Thesis (Ph. D.)--University OF MICHIGAN.

Thesis (M.S.)--Lehigh University, 2009. / Adviser: Wojciech Z. Misiolek.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3735. Adviser: Paul V. Braun. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Thesis (Ph.D.)--Lehigh University, 2009. / Advisers: Hugo S. Caram; Martin P. Harmer.

Thesis (Ph.D.)--Lehigh University, 2009. / Advisers: Helen M. Chan; Richard P. Vinci.

The formation of metastable crystalline phases in lithium disilicate glass has been a subject of controversy for decades. Here, one aspect of this problem relating to the stability of these non-equilibrium phases when glasses are heated for extended time periods in the nucleation regime is addressed. The results of a systematic experimental investigation on the persistence of metastable phases and the factors that may influence the appearance of such phases, e.g., water content, impurities, glass composition, and glass preparation procedure are presented. Growth rates of lithium disilicate crystals in lithium disilicate glass are measured as a function water concentration in the glass and of temperature in the deeply undercooled regime. The growth rate data obtained in this work are combined with data reported in the literature and used to assess the applicability of standard models of crystal growth for the description of experimental results over a very broad temperature range. The reduced growth rate versus undercooling graph is found to consist of three regimes. For undercoolings less than 140°C, the reduced growth rate curve is suggestive of either 2-D surface nucleation or screw dislocation growth. For undercoolings greater than 400°C, the reduced growth rate plot suggests the operative crystal growth mechanism is 2-D surface nucleation, but detailed calculations cast doubt upon this conclusion. In the intermediate undercooling range, there appears to be some sort of transitional behavior for which none of the standard models appear to be applicable. Further, it is observed that small differences in the viscosity data employed can produce enormous differences in the predicted growth rates at larger undercoolings. Results of the kinetic analyses conducted herein seem to indicate that the nature of the kinetic rate coefficient used in the standard growth models may be incorrect. Nucleation rates of sodium metasilicate crystals in a sodium silicate glass of composition 43Na₂O57SiO₂ (mol%) are investigated using the development technique. The results of this study are compared with the nucleation rate results recently obtained for this composition using a novel DTA method. The two techniques are found to agree within experimental error.

The effect of implantation dose and annealing conditions on the microstructure of ultra-thin SIMOX materials formed by 65 keV ion implantation were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), Rutherford backscattering spectrometry (RBS), and optical microscopy. The implantation dose has a strong effect on the microstructure in both the as-implanted and annealed samples. The dominant defects observed in the as-implanted samples were multiply faulted defects (MFDs) near the upper interface and {113} defects beneatht he buried oxide (BOX) layer. The BOX layer started to form continuously at the dose of 7.0x10¹⁷/cm² after implantation. The most noticeable microstructural feature observed in the as-implanted samples was the mixed structure of silicon and oxygen precipitates which formed around the oxygen projected range. The structure, observed in the samples with dose in the range of 3.5 to 5.0x10¹⁷/cm², was found to be the precursor for the formation of silicon islands inthe samples after annealing. For the annealed samples, the dose range of 3.5 to 5.0x10¹⁷/cm² was established as the optimum for the BOX layer to form continuously without silicon islands. At doses above 2.5x10¹⁷/cm², the BOX layer formed continuously with silicon islands. The dose dependence of the defect densities in the top Si layers of the annealed samples was investigated. The dose of 3.5x10¹⁷/cm² was found to contain the lowest density of defects in the top Si layer. Above and below this dose, the defect density increased. The effect of intermediate-temperature annealing on microstructural evolution was investigated. The MFDs and the {113} defects were completely eliminated at 1100°C and 1200°C, respectively. It was found also that the redistribution process for oxygen and silicon interstitials during annealing was initiated at 1100°C, which also recovered the crystallinity of the top Si layer and developed the formation of the BOX layer. Above 900°C, oxygen precipitates in the top Si layer grew in size while they decreased in number with increasing temperature, an indication of Ostwald ripening. The effect of final annealing temperature and surface capping on the microstructure were also investigated. Annealing at 1300°C for 6 hours restored completely the crystal quality of the top Si layer and produced a continuous and uniform BOX layer. While the surface capping during annealing preserved the thickness of the top Si layer, it adversely affected the BOX layer formation especially at much lower doses. It led also to a slightly higher density of defects in the top Si layer by stabilizing defects which otherwise would have been eliminated during the high-temperature annealing. Additionally, the uncapped samples showed slightly lower density of Si islands in the BOX layer. Oxygen from the annealing ambient diffused in the uncapped samples through the thin top Si layer, which helped the BOX layer grow laterally and lowered the Si island density. The correlations between processing conditions and the microstructure of as-implanted and annealed material were established.

The behavior of impurities (in particular arsenic, antimony and bismuth) on copper electrodeposition was investigated using several non-steady state techniques at a temperature of 63°C in cupric sulfate solution (Cu 45 g/l, H₂SO₄ 200 g/l). As a result, group-V elements work as depolarizers against copper deposition and hydrogen evolution. From the result of cyclic voltammetry, copper reduction was subject to an irreversible reaction with a preceding chemical reaction. In general, copper deposition is not significantly effected by group-V impurities at the compositions investigated. Basic electrochemical parameters, except for the transfer coefficient, were also insensitive to these impurity constituents. However, there is a peak due to arsenic reduction (at -0.330 V) in cyclic voltammogram for the As-containing electrolyte. In addition, the effect of impurities on morphologies were investigated by SEM observation and X-ray diffractometry. As a result, group-V promoted truncated deposits and the (110) crystallographic orientation.

The electrical characteristics of nylon 66, charge-modified nylon 66 and PVDF filter membranes were investigated using the electrophoretic and streaming potential techniques. Characterization of surface charge density of nylon based membranes were performed by acid/base titration. The adsorption of an anionic dye was used to determine the charge density of positive sites on the N66 Posidyne membrane. The results show that the isoelectric point (IEP) of N66 Posidyne and Zetapor (E-grade) occurred at pH 7.6 and 6.2, respectively. The point of zero charge (PZC) of E-grade Zetapor occurred at a much higher pH value than the IEP, indicating inhomogeneity in the extent of charge modification in pore walls and on the external surface. Using the dye adsorption test, the charge density of positive sites on N66 Posidyne was calculated to be approximately 9.5 μcoulombs/cm² at a solution of pH of 5.1, which is in agreement with the surface charge density using the acid/base titration.

The interaction of commercially available, iron based magnetic particles with certain particulate media formulation components was investigated using the technique of flow microcalorimetry. The heat of wetting of these particles by solvents was found to be a function of the solvent dipole moment, particle coercivity and surface area. Di(2-ethyl hexyl) phosphoric acid, a model dispersant, appeared to interact chemically with an iron particle of high coercivity. Solvent basicity influenced the heat and extent of interaction of the dispersant. Characterization of the interaction of a vinyl acetate-vinyl chloride copolymer that combined the functionality of a dispersant and a binder was also carried using the techniques of calorimetry and X-ray photoelectron spectroscopy.