Thesis (Ph. D.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 17, 2007) Vita. n following parenthesis in formula (LaTiO₃) should be subscript. Includes bibliographical references.

Thesis (Ph.D.)--Texas Christian University, 2008. / Title from dissertation title page (viewed Feb. 26, 2009). Includes abstract. Includes bibliographical references.

Alternative plasmonic materials of Transparent Nitrides and Conductive Oxides (TNCOs) including Indium Tin Oxide (ITO), Al-doped ZnO (AZO) and Titanium Nitride (TiN), have been proposed as novel material platforms for Si-compatible plasmonics and metamaterials, showing enhanced light-matter interaction over a broad spectral range. It has been recently shown that these materials feature reduced optical losses compared with conventional noble metals such as Au and Ag in the visible and near-infrared spectral range. However, it is still an open challenge to tailor the structural and optical properties of these materials, and to further reduce their optical losses, in order to effectively utilize them in photonic devices. In this thesis work, I demonstrate wide tunability of the optical and structural properties of ITO, AZO and TiN thin films, by using post-deposition annealing treatments, enabling significant reduction of their optical losses. By measuring the optical bandgaps of the investigated materials, I show that the tunability of the optical properties originates from the modulation of the free carrier concentration induced by the annealing treatment. Moreover, I perform XRD characterization of the fabricated films, indicating that the annealing also effectively tunes the grain size, which is consistent with the change of the optical properties. Eventually, I investigate the role of the annealing gases for ITO and AZO, demonstrating that free-carrier modulation in ITO and AZO is due to the change in the density of oxygen vacancies after post-deposition annealing. In particular, TNCOs possess epsilon-near-zero (ENZ) condition in near-infrared range with optical loss ε^"<1, thus providing enhanced internal fields in the medium at the ENZ condition. In collaboration with Prof. Nader Engheta and the previous post-doc in our group Dr. Antonio Capretti, we demonstrate enhanced second-harmonic generation (SHG) and third-harmonic generation (THG) from ITO thin films driven by ENZ condition. It results that the SHG generation efficiency is comparable with that of a crystalline quartz plate of thickness 0.5 mm, and that the THG generation efficiency is ∼600 times larger than crystalline silicon. As an application for the fabricated TiN material, I investigate PL intensity and lifetime in Hyperbolic Metamaterials (HMMs) coupled with emitting Si Quantum Dots (QDs). In collaboration with Hiroshi Sugimoto in Prof. Minoru Fujii’s group and the previous post-doc in our group Dr. Sandeep Inampudi, we demonstrate up to 1.6-times enhanced decay rate of QDs emission. Photonic devices based on TNCO plasmonic materials offer an effective approach for the engineering of novel Si-based photonic devices with enhanced light-matter coupling over a broad spectral range. As an application for the fabricated ITO, in collaboration with Hongwei Zhao in Prof. Jonathan Klamkin’s group, electro-absorption modulators are numerically investigated to show high extinction ration of greater than 6dB, while insertion loss is less than 1.3dB for wavelength range from 1.25 µm to 1.42 µm. Additionally, we demonstrate tunable optical properties of ITO thin films in mid-infrared spectrum by thermal annealing of ITO in oxygen environment. In collaboration with Sajan Shrestha and Adam Overvig in Prof. NanFang Yu’s group, we fabricate 2D periodic arrays of ITO and show wide tuning of plasmonic resonances of ITO nanostructure from 4 µm to 10 µm. Combining with the tunability of ITO thin films in near-infrared, the ITO material platform provides a promising method for the control and engineering of Si-based tunable plasmonic and metamaterial devices in the infrared spectrum. Finally, in collaboration with my colleague Ren Wang, we experimentally demonstrate silicon nanodisk arrays with tunable anapole mode excitation in the visible spectrum. The proposed high index nanostructures can be used to enhance absorption rate for applications in semiconductor photodetector.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第13828号 / 工博第2932号 / 新制||工||1433(附属図書館) / 26044 / UT51-2008-C744 / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 檜山 爲次郎, 教授 大嶌 幸一郎, 教授 松原 誠二郎 / 学位規則第4条第1項該当

Contents: a. The oxidation of metals by atomic and molecular oxygen -- b. Calculation of the heats of formation of point defects in some transition metal oxides.

The crystal growth conditions of compounds of the series Srn+1IrnO3n+1 (n=1, 2 and ∞) are investigated. It was found that the ratio of IrO2:SrCO3 in the starting mixture is the most important variable in determining the phase formed. Good quality samples of Sr3Ir2O7 were found to have a sharp change in gradient at the Néel temperature of 287.5 K and no secondary T* transition between 230 K and 260 K. All crystals of Sr3Ir2O7 grown were found to be heavily oxygen deficient by EPMA regardless of the crystal growth conditions used with an average stoichiometry of Sr2:87Ir2O6:27. Adding more electrons via replacing strontium with lanthanum causes (Sr(1-x)Lax)3Ir2O7 to become metallic by x=0.072, which also fully quenches the long-range antiferromagnetic order. Heat capacity and resistivity measurements show that metallic (Sr(1-x)Lax)3Ir2O7 is a weakly correlated Fermi-liquid metal. Given that there are only subtle changes to the structure upon lanthanum doping, the metal-insulator transition is a result of electron doping rather than structural distortions. No structural phase transitions were found up to a temperature of 800°C and no additional evidence was found to support the Bbcb space group model of the structure of Sr3Ir2O7. Using crystals five times better in quality than those reported in the literature, SrIrO3 was found to be a Fermi-liquid metal, rather than a non-Fermi liquid metal as previously reported, and no superconductivity was found down to temperatures of 20 mK. A known Pt(III) compound, CaPt2O4, was found to be a weakly correlated metal down to 2 K and a novel Pt(III) based compound, K2CaPt3-δ O6 (δ ≈ 0.4), was discovered. K2CaPt3δ-O6 has a structure consisting of monolayers of edge-sharing PtO6 octahedra separated by layers of ordered K+ and Ca2+ ions in a 2:1 ratio. The structure of K2CaPt3-δO6 was found to be flexible to doping with copper, causing the magnetic properties to change from temperature independent to paramagnetic.

xx, 204 p. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Efforts toward developing improved methods of synthesizing acrylamides are ongoing. Several homogeneous organometallic and coordination complexes have proven useful in catalytic acrylonitrile hydration; however, none of these complexes have been tested in the hydration of cyanohydrins used to synthesize substituted acrylamides. This dissertation describes the reactivity of molybdocene and Pt phosphinito nitrile hydration catalysts toward cyanohydrin substrates and the effect of Cp ring substituents on aqueous molybdocene chemistry. Chapter I identifies the motivation for developing a transition metal-catalyzed process for cyanohydrin hydration and the strategy used to improve on the reactivity of molybdocene catalysts. Chapter II reports the effect of cyclopentadienyl ring substituents on the electronic and geometric structure, solution behavior, and hydrolytic activity of molybdocenes. To examine the effect of Cp ring substituents, ansa -molybdocenes containing the fragment {C 2 Me 4 (C 5 H 4 ) 2 }Mo 2+ were compared to non-bridged molybdocenes containing (C 5 H 5 ) 2 Mo 2+ and (C 5 H 4 Me) 2 Mo 2+ . Addition of a tetramethylethylene-bridge decreases the electron density on the Mo center and exerts a small effect on the structure of the metallocene. However, the catalytic activity of the molybdocene catalysts is unchanged or slowed because of counteractive effects on the bound nucleophile and electrophile. Although adding substituents to the Cp rings did not change the catalytic activity of the molybdocene, the substituents led to significant changes in the equilibrium behavior. The equilibria have practical consequences that warrant investigation. Chapters III and IV chronicle the effect of Cp ring substituents on the monomer-dimer equilibria and the acidity of the molybdocene complexes, respectively. Interestingly, the monomer-dimer equilibrium established by ansa -{C 2 Me 4 (C 5 H 4 ) 2 }Mo(OH)(OH 2 ) + exhibits a strong solvent dependence. New equilibrium schemes are reported for the ansa and non- ansa complexes. Chapter V describes the reactivity of the molybdocene and Pt phosphinito catalysts toward cyanohydrins. Both catalysts gave unsatisfactory results; however, the à à à à à ±-hydroxy substituent of cyanohydrins facilitates nitrile hydration. The low reactivity exhibited by these systems was due to liberation of hydrogen cyanide from the cyanohydrin leading to acute poisoning of either catalyst. As discussed in Chapter VI, this study will expedite the innovation of new catalysts that are better suited to overcome the challenges associated with cyanohydrin hydration. This dissertation includes previously published and unpublished co-authored material. / Adviser: David R. Tyler

This thesis reports exploratory studies on the synthesis of new vanadium and copper-containing compounds, with a particular emphasis on preparing new magnetically-active materials with S = ½ spin configurations. Eighteen crystal structures are reported, sixteen of which represent new compounds. These materials were studied for magnetic behaviour where appropriate. The sixteen vanadium-containing compounds were prepared using either the hydrothermal, Solvothermal or ionothermal synthesis methods at temperatures ranging from 60 °C to 200 °C. Inorganic cations and organic moieties were used as templating agents to direct the structures, often targeting potentially frustrated lattices based on triangular motifs by using ‘triangular' templating molecules such as guanidine. Solvent choices, as well as reactant ratios were all varied in order to produce the new oxide, fluoride and oxyfluoride compounds of vanadium. Three families of vanadium compounds were prepared from these methods; a family of 1D vanadium (IV) oxyfluoride ladder compounds of general formula AVOF₃ (A=K⁺, Rb⁺, Cs⁺ or NH₄⁺), and a family of 1D vanadium fluoride chain compounds of general formula A₂VF₅ (A=K⁺ or NH₄⁺). The third family is comprised of three vanadium-containing compounds of varying dimensionality that share guanidine as the common organic moiety. Several miscellaneous compounds of vanadium such as clusters and a new V (IV) layer were synthesized, and are reported. The two copper compounds containing compounds, analogous to the pseudo-kagome compound, Cu₃Bi(SeO₃)₂O₂Br, were prepared via solid-state techniques. A detailed neutron diffraction study was carried out on the two compounds to measure the evolution of the magnetic properties from room temperature down to 2.5 K. Representational analysis was utilised in order to provide a detailed magnetic model of the compounds.

No description available.

Orientador: Elizabete Jordão, Wagner Alves Carvalho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T00:25:36Z (GMT). No. of bitstreams: 1 MartinezJorrin_Michael_M.pdf: 2708172 bytes, checksum: faa00379224d0c77aa738becd7bd1615 (MD5) Previous issue date: 2010 / Resumo: Foram avaliados os catalisadores de Ru suportados em Nióbia, Sílica e Alumina na Hidrogenólise seletiva de Glicerol para a obtenção de propanodióis (1,2 e 1,3 - Propanodiol). O método de preparação utilizado para os três catalisadores foi o de impregnação úmida partindo-se de uma solução aquosa do sal precursor RuCl3.1,37H2O cuja porcentagem em peso do metal ativo foi de 2%. Os catalisadores foram caracterizados pelo método da Área Superficial Específica (método de B.E.T) e Microscopia Eletrônica de Varredura (M.E. V) com EDX. O maior valor de área superficial específica foi alcançado pelo catalisador de Ru/SiO2 seguido pelo catalisador de Ru/Al2O3, mas isto não foi o fator determinante para escolha do melhor sistema catalítico em termos de seletividade para o 1,2-propanodiol e conversão de substrato. A reação de hidrogenólise foi conduzida em um reator Parr, em atmosfera de H2 a qual foi avaliada ás temperaturas de 120°C, 140°C e 200°C, pressão de 50 bar, 0,75 g do catalisador e uma solução aquosa de glicerol de 0,2 g/mL, durante 6 h. Foram ainda realizados testes exploratórios variando a pressão (30 bar) e a quantidade de catalisador( 1,5 g), para avaliar a sua influência. Os resultados dos testes cinéticos mostraram que com os catalisadores utilizados ocorrem reações de degradação envolvendo a ruptura de ligações C-C e conseqüente formação de produtos tais como etilenoglicol, propanol, e outros em menores quantidades tais como metanol, etanol, e metanos que não puderam ser identificados pelas técnicas analíticas utilizadas neste trabalho. O melhor desempenho foi alcançado pelo sistema catalítico Ru/Al2O3(1,5 g) com 97% de seletividade para 1,2-propanodiol e conversão de substrato de 52% à temperatura de 120ºC e pressão de 50 bar de H2 em presença de uma resina de troca iônica (Amberlyst15). Isto pode estar associado à acidez do meio proporcionada pela combinação do suporte (Al2O3) e o aditivo utilizado / Abstract: Ru/SiO2, Ru/Nb2O5 and Ru/Al2O3 catalysts were applied to the hydrogenolysis of glycerol to propanediols( 1,2 and 1,3PD). They were prepared by wet impregnation with an aqueous solution containing RuCl3.1,37H2O. The Ruthenium catalysts were loading in the range of 0,2% wt supported on silica, niobium and alumin oxide and characterized by transmission electronic microscopy(TEM-EDX) and the BET method (N2 adsorption). The Ru/SiO2 catalyst showed the higher specific surface area. Moreover, the test activity revealed that it wasn't the main factor to chose the best catalyst performance. Hydrogenolysis of glycerol was carried out in a high pressure Parr reactor. The standard procedure was as follows, the substrate, 100 mL 20wt% glycerol aqueous solution, and 0,75 g supported catalyst were used in every run. The reaction conditions were 120ºC, 140ºC and 200ºC, 50 bar hydrogen pressure and 6 h reaction time. The effect of hydrogen pressure and the catalyst weight were studied at constant reaction temperature of 120ºC, and were varied to 30 bar and 1,5 g of catalyst respectively. The reaction results indicated that Ru/Al2O3 showed higher performance (with a 97% selectivity of 1,2 PD at 52% conversion ) at reaction temperature of 120ºC, 50 bar hydrogen pressure with the use of ion-exchange resin (Amberlyst15). This may be due to the acidity produced by combination of the support (Al2O3) and the additive used. The kinetic test results showed that catalysts used promoted degradation reactions involving C-C bonds cleavage, which led to degradative products such as ethylene glycol, propanol, and others in smaller quantities such as methanol, ethanol, and methane which were impossible to indentify by the analytical techniques used in this work / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química