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.

Orientador: José Alberto Giacometti / Coorientador: Neri Alves / Banca: Clarissa de Almeida Olivati / Banca: José Leonil Duarte / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: Neste trabalho é apresentada a preparação de filmes finos de Al2O3 usando a técnica eletroquímica de anodização em solução aquosa de etileno glicol e ácido tartárico. Os filmes de Al2O3 foram crescidos sobre camadas de alumínio as quais foram depositadas por evaporação em vácuo sobre lâminas de vidro. No processo de anodização se utilizou a densidade de corrente constante de 0,48 mA/cm2, seguido da aplicação de diferença de potencial constante durante 2 minutos. Filmes com espessuras entre 10 e 60 nm foram crescidos sendo a espessura determinada pela tensão final aplicada na célula. Os filmes de Al2O3 foram caracterizados através de medidas de capacitância e perda dielétrica em função da frequência e das curvas características da corrente elétrica versus a tensão elétrica. Os resultados mostraram que a perda dielétrica é da ordem de 10-3 indicando que os filmes de Al2O3 possuem muito boa qualidade como isolante elétrico. As medidas de corrente versus tensão mostraram que a resistividade elétrica dos filmes é da ordem de 10(13)m. Na parte final do trabalho foi mostrado que os filmes de Al2O3 podem ser usados para a construção do capacitador metal-isolante-semicondutor (MIS) para operar entre no intervalo de tensão de +3V. Além disso, o capacitador MIS apresentou o fenômeno do chaveamento da condução elétrica quando foram aplicadas tensões elétricas elevadas, e, portanto, são candidatos para a fabricação de memórias / Abstract: This work presents the preparation of Al2O3 films using the electrochemical anodisation tehcnique in aqueous solution of ethylene glycol and tartaric acid. The Al2O3 films were grown from aluminum layers deposited by evaporation in vacuum onto glass slides. The anodisation process was performed using a constant current density of 0.48 mA/cm2 followed by application of a constant voltage during 2 minutes. Films with thicknesses ranging from 10 to 60 nm were grown and the thickness was determined by the final voltage applied to the cell. Films were characterized through measurements of capacitance and dielectric loss versus frequency curves and characteristics of electric current versus voltage. The results showed that the dielectric loss is of the order of 10-3 showing that Al2O3 film is a very good electrical insulator. Current versus voltage measurments showed that the electrical resistivity of the Al2O3 films is of the order of 10(13)m. Finally, it is shown that Al2O3 films can be used to fabricate metal-insulator-semiconductor (MIS) capacitor that can be operated in the voltage range of +3V. The MIS capacitor also presented the electrical conduction switching when the applied voltage was increased, therefore, it can be a candidate to be used as memory / Mestre

Uma parcela considerável do consumo energético, e consequentemente, dos custos das operações de tratamento de minérios é atribuída a cominuição. O High Pressure Grinding Rolls (HPGR) surge com o apelo de eficiência energética, o que, potencialmente, reduziria os custos operacionais. Nesta pesquisa, esta tecnologia é analisada como uma alternativa à rota convencional de cominuição de óxido de alumínio eletrofundido de um empreendimento em particular, que compreende um complexo circuito de britadores de rolos. Duas amostras de óxido de alumínio eletrofundido, denominadas BT e TB, foram submetidas a ensaios de HPGR (circuito aberto) e de caracterização física (DWT, WI, AI, densidade). Adicionalmente, foram realizadas simulações no software JKSimMet® 6.0 com o objetivo de prever o desempenho do equipamento em circuito fechado e realizar o escalonamento da unidade industrial. As distribuições granulométricas dos produtos dos ensaios de HPGR em circuito aberto e as distribuições granulométricas dos produtos dos circuitos fechados de HPGR simulados foram comparadas às granulometrias do produto requeridas pelo circuito industrial. Avaliou-se, também, o atendimento da vazão mássica requerida. Os resultados demonstram que a rota alternativa baseada no HPGR oferece um expressivo potencial de simplificação do circuito, com uma redução considerável do número de equipamentos de cominuição de 13 para 1, o que, além de, possivelmente, impactar na redução de custos operacionais, facilita o controle da operação. / A considerable portion of energy consumption and, as a consequence, operational costs in mineral processing is associated with comminution. High Pressure Grinding Rolls (HPGR) are appealing for their energy efficiency, which would potentially reduce operating costs. This study evaluates this technology as an alternative to the conventional electrofused aluminum oxide comminution route of a specific plant comprising a complex roll crushing circuit. Two electrofused aluminum oxide samples, called BT and TB, were submitted to HPGR (open circuit) and physical characterization (DWT, WI, bulk density, specific gravity) tests. In addition, simulations were conducted using JKSimMet® 6.0 software, aiming to predict the performance of a closed-circuit equipment and scale-up of an industrial scale unit. Product size distributions of the open-circuit HPGR tests and closed circuit HPGR simulations were compared with the product size distribution required by industrial comminution circuit. The required throughput was also evaluated. Results show that the alternative HPGR route provides a remarkable potential for circuit simplification, while considerably reducing the number of comminution equipments from 13 to 1, which facilitates operational control and possibly reduces operating costs.

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

Thesis. 1977. Sc.D.--Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIES AND SCIENCE. / Vita. / Includes bibliographical references. / Sc.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / by Ellen Schwartz Tormey. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / by Joseph Michael Dynys. / Ph.D.

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Bibliography: leaves 120-126. / by John Edward Blendell. / Sc.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Vita. / Includes bibliographical references. / by Normand Denis Corbin. / M.S.

Zhou, Wenjia = 聚苯乙烯/銀聚合物納米棒陣列的合成、表征與生長的研究 / 周文佳. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 69-73). / Text in English; abstracts in English and Chinese. / Zhou, Wenjia = Ju ben yi xi / yin ju he wu na mi bang zhen lie de he cheng, biao zheng yu sheng zhang de yan jiu / Zhou Wenjia. / Chapter I. --- Abstract / Chapter IV. --- Acknowledgement / Chapter V. --- Contents / Chapter 1 --- Introduction / Chapter 1.1 --- Motivations / Chapter 1.2 --- Overview of the thesis / Chapter 2 --- Instruments / Chapter 2.1 --- Introduction to electron microscopes / Chapter 2.2 --- Scanning electron microscope / Chapter 2.2.1 --- Introduction to SEM working principle / Chapter 2.2.2 --- Electron specimen interactions and their applications in SEM / Chapter 2.2.3 --- Specific SEM conditions in the experiments / Chapter 2.3 --- Transmission electron microscope / Chapter 2.3.1 --- Introduction to TEM working principle / Chapter 2.3.2 --- Imaging mode and diffraction mode in TEM / Chapter 2.3.3 --- X-ray microanalysis with TEM / Chapter 2.3.4 --- Specific TEM conditions in the experiments / Chapter 3 --- Anodic aluminum oxide templates with different parameters / Chapter 3.1 --- Introduction to self-ordered anodic aluminum oxide / Chapter 3.1.1 --- Electrochemistry of anodic alumina / Chapter 3.1.2 --- Pore growth mechanism / Chapter 3.1.3 --- Self-ordered alumina by two-step anodization / Chapter 3.1.4 --- Other advanced methods for fabrication of monodomain AAO / Chapter 3.1.5 --- Applications of AAO templates in nanomaterials fabrication / Chapter 3.2 --- Preparation procedures of porous AAO templates we used / Chapter 3.2.1 --- Experimental setup / Chapter 3.2.2 --- General preparation procedures of AAO thin film on Al / Chapter 3.3 --- Experimental data of AAO templates with different parameters / Chapter 3.3.1 --- Different interpore distances / Chapter 3.3.2 --- Different pore depths and pore sizes / Chapter 3.3.3 --- Calibration of AAO templates pore depths and pore sizes at different anodic potentials / Chapter 4 --- Preparation of free standing polystyrene nanorods arrays with different parameters / Chapter 4.1 --- General preparation procedures of free standing polymer nanorods arrays / Chapter 4.2 --- Different rods intervals and diameters / Chapter 4.3 --- Limitations to the rods lengths control / Chapter 4.4 --- Discussion on the polymer properties for the successful preparation of free standing polymer rods arrays / Chapter 5 --- Thermal reduction method to embed Ag nanoparticles inside the polymer rods / Chapter 5.1 --- General preparation procedures of PS/Ag nanorods arrays / Chapter 5.2 --- Analysis method and procedure of Ag nanoparticles inside PS rods / Chapter 5.3 --- Typical TEM images of the three series samples / Chapter 5.4 --- Data analysis of Ag nanoparticles inside PS rods / Chapter 5.5 --- Discussion on Ag particles growth process / Chapter 5.6 --- Conclusion and suggestions for improvement / Chapter 6 --- Conclusion / Reference / Appendix