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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 13 of 13 for “"oxygen stoichiometry"”.
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The effects of spatial confinement and oxygen stoichiometry on complex metal oxides
… Novel phenomena emerge by spatial confinement. Stoichiometry can have more profound effect on spatially confined materials than on the bulk. The purpose of the thesis is to explore and understand the spatial confinement and oxygen stoichiometry effect on complex metal oxides to pave the way for …
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A study of oxide superconductors by electron energy loss spectroscopy in STEM.
… the superconducting properties are a function of oxygen stoichiometry. In the case where 8=0 the material is a superconductor, and when O=l an antiferromagnetic insulator. In the production of bulk superconductors the oxygen anneal is therefore important in determining the properties of the …
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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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Study of colossal magnetoresistance and pressure effects in La2/3Ca1/3MnO2 thin films /
… spin-dependent scattering of DE electrons. Oxygen stoichiometry plays an important role in the magnitude and position of MR(T) maximum. The distortions of structure and Mn-O-Mn bonds in applied pressure axe discussed. The fabrication of La2/3Cai/3Mn03 thin films by pulsed laser deposition …
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Electrical and structural properties of compositions in the systems Y₁₋ₓCaₓMnO₃ and La₁₋ₓCaₓMnO₃
… studied as functions of temperature and ambient oxygen activity in order to determine the mechanism of electrical transport and defect structure. Thermal expansion was also measured. Electrical conduction appeared to occur via a small polaron hopping mechanism for compositions with 0.30 ≤ x ≤ …
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Oxygen-17 nuclear magnetic resonance studies of high-temperature superconductors
… Measurements of the angular dependence of the oxygen frequency shifts and corresponding satellite transitions have enabled us to assign the oxygen sites of magnetically oriented YBa$\sb2$Cu$\sb3$O$\sb{\rm 7-x}$, as well as determine the e.f.g. parameters for various sites. The temperature and …
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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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Voltage programmable materials
… and magnetism all depend sensitively on oxygen stoichiometry and defect structure at the metal/metal-oxide interface. The possibility to dynamically control interface characteristics through electric-field-induced oxygen transport and electrochemical interface reactions paves the way …
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A thermogravimetric study of oxygen diffusion in YBa2Cu3O7-d
… properties are strongly dependent on oxygen stoichiometry. A large amount of work has been done on the variation of stoichiometry and its effect on the superconducting properties of the material. However, in spite of all the work done, the results published in the literature are very …
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A Schottky-to-Ohmic Transition in Epitaxial Ferroelectric Hafnia Devices
… industrial compatibility. Both the migration of oxygen ions and ferroelectricity are two mechanisms actively being explored to drive resistance change in hafnia based devices. This thesis explores the interplay between interfacial redox chemistry and ferroelectricity and how these influence the …
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Interactions between catalysts and oxygen carriers in chemical looping processes
… system. In chemical looping processes, lattice oxygen is provided from a metal oxide (termed the oxygen carrier) to generate purified oxygen, or, to react with a reducing gas (e.g. a hydrocarbon) to form oxygenated products, in the absence of gaseous oxygen. The oxygen carrier is then …
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Electro-Optic And Magneto-Dielectric Properties Of Multifunctional Nitride And Oxide Materials
… highly degenerate n-type behaviour due to oxygen defects introduced during growth. The effect of oxygen in InN matrix has been further investigated by intentionally adding oxygen into the films. These studies confirm that oxygen is one of the main sources of donor electrons in degenerate …
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Complex oxides of the system Cu-Ni-Fe-O: synthesis parameters, phase formation and properties
… and the preparation conditions (temperature, oxygen partial presssure) which lead to the formation of single phase materials within the quaternary system Cu-Ni-Fe-O. The investigated compositions are the solid solutions CuxNi1-xFe2O4, the ferrites occurring in the phase triangle …