Thesis (M.S.)--Ohio University, November, 2000. / Title from PDF t.p.

Thesis (Ph.D.)--University of Western Sydney, Nepean, 1995. / Bibliography: leaves [214]-227.

Thesis (Ph. D.)--Princeton University, 1922.

Thesis (Ph. D.)--Princeton University, 1922. / Description based on print version record.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xvii, 109 p.; also includes graphics (some col.). Includes bibliographical references (p. 105-109). Available online via OhioLINK's ETD Center

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains vi, 100 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 98-100).

We use a combination of Density Functional Theory and Dynamical Mean Field Theory (DFT+DMFT) to study electronic correlations in unconventional superconductors, with a focus on nickelate analogs of cuprate superconductors. We study the infinite layer nickelate superconductor NdNiO₂ in parallel with the isostructural CaCuO₂. Our results point to superconductivity in the nickelate being cupratelike, with correlations dominated by a hybrid Ni-𝑑_{𝑥²-𝑦²} and O-𝑝 band, and with the extra bands not contributing substantially to the superconducting state. We find that the infinite layer nickelate NdNiO₂ and the trilayer nickelate Pr₄Ni₃O₈ are virtually identical in terms of correlation physics when compared at the same chemical doping, despite the differences in Fermiology, indicating that the number of layers can stand in for chemical doping for some properties related to electronic correlations. We find that as opposed to in narrow window DFT+DMFT, in wide window DFT+DMFT the choice of downfolding procedure leads to very different results. This is an important ambiguity in the method that must be resolved or the method is incomplete by itself. We also study Sr₂MoO₄ in parallel with the Hund's superconductor Sr₂RuO₄, and find that Sr₂MoO₄ is a particle-hole dual of Sr₂RuO₄ but without the van Hove singularity at the Fermi level, which disentangles the influence of the van Hove singularity from Hund's physics. We show that Sr₂MoO₄ has a characteristic Hund's peak on the occupied of the spectral function, indicating that the peak should be observable by photoemission experiments.

Yes / A digital baffle batch reactor (DBBR) for oxidative desulfurization (ODS) reactions is designed and applied here in order to reduce the sulfur concentration presented in light gas oil (LGO) based on a novel homemade nano-catalyst (Copper Oxide (CuO)/Activated Carbon (AC)). With efficient impregnation, good pore size distribution, high activity and higher surface area, the designed nano-catalyst (CuO/AC) demonstrated excellent catalytic efficiency. To evaluate the effectiveness of nano catalyst (prepared experimentally), several experiments related to ODS reactions using the digital baffle batch reactor are carried out under moderate process conditions (reaction temperature (100, 120 and 140 °C), contact time (15, 30 and 45 min) and oxidant (H2O2) amount (2, 3 and 5 ml)). The experimental outcomes indicated that increasing the reaction temperature, batch time and oxidant amount lead to reduced sulfur concentration of oil feedstock leading to a greener fuel. The efficiency of sulfur conversion is reported to be 83.1 % using the modified nano-catalysts and new reactor (DBBR) at reaction temperature 140 oC, batch time 45 min and H2O2 amount of 5 ml. So, such new results using DBBR for ODS reactions based on CuO/AC as a new modified nano catalyst has not been reported in the public domain and it is considered as new results.

Increased interest in the field of sensor technology stems from the availability of an inexpensive and robust sensor to detect and quantify the presence of a specific gas. Bulk p-CuO/n-ZnO heterocontact based gas sensors have been shown to exhibit the necessary sensitivity and selectivity characteristics, however, low interfacial CuO/ZnO contact area and poor CuO/ZnO connectivity limits their effective use as gas sensors. The phase equilibria between CuO and ZnO exhibits limited solubility. By exploiting this concept, a CuO/ZnO mixed solution is formed by combining CuO and ZnO precursors using wet chemical (sol-gel) techniques. Thin films fabricated using this mixed solution exhibit a unique CuO/ZnO microstructure such that ZnO grains are surrounded by a network of CuO grains. This is highly beneficial in gas sensing applications since the CuO/ZnO heterostructure interfacial area is considerably increased and is expected to enhance sensing characteristics. This work builds on previous research by Dandeneau et al. (Thin film chemical sensors based on p-CuO/n-ZnO heterocontacts, Thin Solid Films, 2008). CuO/ZnO mixed solution thin films are fabricated using the sol-gel technique and subsequently characterized. X-ray diffraction (XRD) data confirms the phase separation between ZnO and CuO grains. Scanning electron microscopy (SEM) as well as energy dispersive spectroscopy (EDS) reveal a network of ZnO grains amidst a matrix of CuO grains. Optical and electrical characterization provide material parameters used to construct an energy band diagram for the CuO/ZnO heterostructure. Aluminum interdigitated electrodes (IDEs) are patterned on the thin film and gas sensing characteristics in the presence of oxygen and hydrogen are investigated. Optimization of the electrode geometry is explored with the aim of increasing the sensitivity of the sensor in the presence of hydrogen gas. / Graduation date: 2010

L’étude de l’oxydation de films minces de cuivre déposés par pulvérisation magnétron sur des substrats de silicium et de verre a été menée au moyen d’une micro-post-décharge micro-ondes dans l’objectif de faire croître de manière localisée des nanostructures contrôlées d’oxyde. L’utilisation de plasma permet d’utiliser des atomes d’oxygène plutôt que de molécules d’oxygène et de pouvoir diminuer les températures de synthèse d’environ 100° typiquement. Il a ainsi été possible de faire croître des nanostructures hiérarchiques formées de nanoparois en boule, des nanoparois d’épaisseurs variables, des nanofils et des nanoplots de CuO. Ces différentes nanostructures se forment à des instants successifs et se répartissent radialement par rapport au centre de l’impact de la post-décharge. Elles croissent en suivant des cinétiques paraboliques qui traduisent une limitation par un transport diffusionnel. La diffusion est externe et conduit la formation de porosités Kirkendall à l’interface substrat-cuivre. Les analyses TEM ne montrent pas d’orientation privilégiée. Les nanofils sont soit mono- soit bi-cristallins. Des contraintes de compression (respectivement de tension) ont été mesurées dans Cu2O (respectivement dans CuO). La taille de grain est plus élevée au centre que sur les bords du traitement. Cela permet la croissance de nanoparois et de nanofils de diamètres relativement importants près du centre alors qu’une taille de grains plus petites sur les extérieurs entraîne la formation de nanofils plus fins mais avec une densité surfacique supérieure. Les différents modèles de croissance existant ont été repris pour interpréter ces nouveaux résultats / Oxidation of copper thin films deposited by magnetron sputtering on silicon and soda-lime glass substrates was performed by means of a microwave micro-afterglow to grow locally controlled nanostructures of copper oxide. The use of plasma discharges offers the possibility to handle oxygen atoms instead of oxygen molecules, which enable a substantial decrease in the synthesis temperature of about 100° typically. It was thus possible to grow hierarchical nanostructures made of nanowalls shaped in balls, nanowall with variable thicknesses, nanowires and nanodots of CuO. These different nanostructures forms successively and are distributed radially from the impact center of the post-discharge outwards. They grow by following parabolic growth rates that are due to a diffusion transport limitation. Outward diffusion occurs and creates a Kirkendall porosity at the substrate-copper interface. TEM analyses do not show any preferential orientation. Nanowires are either mono- or bi-cristals. Compressive (respectively tensile) stress was measured in Cu2O (respectively CuO). The grain size is larger in the center than on the edges of the treatment area. This enables the growth of nanowalls and nanowires with diameters pretty large close to the center whereas a smaller grain size on the edges leads to the formation of thinner nanowires but with higher surface density. The different existing growth models were considered to interpret these new results.