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 16 of 16 for “"lattice distortions"”.
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The effect of applied uniaxial stresses on the optical absorption of F centers in alkali halides
… the coupling of the F center excited state to lattice distortions of tetragonal and trigonal symmetry is evaluated. By measuring the third moment change due to the same ~pplied stresses, the separate contributions to the second moment of the F band of dynamic lattice distortions of tetragonal, …
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Superconductivity of a Precipitation Hardening Alloy of Aluminum
… of this study was to determine the effect of the lattice distortions produced by the precipitating particles on the superconducting behavior of the aluminum.
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Generic Influences of Charged Defects on the Structure-Property Relationships of Modified Ferroelectric Barium Titanate and Antiferroelectric Sodium Niobate
… neglected the elastic effects associated with lattice distortions. Simulations demonstrated a general distribution pattern for charged defects. With increasing substituent concentration, more and larger defect clusters formed, which might be related with the formation of polar nanodomains in …
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Einfluß der magnetischen Ordnung auf Supraleitung und Kristallstruktur in Seltenerd-Nickel-Borkarbid-Verbindungen
… neutron diffraction, tetragonal-to-orthorhombic lattice distortions are found. They are induced by those magnetic structures with either parallel or anti-parallel alignement of R3+ magnetic moments. The direction of the lattice distortions, the dependence of their size on the square of the …
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Quantum Electronic Effects in Ultrathin Metal Films on Semiconductors
… are investigated in detail: the structural distortions that arise due to quantum confinement of a metal's itinerant electrons to an ultrathin film and variations in the surface energy (relative stability) of such films as a function of thickness. These effects are first examined from a …
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Theory of lattice effects on magnetic interactions in solids
… dissertation focuses on studying the effect of lattice distortions on the magnetic properties of nickelates and manganites. These two families of materials have great potential in industrial applications in the fields of magnetic (superdense hard-drives, fast memory) and charge storage …
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Theory of phase transitions in liquid crystals and plastic crystals
… are positioned on a two dimensional hexagonal lattice; and the smectlc H phase which has both rotational and hexagonal translational order. By considering both the intermolecular dipole-dipole and intermolecular phenyl or benzene group interactions the properties of the phases with two …
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Molecular Dynamics and X-ray Powder Diffraction Simulations: Investigation of nano-polycrystalline microstructure at the atomic scale coupling local structure configurations and X-ray powder Diffraction techniques
… Molecular Dynamics (MD) were used to model the lattice distortions in metallic nano-polycrystalline microstructures, with the purpose of supporting the analysis of the X-ray powder diffraction patterns with a better, atomic level understanding of the studied system. Complex microstructures were …
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Electrochemical and Modelling Studies on Simulated Spent Nuclear Fuel Corrosion under Permanent Waste Disposal Conditions
… can be attributed to the onset of tetragonal lattice distortions as oxidation proceeds which leads to the clustering of defects, enhanced diffusion of OI (interstitial oxygen)to deeper locations and destabilization of the fluorite lattice. A further investigation of the doping effect was …
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Topological Phases in Perovskite Iridates with Strong Spin-Orbit Coupling
… metals” with surface states protected by lattice symmetry and a pair of topological invariants. We show that these novel metallic phases can give rise to various non-trivial topological phases when different symmetries are broken, including a Weyl and nodal-line semimetal. Secondly, we …
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Investigating Chemical and Structural Heterogeneities of High-Voltage Spinel Cathode Material for Li-ion Batteries
… We develop a method to measure and relate lattice strain to phase distribution at the tens of nanometers scale. In Chapter 3, mapping lattice distortions of LNMO particles with varying global Mn oxidation states reveals inherent structural defects and distortion heterogeneities. In Chapter …
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Ultrafast photoinduced phase transitions in complex materials probed by time-resolved resonant soft x-ray diffraction
… of spins, charges, orbital occupation and by lattice distortions, which make these material attractive. Magnetite served as a prototype for functional TMOs showing a metal-to-insulator-transition (MIT) at T = 123 K. By probing the charge and orbital order as well as the structure after an …
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Ultrafast dynamics in quantum materials probed by time-and-momentum-resolved techniques
… of freedom, such as charge, spin, orbital, and lattice. To fully understand such strongly correlated systems, a suite of experimental techniques that respectively probes various degrees of freedom and simultaneously resolves multiple channels, including energy, momentum, time, and space, are …
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Probing interfacial electronic structure in quantum materials using stem cathodoluminescence spectral imaging
… four-dimensional electron microscopy for imaging lattice distortion and electron energy-loss spectroscopy (EELS), the STEM/CL setup enables the study of where and why emission is enhanced in a material down to precise nanoscale. Specifically, STEM/CL is co-registered for structure, composition, …
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Control of chiral optical and spin properties in low-dimensional perovskites
… exhibit broken inversion symmetry and intrinsic lattice distortions, which underpin their strong chiroptical responses. Chiral optical properties are explored, with emphasis on the coupling of circularly polarized photoluminescence and second harmonic generation (SHG). Chiral perovskites exhibit …