutes ces surfaces par DFT-MD, nous avons démontré que seule la surface C1 est stable au contact de l'eau liquide, et l'interface aqueuse possède un spectre SFG qui coïncide exactement avec le spectre expérimental. Cependant, la surface (1102)-R-C2 est connue comme étant la plus stable au contact de l'air. Afin de réconcilier ces deux informations, nous avons démontré que la calcination de l'interface aqueuse (1102)-R-C1 à haute température (~1000 K) conduit à sa conversion vers la surface (1102)-R-C2, dorénavant au contact de l'air, tandis que la surface (1102)-R-C2 se reconstruit vers la surface (1102)-R-C1 une fois mise au contact de l'eau. Nous avons aussi résolu les controverses de la littérature sur l'interface α-(0001)-C/eau liquide. Il a donc été démontré qu'il existe une organisation particulière de l'eau liquide, consistant en un réseau 2D de liaisons hydrogène formé dans la couche d'eau au contact du solide par le biais de liaisons-H eau-eau orientées parallèlement à la surface. Cette structure est identique au réseau 2D de liaisons-H formé par l'eau à l'interface avec le milieu hydrophobe ultime, i.e. le vide. Quand des électrolytes (1.0M KCl) sont placés à cette interface aqueuse, nous avons montré que leur présence n'affecte pas l'organisation du réseau 2D de liaisons hydrogène. Les interfaces gamma-alumine/eau liquide γ-(110) et γ-(100) ont aussi été simulées. Nous avons montré que l'interface γ-(110)/eau liquide en particulier partage de nombreux points communs avec les interfaces aqueuses d'α-alumine, ce qui démontre que les modèles-α sont pertinents pour fournir des informations sur la structure de la γ-alumine aqueuse effectivement utilisée en catalyse hétérogèneThis PhD thesis, funded by ANR SLIMCAT (Solid-Liquid Interface at Molecular Scale for Catalysis), has for goal to characterize the structure of alumina/liquid water interfaces, both from the point of view of the solid and liquid in contact. Beyond structural properties, we aim to provide some details on the chemistry occurring at the interface, and also to understand to what extent α-alumina surfaces models are relevant for γ-alumina surfaces effectively used in experiments in heterogeneous catalysis. DFT-MD (Density Functional Theory based Molecular Dynamics) was used for the simulations, multiple codes were developed to compute all relevant structural and spectroscopic properties from the simulations data. SFG (Sum Frequency Generation) spectroscopy was also employed in the theory to definitely assign the composition, speciation and structure of the aqueous α-(0001)-C and α-(1102)-R alumina surfaces. Multiple surfaces have been presented in the literature as being the most stable for the (1102)-R orientation of α-alumina. By investigating all of them by DFT-MD, we have shown that, when placed in contact with liquid water, only the C1 surface is stable and simultaneously provide a SFG spectrum consistent with the experimental one. However, the (1102)-R-C2 surface is known to be the most stable in contact with the air. To reconcile these two observations, we demonstrated that the calcination of the (1102)-R-C1/liquid water interface at high temperature (~1000 K) leads to the conversion to the (1102)-R-C2 surface, now in contact with the air, while the (1102)-R-C2 recontructs towards the (1102)-R-C1 surface once put in contact with water. We have also resolved the controversies in literature on the α-(0001)-C/liquid water interface. A particular organization of liquid water has hence been shown to exist, consisting of a 2D-HBond-network formed in the topmost interfacial water layer via water-water H-bonds oriented parallel to the surface. This structure is reminiscent of the 2D-HBond-Network formed by water at the interface with the ultimate hydrophobic medium, i.e. vacuum. When electrolytes (1.0M KCl) were placed at this interface, their presence was found not to affect the organization of the 2D-Hbond-network. The γ-(110) and γ-(100) gamma-alumina/liquid water interfaces were also investigated. We find that the γ-(110)/liquid water interface especially shares many common points with α-alumina aqueous interfaces, which shows that α-models are relevant to provide information for the structure of the aqueous γ-alumina employed in catalysis
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Bittau, Francesco. "Analysis and optimisation of window layers for thin film CDTE solar cells." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/32642.
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The work presented in this thesis focuses on the investigation and improvement of the window stack of layers for thin film CdTe solar cells fabricated in the Center for Renewable Energy Systems Technology (CREST) laboratories. In particular the aim was to change the standard structure including TCO, high resistive transparent (HRT)layer and CdS which is limited by the low transparency of the CdS layer, to a better performing one. The first result chapter of the thesis describes the study of ZnO HRT layers. ZnO thin films were deposited by radio frequency (RF) magnetron sputtering with different structural, optical and electrical properties which were characterized by X-ray diffraction, electron microscopy, spectrophotometry, Hall Effect method and 4-point probe. ZnO films were then incorporated in CdTe solar cells with the structure: FTO/ZnO/CdS/CdTe/Au back contact and the performance of these devices were compared with the film properties to single out trends and identify optimal film characteristics. By varying the deposition pressure of ZnO films, it was possible to increase their transparency and significantly increase their resistivity. While better transparency positively affected the solar cell current density output and efficiency, the resistivity of ZnO films did not show any clear impact on device efficiency. By increasing the deposition temperature the ZnO film grain size was increased. Increased FF was observed in devices incorporating ZnO layers with bigger grains, although this gain was partially counterbalanced by the Voc degradation, leading to a limited efficiency improvement. Finally the addition of oxygen had the main effect of increasing the resistivity of ZnO films, similarly to what happened with the increase of the sputtering pressure. In this case however, an improvement of FF, Jsc and efficiency was observed, especially at an O2/Ar ratio of 1%. By simulating the solar cells behavior with SCAPS-1D, it was found that these performance change can be explained by the variation of interface properties, precisely the amount of interface defects, rather than by bulk properties. The study presented in the second result chapter focuses on magnesium-doped zinc oxide (MZO) and the variation of its energy band structure. MZO was initially used as the HRT layer within a solar cell structure: FTO/MZO/CdS/CdTe/Au back contact. Sputtering MZO films with a target containing MgO 11 weight% and ZnO 89 weight% allowed for and increased band gap from 3.3 eV of intrinsic ZnO to 3.65 eV for MZO deposited at room temperature. Increasing the superstrate deposition temperature allowed for a further band gap increase up to 3.95 eV at 400 °C due mainly to an conduction band minimum upward shift. It was highlighted the importance to create a positive conduction band offset with the MZO layer conduction band slightly above the CdS conduction band, with an optimum found in this case to be 0.3 eV (efficiency 10.6 %). By creating a positive conduction band offset all the performance parameters (Voc, FF, Jsc, efficiency) significantly increased. One of the reasons for this improvement was found to be a diminished interface recombination due to a more ideal MZO/CdS band alignment. In the second part of this investigation the MZO was used as a replacement for the CdS in a simplified structure: FTO/MZO/CdTe/Au back contact. The concepts used to optimise the performance of these devices also involved tuning the conduction band alignment between MZO/CdTe and efficiencies of 12.5 % were achieved with a at conduction band offset. The efficiency increase was achieved mainly thanks to a better transparency of the MZO layer and a higher Jsc output, compared to devices using a CdS buffer layer. The MZO buffers have been tested in combination with different TCOs. Results are presented in the third result chapter and showed that AZO is a good alternative to FTO working effectively in combination with MZO. AZO/MZO efficiency thin film CdTe solar cells (12.6%, compared to 12.5% with FTO). It was found that increasing the IR transparency of the TCOs leads to a potentially higher Jsc. Achieving a better transparency was obtained by using TCOs with high mobility and lower carrier concentration (AZO and ITiO) and also by using a boro-aluminosilicate glass with low iron content. ITiO yielded the best opto-electrical properties among all the TCO materials. Devices incorporating ITiO however, showed lower performance then those using FTO and AZO. ITO/MZO windows also yielded poor performance. In addition, the ITO films deposited had a high carrier concentration leading to a high NIR absorption by plasma resonance and resulted not ideal for application in thin film CdTe PV.
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Issa, Inas. "In situ TEM nanocompression and mechanical analysis of ceramic nanoparticles." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI008/document.
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Dans cette étude, nous proposons d’utiliser la compression in situ dans le MET afin de caractériser les propriétés mécaniques de nanoparticules céramiques dont la taille caractéristique est de l’ordre de quelques dizaines de nanomètres. Nous appliquerons cette méthode à des nanocubes monocristallins de MgO, une céramique modèle dont la plasticité est bien connue dans le matériau massif. Les essais de nanocompression montrent que les nanocubes de MgO se déforment de façon homogène jusqu’à de grandes déformations (>50%) sans fissure apparente. L’analyse des résultats est assistée par des méthodes de corrélation d’images numériques et simulations de type dynamique moléculaire. Le mécanisme de déformation et l'effet de taille sur la limite élastique sont identifiés. Dans une deuxième partie de la thèse, nous présentons une étude sur des nanoparticules d’alumine de transition compactée en CED (Cellule à Enclumes en Diamant) à température ambiante, sous plusieurs pressions (5 GPa, 15 GPa et 20 GPa). Des lames minces préparées par FIB ont été étudiées en MET. Des images HRTEM montrent une texture cristallographique qui devient plus importante à des pressions plus élevées. Une orientation cristallographique préférentielle est observée, avec les plans {220} de la phase gamma de l’alumine la plupart du temps parallèles à la surface de contact avec une particule voisine. Ce comportement mécanique est cohérent avec un système de glissement, connu pour les structures spinelles. Une corrélation de ce comportement avec les tests in situ MET réalisés sur des nanoparticules similaires, par Emilie Calvié lors de sa thèse, est présentée. Enfin, des clichés de diffraction de type Debye Scherrer sont réalisés sur ces lames minces de nanoparticules d’alumine de transition compactées en CED à différentes pressions. L’analyse quantitative de ces clichés montre une transformation de phase de ces nanoparticules d’alumine de phase gamma en phase delta, de manière croissante avec la pressionIn this study, we propose an innovative mechanical observation protocol of ceramics nanoparticles in the 100nm size range. This Protocol consists of in situ TEM nanocompression tests of isolated nanoparticles. Load–real displacements curves, obtained by Digital Image Correlation, are analyzed and these analyses are correlated with Molecular Dynamics simulations. By this protocol a constitutive law with its mechanical parameters (Young modulus, Yield stress...) of the studied material at the nano-scale can be obtained. In situ TEM nano-compression tests on magnesium oxide nanocubes are performed. Magnesium oxide is a model material and its plasticity is very well known at bulk. The MgO nanocubes show large plastic deformation, more than 50% of plastic strain without any fracture. The TEM results are correlated to MD simulations and the deformation mechanism can be identified.The size effect and the electron beam effect on the yield strength are investigated. In a second part of the dissertation, we present a study on transition alumina nanoparticles compacted in a Diamond Anvil Cell at different uniaxial pressures. Thin Foils of these compacted nanoparticles are prepared by FIB for HRTEM Observations. Their analysis reveals the plastic deformation of the nanoparticles. The crystallographic texture observed inthese compacted nanoparticles in DAC shows a preferred orientation of the {110} lattice planes, orientated perpendicular to the compression direction. This is compatible with the slip system. This argument was reinforced with a preferred orientation of slip bands observed during in situ TEM nano-compression tests. Moreover, electron diffraction patterns (Debye Scherrer) analysis on these compacted transition alumina nanoparticles reveals the decrease of the presence of gamma-alumina and the increase of delta-alumina with increasing pressure. This reveals the phase transformation with increasing pressure from gamma to delta* alumina
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SILVA, JOSE E. R. da. "Aplicação de métodos não destrutivos para qualificação de combustíveis tipo dispersão de Usub(3)Osub(8)-Al e Usub(3)Sisub(2)-Al no reator IEA-R1." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10058.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Zhao, Yanyan. "Synthesis and characterisation of metal (Fe, Ga, Y) doped alumina and gallium oxide nanostructures." Queensland University of Technology, 2008. http://eprints.qut.edu.au/20529/.
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It is well known that nanostructures possess unique electronic, optical, magnetic, ferroelectric and piezoelectric properties that are often superior to traditional bulk materials. In particular, one dimensional (1D) nanostructured inorganic materials including nanofibres, nanotubes and nanobelts have attracted considerable attention due to their distinctive geometries, novel physical and chemical properties, combined effects and their applications to numerous areas. Metal ion doping is a promising technique which can be utilized to control the properties of materials by intentionally introducing impurities or defects into a material.
γ-Alumina (Al2O3), is one of the most important oxides due to its high surface area, mesoporous properties, chemical and thermal properties and its broad applications in adsorbents, composite materials, ceramics, catalysts and catalyst supports. γ-Alumina has been studied intensively over a long period of time. Recently, considerable work has been carried out on the synthesis of 1D γ-alumina nanostructures under various hydrothermal conditions; however, research on the doping of alumina nanostructures has not been forthcoming. Boehmite (γ-AlOOH) is a crucial precursor for the preparation of γ-Alumina and the morphology and size of the resultant alumina can be manipulated by controlling the growth of AlOOH.
Gallium (Ga) is in the same group in the periodic table as aluminum. β-Gallium (III) oxide (β-Ga2O3), a wide band gap semiconductor, has long been known to exhibit conduction, luminescence and catalytic properties. Numerous techniques have been employed on the synthesis of gallium oxide in the early research. However, these techniques are plagued by inevitable problems. It is of great interest to explore the synthesis of gallium oxide via a low temperature hydrothermal route, which is economically efficient and environmentally friendly.
The overall objectives of this study were: 1) the investigation of the effect of dopants on the morphology, size and properties of metal ion doped 1D alumina nanostructures by introducing dopant to the AlOOH structure; 2) the investigation of impacts of hydrothermal conditions and surfactants on the crystal growth of gallium oxide nanostructures. To achieve the above objectives, trivalent metal elements such as iron, gallium and yttrium were employed as dopants in the study of doped alumina nanostructures. In addition, the effect of various parameters that may affect the growth of gallium oxide crystals including temperature, pH, and the experimental procedure as well as different types of surfactants were systematically investigated.
The main contributions of this study are: 1) the systematic and in-depth investigation of the crystal growth and the morphology control of iron, gallium and yttrium doped boehmite (AlOOH) under varying hydrothermal conditions, as a result, a new soft-chemistry synthesis route for the preparation of one dimensional alumina/boehmite nanofibres and nanotubes was invented; 2) systematic investigation of the crystal growth and morphology and size changes of gallium oxide hydroxide (GaOOH) under varying hydrothermal conditions with and without surfactant at low temperature; We invented a green hydrothermal route for the preparation of α-GaOOH or β-GaOOH micro- to nano-scaled particles; invented a simple hydrothermal route for the direct preparation of γ-Ga2O3 from aqueous media at low temperature without any calcination.
The study provided detailed synthesis routes as well as quantitative property data of final products which are necessary for their potential industrial applications in the future. The following are the main areas and findings presented in the study:
• Fe doped boehmite nanostructures
This work was undertaken at 120ºC using PEO surfactant through a hydrothermal synthesis route by adding fresh iron doped aluminium hydrate at regular intervals of 2 days. The effect of dopant iron, iron percentage and experimental procedure on the morphology and size of boehmite were systematically studied. Iron doped boehmite nanofibres were formed in all samples with iron contents no more than 10%. Nanosheets and nanotubes together with an iron rich phase were formed in 20% iron doped boehmite sample. A change in synthesis procedure resulted in the formation of hematite large crystals. The resultant nanomaterials were characterized by a combination of XRD, TEM, EDX, SAED and N2 adsorption analysis.
• Growth of pure boehmite nanofibres/nanotubes
The growth of pure boehmite nanofibres/nanotubes under different hydrothermal conditions at 100ºC with and without PEO surfactant was systematically studied to provide further information for the following studies of the growth of Ga and Y doped boehmite. Results showed that adding fresh aluminium hydrate precipitate in a regular interval resulted in the formation of a mixture of long and short 1D boehmite nanostructures rather than the formation of relatively longer nanofibres/nanotubes. The detailed discussion and mechanism on the growth of boehmite nanostructure were presented. The resultant boehmite samples were also characterized by N2 adsorption to provide further information on the surface properties to support the proposed mechanism.
• Ga doped boehmite nanostructures
Based on this study on the growth of pure boehmite nanofibre/nanotubes, gallium doped boehmite nanotubes were prepared via hydrothermal treatment at 100ºC in the presence of PEO surfactant without adding any fresh aluminium hydrate precipitate during the hydrothermal treatment. The effect of dopant gallium, gallium percentage, temperature and experimental procedure on the morphology and size of boehmite was systematically studied. Various morphologies of boehmite nanostructures were formed with the increase in the doping gallium content and the change in synthesis procedure. The resultant gallium doped boehmite nanostructures were characterized by TEM, XRD, EDX, SAED, N2 adsorption and TGA.
• Y doped boehmite nanostructures
Following the same synthesis route as that for gallium doped boehmite, yttrium doped boehmite nanostructures were prepared at 100ºC in the presence of PEO surfactant. From the study on iron and gallium doped boehmite nanostructures, it was noted both iron and gallium cannot grow with boehmite nanostructure if iron nitrate and gallium nitrate were not mixed with aluminium nitrate before dissolving in water, in particular, gallium and aluminium are 100% miscible. Therefore, it’s not necessary to study the mixing procedure or synthesis route on the formation of yttrium doped boehmite nanostructures in this work. The effect of dopant yttrium, yttrium percentage, temperature and surfactant on the morphology and size of boehmite were systematically studied. Nanofibres were formed in all samples with varying doped Y% treated at 100ºC; large Y(OH)3 crystals were also formed at high doping Y percentage. Treatment at elevated temperatures resulted in remarkable changes in size and morphology for samples with the same doping Y content. The resultant yttrium doped boehmite nanostructures were characterized by TEM, XRD, EDX, SAED, N2 adsorption and TGA.
• The synthesis of Gallium oxide hydroxide and gallium oxide with surfactant
In this study, the growth of gallium oxide hydroxide under various hydrothermal conditions in the presence of different types of surfactants was systematically studied. Nano- to micro-sized gallium oxide hydroxide was prepared. The effect of surfactant and synthesis procedure on the morphology of the resultant gallium oxide hydroxide was studied. β-gallium oxide nanorods were derived from gallium oxide hydroxide by calcination at 900ºC and the initial morphology was retained. γ-gallium oxide nanotubes up to 65 nm in length, with internal and external diameters of around 0.8 and 3.0 nm, were synthesized directly in solution with and without surfactant. The resultant nano- to micro-sized structures were characterized by XRD, TEM, SAED, EDX and N2 adsorption.
• The synthesis of gallium oxide hydroxide without surfactant
The aim of this study is to explore a green synthesis route for the preparation of gallium oxide hydroxide or gallium oxide via hydrothermal treatment at low temperature. Micro to nano sized GaOOH nanorods and particles were prepared under varying hydrothermal conditions without any surfactant. The resultant GaOOH nanomaterials were characterized by XRD, TEM, SAED, EDX, TG and FT-IR. The growth mechanism of GaOOH crystals was proposed.
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Romeo, Michelangelo. "Proprietes des catalyseurs intermetalliques platine-uranium, platine sur oxyde d'uranium et platine-cobalt-oxyde d'uranium sur alumine pour les reactions de rearrangement de squelette des hydrocarbures." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13098.
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Le, Pévédic Séverine. "Etude de la formation et de l'oxydation de couches minces d'alliages Al-Ni après dépôt d'Al sur un monocristal de Ni(111)." Paris 6, 2007. https://tel.archives-ouvertes.fr/tel-00165301.
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Cette étude porte sur la formation et l’oxydation de couches minces d’alliages Al-Ni après dépôt d’Al, à 130 K, sur un monocristal de Ni(111), sous UHV. Leur composition, leur structure, en surface et en volume, et leur relation d’épitaxie ont été déterminées in situ par analyse par faisceau d’ions, diffraction d’électrons lents et spectroscopie Auger, en fonction de la quantité d'Al déposée et de la température de recuit. La formation d’une couche ordonnée et épitaxiée de Ni3Al(111) est suivie, au-delà d’une épaisseur critique d’Al de 3,8 nm, par celle d’une couche ordonnée et relaxée de NiAl(110). La cinétique de formation de ces couches alliées est complexe et correspond probablement à une croissance hétérogène. En oxydant à 300 K puis en recuisant à 1000 K ces alliages minces on obtient une couche ultramince (épaisse d'environ 5 Å) d'oxyde d’aluminium épitaxiée sur Ni(111), de stoechiométrie voisine d'Al2O3.
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ROCHA, SORAYA M. R. da. "Síntese e caracterização de precursores para catalisadores termicamente estáveis à base de lantanideos pelo método sol-gel." reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11271.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
20
Herry, Soazic. "Étude de l'activation de catalyseurs d'hydrodésulfuration des gazoles préparés par modification du précurseur oxyde." Lille 1, 2006. http://www.theses.fr/2006LIL10160.
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La présence des hétéroatomes tel que le soufre constitue une source de pollution atmosphérique en raison de ses produits de combustion. L'année 2005 est importante par l'application de la norme Euro4, au sein de l'Union européenne, fixant le taux de soufre autorisé, dans les gazoles et les essences, à 50 ppm de soufre et en 2009 cette teneur sera fixée à 10 ppm. Ceci nécessite l'optimisation des procédés d’hydrodésulfuration et notamment la mise en œuvre de catalyseurs plus performants. Une des voies de recherche étudiée pour l'amélioration des catalyseurs d'HDS est l'emploi d'agents organiques lors de leur préparation. Ce travail a pour but de comprendre le rôle de ces molécules modifiantes sur un précurseur oxyde de type CoMo/Al2O3 industriel, l'étape d'activation et la morphologie de la phase active. Pour cela une étude de l'activation en phase gaz et en phase liquide, complétée par des caractérisations physico-chimiques, a mis en évidence le rôle principal des molécules modifiantes. L'évolution particulière des métaux lors de la sulfuration induit une optimisation de la morphologie de la phase active à l'origine de l'amélioration des performances catalytiquesThe presence of heteroatoms such as sulphur is an atmospheric pollutant because of its combustion products. 2005 is important year with the application of Euro4 regulations, in the European Union, which allowed 50 ppm of sulphur in gasoline and diesel and in 2009 this will decrease to 10 ppm. This implies an optimization of HDS process as well as the improvement of HDS catalysts. One of way of study to improve HDS catalysts is to add organic compounds in the preparation of catalysts. The purpose of this work is to understand the role of these molecules on the oxidic precursors, on the activation step and on the active phase morphology. An activation study has thus been done, in both gas and liquid phases which completed by physico-chemical characterizations, and showed the main role of organic compounds. The characteristic evolution of metals during sulfidation induces an optimization of the active phase morphology which is in correlation with the improvement of the catalytics performances
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RAMBO, CARLOS R. "Sintese e caracterizacao de ceramicas biomorficas." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10973.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
22
Rankin, Andrew Gordon McLaughlin. "Applications of multinuclear solid-state NMR spectroscopy to the characterisation of industrial catalysts." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/12793.
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This thesis describes applications of advanced multinuclear solid-state nuclear magnetic resonance (NMR) experiments to the characterisation of industrially-relevant catalyst materials. Experiments on γ-Al₂O₃ introduce the use of solid-state NMR spectroscopy for the investigation of disordered solids. The existence of Al(V) sites on the surface of this material is demonstrated, showing that removal of adsorbed H₂O may facilitate a rearrangement effect in γ-Al₂O₃ that promotes the formation of these Al environments. A range of aluminium oxide-based supported metal catalysts has been investigated. Studies of these systems by ¹H and ²⁷Al solid-state NMR spectroscopy indicate that a metal-support interaction (MSI) exists between surface cobalt oxide crystallites and the γ-Al₂O₃ support, and is strongest for materials containing small, well dispersed Co oxide crystallites. It is shown that the hygroscopic nature of γ-Al₂O₃ allows the extent of the MSI to be visualised by ¹H MAS NMR, by observing the extent of the proton-metal oxide interaction resulting from the presence of adventitious adsorbed H₂O. The surface/bulk chemistry of Co spinel aluminate materials is also investigated. ¹H, ²⁹Si, ²⁷Al and ¹⁷O solid-state NMR techniques are used to gain insight into the structural nature of silicated alumina catalysts. The combination of isotopic enrichment and dynamic nuclear polarisation (DNP) surface-enhanced NMR spectroscopy can provide a definitive and fully quantitative description of the surface structure of Si-γ-Al₂O₃ (1.5 wt% Si), and the role of adventitious surface water is highlighted. Analysis of silicated aluminas prepared by “sequential grafting” and “single shot” approaches shows that silica growth on γ-Al₂O₃ follows two distinct morphologies. ¹⁷O gas exchange enrichment is also shown to be successful in facilitating ¹⁷O solid-state NMR studies of these materials. It is demonstrated that double (²⁹Si and ¹⁷O) enrichment of Si-γ-Al₂O₃ (1.5 wt% Si) can facilitate access to ²⁹Si-¹⁷O 2D correlation experiments, even at low silica loading. An exploratory investigation of Ti-alumina model catalysts has also been carried out using ¹H, ²⁷Al and ¹⁷O solid-state NMR spectroscopy. These studies indicate that Ti-γ-Al₂O₃ and Ti-Al M50 may be structurally distinct materials.
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Le, Pévédic Séverine. "Etude de la formation et de l'oxydation de couchesminces d'alliages Al-Ni après dépôt d'Al sur unmonocristal de Ni(111)." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00165301.
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Cette étude porte sur la formation et l'oxydation de couches minces d'alliages Al-Ni après dépôt d'Al, à 130 K, sur un monocristal de Ni(111), sous UHV. Leur composition, leur structure, en surface et en volume, et leur relation d'épitaxie ont été déterminées in situ par analyse par faisceau d'ions, diffraction d'électrons lents et spectroscopie Auger, en fonction de la quantité d'Al déposée et de la température de recuit. La formation d'une couche ordonnée et épitaxiée de Ni3Al(111) est suivie, au-delà d'une épaisseur critique d'Al de 3,8 nm, par celle d'une couche ordonnée et relaxée de NiAl(110). La cinétique de formation de ces couches alliées est complexe et correspond probablement à une croissance hétérogène. En oxydant à 300 K puis en recuisant à 1000 K ces alliages minces on obtient une couche ultramince (épaisse d'environ 5 Å) d'oxyde d'aluminium épitaxiée sur Ni(111), de stoechiométrie voisine d'Al2O3.
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FERREIRA, MATHEUS C. "Obtenção de fritas vitroceramicas a partir de resíduos sólidos industriais." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11469.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
25
VILLANI, DANIEL. "Avaliação de dosímetros de óxido de alumínio pela técnica OSL na dosimetria de campos de fótons clínicos utilizados no tratamento radioterápico em arco modulado volumétrico." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27977.
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O tratamento utilizando Radioterapia em Arco Modulado Volumétrico é a modalidade mais moderna de radioterapia conformacional de forma que, com superposição de vários campos, as distribuições de dose forneçam uma perfeita conformação ao tumor, diminuindo a probabilidade de complicações nos tecidos normais adjacentes. Nesse sentido, muitos esforços estão sendo investidos para melhorar a conformidade de distribuição de dose, bem como a integração de técnicas de imagem para rastreamento de tumores e correção de variações inter e intrafração. Para isso, um intenso acompanhamento da qualidade dos processos e um programa de garantia de qualidade são fundamentais para a segurança dos pacientes e o cumprimento da legislação vigente; além do uso de diferentes metodologias de dosimetria para inter comparação e validação dos resultados. Este trabalho tem por objetivo avaliar e comparar o desempenho dos dosímetros OSL de óxido de alumínio (Al2O3:C) fabricados pela Landauer Inc. com os fabricados pela Rexon™ na dosimetria de feixes clínicos de fótons de energias altas empregados em radioterapia com tratamento em arco modulado volumétrico (VMAT) utilizando diferentes objetos simuladores. Os dosímetros foram caracterizados para radiação gama do 60Co e para feixes clínicos de fótons de 6 MV típicos de tratamentos por VMAT em condições de equilíbrio eletrônico e de dose máxima respectivamente. Testes de desempenho das leitoras TL e OSL utilizadas e repetibilidade das amostras foram avaliadas. Após realizados todos os testes, os dosímetros foram irradiados na simulação de diferentes tratamentos radioterápicos por VMAT e suas respostas comparadas ao sistema de planejamento. Todos os tipos de dosímetros apresentaram resultados satisfatórios na verificação das doses desse tipo de simulação de planejamento. Os dosímetros de Al2O3:C apresentaram resultados compatíveis entre si e validados pelos outros dosímetros e câmara de ionização. Em relação a melhor técnica, o sistema comercial OSL InLight apresenta maior praticidade e versatilidade para uso e aplicação na rotina clínica.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
26
Pibaleau, Baptiste. "Elaboration et caractérisation d'électrodes VACNT/MnO2 pour application aux supercondensateurs hybrides." Thesis, Tours, 2018. http://www.theses.fr/2018TOUR4034/document.
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Les travaux de cette thèse ont porté sur l'élaboration, l'optimisation et l'étude d'électrodes composites de nanotubes de carbone verticalement alignés (VACNT) sur un collecteur d'aluminium et modifiés par l'oxyde de manganèse (MnO₂). Les VACNT synthétisés par voir CVD à basse température (580°C:) directement sur le collecteur ont permis d'obtenir des tapis de NTC parfaitement alignés d'une épaisseur allant de 20 à 80 µm et possédant des densités de 10¹¹ NTC.cm² et dont le taux de catalyseur (Fe) est inférieur à 1%. Leur modification par du MnO2 permet d’accroître leur capacité de stockage électrochimique. Afin de réaliser un enrobage optimal des VACNT par le MnO₂, différents précurseurs de l'oxyde ainsi que diverses méthodes(dépôts électrochimiques, chimiques, CVD) ont été utilisées et optimisées. Les composites élaborés ont ensuite été étudiées en tant que matériau d'électrode pour la réalisation de supercondensateurs asymétriques eu milieux aqueuxThis thesis was focused on the development, optimization and study of composite electrodes of vertically aligned carbon nanotubes (VACNT) on an aluminum collector and modified with manganese oxide (MnO₂).VACNT were synthesized by a CVD process at low temperature (580° C) directly on the collector. Perfectly aligned CNT forest with a thickness of 20 to 80 μm were obtained with high densities of 10¹¹ NTC.cm² and whose catalyst (Fe) content is less than 1%. Their modification with MnO₂ increase their electrochemical storage capacity. In order to achiew optimal coating of VACNT by MnO₂, different precursors of the oxide and various methods ( electrochemical, chemical, CVD) were used and optimized. Composites were studied as electrode material for the realization of asymmetric supercapacitors in aqueous media. In addition, structurals, morphologicals and electrochemicals analyzes carried out on the different materials allowed a better understanding of the role of the elaboration's conditions on the properties of the VACNT/MnO₂ composites obtained
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Ferreira, Matheus Chianca. "Obtenção de fritas vitrocerâmicas a partir de resíduos sólidos industriais." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-14052012-111305/.
Full textAbstract:
O resíduo estudado neste trabalho é originado do processo de obtenção de alumínio metálico, de grande interesse no Brasil pelo fato do país ser detentor de algumas das maiores reservas do mineral bauxita no mundo, utilizado como fonte de alumínio. Tendo como estratégia a geração de resíduo zero, colaborando para as tecnologias ambientalmente amigáveis, este trabalho estuda a incorporação de um resíduo resultante da recuperação de alumínio presente na escória gerada durante o processo de produção primária do alumínio metálico, por plasma térmico. Utilizando-se o diagrama de equilíbrio de fases do sistema Al2O3-CaO-SiO2, fez-se a adequação das composições visando a incorporação de resíduo no produto cerâmico sem alterar as características de processamento do material. A obtenção de vidros e de fritas vitrocerâmicas com o resíduo borra branca foi realizada fazendo-se a fusão das composições calculadas e, para os vitrocerâmicos, tratamento térmico posterior de devitrificação. Os produtos obtidos foram caracterizados utilizando-se técnicas de análise tais como difração de raios X (DRX), microscopia eletrônica de varredura (MEV) e espectroscopia do infravermelho (FTIR). Foi possível obter material vitrocerâmico com até 30% de resíduo de alumínio, após a fusão a 1300°C e devitrificação a 900°C. Em adição, o resíduo demonstrou ser um promissor material auxiliar na formação de fases cristalinas em baixos tempos de tratamento térmico.This work studies the residue obtained from the process of aluminum metal extraction activities, a great interest process, because of Brazil own some of the biggest bauxite mineral reserves in all the world. As a useful choice for no residue generation, and a support for environmentally friendly technologies, this work studies the white dross residue (WDR), from the process of aluminum metal reduction by thermal plasma. The phase equilibrium diagram of Al2O3-Ca O-SiO2 system was used to calculate the compositions. The WDR were incorporated in a ceramic product without modifying its principal characteristics. The fusion and devitrification treatments were studied. XRD (X-ray diffractometry), SEM (scanning electron microscopy) and FTIR (transformed Fourier infrared) were used to investigate the glass and glassceramic samples. These techniques showed that is possible to get glassceramic with up to 30 mass% of WDR after molten at 1300 deg C and annealed at 900 deg C. In addition, the WDR showed to be a promising material in attainment of crystalline phases in less times of heat treatment for annealing.
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Lontsi, Fomena Mireille. "Etude théorique de la diffusion de l’oxygène dans des oxydes diélectriques." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13703/document.
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La miniaturisation des composants CMOS (Complementary Metal Oxide Semiconductor) impose l’emploi de matériaux diélectriques de permittivité élevée. LaAlO3 et SrTiO3 sont aujourd’hui parmi les meilleurs candidats ; toutefois, la diffusion de l’oxygène dans ces matériaux conduit à la dégradation des propriétés électriques et de l’interface avec le silicium. Ce travail théorique a pour but d’étudier les facteurs gouvernant, à l’échelle de la liaison chimique, la diffusion de l’ion oxygène. L’approche choisie repose sur la théorie de la fonctionnelle de la densité (DFT), couplée à des méthodes d’analyse de la densité électronique, et sur le développement d’un outil original : les cartes de densité d’énergie. Les régions de la densité électronique contribuant à la barrière de diffusion ont ainsi pu être identifiées; une optimisation de ces matériaux à l’échelle de la liaison chimique peut alors être envisagéeThe miniaturization of CMOS (Complementary Metal Oxide Semiconductor) components requires the use of high dielectric permittivity materials as gate oxide. LaAlO3 and SrTiO3 are among the best candidates, but the oxygen diffusion in these materials leads to the degradation of both the electrical properties and the interface with silicon. In this context, the aim of this theoretical work is to study the factors governing the oxygen ion diffusion at the chemical bonding scale. This approach is based on Density Functional Theory (DFT), coupled with electron density analysis methods, and the pioneering development of energy density cards. The regions of the electron density contributing to the diffusion barrier have been identified allowing new routes of optimization of these materials across the chemical bonding
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"Spectrophotometric determination of aluminium oxide, calcium oxide and iron (III) oxide in Portland cement." Chinese University of Hong Kong, 1993. http://library.cuhk.edu.hk/record=b5887734.
Full textAbstract:
Shu King-hung.Thesis (M.Phil.)--Chinese University of Hong Kong, 1993.
Includes bibliographical references (leaves 80-81).
ABSTRACT --- p.1
Chapter CHAPTER I. --- INTRODUCTION --- p.3
REFERENCES --- p.6
Chapter CHAPTER II. --- BRIEF REVIEW OF THE ANALYTICAL METHODS USED
Chapter 1. --- Spectrophotometry --- p.8
Chapter 2. --- Derivative spectrophotometry --- p.9
Chapter 3. --- Atomic absorption spectrometry --- p.12
Chapter 4. --- X - Ray fluorescence --- p.12
REFERENCES --- p.14
Chapter CHAPTER III. --- SIMULTANEOUS DETERMINATION OF ALUMINIUM OXIDE AND IRON (III) OXIDE
Chapter 1. --- Introduction
Review of the reported methods --- p.15
Determination of aluminium and iron with
8-hydroxyquinoline --- p.18
Chapter 2. --- Experimental --- p.21
Chapter 3. --- Results and discussion
Determination of iron --- p.28
Determination of aluminium --- p.38
Chapter 4. --- Conclusion --- p.52
REFERENCES --- p.53
Chapter CHAPTER IV. --- RAPID DETERMINATION OF CALCIUM OXIDE
Chapter 1. --- Introduction --- p.56
Chapter 2. --- Experimental --- p.62
Chapter 3. --- Results and discussion --- p.66
Chapter 4. --- Conclusion --- p.79
REFERENCES --- p.80
FIGURES
Chapter II-1 --- Attenuation of a beam of radiation by an absorbing solution --- p.8
Chapter II-2 --- Gaussian curve and its first to fourth derivatives --- p.11
Chapter III-l --- Effect of pH on the extraction of metals with8- hydroxyquinoline --- p.19
Chapter III-2 --- "Normal absorbance spectra of the metal - oxinates: A1 (5ppm), Fe (5ppm)" --- p.20
Chapter III-3 --- Effect of pH on the determination of iron (5ppm) --- p.29
Chapter III-4 --- Calibration curve for the determination of iron (III) by spectrophotometry at 580 nm --- p.33
Chapter III-5 --- "The first derivative spectra of metal-oxinates A1: 5ppm, Fe : 5ppm" --- p.39
Chapter III-6 --- "The second derivative spectra of metal-oxinates, A1: 5ppm, Fe : 5ppm" --- p.39
Chapter III-7 --- "Normal absorption spectra of the metal-oxinates : A1(5 ppm), Ti (5 ppm)" --- p.41
Chapter III-8 --- Effect of pH on the determination of aluminium --- p.43
Chapter III-9 --- Calibration curve for the determination of aluminium by second derivative spectrophotometry at 390 nm --- p.47
Chapter IV-1 --- "Effect of pH on the development of colour of Ca- GBHA complex. Ca : 1.2 ppm, wavelength : 530 nm" --- p.68
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Tang, Kuang-Yu, and 湯光煜. "Preparation and Analysis of Zinc Oxide and Lead Sulfide Nanowires by Anodic Aluminum Oxide Film." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/23rq8p.
Full textAbstract:
碩士國立勤益科技大學
機械工程系
105
In this study, the Anodic Aluminium Oxide(AAO) template, having ordered the array nanoporous structure was fabricated by two-step anodization. Then make Zn-nanowires and Pb-nanowires by vacuum, high temperature, injection technique. Fabricate ZnO-nanowires and PbS-nanowires with after-treatment .And analyze the result about manufactures of ZnO-nanowires and PbS-nanowires. The experiment is about use high-purity aluminum to make array nanoporous structure template by two-step anodization .Make some templates with many different holes size by adjust the parameter of solution, voltage and anodizing time ,and in order holes structure size to balance. Then, the Zn and Pb was melted in the vacuum furnace and injected into an template and use heat treatment as well as other after-treatments to fabricate ZnO-nanowires and PbS-nanowires. With scanning electron microscopy(SEM),we can find the structure of AAO template and the padding of metal nanowires. Then analyze the proportion of chemical composition and the branch of elements by energy dispersive X-ray spectrum (EDS).At last we can analyze the proportion of elements and the structure of crystals by x-ray diffraction(XRD). Final results of the experiment, both of Zn and Pb injected into an template. Analyze the proportion of chemical composition about Zn-nanowires, by vulcanization and oxidation. We can find the structure of nanowires including ZnO. The part of Pb-nanowires, we turn it to PbS-nanowires successfully by vulcanize treatment with many parameters. And then, we can find the variation of Pb turn into PbS in template at different of temperature.
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Huang, Yeong-shyang, and 黃永祥. "The Analysis of Mechanical Properties of Nano-Template with Anodic Aluminum Oxide." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/60988687255034080023.
Full textAbstract:
碩士逢甲大學
航太與系統工程所
95
This research used an anodic treatment technology to manufacture array nanopores by nanoindentation to measures the mechanical property and investigated the influences of different post-processing to mechanical property. The array nanopores use anodic treatment technology which manufactures the anodic treatment aluminum oxide pattern plate (Anodic Aluminum Oxide, AAO), and uses two times of anodic treatments technology to manufacture the uniform and arranging in order of nanopores. The measurement of nanoindentation is used the continuous stiffness measurement, CSM model. The surface microstructure, and between the discussion aperture change and the mechanical property relations, characteristic and so on young''s modulus, degree of hardness with soaks the time to have the inverse ratio. In the experiment, the surface structures of nanopores is used field scan type electron microscope (FE-SEM) to observe passes through the indentation the superficial microstructure change, and uses X-ray diffraction (XRD) to determine its lattice structure.
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Jeng, Kai-Sheng, and 鄭凱聲. "Characteristic Analysis of Poly(3-hexylthiophene) Confined in the Nanoporous of Anodic Aluminum Oxide Templates." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/3qcdtr.
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碩士國立交通大學
應用化學系碩博士班
103
Poly(3-hexylthiophene) (P3HT) has attracted great attention recently because of their unique optoelectronic properties and self-assembly behavior, which can form well-ordered nanostructures. It has also been widely applied to optoelectronic devices such as conjugated polymer solar cells (CPSCs) and organic field-effect transistors (OFETs). Although there have been many studies on P3HT, it is still a great challenge to control the nanostructures and properties of P3HT. In this study, we investigate the fabrication of P3HT nanostructures confined in the nanopores of anodic aluminum oxide（AAO） templates. The morphologies and properties of P3HT nanostructures can be controlled by changing the preparation methods and experimental conditions. This thesis is divided into 8 chapters. In Chapter 1, we first introduce the badsic concept of the fabrication of AAO templates, the template method, and the P3HT material. In Chapter 2, the papers which are related to the fabrication of P3HT nanowires are reviewed. In Chapter 3, the experimental materials, solvents, and instruments used in this work are listed. From Chapter 4 to Chapter 6, we discuss the experimental results of three topics. In the first topic (Chapter 4), we study the fabrication of P3HT nanowires by solvent-annealing-induced nanowetting in template (SAINT) using AAO templates. The morphologies and properties of the P3HT nanowires are also characterized by the instruments and compared to those prepared by the solution wetting method. It is found that the morphologies and properties of the P3HT nanowires are affected by the preparation methods. In the second topic (Chapter 5), following the first topic, we investigate the fabrication of P3HT nanowires using different solvent vapors by SAINT. The morphologies and properties of the P3HT nanowires can be controlled by changing the solvent vapors. The result shows that the solubility of solvent is the main factor for the properties of the P3HT nanowires. In the third topic (Chapter 6), we devlope a new method to fabricate P3HT nanostructures using the AAO templates. The new method combines the process of the whisker method and the solution-wetting method, and we call it the hot solution-wetting method. The P3HT solution is first heated and dissolved in the marginal solvent (p-xylene). After the hot solution is dropped on the AAO templates, P3HT nanowires can be formed by the self-assembly process. In Chapter 7, we summarize all experimental results and propose possible future works. In Chapter 8, the references cited in this thesis are listed.
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Chu, Chien-Wei, and 朱建威. "Fabrication of Porous Anodic Aluminum Oxide Templates and Property Analysis of Confined Functional Polymer Nanomaterials." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/y28u6g.
Full textAbstract:
博士國立交通大學
應用化學系碩博士班
105
Polymer nanomaterials recently have attracted great interest because of their unique properties compare to the bulk materials. To have a deeper understanding of the properties of confined functional polymer nanomaterials, a simple route to fabricate polymer nanostructures is desired. In this work, we build up a well-controlled system in our laboratory to fabricate AAO templates using the second anodization method (Chapter 3). Subsequently, cylindrical anodic aluminum oxide (c-AAO) templates can be synthesized using similar anodizing process on the Al wires and the polymer nanorod arrays on the curved surfaces can be obtained by infiltrating polymers into the nanopores of the c-AAO templates (Chapter 4). Furthermore, light-emitting polymer nanotubes are also fabricated by infiltrating the light-emitting polymer into the nanopores of the AAO templates. The optical properties and polymer chain packings of confined polymer nanotubes are also characterized (Chapter 5). Finally, stimuli-responsive polymer brushes are grafted from the surfaces of the AAO templates by surface-initiated atom transfer radical polymerization (SI-ATRP). The confinement effect on polymer chain growth in the nanopores of AAO membranes is investigated (Chapter 6).
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Lo, Chen-Hao, and 羅振豪. "Magnetic characteristics and structural imaging analysis of the magnetic film on the anodic aluminum oxide template." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/n83v3d.
Full textAbstract:
碩士國立虎尾科技大學
電子工程系碩士班
103
The study is divided into two parts. The first part of the experiment, we use ImageJ image analysis software to analyze anodic aluminum oxide template structure under preparation in different conditions. The second part of the experiment, we use OOMMF magnetic simulation program, magnetic properties of simulations designed patterned thin film. Samples were obtained by two-step anodize processes. we use 0.3M oxalic acid solution as the electrolyte, the anodizing potential ranged from 20 to 60 V , and working temperature at 10-30 ℃. Films with antidot array have been prepared by the sputtering of Ni80Fe20 onto anodic alumina membrane templates. The pores diameter varies from 30 to 90 nm. A counterpart continuous thin film grown on Al substrate was also prepared. The coercivities of the antidot arrays are not only greater than those of un-patterned films, but it change by the films integrity and the pore diameter. The results show that the pore diameter become higher, the coercivity is increase. It is presumed that the parameters of the size and type of defects hinder the movement of the magnetic moment.
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Collins, Marc Kevin. "The use of diffuse reflectance infrared spectroscopy in the study of alumina." 1986. http://hdl.handle.net/2097/27609.
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Fang-YuWeng and 翁芳瑜. "Raman analysis of algal cells by filtration with anodic aluminum oxide membrane and intercellulary biosynthesized gold nanoparticles." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/99564507390595320680.
Full textAbstract:
碩士國立成功大學
化學工程學系
104
In this study, rapid and direct Raman analysis of microalgae was proposed and demonstrated through microwells-assisted filtration using anodic aluminum oxide (AAO) membrane. Instead of evaporation, a droplet of algal solution was dispensed in the polydimethylsiloxane (PDMS) microwells, which was placed on top of the AAO membrane, followed by applying the vacuum. The algal cells deposited inside the microwells and were subsequently analyzed by Raman spectroscopy. The results showed that the algal cells were effectively concentrated and distributed quite uniformly inside the microwells, which led to uniform Raman signals among different algae pastes. Moreover, the time for preparing the algae paste was reduced to about 5 minutes. We also added HAuCl4 reagent to biosynthesize gold nanoparticles (AuNPs) and intended to enhance the Raman signals of the algal cells. The results showed that the lipid signals of the algal cells with biosynthesized gold nanoparticles were enhanced up to 20 times after algal cells being incubated in 10mM HAuCl4 for 15min. It was also found that carotenoids and chlorophyll may serve as reducing agents during reduction reaction.
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Luo, Ke-Hsuan, and 羅可軒. "Characteristic Analysis of Poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) Confined in the Nanopores of Anodic Aluminum Oxide Templates." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/68wmn7.
Full textAbstract:
碩士國立交通大學
應用化學系碩博士班
107
Recently, conducting polymers have attracted great attention due to their special optoelectronic properties. Conducting polymers have been applied in different applications, such as organic solar cells, organic light-emitting diodes, and field-effect transistors. Compared with studies of conducting polymers in the bulk and thin film states, less studies focus on the physical and optical characterization of conducting polymers un the nanoscales. In this work, we study the fabrication and characterization of nanomaterials of poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT), an important material in conducting polymer fields. Although, F8BT nanotubes have been prepared using the solution wetting method, the chain packing behaviors still need to be investigated. Here, we study the fabrication of F8BT nanostructures using the solvent annealing induced nanowetting in templates (SAINT) method. Three good solvents for F8BT, chloroform (CF), toluene (Tol), and tetrahydrofuran (THF), are used as the annealing solvents. Scanning electron microscope (SEM), photoluminescence spetrometer (PL), Raman spectrometer, and X-ray diffractometer are used to characterized the nano structures. The results demonstrate that the chain packings of F8BT nanotubes are looser than those in the bulk state, mainly due to the confinement effect of the nanopores. This thesis is divided into 6 chapters. In Chapter 1, we introduce the basic concept of the fabrication of anodic aluminium oxide templates and the template methods. In Chapter 2, we review the literature about the optical properites and polymer chain packings of F8BT under different conditions. Raman spetrometer and X-ray diffractometer are mainly used. Also, some principles about how polymer solutions are infiltrated into the nanopores of AAO templetes are metioned. In Chapter 3, the experimental instruments applied in this work and the sample preparation procedures are introduced. In Chapter 4, we study the fabrication of F8BT nanotubes by the solution wetting method and the solvent-annealing-induced nanowetting in templates (SAINT) methods via AAO templates. The morphologies, optical properties, crystallinities, and chain packing of the F8BT nanotubes are also characterized by instruments such as SEM, PL, Raman, and X-ray diffactometer. The results of the F8BT nanotubes prepared by the SAINT method are also compared to those by the solution weeting methods. In Chapter 5, we summarize all the experimental results and propose some possible future works. The future works include the applications of nanotubes, the preparation of nanotubes with high crystallinities, and the crystallinity studies of nanotubes prepared by AAO templates with smaller sizes. In Chapter 6, the references cited in this thesis are listed.
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Zhou, Xuan, and 周萱. "Lead nanowires fabricated by vacuum injection molding process with anodic aluminum oxide template and the analysis of their optical properties after sulfurization treatment." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/q4m5uq.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
107
In this study, lead sulfide(PbS) nanowires were fabricated with anodic aluminum oxide(AAO) by using vacuum injection molding and sulfurization processes. Using different types of electrolytes including sulfuric acid, oxalic acid and phosphoric acid, the varied anodic aluminum oxide(AAO) pore size can be controlled between 30 nm – 300 nm. The diameter of nanowires depends on the pore size of anodic aluminum oxide(AAO) template, and the nanowires with diameters of approximately 30, 100 and 300 nm were prepared for analyses. In order to investigate the effect of growth conditions for the fabrication of lead sulfide, the correlation between control variables (sulfurizing temperature and time) and the properties of lead sulfide was established. The morphology of AAO templates and nanowires were observed by Field-Emission Scanning Electron Microscope(FE-SEM). The compositions of the nanowires with different sulfurization conditions were analyzed by Energy Dispersive X-ray spectroscopy(EDS) and the crystal structure was identified by X-ray diffractometer(XRD) and Transmission Electron Microscopy(TEM). Furthermore, the absorption spectrum of lead sulfide nanowires were obtained by UV-VIS/NIR spectrophotometer. The results show that absorption peak shift as nanowires diameter change due to the quantum confinement effect.
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Jhong-HamLin and 林忠翰. "The Analysis on The Thin Film Properties of Indium Zinc Gallium Oxide Co-sputtering with Aluminum and Its Application to The Thin Film Transistor." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/90283444756250190483.
Full textAbstract:
碩士國立成功大學
微電子工程研究所碩博士班
101
In this work, we reported the single quaternary oxide target, indium gallium zinc oxide co-sputtering with metal aluminum target by magnetron co-sputtering system. Literature showed that doping aluminum to the zinc oxide based transparent conducting oxide and semiconductor will increase either carrier concentration or conductivity. But aluminum with highly reactivity to the oxygen will become an obstacle during carrier transport. For that reason, we will investigate the method co-sputtering indium zinc gallium oxide and aluminum by using magnetron co-sputtering system. And the experimental result showed that doping via aluminum can really improve the electrical conductivity of the thin film. The reason is due to the atoms with larger outer most vacant s orbital existed in the film, like indium or zinc, and the doping of smaller outer most vacant s orbital will increase the overlapping region between s orbitals. This increased overlapping region will enhance the carrier transportation efficiency thus leading to the carrier mobility increment. During the experiment, we first did the qualitative and quantitative measurement to confirm the thin film composition. Later, we investigated the changes of electrical conductivity property by Hall-measurement then analyzed the changes of electrical property by ways used to analyze the basic transparent oxide, from conducting and bonding point of view. Then we utilized the X-ray diffraction measurement to confirm that there is no evident change between thin film crystallinity. And also for the possible application within optical-electronic device in the future, we confirmed the transmittance between the near infrared and visible region to ensure the transmittance property. Lastly, from the changes of the thin film electrical property caused by doping aluminum. We then applied this thin film to the thin film transistor and the results proved that via the doping process will make the thin film much more applicable to the active layer of thin film transistor. This work utilized the optimized film which having the optimized thin film transistor performance got from co-sputtering indium zinc gallium oxide film as the basis for this aluminum doping experiment. In the co-sputtering experiment, we used three separate targets, the indium oxide with radio frequency power of fifty watts, gallium oxide with radio frequency power of twenty-five watts and zinc with direct current power of ten watts. We used the metal atomic ratio( In: Zn: Ga= 3.52: 2.72: 1) within the co-sputtered film to fabricate a mixed target in order to conducting this co-sputtering experiment with aluminum. The first part of this experiment was to tune the oxygen flow ratio to control the electrical property change of thin film, and used the result with optimized electrical transportation property( 0% O2，carrier concentration：1.76×1020 cm-3、conductivity：6.67×102 S/cm and carrier mobility：2.33×101 cm2/V-s) and most suitable for use in the active layer of device( 40% O2，9.97×1016 cm-3、1.32×10-1 S/cm及3.13×10-1 cm2/V-s) as the starting point to do the co-sputtering with various aluminum radio frequency power. After thin film deposition, we used the energy dispersive spectrometry to confirm qualitatively and quantitatively to the thin film, making sure that there is no clear atomic ratio difference between thin film and the target. And then came to the device fabrication, we first tuned the deposition oxygen flow ratio to make the current voltage characteristic close to those obtained from trinal target co-sputtering. And the result showed that under forty percent oxygen flow ratio, the device performance was the most alike to those obtained from trinal target co-sputtering. Under this oxygen flow ratio condition, the carrier concentration is about 1017cm-3, which is closed to the proposed carrier concentration that is suitable for use in the channel layer of thin film transistor. Later we confirmed that the metal element ratio between target and thin film were alike for reliably comparing with different aluminum co-sputtering power. The final optimized device performance is under the deposition with forty percent oxygen flow ratio and aluminum radio frequency power with forty-five watts. And this device with field effect mobility of 170.25cm2/V-s, threshold voltage of 0.7V , current on/off ratio of 7.81×106 and subthreshold swing of 130mV/decade. On the other hand, due to the easy variable device property of oxide based semiconductor device when exposed to the air. So, the device property between aluminum un-doped and optimized aluminum doping power device with time were compared, and the device surface passivation formed respectively by sputtered silicon-oxide-nitride and atomic layer deposited aluminum-oxide was performed. And the experiment result showed that the device without surface passivation and with forty-five watts aluminum doping power behaved the best device stability.
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Rashid, Zahra Shamshudin. "The effect of taper and height of a customized implant abutment on the tensile force needed to remove an aluminum oxide coping a thesis submitted in partial fulfillment ... for the degree of Master of Science in Prosthodontics ... /." 1999. http://catalog.hathitrust.org/api/volumes/oclc/68944846.html.
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Lo, Sut-I., and 羅雪怡. "Synthesis of Gold Nanoparticles-Aluminium Oxide Adsorbents for Analysis of Mercury Species." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/00880373190165224496.
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碩士國立臺灣大學
化學研究所
99
We report a new and effective adsorbent for removal of metal ions and mercury species. By mixing Au NPs (13 nm in diameter) with aluminum oxide particles (50-200 μm in diameter), Au NPs─Al2O3 adsorbents are easily prepared. Three adsorbents—Al2O3, Au NPs, and Au NPs─Al2O3—have been tested for removal of the metal ions (Cd2+, Co2+, Cr3+, Ni2+, Pb2+) and mercury species [Hg2+, methylmercury (CH3Hg+), ethylmercury (C2H5Hg+), and phenylmercury (C6H5Hg+)]. The Au NPs adsorbent has higher binding affinity toward Hg2+ ions (Kd = 0.3 nM; Bmax = 3370 μmol/g Au NP) than that of Al2O3 adsorbent (Kd = 52.9 nM; Bmax = 130 μmol/g Al2O3). Relative to the individual Al2O3 and Au NPs adsorbents, the Au NPs─Al2O3 adsorbents have higher affinity for mercury species (CH3Hg+: Kd = 6.9 nM; C2H5Hg+: Kd = 6.2 nM; C6H5Hg+: Kd = 7.9 nM; Hg+: Kd = 19.2 nM) and other tested metal ions (Cd2+: Kd = 5.5 nM; Co2+: Kd = 8.1 nM; Cr3+: Kd = 40.5 nM; Ni2+: Kd = 16.9 nM; Pb2+: Kd = 4.6 nM), respectively. The Au NPs─Al2O3 adsorbents provide a synergic effect and thus are effective for removal of most tested metal ions and organic mercury species. After preconcentration of mercury ions by Au NPs─Al2O3 adsorbent, inductively coupled plasma-mass spectrometry (ICP-MS) allows the detection of mercury ions down to sub-fM level in aqueous solution. The Au NPs─Al2O3 adsorbent allows effective removal of mercury species spiked in nature waters (lake water, ground water and sea water), with the efficiencies greater than 97%. We have used sequentially Al2O3 and Au NPs─Al2O3 adsorbents for selective removal of Hg2+ and CH3Hg+ ions from a certified fish sample (DORM-2). The ICP-MS has been applied to determine the concentrations of the preconcentrated Hg2+ and CH3Hg+ ions, with results that are in good agreement with the certified values. The low-cost, effective, and stable Au NPs─Al2O3 adsorbents show great potential for economic use in removal of metal ions and various mercury species.
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Wang, Long-da, and 王隆達. "Cu and Ni-Aluminum oxide membrane production by sol-gel method and characteristic analyses." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/85915672430078243109.
Full textAbstract:
碩士國立聯合大學
化學工程學系碩士班
96
In this study, these polyvinyl alcohol/alumina PVA/Al2O3, polyvinyl alcohol/nickel/alumina PVA/Ni/Al2O3 and polyvinalcohol/copper/alumina PVA/Cu/ Al2O3 non-supported alumina membrane are prepared by sol-gel method. After different calcinations temperature, the different composite membranes of thermal stability, functional groups, crystal structure, surface morphology, surface area and gas permeability were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), Fourier transform infrared spectrometer (FTIR), X-ray diffraction(XRD), Scanning electron microscope (SEM), (BET) and gas permeability analyzer (GPA). PVA/Al2O3 25.3 w% can make non-break membranes. The order of thermal stability is PVA/Cu/ Al2O3 composite membranes, and PVA/Ni/Al2O3 composite membranes, and PVA/Al2O3 composite membranes, Additional hydrogen calcinations make composite membranes increase thermal stability. By increasing temperature, PVA/Al2O3 membranes surface morphology is from thin-line network morphology to thickness -line network morphology. In high calcinations temperature, PVA/Ni/Al2O3 and PVA/Cu/ Al2O3 membranes is from thickness -line network morphology to cloud-mass morphology. In hydrogen calcinations, the cloud-mass morphology easily forms, and in X-ray diffraction is stillγ- Al2O3 crystal structure. In Additional hydrogen calcinations at 650℃, PVA/Ni/Al2O3 composite membranes have the least permeability (8.00×10-8(mol．cm/cm2．s．cmHg)) and the most surface area (250.751 m2/g). PVA/Ni/Al2O3 composite membranes can make the range of temperatureγ- Al2O3 crystal structure more wide, and its more 200℃temperature PVA/ Al2O3 and PVA/Cu/ Al2O3 composite membranes than, The distribution of γ- Al2O3 crystal structure is amorphous,It’s more helpful to separate gas.
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Liao, Wan-ting, and 廖婉婷. "Pd-Ag/PVA-Aluminum oxide membrane prepared by sol-gel method and characteristic analyses." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/16824424879700678858.
Full textAbstract:
碩士國立聯合大學
化學工程學系碩士班
97
In this study , the polyvinyl alcohol / alumina (PVA/Al2O3) , palladium / polyvinyl alcohol / alumina (Pd/PVA/Al2O3) and silver/ polyvinyal alcohol / alumina (Ag/PVA/Al2O3) and palladium-silver alloy / polyvinyal alcohol /alumina (Pd-Ag/PVA/Al2O3) non-supported alumina membranes are prepared by sol-gel method. After different calcinations temperature, the different composite membranes of thermal stability, functional groups, crystal structure, surface morphology, surface area, pore size distribution and gas permeability were characterized by differential scanning calorimetry (DSC) , thermogravimetric analysis (TGA) , Fourier transform infrared spectrometer (FTIR) , X-ray diffraction(XRD), Scanning electron microscope (SEM), porisometry (BET) and gas permeability analyzer (GPA). PVA/Al2O3 = 42.24 wt% can make non-broken membranes. The thermal stability of Pd(60)-Ag(40) /PVA/Al2O3 composite membranes , and Pd(77)-Ag(23)/PVA/Al2O3 composite membranes is high. Additional hydrogen calcinations make composite membranes increase thermal stability . By increasing temperature, PVA/Al2O3 membranes surface morphology is from thin-line network morphology to thickness-line network morphology. With hydrogen high calcinations temperature, Pd/PVA/Al2O3 and Ag/PVA/Al2O3 membranes is from thickness-line network morphology to cloud-mass morphology, specially surfaces of Pd-Ag/PVA/Al2O3 membranes show palladium-silver alloy. In X-ray diffraction, the variation of phases from γ to δ、θ、α is due to different temperature calcinations. The addition of Pd、Ag or Pd-Ag makes γ-Al2O3 peak stronger and inhibits δ、θ、α-Al2O3 peaks. The γ- Al2O3 crystal structure is amorphous, so it is more helpful to separate gas. With hydrogen calcinations at 650 ℃, Pd(77)-Ag(23)/PVA/Al2O3 composite membrane has the biggest surface area (259.5386m2/g) and the smallest average pore diameter (8nm) , so it has the least permeability (7.6×10-8 mol - cm / cm2 - s - cmHg) . These membranes are able to separate gas mixtures CO2 and purify hydrogen gas.
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Ильин, Д. О., and D. O. Ilin. "Синтез и люминесцентные свойства нанопористых структур анодированного оксида алюминия : магистерская диссертация." Master's thesis, 2015. http://hdl.handle.net/10995/36208.
Full textAbstract:
Цель магистерской диссертации состояла в изучении влияния режимов анодирования и условий последующей температурной обработки на структурные и люминесцентные свойства нанопористого оксида алюминия.
Рассмотрены основные структурные особенности анодированного оксида алюминия (АОА) и методики получения его упорядоченных структур, его области применения и люминесцентные свойства. Успешно синтезирована серия из 20 образцов АОА в условиях варьирования электрохимических, временных и температурных режимов. Проведена аттестация полученных образцов методами сканирующей электронной микроскопии и рентгеноструктурного анализа. Проведена статистическая обработка полученных снимков с помощью анализатора изображений SIAMS 700. Проанализированы зависимости среднего диаметра пор от напряжения анодирования и толщины оксидного слоя от времени анодирования. Рассчитана средняя скорость роста АОА для гальвано- и потенциостатических режимов.
Изучены особенности и трансформация спектров диффузного отражения, фото- и катодолюминесценции образцов АОА в зависимости от условий электрохимического окисления и последующей термообработки. На основе сравнительного анализа литературных данных проведена идентификация активных центров свечения собственной (F-, F+-центры) и примесной (комплексы C2O42- и HC2O4-, ионы Cr3+ и Mn4+) природы. Рассмотрены перспективы дальнейших исследований и возможных применений синтезируемых мембран анодированного оксида алюминия.The aim of this Master paper is to study the effect of anodizing modes and subsequent temperature treatment on structural and luminescent properties of nanoporous anodic alumina. Structural features of anodic aluminum oxide (AAO), its ordered structures obtaining methods, fields of application and luminescent properties were discussed. A series of twenty samples varying electrochemical, time and temperature regimes was obtained. Obtained samples were characterized by scanning electron microscopy and X-ray diffraction analysis techniques. Images of structures were quantitavely analyzed using SIAMS 700 software package. It was studied how average pore diameter and oxide layer thickness depend on anodizing voltage and duration accordingly. Average AAO growth rate for galvanostatic and potentiostaic modes was calculated. Features and transformation of diffuse reflection, photo- and cathodoluminescence of AAO samples obtained under various electrochemical oxidation conditions and after subsequent temperature treatment were studied. Active emission centers of intrinsic (F-, F+-centers) and impurity (C2O42- and HC2O4- complexes, Cr3+ и Mn4+ ions) nature were identified on the basis of literature data comparative analysis. Further promising directions of studies and possible applications of synthesized AAO membranes were discussed.
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Liao, Ruei-Chang, and 廖瑞章. "The Study of Growth Kinetics of Anodic Aluminium Oxide and the Analysis of Electrochemical Characteristics." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/73147783672935408443.
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Chiang, Lan-Shin, and 姜蘭欣. "Investigation of the Electrical Characteristics and Material Analyses on Manganese Dioxide and Aluminum Oxide for Resistive Random Access Memory Applications." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/75680461068858780503.
Full textAbstract:
碩士國立交通大學
電子研究所
98
The resistive switching random access memories (RRAMs) have advantages of low power consumption, high-density integration, and high speed operation as one of the next-generation nonvolatile memory candidates. In this study, electrical properties and switching mechanism of manganese dioxide (MnO2) and aluminum oxide (Al2O3) as the resistive switching layer are investigated. For MnO2-based resistive switching memory, the current-voltage characteristics with various top electrodes are presented. Secondary ion mass spectrometry (SIMS) depth profile reveals that different top electrodes react in different oxygen concentration distribution at the interface between the electrodes and MnO2. It suggested that the interface play an important role on the resistive switching behavior. The device structure of Ti/MnO2/Pt shows reproducible and stable resistive switching behavior traced over 1000 times at room temperature. Besides, the retention behavior at 0.2V read voltage of the memory in Ti/MnO2/Pt device at 85℃ is investigated. The resistance ratio between LRS and HRS is close to 102 and is stable for 104 sec retention time. It can say that the data can store completely without supplying power. These indicate that the Ti/MnO2/Pt device is a great candidate for non-volatile memory application. Electrode effects are also considered in Al2O3 as the resistive switching layer. We have used Pt or Ti as the top electrodes and Pt or TiN as the bottom electrode. Hence, there are four different structures, Pt/Al2O3/Pt, Ti/Al2O3/Pt, Pt/Al2O3/TiN, and Ti/Al2O3/TiN. By comparing electrical characteristics of different structures, the influence of electrode materials on the resistive switching properties of Al2O3-based resistive switching film can be investigated. With Pt as the bottom electrode, the electrical characteristics of Ti top electrode are better than Pt top electrode. With TiN as the bottom electrode, the electrical characteristics of Pt top electrode are better than Ti top electrode. The probable switching models of different top and bottom electrodes have been proposed in this study. Furthermore, nonvolatile memory characteristics of Ti/Al2O3/Pt embedded with Ni nanocrystals are also investigated. Compared to the Al2O3 without Ni nanocrystals, the resistive switching random access memories with Ni nanocrystals can stabilize the distribution of SET voltage.
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Νικολάου, Νικόλαος. "Διατάξεις παγίδευσης φορτίου (Memories) με τη χρήση νέων υλικών υψηλής διηλεκτρικής σταθεράς." Thesis, 2014. http://hdl.handle.net/10889/8504.
Full textAbstract:
Στη παρούσα Διατριβή διερευνήθηκε η χρήση υλικών υψηλής διηλεκτρικής σταθεράς (high-k) ως οξειδίων ελέγχου σε διατάξεις παγίδευσης φορτίου τύπου MONOS (Μetal-Οxide-Νitride-Οxide-Silicon). Τα οξείδια που εξετάστηκαν ήταν το HfO2, τo ZrO2 και το Al2O3. Η ανάπτυξή τους πραγματοποιήθηκε με χρήση της μεθόδου εναπόθεσης ατομικού στρώματος (ALD).
Οι ιδιότητες των δομών μνήμης μελετήθηκαν συναρτήσει: (α) των πρόδρομων μορίων της εναπόθεσης για τα HfO2 και ZrO2, (β) του οξειδωτικού μέσου της εναπόθεσης για την περίπτωση του Al2O3 και (γ) της επακόλουθης ανόπτησης. Η ηλεκτρική συμπεριφορά των δομών εξετάστηκε με την κατασκευή πυκνωτών τύπου MOS.
Τα υμένια του HfO2 αναπτύχθηκαν επί διστρωματικής στοίβας SiO2/Si3N4 με (α) αλκυλαμίδιο του χαφνίου (ΤΕΜΑΗ) και Ο3 στους 275 oC, και (β) κυκλοπενταδιενύλιο του χαφνίου (HfD-04) και Ο3 στους 350 οC. Ομοίως, τα υμένια του ZrO2 αναπτύχθηκαν επί διστρωματικής στοίβας SiO2/Si3N4 με: (α) αλκυλαμίδιο του ζιρκονίου (ΤΕΜΑΖ) και Ο3 στους 275 oC και (β) κυκλοπενταδιενύλιο του ζιρκονίου (ZrD-04) με Ο3 στους 350 oC. Ο δομικός χαρακτηρισμός, για το HfO2, φανέρωσε πως η ύπαρξη ή όχι κρυσταλλικού χαρακτήρα και η σύσταση του οξειδίου εξαρτάται τόσο από το πρόδρομο μόριο αλλά και από την ανόπτηση (600 οC, 2 min). Αντίθετα, το ZrO2 έχει σε κάθε περίπτωση κρυσταλλικότητα. Τα ηλεκτρικά χαρακτηριστικά των πυκνωτών Si/SiO2/Si3N4/high-k/Pt, δείχνουν ότι οι δομές έχουν ικανοποιητική συμπεριφορά ως στοιχεία μνήμης αφού όλες οι ιδιότητες πληρούν τις βασικές προϋποθέσεις ως στοιχεία μνήμης, παρά την ανυπαρξία ενεργειακού φραγμού μεταξύ στρώματος παγίδευσης και οξειδίου ελέγχου. Η ικανότητα παγίδευσης και η επίδοση των δομών με HfO2 και ZrO2 δεν διαφοροποιούνται σημαντικά με χρήση διαφορετικού πρόδρομου μορίου ή με την ανόπτηση. Ο έλεγχος όμως της αντοχής των δομών σε επαναλαμβανόμενους παλμούς εγγραφής/διαγραφής αναδεικνύει ότι αμφότερες οι δομές που ανεπτύχθησαν με βάση το κυκλοπενταδιενύλιο έχουν μειωμένη αντοχή ηλεκτρικής καταπόνησης.
Τo Al2O3 αναπτύχθηκε χρησιμοποιώντας το μόριο ΤΜΑ και ως οξειδωτικό μέσο: (α) H2O, (β) O3 και (γ) Plasma Ο2 (μέθοδος PE-ALD) σε συνδυασμό με ΤΜΑ. Οι δομές στην αρχική κατάσταση, χωρίς ανόπτηση, χαρακτηρίζονται από ισχυρό ρεύμα έγχυσης ηλεκτρονίων από την πύλη (υπό αρνητικές τάσεις) περιορίζοντας την ικανότητα φόρτισης και την επίδοση διαγραφής. Η ανόπτηση σε φούρνο και αδρανές περιβάλλον (850 ή 1050 oC, 15 min) προκάλεσε σημαντική βελτίωση των ηλεκτρικών χαρακτηριστικών των δομών λόγω του σημαντικού περιορισμού του παραπάνω φαινομένου. Μετά το στάδιο της ανόπτησης οι συνδυασμοί ΤΜΑ/Η2Ο και ΤΜΑ/Plasma Ο2 έχουν καλύτερες χαρακτηριστικές σε σχέση με αυτές του συνδυασμού ΤΜΑ/Ο3. Το φαινόμενο της διαρροής ηλεκτρονίων από την πύλη αποδίδεται στη μεγάλη συγκέντρωση και χωρική κατανομή του υδρογόνου στο υμένιο υψηλής διηλεκτρικής σταθεράς.
Τέλος, διερευνήθηκε η τροποποίηση των ιδιοτήτων μνήμης των δομών με εμφύτευση ιόντων αζώτου χαμηλής ενέργειας και υψηλής δόσης στο Al2O3 και επακόλουθη ανόπτηση υψηλής θερμοκρασίας. Η παρουσία αζώτου στο υμένιο καθώς και ο χημικός δεσμός του εμφυτευμένου αζώτου είναι συνάρτηση της θερμοκρασίας ανόπτησης. Επομένως, οι ιδιότητες μνήμης εξαρτώνται από τη μορφή σύνδεσης και την συγκέντρωση του εμφυτευμένου αζώτου στο τροποποιημένο Al2O3. Η υψηλή θερμοκρασία ανόπτησης (1050 οC, 15 min) φαίνεται να αποφέρει δομές με τις καλύτερες ιδιότητες μνήμης.This thesis studies the functionality of high-k oxides as blocking oxide layers in SONOS type charge-trap memory devices. The oxide materials that were examined were the HfO2, the ZrO2 and the Al2O3. All these blocking oxide layers were deposited by atomic layer deposition technique (ALD). The electrical performance of the trilayer stacks was examined using Pt-gate MOS-type capacitors. The properties of the memory structures were examined as a function of: (a) precursor chemistry of HfO2 and ZrO2 deposition, (b) the deposition oxidizing agent in the case of Al2O3 and (c) subsequent high temperature annealing steps. The HfO2 films were deposited on SiO2/Si3N4 bilayer stacks using: (a) hafnium alkylamide (TEMAH) and O3 at 275 oC, and (b) hafnium cyclopentadienyl (HfD-04) and O3 at 350 oC. Similarly the ZrO2 films were deposited by (a) zirconium alkylamide (TEMAZ) and O3 at 275 oC, and (b) zirconium cyclopentadienyl (ZrD-04) and O3 at 350 oC The structural characterization of the HfO2 showed that the crystallinity of the deposited high-k material depends on the precursor choice and the post deposition annealing step (600 °C, 2 min). On the contrary ZrO2 is deposited in a crystalline phase independent of the deposition conditions and the choice of the precursors. The electrical characterization of Si/SiO2/Si3N4/high-k/Pt capacitors showed that all fabricated structures operate well as memory elements, despite the absence of an energy barrier between the trapping layer and control oxide. The trapping efficiency and the performance of structures with HfO2 or ZrO2 blocking layers do not revealed a dependence upon the precursor chemistry. However, endurance testing using continuous write/erase pulses showed that both structures deposited by cyclopentadienyl precursors cannot sustain the resulting electrical stress. The Al2O3 layers were deposited using the TMA molecule while three different oxidizing agents were used: (a) H2O, (b) O3 and (c) oxygen plasma. Electrical testing of the resulting Pt-gate trilayer capacitors showed that in the deposited condition all three samples were characterized by gate electrode induced electron leakage currents in the negative bias regime, which completely masked the substrate hole injection effects. This effect limits the performance and the functionality of the memory stacks. After a high temperature annealing step (850 or 1050 oC, 15 min) this leakage current is reduced significantly and the stacks can function as memory elements. The results point to suggest that after annealing the best performance is exhibited by the TMA/H2O and TMA/Plasma O2 samples. The effect of gate induced electron leakage current is attributed to hydrogen related contamination, which has been verified by ToF-ERDA in depth profile measurements, at least for the case of TMA/H2O samples. The modification of the memory properties of the SiO2/Si3N4/Al2O3 stacks was also investigated using low energy and high fluence nitrogen implantation into Al2O3 layer. The concentration and the chemical bonding of the implanted nitrogen is a function of annealing temperature. The memory properties of the stack depend therefore on the chemical bonding and the concentration of the remaining nitrogen in the modified Al2O3. The high temperature annealing (1050 oC, 15 min) appears to provide the structures with improved memory properties in terms of retention and fast erase performance.
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Vogt, Lorenz. "Additive Fertigung von Keramiken mittels Mikrofluidik und elektrophoretischer Abscheidung." 2020. https://monarch.qucosa.de/id/qucosa%3A73275.
Full textAbstract:
In dieser Dissertation wurde untersucht, inwieweit die Kombination von Mikrofluidik mit elektrophoretischer Formgebung zur additiven Herstellung von Keramikbauteilen genutzt werden kann. Mit Verfahren der Mikrofluidik sollten räumliche Strukturierung und Materialdifferenzierung erfolgen, während die elektrophoretische Abscheidung für die Ausbildung einer homogenen Mikrostruktur sorgt. Es wurde eine Versuchsanlage aufgebaut, die eine kontrollierte elektrophoretische Abscheidung von Keramikpartikeln, die durch eine Hohlelektrode zugeführt werden, auf porösen Membranen ermöglicht. Die Anlage bietet – im Unterschied zu bereits beschriebenen Verfahren – das Potenzial für eine hochgradige Parallelisierung und Multimaterialdruck. Schließlich wurden Finite-Elemente-Modelle zur Feldverteilung und zur Partikelbewegung entwickelt, mit denen die experimentellen Ergebnisse verglichen wurden. Bei den Versuchen traten viele in ihrem Ausmaß nicht erwartete Phänomene auf: elektrohydrodynamische Effekte und nichtelektrisch verursachte Strömungen des Lösungsmittels, die die Ausbeute und Reproduzierbarkeit sowie die Eigenschaften der abgeschiedenen Strukturen verschlechterten, was zusätzlichen Untersuchungen notwendig machte. In Ethanol wurden relevante Abscheideparameter systematisch variiert und die Struktur und das Gefüge der abgeschiedenen Al2O3-Partikel methodisch analysiert.
Die Arbeit war Teil eines von der Deutschen Forschungsgemeinschaft geförderten Sachbeihilfe-Projekts (KU 1327/10-1 | RA 614/7-1).:Inhaltsverzeichnis
1 Einleitung 7
2 Stand der Forschung 8
2.1 Stand der Forschung additive Fertigung keramischer Bauteile 8
2.1.1 Feedstockbasierte additive Fertigungsverfahren 9
2.1.2 Pulverbasierte additive Fertigungsverfahren: 10
2.1.3 Schlickerbasierte additive Fertigungsverfahren 11
2.2 Stand der Forschung elektrophoretische Abscheidung 12
2.3 Stand der Forschung Dielektrophorese 15
2.4 Stand der Forschung EHD-Effekt 16
3 Methodisches Vorgehen 19
3.1 Allgemeiner Aufbau 19
3.2 Elektroden 22
3.3 Lösungsmittel 24
3.4 Abscheidemembranen 25
3.5 Partikel und Suspensionen 27
3.6 Durchführung der Depositionsexperimente 30
3.7 Analyse der abgeschiedenen Strukturen 32
3.7.1 Konfokale 3D Laserscanningmikroskopie (CLSM) 32
3.7.2 Dynamische Differenzkalorimetrie und Thermogravimetrie (DSC/TGA) 33
3.7.3 Rasterelektronenmikroskopie (REM) und Varianzanalyse 33
4 Computersimulationen 35
5 Experimentelle Ergebnisse 41
5.1 Untersuchung des EHD-Effekts 41
5.2 Abscheidung mit verschiedenen Lösungsmitteln und Partikeln 45
5.3 Abscheidung von PEI-Aluminiumoxidpartikeln in Ethanol 51
5.4 DSC-TGA einer bedruckten Membran 60
5.5 Varianzanalyse der Gefügehomogenität elektrophoretisch abgeschiedener
Proben 63
6 Zusammenfassung und Ausblick 66
7 Quellenverzeichnis 69
8 Formelverzeichnis 78
9 Tabellenverzeichnis 78
10 Abbildungsverzeichnis 79
11 Anhang 83In this dissertation it was examined to what extent the combination of microfluidics with electrophoretic shaping can be used for the additive manufacturing of ceramic components. The spatial structuring and material differentiation should take place using microfluidic methods, while the electrophoretic deposition ensures the formation of a homogeneous microstructure. A test facility was set up that enables controlled electrophoretic deposition of ceramic particles, which are fed through a hollow electrode, onto porous membranes. In contrast to known processes, the system offers the potential for high-quality parallelization and multi-material printing. Finally, finite element models for field distribution and particle movement were developed, with which the experimental results were compared. During the experiments, many phenomena that were not expected occurred: electrohydrodynamic effects and non-electrically induced solvent flows, which reduced the yield and reproducibility as well as the properties of the deposited structures, that made additional studies necessary. We systematically varied relevant deposition parameters in the solvent ethanol and the microstructure of the deposited Al2O3 particles was methodically analyzed. The work was part of a research grant project funded by the German Research Foundation (KU 1327 / 10-1 | RA 614 / 7-1).:Inhaltsverzeichnis 1 Einleitung 7 2 Stand der Forschung 8 2.1 Stand der Forschung additive Fertigung keramischer Bauteile 8 2.1.1 Feedstockbasierte additive Fertigungsverfahren 9 2.1.2 Pulverbasierte additive Fertigungsverfahren: 10 2.1.3 Schlickerbasierte additive Fertigungsverfahren 11 2.2 Stand der Forschung elektrophoretische Abscheidung 12 2.3 Stand der Forschung Dielektrophorese 15 2.4 Stand der Forschung EHD-Effekt 16 3 Methodisches Vorgehen 19 3.1 Allgemeiner Aufbau 19 3.2 Elektroden 22 3.3 Lösungsmittel 24 3.4 Abscheidemembranen 25 3.5 Partikel und Suspensionen 27 3.6 Durchführung der Depositionsexperimente 30 3.7 Analyse der abgeschiedenen Strukturen 32 3.7.1 Konfokale 3D Laserscanningmikroskopie (CLSM) 32 3.7.2 Dynamische Differenzkalorimetrie und Thermogravimetrie (DSC/TGA) 33 3.7.3 Rasterelektronenmikroskopie (REM) und Varianzanalyse 33 4 Computersimulationen 35 5 Experimentelle Ergebnisse 41 5.1 Untersuchung des EHD-Effekts 41 5.2 Abscheidung mit verschiedenen Lösungsmitteln und Partikeln 45 5.3 Abscheidung von PEI-Aluminiumoxidpartikeln in Ethanol 51 5.4 DSC-TGA einer bedruckten Membran 60 5.5 Varianzanalyse der Gefügehomogenität elektrophoretisch abgeschiedener Proben 63 6 Zusammenfassung und Ausblick 66 7 Quellenverzeichnis 69 8 Formelverzeichnis 78 9 Tabellenverzeichnis 78 10 Abbildungsverzeichnis 79 11 Anhang 83