Thesis (Ph. D.)--Washington State University, May 2007. / Includes bibliographical references.

A 3D lattice model of three-component microemulsion employed previously to describe the equilibrium phase behavior has been extended to investigate the nonequilibrium dynamics of such system. The model is based on "Dynamical Monte Carlo" simulations which apply a coarse-grained velocity field onto a conventional Monte Carlo lattice, so as to represent realistically interactions between particles, and which permits the observation of time-dependent behavior. The results for viscosity are obtained by applying the velocity gradient onto the system. The simulations are performed over a range of shear rates and temperatures. Compared to the oil-rich (water-rich) phase, the microemulsion phase shows a typical (non-Newtonian) behavior and considerably lower viscosity at a given temperature. Both phases exhibit the characteristic viscosity decrease with an increase in temperature. The velocity auto-correlation function of a microemulsion phase is found to follow a Kohlrausch-Wiliams-Watts (KWW) stretched-exponential law, rather than a simple exponential decay. The stretched exponent is related to the normal, inhibited and enhanced diffusion behaviors of the system.

No description available.

This investigation is devoted to the study of the Fermi-Pasta-Ulam (FPU) lattice dynamics. Approximations of the FPU lattice dynamics have been an old subject, it is believed that the stability of the FPU traveling waves depends on the stability of the KDV solitary waves. The key question is: Are the traveling waves of the FPU lattice stable if the traveling waves of KDV type equation are stable?. We consider the FPU lattice with the nonlinear potential which leads to the generalized Korteweg-de Vries (gKDV) equation, which is known to have orbitally stable traveling waves in a subcritical case and orbitally unstable traveling waves in critical and supercritical cases. In order to pursue the question asked above, we use the energy method. We establish that the H^s(R) norm of the solution of the gKDV equation is bounded by a time-independent constant in the subcritical case, whereas the H^s(R) norm grows at most exponentially in the critical and supercritical cases. With the help of these results, we extend the time scale for the approximation of the traveling waves of the FPU lattice by the traveling waves of the gKDV equation logarithmically in the subcritical case. In the critical and supercritical cases, we extend the time scale by a double-logarithmic factor. Our results show that the traveling waves of the FPU lattice are stable if the solitary waves of the gKDV equation are stable in the subcritical case. On the other hand, in the critical and supercritical cases, our results are restricted to small-norm initial data, which exclude solitary waves. / Thesis / Master of Science (MSc)

<p> A study is made of the effects of pairing of defects on the dynamics of impure lattices, with the prospect of calculating the properties of crystals with a reasonably high concentration of impurities. A harmonic theory is used, with a mass-defect model, i.e. mass differences only are considered.</p> <p> Various parameters of lattice dynamics are studied, such as the atomic mean square displacement, by use of the Green's functions of Zubarev (1960), as evaluated by Bruno (1971).</p> <p> Finally, a calculation is made of the shifts and widths in the phonon spectrum of Copper due to the addition of 20% Gold impurities. The theory of Aiyer et al. (1969) is used, as corrected by Nickel and Krumhansl (1971), with a derivation along the lines of Langer (1961).</p> <p> It is shown that pairing effects are small and that the high-concentration calculation does not reproduce the experimental results of Svensson and Kamitakahara (1972) so that a more detailed model must be employed, in particular the inclusion of force constant changes and volume effects appears to be necessary.</p> / Thesis / Master of Science (MSc)

In the course of experiments using uniaxial double alignment channeling to investigate radiation damage in single crystals, an anomalously large ion-scattering yield from the near surface of disordered or simulated disordered solid targets was observed. The chronology of the discovery of this new ion-solid effect and its explanation are presented along with experiments detailing the dependence of the new effect upon ion type and energy, as well as target atomic number and density. Targets included a spectrum of polycrystalline elemental targets in a range Z = 29 to Z = 82. Also, the influence of the effect upon scattering yields from an aligned Au(110) single crystal is demonstrated.

This dissertation focuses on two areas of garnet porphyroblast crystallization that have until now remained largely uninvestigated: epitaxial nucleation of garnet porphyroblasts and yttrium and rare earth (Y+REE) uptake in metamorphic garnet. The mechanism of epitaxial nucleation is explored as a step towards determining which aspects of interfaces are significant to interfacial energies and nucleation rates. Garnet from the aureole of the Vedrette di Ries tonalite, Eastern Alps, shows a clear case of epitaxial nucleation in which garnet nucleated on biotite with (110)grt || (001)bt with [100]grt || [100]bt. The occurrence is remarkable for the clear genetic relationships revealed by the microstructures and for its preservation of the mica substrate, which allows unambiguous determination of the coincident lattice planes and directions involved in the epitaxy. Not all epitaxial nucleation is conspicuous; to increase the ability to document epitaxial relationships between garnet and micas, I develop and apply a method for determining whether evidence for epitaxial nucleation of garnet is present in porphyroblasts containing an included fabric. Although the magnitude of uncertainties in orientation measurements for garnets from Passo del Sole (Switzerland), the Nevado Filabride Complex (Spain), and Harpswell Neck (USA) preclude definitive identification of epitaxial relationships, the method has potential to become a viable technique for creating an inventory of instances and orientations of epitaxial nucleation with appropriate sample selection. Using lattice-dynamics simulations, I explore the most commonly documented epitaxial relationship, (110)grt || (001)ms. The range of interfacial energies resulting from variations in the intracrystalline layer within garnet at the interface, the initial atomic arrangement at the interface, and the rotational orientation of the garnet structure relative to the muscovite structure shows that the intracrystalline layer within garnet has the greatest effect on interfacial energy. A complete understanding of the role of intergranular diffusion for yttrium and rare-earth-element uptake in porphyroblastic garnet is critical because the complexities of Y+REE zoning in garnets and the mechanisms of Y+REE uptake have implications for petrologic interpretations and garnet-based geochronology. Y+REE distributions in garnets from the Picuris Mountains (USA), Passo del Sole (USA), and the Franciscan Complex (USA) imply diverse origins linked to differing degrees of mobility of these elements through the intergranular medium during garnet growth.

This dissertation focuses on two areas of garnet porphyroblast crystallization that have until now remained largely uninvestigated: epitaxial nucleation of garnet porphyroblasts and yttrium and rare earth (Y+REE) uptake in metamorphic garnet. The mechanism of epitaxial nucleation is explored as a step towards determining which aspects of interfaces are significant to interfacial energies and nucleation rates. Garnet from the aureole of the Vedrette di Ries tonalite, Eastern Alps, shows a clear case of epitaxial nucleation in which garnet nucleated on biotite with (110)grt || (001)bt with [100]grt || [100]bt. The occurrence is remarkable for the clear genetic relationships revealed by the microstructures and for its preservation of the mica substrate, which allows unambiguous determination of the coincident lattice planes and directions involved in the epitaxy. Not all epitaxial nucleation is conspicuous; to increase the ability to document epitaxial relationships between garnet and micas, I develop and apply a method for determining whether evidence for epitaxial nucleation of garnet is present in porphyroblasts containing an included fabric. Although the magnitude of uncertainties in orientation measurements for garnets from Passo del Sole (Switzerland), the Nevado Filabride Complex (Spain), and Harpswell Neck (USA) preclude definitive identification of epitaxial relationships, the method has potential to become a viable technique for creating an inventory of instances and orientations of epitaxial nucleation with appropriate sample selection. Using lattice-dynamics simulations, I explore the most commonly documented epitaxial relationship, (110)grt || (001)ms. The range of interfacial energies resulting from variations in the intracrystalline layer within garnet at the interface, the initial atomic arrangement at the interface, and the rotational orientation of the garnet structure relative to the muscovite structure shows that the intracrystalline layer within garnet has the greatest effect on interfacial energy. A complete understanding of the role of intergranular diffusion for yttrium and rare-earth-element uptake in porphyroblastic garnet is critical because the complexities of Y+REE zoning in garnets and the mechanisms of Y+REE uptake have implications for petrologic interpretations and garnet-based geochronology. Y+REE distributions in garnets from the Picuris Mountains (USA), Passo del Sole (USA), and the Franciscan Complex (USA) imply diverse origins linked to differing degrees of mobility of these elements through the intergranular medium during garnet growth.

No presente trabalho propomos e estudamos um modelo teórico que denominamos Cristal de Wigner Blindado. Assumindo para este sistema uma estrutura ordenada, nos foi possível verificar a ocorrência de uma transição de fase entre as estruturas bcc e fcc, para este modelo em função da densidade e/ou do parâmetro de blindagem. Após esta análise estática nos estendemos aos aspectos dinâmicos. Determinamos os modos normais para estas estruturas obtendo espectros de frequência para diversas blindagem e/ou densidade. Levando o parâmetro de blindagem para o limite zero, recuperamos diversos resultados conhecidos para o Cristal de Wigner. Isto era esperado urna vez que este modelo apenas difere do nosso pela natureza das interações, que neste caso são puramente coulombianas, sem blindagem. Além disto, nos foi possível efetuar comparação com sistemas reais formados por esferas de poliestireno em suspensão aquosa, permitindo-nos concluir que o modelo por nós proposto é aplicável aos mesmos / We present and develop a theoretical model which we designate Screened Wigner Lattice (SWL). In the ordered phase of this system we were able to predict a bcc-fcc transition, by varying the screening parameter and/or the density. After this static analysis we calculated the normal modes of such crystals and got the frequency spectra in function of the screening and/or density. Taking for the screening parameter the limit zero we reproduced several results already known for the Wigner Lattice (WL). This was expected since the only difference between the SWL and WL models consists on the nature of the interaction, some of our theoretical results with experimental data obtained for crystals formed by polystyrene spheres in aqueous suspension. The agreement allows us to conclude that the SWL model applies for such systems

I have used the Embedded Atom Method (EAM) to investigate the vibrational behaviors of a large number of metallic systems. The systems examined are the bulk bcc metals Li, Na, K, Rb, Cs, Nb, Ta, Mo, W, and Fe, the bulk fcc metals Ni, Cu, and Al, the (100), (110), (111), and (211) surfaces of the Li, Na, K, Rb, and Cs, and the (100), (110), and (111) surfaces of Ni and Cu. I have conducted a more detailed and extensive review of existing EAM models and their ability to characterize bulk vibrational behavior than has ever previously been reported. I show the ability of an EAM model to quantitatively predict the vibrational properties of the bulk alkali metals in excellent agreement with experiment. The present work remedies a lack of computational investigation into bcc metallic surfaces by performing lattice dynamics calculations of the (110), (100), (111), and (211) alkali metal surfaces. Additionally, I present lattice dynamics calculations on the (111), (100), and (110) surfaces of Cu and Ni. An accurate set of surface Debye temperatures for these metal surfaces has been calculated. The extensive number of metals and planar geometries studied has enabled the identification and clarification of general relationships between surface phonons, surface coordination, and atomic density. The changes in vibrational behavior due to the truncation of the bulk near a surface can be understood by the consideration of three things: the vibrational behavior of a 1-D chain of harmonic oscillators, the bulk dispersion relation in the direction perpendicular to a surface, and the atomic coordination of near surface atoms. In general, relaxation causes force constants between atoms to stiffen, resulting in higher vibrational frequencies. The impact of stiffening on the vibrational characteristics depends largely on the surface geometry, as well as the particular properties of the metal. It can cause new surface modes and resonances, or cause surface vibrations to be more strongly coupled to the vibrations of bulk atoms.