Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 14 of 14 for “"oxygen defects"”.
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Synthesis, characterization and catalytic testing of metal tungstates as catalysts for activation of lower alkanes
… stabilizes a defect-rich MnOx surface phase. Oxygen defects can be reversibly replenished and depleted at the reaction temperature. Terminating MnOx zigzag chains on the (010) crystal planes are supposed to bear structurally site-isolated oxygen defects that account for the unexpectedly good …
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Controlling properties of functional oxides by tuning oxygen defect chemistry
Oxygen defects are essential building blocks for properties and functionalities of oxides, including electrical conductivity, magnetism, ferroelectricity as well as catalytic and electrocatalytic activity. Therefore, fundamental understanding of how to tune the oxygen defect chemistry is essential …
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Anti-inflammatory Effects and Biodistribution of Cerium Oxide Nanoparticles
… antioxidants. Their redox nature is due to oxygen defects in the lattice structure, which are more abundant at the nanoscale. Reactive oxygen species (ROS) are pro-oxidants whose presence is increased during periods of inflammation in the body. ROS damage tissues and cellular function by …
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Oxygen defect engineering for silicon solar cell applications : process design and modeling
… lowers efficiencies of silicon solar cells are oxygen ring defects that are incorporated into the material during growth. These defects decrease overall cell efficiencies by around 20% (rel.) resulting in a yield loss of about 1/4 h of each monocrystalline silicon ingot. To control the oxygen …
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Metal-insulator transition in yttrium- and neodymium-doped lanthanum nickelates
… regarding the effect on superconductivity of oxygen defects (vacancies and interstitials, e.g., apical) and of strain (due to cation substitutions and substrate-film mismatch). The study also re-prompted the search for SC in the bulk material. The parent RNiO₃ bulk compounds are known to have …
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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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Investigations into b-o defect formation-dissociation in cz-silicon and their effect on solar cell performance
… degrades due to the formation of metastable defects when excess electrons are created by illumination or minority carrier injection during forward bias. The recombination path can be removed by annealing the cell at about 200 C but recombination returns on exposure to light. Several …
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A first principles investigation of transitional metal doping in lithium battery cathode materials
… shows a continuous, gradual slope. The effect of oxygen defects in the Li(Al,Co)O2 system was investigated. A model for the effect of oxygen vacancies on the free energy of doped layered oxides was created by combining an ideal gas approximation and first-principles energy defect calculations. The …
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Electronic structure of perovskite oxide surfaces at elevated temperatures and its correlation with oxygen reduction reactivity
… is to understand the origin of the local oxygen reduction reaction (ORR) activity on the basis of the local electronic structure at the surface of transition metal oxides at elevated temperatures and in oxygen gas. This goal presents a key challenge to traditional surface science …
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Predicting the equilibria of point defects in zirconium oxide : a route to understand the corrosion and hydrogen pickup of zirconium alloys
… processes are governed by the behavior of point defects in the ZrO₂ layer that grows natively on these alloys. In this thesis, we developed a general, broadly applicable framework to predict the equilibria of point defects in a metal oxide. The framework is informed by density functional theory …
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The two-dimensional vibrating reed technique: a study of anisotropic pinning in high-temperature superconductors
… displacement of the vortices from the point-like oxygen defects, which act as pinning centers. The pinning force leads to additional restoring force which causes a typical magnetic field dependence of the resonance frequency. Such an experimental configuration has never been used before and gives …
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Surface-mediated mechanisms for defect engineering in metal oxides
… and spatial distributions of solid point defects such as vacancies and interstitial atoms influence the performance of metal oxides in gas sensing, electronics, photonics and solar-induced photochemistry for fuel production and environmental cleanup. Controlling these aspects of defect …
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Electro-Optic And Magneto-Dielectric Properties Of Multifunctional Nitride And Oxide Materials
… to understand the effects of intrinsic defects on the materials properties while considering possible applications of highly degenerate InN thin films. As grown rf sputtered InN films on c-axis (0001) sapphire exhibit highly degenerate n-type behaviour due to oxygen defects introduced …
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Surface chemistry to control bulk reaction dynamics of native point defects in rutile titanium dioxide
… spatial distribution of the point and extended defects it contains. For ceramic oxide semiconductor materials, the concentration and diffusion of cations and anions, in the form of interstitials and vacancies, plays a large role in the performance of these materials for gas sensing, …