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Showing 1 to 20 of 35 for “"Defect chemistry"”.
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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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Defect chemistry and electrical properties of ruthenium- and bismuth-substituted gadolinium titanate pyrochlore
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995.
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Mixed conduction and defect chemistry of manganese and molybdenum substituted gadolinium titanate pyrochlore
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1999.
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Grain boundary defect chemistry and electrostatic potential in acceptor- and donor-doped titanium dioxide
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1992.
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Defect chemistry, transport properties and thermodynamic stability of acceptor doped and undeoped layered La 2 NiO 4
… according to theoretical calculations on point defect formation and migration. The phasal composition of the ceramic powder prepared by a modified Pechini process, was analysed by X-ray diffraction. The prepared disc-shape membranes was analised by SEMM and EDX. Oxygen permeation measurements in …
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The effect of Niobium on the defect chemistry and corrosion kinetics of tetragonal ZrO₂ : a density functional theory study
… 48, 201. Even the charge state of Nb as a defect in zirconia is debated. Experimental findings of Froideval et al [5] indicate charge state between +2 and +4 whereas other authors assume it to be +5 [21, 31, 34]. In order to uncover the role of Nb on the local oxide protectiveness we …
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Electro-chemo-mechanical Studies of Perovskite-Structured Mixed Ionic-Electronic Conducting SrSni-₁₋xFexO₃₋x/₂₊[epsilon]
… density in STF, which in turn depends on its defect chemistry and band structure. In this work, an alternate B site host cation, Sn, was selected to replicate and extend the STF studies, due to its distinct band structure and higher electron mobility. Oxygen nonstoichiometry and the defect …
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Chemomechanics of non-stoichiometric oxide films for energy conversion
… that contain large concentrations of point defects such as oxygen or lithium vacancies. While this non-stoichiometry provides the essential functional properties of ionic conductivity or reactivity that make these materials useful, it also tends to couple to material volume through the …
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Engineering Functional Defects in Oxides Using External Stimuli
… often depend strongly on the functional defects of various dimensionalities, such as vacancies, interfaces, and precipitates. Therefore, defect engineering lies at the heart of materials innovations for the next-generation technologies. However, due to the enormous span in the length …
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Oxygen Transport in Vapor-Deposited Tin-Doped Indium Oxide Films (Diffusion, Electrochemical)
… transport data to a diffusion model based on the defect chemistry of In(,2)O(,3); however, the evidence suggests that oxygen transport through these cells is controlled by the film-electrolyte interface. Low temperature electronic properties of the films were measured using the van der Pauw …
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Defect and electrical properties of high-K̳ dielectric Gd₂O₃ for magneto-ionic and memristive memory devices
… we focused our investigation on the defect chemistry and electrical properties of Gd₂O₃ in order to better understand the relationship between the structure, chemistry, processing conditions, and operating environment and the material's low-temperature ionic and electronic transport …
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FLUORESCENT ULTRASHORT NANOTUBES FROM DEFECT-INDUCED CHEMICAL CUTTING
… based on a fundamental new understanding of defect-induced chemical cutting of SWCNTs. The method includes implanting fluorescent quantum defects onto the carbon nanotubes, and then cutting the nanotubes preferentially from the defect sites. Firstly, I demonstrate that this simple two-step …
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Surface-mediated mechanisms for defect engineering in zinc oxide
… depends upon the types and concentrations of the defects it contains. In semiconducting metal oxides like zinc oxide, the concentration and diffusion of oxygen point defects, like interstitials and vacancies, play a central role in various physical phenomena, such as gas sensing, bipolar …
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External field effects on electronic and ionic defects in functional oxides: Experiments and simulations
… of external stimuli on electronic and ionic defects in functional oxides is the key to design next generation energy conversion/storage and memory devices. Mechanical strain and high electric fields are known to commonly exist in thin film functional oxides and significantly affect the …
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Langasite bulk acoustic wave resonant sensor for high temperature applications
(cont.) The self consistent defect model established the defect chemistry of langasite, enabling important parameters describing reduction (Er = 5.70± -0.06eV and 6.57±-0.24eV for acceptor and donor doped langasite respectively) and oxidation (Eo = 2.18±0.08eV), intrinsic electron-hole generation …
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Development of manganese oxide based nanostructures by wet chemical methods for enhanced energy storage and photocatalytic applications
Owing to wide diversity of crystal forms, defect chemistry, morphology, porosity and textures, manganese oxides exhibit a variety of distinct electrochemical and dye degradation applications. This work mainly comprised of development of manganese oxide nanostructures via wet chemical approaches …
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Ceramic dielectrics for high energy density capacity application
… parameters, microstructural development, defect chemistry and electrical properties of titanium oxide (TiO₂) dielectrics for high energy density capacitor applications. The effects of aliovalent dopants on the dielectric properties of TiO₂ ceramics were investigated, aiming to further …
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Electrical properties and defect structures of praseodymium-cerium oxide solid solutions
A defect chemistry model consistent with observed trends in the pO2 and temperature dependence of electrical conductivity in praseodymium cerium oxide (PCO) was developed. Four point DC conductivity measurements were made from 1 atm to 1018 atm p02 over isotherms ranging from 600-1 000Ê»C in …
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Impact of Structure and Defect Modification on Vanadium Oxide for Alkali-ion Battery Electrodes
… has seen gains in performance based on materials chemistry over the past several decades. Despite years of intensive research accompanied with significant progress, the cathode remains a limiting factor towards improved battery performance because of its low capacity and exasperated degradation …
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