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Showing 1 to 20 of 90 for “"oxygen vacancies"”.
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Oxygen ion conduction in layered intergrowth structures with intrinsic oxygen vacancies
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1994.
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Influence of oxygen vacancies on oxygenate reactions over SnO₂(110) single crystal surfaces
… Two crystallographically inequivalent types of oxygen vacancies can be introduced onto SnO0₂ (110) surfaces, and the kinetics of the reactions of Brønsted acids is influenced by the number and type of oxygen vacancies present on each surface. The site requirement for dissociation of Brønsted …
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Urea Pre-treatment of N2-annealed Transition Metal Oxides for Low Cost and Efficient Counter Electrodes in Dye-sensitized Solar Cell
… alternative material to Pt. The introduction of oxygen vacancies inside metal oxides helps to facilitate electron transport to the electrolyte to enhance the reduction process of triiodide ions. Annealing n-type metal oxides under a reducing agent gas such as hydrogen (H2) at temperature ≥400 oC …
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Colloidal Cerium Oxide Nanoparticle: Synthesis and Characterization Techniques
… composition, CeO2-γ, due to the presence of oxygen vacancies and the formation of Ce2O3 at the grain boundaries. The Ce(III) ions, which are more reactive and therefore more desirable for various applications, are created by oxygen vacancies, which act as defects in the CeO2-γ crystal …
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Surface Structure/Property Relationship for (001) Surface of Magnetite
… methods. Conventional processed surfaces in an oxygen-rich environment are found to be oxygen deficient, with a significant amount of ordered oxygen vacancies on the surface and even penetrate deep into the bulk. The more stoichiometric surface is then obtained by ozone treatment, which …
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Nanopartículas de ouro suportadas em óxidos mistos de cério e ferro para a redução de NO por CO
… size and increased the concentration of oxygen vacancies. Consequently, doping had effect on the performance of the catalysts in the redox reaction between NO and CO. As the Ce0,8Fe0,2O2-δ solid solution showed the most interesting properties, it was choosen for the deposition of gold …
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Steam Electrolysis Coupled with CO2 Conversion in a Pressurized Proton Conducting Solid Oxide Electrolysis Cell
… iron oxides and conducting substrates with oxygen vacancies, and the degradation of proton conducting perovskites in the presence of CO2. Ceramic supports containing oxygen vacancies as extrinsic defects (such as proton conducting perovskites) promote the reduction of iron oxide with …
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Adsorption of water and carbon monoxide on Cu₂O(111) single crystal surfaces
… were studied over the stoichiometric and the oxygen-deficient Cu₂O(111) surfaces, using thermal desorption spectroscopy (TDS), ultraviolet photoelectron spectroscopy (UPS), and X-ray photoelectron spectroscopy (XPS). Water is the only desorbing species detected in TDS and the extent of …
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Atomic scale diffusion in complex systems from first principles
… Be, Al and Ni in HCP Zr, and the transport of oxygen vacancies in LaGaO$_3$. Zirconium alloys are used as nuclear fuel cladding materials for light water power reactors and understanding point defect diffusion in Zr will provide a step forward for developing oxidation tolerant alloys. We …
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Synthesis and characterization of cobalt-containing perovskite-type oxides
… (10% H2/N2, up to 1000 ºC) with the formation of oxygen deficient compounds, while no evidence for oxygen hyperstoichiometry was observed under oxidizing conditions. Materials such La1.2Sr0.8Co0.5Mn0.5O4.1 and La1.7Sr0.3Co0.5Ni0.5O4.08, however, exhibit oxygen hyperstoichiometry under oxidizing …
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Correlation of Photocatalytic Activity with Band Structure of Low-dimensional Semiconductor Nanostructures
… were studied.;First, we studied the effect of oxygen vacancies on the photocatalytic activity of one-dimensional anatase TiO2 nanobelts. Given that the oxygen vacancy plays a significant role in band structure and photocatalytic performance of semiconductors, oxygen vacancies were introduced …
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Growth Study and Characterization of TiO2 Based Thin Films for Low Temperature Synthesis of Transparent Conductive Films
… phase with respect to rutile and with the oxygen vacancies in the films. The approach adopted in this work for the generation of oxygen vacancies could be useful for other oxide-based films, where the oxygen vacancies-dependent properties are crucial, for room temperature ferromagnetism and …
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Controlling and understanding electro-chemo-mechanical properties of layered cuprate thin films
… explored as model systems to understand oxygen surface exchange kinetics for solid oxide fuel cell (SOFC) electrodes. Traditionally, transport properties are examined as functions of type and concentration of aliovalent cations, requiring multiple samples, resulting in changes in multiple …
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Structural and magnetotransport study of SrTiO3-δ/Si structures grown by molecular beam epitaxy
… substrates using molecular beam epitaxy (MBE). Oxygen vacancies were introduced by controlling the Oxygen Pressure (PO2) that varied from 10-8 to 10-7 torr during growth, resulting in SrTiO3-δ with δ ~ 0.02% for the lowest pressure. The single phase STO/Si films were of high crystalline quality …
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Cation Site Occupancy and Defect Engineering in Perovskite Heterostructures
… thin films. This thesis assesses how cation and oxygen stoichiometry and growth dynamics can control the material properties of single- and multi-phase perovskite oxide thin films. We start with the generation of ferroelectricity in an antiferromagnet LuFeO₃ through cation antisite defects and …
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Magnetic and Transport Properties of Oxide Thin Films
… annealing, which is explained by the increased oxygen vacancies/defects due to the H2 treatment of the films. The ferromagnetism may be associated with the presence of oxygen vacancies although AMR was not observed in the samples. Pure HfO2 and Gd-doped HfO2 thin films have been grown on …
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The effects of spatial confinement and oxygen stoichiometry on complex metal oxides
… and understand the spatial confinement and oxygen stoichiometry effect on complex metal oxides to pave the way for oxide electronics. To achieve this goal, I first investigate the properties of the La2/3Sr1/3MnO3 (LSMO) thin films of different thicknesses with different oxygen deficient …
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Visible Light Photocatalytic MoO3-Based Nanomaterials Synthesis, the Effect of Polymer Coatings on Their Photocatalytic Activity and Dissolution, and Their Applications in Water Treatment
… decontamination as they can generate reactive oxygen species (ROS) that degrade pollutants. MoO3 is an environmentally friendly, low-cost, visible light photocatalyst that has gained much popularity in research due to its effectiveness. Furthermore, MoO3 morphology and surface chemistry are …
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Bismuth Oxyhalide Nanosheets with Adjustable Band Edge Potentials for Photocatalytic Ammonia Generation
… band edge potentials, and abundant surface oxygen vacancies to activate nitrogen molecules. In the third chapter, we fabricated ultrathin BiOI nanosheets by a surfactant-assisted hydrothermal method. Unlike bulk BiOI, ultrathin nanosheets were active for water splitting and nitrogen …
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Defects and alloying in semiconductors: computational studies of clusters and surfaces
… of metal-oxide surfaces. Defects such as oxygen vacancies are always present on rutile surfaces and, depending on their coverage and spatial distribution, can strongly influence the reactivity of the surface. The interactions between vacancies determine their spatial distribution on the …
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