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 20 of 80 for “"Disordering"”.
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Disordering kinetics in orthopyroxenes
Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences.
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Dipole Ordering or Disordering in Selected Perovskite Ferroelectric Systems
The microstructural and electrical properties of several compositions of BSZT bulk ceramics were studied. The ceramics were found to be single phase cubic perovskites at room temperature. The substitution of zirconium for titanium in Ba0.7Sr0.3TiO3 in bulk ceramic form increases the disorder in the …
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DISORDERING IN PYROCHLORE PHASES FOR RADIONUCLIDES DISPOSAL: A MULTISCALE STRUCTURE STUDY
Oxides with the general formula A2B2O7 and the pyrochlore structure have drawn much attention in the field of radionuclides immobilization. The Gd2Zr2O7 composition, in particular, has demonstrated high radiation resistance, making it an ideal host-matrix for encapsulating radioactive elements …
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Disordering of small metal particles in a scanning transmission electron microscope
… seen to fully disorder. We have observed this disordering in Platinum, Palladium, Rhodium, and Iridium and have developed a model for the disordering process. In this model, electrons scattering from surface atoms transfer enough energy to break the surface atoms from their binding site. A …
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Characteristics of semiconductor optical waveguides fabricated by impurity-induced layer disordering
Impurity induced layer disorder-delineated buried channel optical waveguide non-rectilinear routing structures are found to have loss properties equal to or better than other planar optical waveguides. With 3 dB loss angles of 3$\sp\circ$, for simple abrupt bends, and 7$\sp\circ$, for modified …
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Disordering Capital: The Politics of Business in the Business of Water Provision
This dissertation consists of three articles that together seek to deconstruct, or disorder, monolithic treatments of “private sector” participation in the delivery of urban water and sanitation services. The studies interrogate how variation in forms of business ownership and politics not only …
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Non-Equilibrium Disordering Processes In binary Systems Due to an Active Agent
In this thesis, we study the kinetic disordering of systems interacting with an agent or a walker. Our studies divide naturally into two classes: for the first, the dynamics of the walker conserves the total magnetization of the system, for the second, it does not. These distinct dynamics are …
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High-power single-mode vertical-cavity surface-emitting lasers via impurity induced disordering
Design principles of impurity-induced disordered (IID) vertical-cavity surface-emitting lasers (VCSELs) are presented, including the influence of IID on electrical, optical, and mode-control properties. A transfer matrix method (TMM) is developed to account for the diffusion of Group III atoms of …
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Characterization of S-bend optical waveguides fabricated by impurity- and vacancy-induced layer disordering
… and In/SiO$\sb2$ Impurity-Induced Layer Disordering (IILD) of a single GaAs quantum-well graded barrier laser structure are investigated using raised-cosine S-bend geometries. The 3-dB transition length for a 100 $\mu$m offset S-bend waveguides fabricated using the Zn, SiO$\sb2$, or …
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Atom diffusion and impurity-induced layer disordering in quantum well III-V semiconductor heterostructures
The process of impurity-induced layer disordering (IILD), or layer intermixing, in Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As-GaAs quantum-well heterostructures (QWHs) and superlattices (SLs), and in related III-V quantum well heterostructures, has developed extensively. A large variety of experimental data …
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Layer disordering and aluminum-gallium interchange in aluminum-gallium arsenide - gallium-arsenide quantum well heterostructures
In the experiments described here, Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As-GaAs superlattice and quantum well heterostructure (QWH) crystals have been used as test vehicles to study Al-Ga interdiffusion. The data demonstrate that Al-Ga interchange is strongly influenced by the interdependence of the …
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Strain-controlled impurity-induced disordering for apertures in single-mode vertical-cavity surface-emitting lasers
… the initiation of Zn diffusion, impurity-induced disordering (IID) has been demonstrated to enable optical mode control, increased modulation frequencies, and provide carrier and photon confinement in vertical-cavity surface-emitting lasers. While disordering provides a wafer-scale method of …
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Co-Authoring Beyond the Human: Disordering Architectural Processes through Play and Multi-Agent Co-Existence
This thesis reconsiders architectural authorship and the extended processes through which the built environment is shaped, using a series of playful, participatory interventions to expose the human-centric assumptions embedded in spatial decision-making. Presented as a collection of games and …
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Disordering the Land: Visual and Material Strategies of Creating Futurity and the Otherwise in Contemporary Caribbean Art
“Disordering the Land: Visual and Material Strategies of Creating Futurity and the Otherwise in Contemporary Caribbean Art” seeks to destabilize static meanings and complicate conventional academic sources, thus shifting away from the over-reliance on traditional archives and toward expansive …
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Impurity-induced disordering of vertical-cavity surface-emitting lasers: Applications to polarization control and high-speed modulation
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-11-11 without embargo terms
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Impurity-induced layer disordering and hydrogenation in the indium aluminum gallium phosphide material system: Visible spectrum semiconductor lasers
The development of visible-spectrum semiconductor lasers is of immense economic and practical importance. Because of the extremely high efficiency of semiconductor lasers, coherent visible light sources can be made with extremely low power requirements. Applications for such sources include …
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Impurity-induced layer disordering of quantum well heterostructures by silicon diffusion from aluminum-reduced silicon dioxide and silicon nitride
In these experiments, impurity-induced layer disordering (IILD) utilizing the chemical reduction of SiO$\sb2$ by Al (from high-percentage Al$\sb{\rm x}$Ga$\sb{\rm 1-x}$As) is employed to produce Si and O to effect layer disordering. This diffusion process is examined using secondary ion mass …
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Disorder and nanopatterning in ordered binary alloys: in situ ion irradiation and kinetic Monte Carlo simulation
We study the effects of temperature and disordering rate on the ordered microstructures of real and simulated binary alloys. The behavior of Cu3Au, an alloy with L12 chemical order, is investigated experimentally through in situ electron diffraction and dark-field transmission electron microscopy. …
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Donor-Induced Layer Disordering via Silicon Diffusion in Aluminum-Gallium Arsenide - Gallium-Arsenide Quantum-Well Heterostructures, and Disorder-Defined Index-Guided Stripe Geometry Laserdiodes
The use of Si diffusion to disorder Al(,x)Ga(,1-x)As-GaAs quantum-well heterostructures (QWHs) and quantum-well (QW) p-n junction lasers is described. Under the proper diffusion conditions Si produces n-type conductivity in Al(,x)Ga(,1-x)As layers, and will counterdope (to n-type) initially p-type …
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Wavelength Modification by Thermal Annealing and Stripe Geometry Definition by Impurity-Induced Disordering in Quantum-Well Laser Diodes (Diffusion, Gallium-Arsenide, Iii-v Semiconductors)
The effects of thermal annealing ((TURN)900(DEGREES)C) on quantum-well laser diode properties are investigated. The shift to higher energies caused by inter-diffusion of Al and Ga at the quantum-well interfaces in modeled by a modified Poschl-Teller potential. The interdiffusion coefficient …
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