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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 20 of 48 for “"Crystal orientation"”.
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Insights into magmatic processes from the crystal orientation mapping of igneous microstructures
The crystallisation of magma to form solid rock involves many complex physical and chemical processes that remain poorly understood. Mapping crystallographic orientations using electron backscatter diffraction (EBSD) has revolutionised the study of deformed rocks, and is now emerging as a useful …
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Multiscale In-Situ Characterization of Crystal Orientation, Temperature, and Microstructure Effects on Creep Defromation of Pure Magnesium and Mg-Al-RE Alloys
… elevated temperatures. This thesis examines how crystal orientation, temperature, and β-phase morphology govern creep behavior in pure Mg and AE44 alloys. Novel in-situ nanoindentation creep methods were developed using an indenter inside a SEM. Additional techniques included in-situ tensile …
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Multiphysics Modelling on the Effects of Composition and Microstructure during Tribocorrosion of Aluminum-based Metals and Structures
… layer thickness (from 10 to 100 nm) and layer orientation (horizontally and vertically aligned) on the tribocorrosion behavior of Al/Cu NMMs was studied. Both factors were found to affect the subsurface stress and plastic strain distribution and localized surface corrosion kinetics, hence …
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Mechanism of remote epitaxy using two dimensional materials
… conventional epitaxy of covalent or ionic single crystal substrates. With the rise of two-dimensional (2D) materials since the isolation of graphene in 2004, vdWE has been attempted on 2D materials, transferred, or grown on substrates. However, there has been the notion that the 2D material is the …
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Processing and Optical Uses of Van der Waals Layered Materials
… Wefirst study processing of large-area polycrystalline MoS₂ and TiS₂ film for photonics and microelectronics, which mainly focus on lowering processing temperature by controlling oxygen concentration. We identify opposite roles of oxygen during the sulfurization process as a reaction …
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Characterising the deformation behaviour of human tooth enamel at the microscale
… evolution (i.e., the rotation of mineral crystals) of enamel. The effective crystal orientation angle was found to be between 44o and 48o for indentation depths from 0.8 and 2.4 μm below according to the analytical model. The range of angles facilitated the shear sliding of mineral …
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A variable capacitor made from single crystal silicon fracture surface pairs
Complementary and nano-smooth single-crystal-silicon surfaces have been fabricated by deliberately fracturing a weakened portion of a larger structure whose flexural mechanism refines and concentrates an externally applied load to a notched specimen region pre-.fracture and acts as a precision …
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Electron paramagnetic resonance studies of molecular orientation and nuclear exchange in single crystals of morphine N-oxide.
… nitroxide generated photolytically in a single crystal of N-nitromorpholine are complicated by the presence of two magnetically distinct orientations of the N-0 bond within the crystal. As the temperature is raised, the spectra are further complicated by motional effects. Since at -150° the …
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Study of tunneling impurities in alkali halides at low temperatures
… dependent and anisotropic with respect to crystal orientation, probably because of interactions between Li+ sites. All measurements were for Li+ concentrations < 200 ppm. The KBr:CN system has been studied for CN-concentrations ranging from 0.034% to 50%. At the lowest concentration, the …
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Magnetic resonance imaging via radio frequency gradient with examples from NMR and pure NQR
… the principle axis system is defined by the crystal orientation rather than an external field. The RF field breaks this symmetry and introduces another level of complexity to the spin dynamics.
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Quantitative analysis of crystal lattice and defects in nanoscale functional materials by electron diffraction
Crystalline defects are critical to the properties of the material in both desired and undesired ways. In nanoscale functional materials, a small number of defects can change the material performance significantly. Transmission electron microscopy (TEM) has been one of best techniques to study …
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n-type silicon-germanium based terahertz quantum cascade lasers
… taking into account the effects of strain and crystal orientation. Scattering models for Coulombic interactions, structural imperfections and interactions with phonons (lattice vibrations) are developed and used to predict the electron distribution, current density and gain in a range of device …
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Metal-assisted chemical etching of III-V semiconductors for advanced optoelectronic device fabrication
… of InGaAsP in H2SO4 and H2O2 is dependent on the crystal orientation and material of the metal catalyst, as well as the stoichiometric composition of InGaAsP. The textured GaAs photodiodes, with GQDs self‐embedded in the monolithically integrated transparent graphene electrode, demonstrate a …
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Metal-assisted chemical etching of β-gallium oxide
… surface quality, are demonstrated. The strongly crystal-orientation-dependent etching behaviors are found and three kinds of vertical structures are formed after the MacEtch process. The Schottky barrier heights (SBHs) between platinum (Pt) and different MacEtch-formed β-Ga2O3 surfaces and …
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Effects of Thickness and Indenter Tip Geometry in Nanoindentation of Nickel Films
… performed on these materials to determine the crystal orientation, grain size of the material, and also to measure any substrate effects like pile-up or sin-in respectively. The results indicate that indentation size effect (ISE) strongly depends on shape of the indenter and less sensitive to …
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Three-dimensional nanostructure determination based on scanning electron nanodiffraction
Nanocrystalline materials in general feature a large density of surfaces, interphase and grain boundaries, and a large surface/volume ratio, which have attracted tremendous interest for their unique mechanical, chemical and electronic properties. For example, nanocrystalline metals and alloys …
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Strain-induced self-rolled-up semiconductor micro/nanotubes: Fabrication and characterization
… (3D) structures are determined by the crystal orientation of the defined mesa patterns, and they can be formed as 3D tubular structures, helices, or just curved structure. The tube wall consists of compound semiconductor materials such as GaAs, AlxGa1-xAs, and InxGa1-xAs and therefore …
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Interfacial Magnetism and Exchange Bias in Metal Oxide Thin Films
… by means of strain, ion implantation, and crystal orientation. Four thin film systems are included: MnxOy/Ni80Fe20, La0.7Ca0.3MnO3/CaMnO3, La0.7Ca0.3MnO3 and BiFeO3/SrRuO3. Oxygen ion implantation was performed on MnxOy/Ni80Fe20 bilayers, and the results show an enhancement of exchange bias …
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Electronic device fabrication and characterization based on two-dimensional materials
… and high-speed photodetectors. In addition, the crystal orientation and electronic transport in germanium selenide (GeSe) are also studied. The crystallographic direction of the GeSe is determined by angle-resolved polarized Raman measurement. The anisotropic electronic transport of the GeSe is …
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Aluminium nitride (AlN) as buffer layer for deposition of gallium nitride (GaN) thin films on silicon substrates using magnetron sputtering technique
… diodes (UV-LEDs) are difficult to achieve highly crystalline GaN because lack of suitable substrates available and needed for high-temperature deposition process. Hence, the present research is focused on the enhancement of AlN as a buffer layer for the deposition of GaN thin films on Si substrate …
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