Graduation date: 1991

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Thesis (Ph. D.) -- California Institute of Technology, 2009. / Title from home page (viewed 03/03/2010). Advisor and committee chair names found in the thesis' metadata record in the digital repository. Includes bibliographical references.

Mak, Chun Chung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 83-85). / Abstracts in English and Chinese. / ABSTRACT --- p.iv / DECLARATION --- p.vi / ACKNOWLEDGEMENT --- p.vii / TABLE OF CONTENTS --- p.ix / LIST OF TABLES --- p.xii / LIST OF FIGURES --- p.xiii / Chapter Chapter One: --- Overview --- p.1 / Introduction to Cerium Oxide --- p.1 / Defects --- p.2 / Effect of dopants --- p.5 / Nano-structures of ceria --- p.8 / Loading metals in ceria supports --- p.10 / Summary --- p.11 / Scope of work --- p.12 / References --- p.14 / Chapter Chapter Two: --- Synthesis of Ceria Nano-feathers / Introduction --- p.17 / Experimental Section (Preparation of nano feathers) --- p.19 / Experimental Section (Preparation of conventional ceria spheres) --- p.19 / Experimental Section (Encapsulation the feather with gold) --- p.19 / Experimental Section (Instrumentation) --- p.20 / Results and Discussion (XRD) --- p.22 / Results and Discussion (SEM) --- p.23 / Results and Discussion (TEM) --- p.24 / Formation Mechanism --- p.30 / Results and Discussion (Nano-beam diffraction) --- p.33 / Results and Discussion (HREM) --- p.35 / Results and Discussion (TEM of gold encapsulated ceria) --- p.36 / Results and Discussion (XPS) --- p.39 / Summary --- p.41 / References --- p.41 / Chapter Chapter Three: --- Preparation of Homogenous Cerium Mixed Oxide Nano-feathers --- p.43 / Introduction --- p.43 / Experimental Section (Preparation of nano-feathers) --- p.44 / Experimental Section (Instrumentation) --- p.45 / Results and Discussion (XRD) --- p.47 / Results and Discussion (XPS) --- p.49 / Results and Discussion (TEM and EELS) --- p.56 / Summary --- p.64 / References --- p.64 / Chapter Chapter Four: --- Engineering Ceria Nano-feathers with Noble Metals: A Sono-chemistry approach --- p.66 / Introduction --- p.66 / Experimental Section (Sample Preparation) --- p.68 / Experimental Section (Instrumentation) --- p.69 / Results and Discussion (XRD) --- p.70 / Results and Discussion (XPS) --- p.71 / Results and Discussion (TEM and HREM) --- p.76 / Summary --- p.82 / References --- p.84 / Conclusions --- p.86

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Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references. Also available on the World Wide Web.

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Thesis (Ph. D.)--Institute of Paper Chemistry, 1968. / Bibliography: leaves 89-93.

Made available in DSpace on 2014-10-09T12:40:52Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:30Z (GMT). No. of bitstreams: 1 02944.pdf: 4594113 bytes, checksum: a3a3f6866bfb45e2b9c9b02b0a6f7796 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Orientador: Miguel Angel Ramírez Gil / Coorientadora: Maria Olívia Berengue / Banca: José Vitor Candido de Souza / Banca: Miguel Adolfo Ponce / Resumo: Este trabalho apresenta e discute o uso do óxido de cério na fabricação de filmes espessos por "screen printing" para aplicações em sensores de gás. Nesse estudo o CeO2 puro foi obtido pelo método dos precursores poliméricos utilizando como resina precursora o citrato de céria. O "puff" - espuma resultante da primeira fase do tratamento térmico da resina- foi calcinado a 550, 600, 700 e 750°C. O pó foi caracterizado por termogravimetria (TG) e as propriedades estruturais, morfológicas foram avaliadas por difratometria de raios X (DRX), espectroscopia Raman, área de superfície por isotermas Brunauer, Emmett e Taller (BET) e microscopia eletrônica de varredura (MEV). A resposta sensora foi estudada em uma câmara de teste construída no Laboratório de Catálise e Superfícies do Instituto de Ciência de Tecnologia de Materiais (INTEMA) da Universidade de Mar del Plata. A TG mostrou a formação de óxido de cério a 550°C, temperatura relativamente baixa quando comparada com outros métodos. Mediante DRX todas as amostras mostraram picos correspondentes à fase pura de CeO2 o qual cristaliza em uma estrutura cúbica do tipo fluorita, entretanto, maiores temperaturas de calcinação mostraram aumento da cristalinidade e tamanho do cristalito. No espectro Raman, um forte pico em torno do 461 cm-1 foi detectado, atribuído às vibrações simétricas do Ce-O. A área de superfície BET dos pós foi de 301, 77 m2/g o que evidencia a formação de partículas muito pequenas e altamente reativas. As microgra... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This paper presents and discusses the use of cerium oxide in the production of thick films for "screen printing" for applications in gas sensors. In this study the pure CeO2 was obtained by the polymeric precursor method using as a precursor resin citrate ceria. The "puff" - resulting foam from the first stage of thermal treatment of the resin-calcined at 550, 600, 700 and 750 °C. The powder was characterized by thermogravimetry (TG) and structural, morphological were evaluated by X-ray diffraction (XRD), Raman spectroscopy, isothermal Brunauer surface area, Emmett and Taller (BET) and scanning electron microscopy (SEM) . The sensor response was studied in a test chamber built in the Laboratory of Catalysis and Surface Materials Technology Institute of Science (INTEMA), University of Mar del Plata. The thermogravimetry showed the formation of cerium oxide at 550° C, relatively low temperature compared with other methods. Upon XRD all samples showed peaks corresponding to pure CeO2 phase which crystallizes in a cubic fluorite type structure, however, higher calcination temperatures showed increased crystallinity and crystallite size. In the Raman spectrum, a strong peak around 461 cm-1 was detected, assigned to symmetric vibrations of the Ce-O. The BET surface area of the powders was 301, 77 m2 /g which shows the formation of very small and highly reactive particles. The SEM micrographs show the presence of different sizes in the form of agglomerates. The characterization of the sensor response showed that the sensors manufactured from pure CeO2 powder has a good response time, achieving better performance at 400 °C working temperature in both reducing and oxidizing atmospheres. The main feature observed was that the results are dependent on previous cycles, the system reproducibility is guaranteed when it deletes the "memory" of the system, exposing it to vacuum / Mestre