<p>The effect of surfaces on the electron transport at reduced scales is attracting continuous interest due to its broad impact on both the understanding of materials properties and their application for nanoelectronics. The size dependence of for conductor?s electrical resistivity ? due to electron surface scattering is most commonly described within the framework of Fuchs and Sondheimer (FS) and their various extensions, which uses a phenomenological scattering parameter p to define the probability of electrons being elastically (i.e. specularly) scattered by the surface without causing an increase of ? at reduced size. However, a basic understanding of what surface chemistry and structure parameters determine the specularity p is still lacking. In addition, the assumption of a spherical Fermi surface in the FS model is too simple for transition metals to give accurate account of the actual surface scattering effect. The goal of this study is to develop an understanding of the physics governing electron surface/interface scattering in transition metals and to study the significance of their Fermi surface shape on surface scattering. The advancement of the scientific knowledge in electron surface and interface scattering of transition metals can provide insights into how to design high-conductivity nanowires that will facilitate the viable development of advanced integrated circuits, thermoelectric power generation and spintronics. Sequential in situ and ex situ transport measurements as a function of surface chemistry demonstrate that electron surface/interface scattering can be engineered by surface doping, causing a decrease in the ?. For instance, the ? of 9.3-nm-thick epitaxial and polycrystalline Cu is reduced by 11-13% when coated with 0.75 nm Ni. This is due to electron surface scattering which exhibits a specularity p = 0.7 for the Cu-vacuum interface that transitions to completely diffuse (p = 0) when exposed to air. In contrast, Ni-coated surfaces exhibit partial specularity with p = 0.3 in vacuum and p = 0.15 in air, as Cu2O formation is suppressed, leading to a smaller surface potential perturbation and a lower density of localized surface states, yielding less diffuse electron scattering. The localized surface density of states (LDOS) at the Fermi level N(Ef) as a primary parameter determining the surface scattering specularity is further confirmed by a different surface dopant. In particular, the measured sheet resistance of 9-25-nm-thick epitaxial Cu(001) layers increases when coated with dTi = 0.1-4.0 monolayers (ML) of Ti, but decreases again during exposure to 37 Pa of O2. The corresponding changes in ? are a function of dCu and dTi and are due to a transition from partially specular electron scattering at the Cu surface to completely diffuse scattering at the Cu-Ti interface, and the recovery of surface specularity as the Ti is oxidized. X-ray reflectivity and photoelectron spectroscopy indicate the formation of a 0.47?0.03 nm thick Cu2O surface layer on top of the TiO2-Cu2O during air exposure, while density functional calculations of TiOx cap layers as a function of x = 0-2 and dTi = 0.25-1.0 ML show a reduction of N(Ef) by up to a factor of four. This reduction is proposed to be the key cause for the recovery of surface specularity and results in electron confinement and channeling in the Cu layer upon Ti oxidation. Transport measurements at 293 and 77 K confirm the electron channeling and demonstrate the potential for high-conductivity metal nanowires by quantifying the surface specularity parameter p = 0.67?0.05, 0.00?0.05, and 0.35?0.05 at the Cu-vacuum, Cu-Ti, and Cu-TiO2 interfaces. In order to determine the effect of the Fermi surface shape on the size effect, experimental and simulation results are combined to study how the resistivity changes with film thickness dw on monocrystalline W layers with different surface orientation, W(001) and W(110). As the first step of the experiments, the growth of epitaxial W(001) layers on MgO(001) substrates by ultra-high vacuum magnetron sputtering is studied, in order to obtain an alternative W layer orientation in addition to the well-known growth of epitaxial W(011) on Al2O3 substrates. X-ray diffraction ?-2? scans, ?-rocking curves, and pole figures show that 5-400 nm thick W(001) layers grown at Ts = 900 ?C are monocrystalline with a relaxed lattice constant of 3.167?0.001 nm, as determined from high resolution reciprocal space mapping. The magnitude of the residual in-plane compressive strain decreases from -1.2?0.1% to 0.1?0.1% with increasing dw. This is attributed to the glide of threading dislocations which increases the average misfit dislocation length, causing relaxation of the stress associated with differential thermal contraction. X-ray reflectivity measurements indicate smooth surfaces with a root-mean-square surface roughness ?1.0 nm and a roughness exponent of 0.38 for dw below 20 nm. Secondly, the effect of surface roughness on surface scattering is investigated to ensure its contribution to the resistivity size effect is properly included when comparing W films grown on different substrates. In fact it is found the ? of in situ annealed 4-20 nm thick epitaxial W(001) layers grown on MgO(001) samples show weaker dw dependence than that of unannealed samples in vacuum and air at both 295 and 77 K although completely diffuse surface scattering are present on both sets of films. No significant change in the structural quality of the samples after annealing is observed for d ? 20 nm. While a combination of X-ray reflectivity and Atomic Force Microscope study on surface morphology shows flatter surface mounds after annealing. Consequently, in situ annealing treatment is carried out on both epitaxial W(110) and W(001) from dw =4-320 nm to obtain surface with comparable rms roughness and lateral correlation length. Thus the ? increase due to the surface roughness is estimated in similar degree for the two types of films. Finally, a transport model for thin films with anisotropic Fermi surfaces is presented, which includes the effect of electron surface scattering. Simulations done using the calculated W Fermi surface show the resistivity ? to be 1.15-2.23 and 1.21-3.14 times larger than that of bulk W for (011) and (001) oriented thin films, respectively at a layer thickness d = 37.5- 3.75 nm, indicating an orientation dependent surface scattering effect on ?. The resistivity of epitaxial W(110) increases from 5.77?0.03 to 13.24?0.24 ??-cm as d decreases from 320 to 5.7 nm, but increases stronger for epitaxial W(001) from ? = 5.77?0.03 to 24.42?0.58 ??-cm for d = 320 and 4.5 nm. This orientation dependence is quantified with a different effective mean free path lambda(110) = 18.5?0.3 nm vs lambda(001) = 33?0.4 nm at 295 K by fitting using ? vs t with the Fuchs-Sondheimer (FS) model for spherical Fermi surfaces since their surface scattering is found completely diffuse by sequential in situ and ex situ electron transport measurements. Similarly, the ? from simulation can be fitted to obtain another set of lambda(110) and lambda(001) . The ratio lambda(110)/lambda(001) = 0.57?0.01 from simulations, in good agreement with 0.56?0.01 from experiment. The orientation dependent size effect is the result of (1) the projected Fermi surface area along the surface normal and (2) the rate of electrons approaching the surfaces due to the anisotropic electron Fermi velocity distribution along different directions.

<p>Among the existing corrosion control methods, surfactant inhibitors have widely been used for corrosion inhibition of pipelines in water-oil-steel pipe (WOS) environments. This dissertation includes a systemic review of the causes of pipeline corrosion in WOS environments containing carbon dioxide (CO2), general corrosion control using surfactant inhibitors and associated concerns, and commonly used classes of surfactants and their properties, various processes and phenomena that affect overall surfactant performance. This dissertation also provides a review of experimental evaluation techniques and various developed models (semi-empirical model, mechanistic model, and multiphysics model) in evaluation of surfactant inhibition efficiency. An integrated corrosion inhibition (ICI) model is proposed, developed, and validated based on the current understanding of the inhibition of CO2 corrosion in WOS environments using surfactants. The developed ICI model for the modeling and prediction of corrosion inhibition efficiency of mixed surfactant inhibitors is a multiphysics model, based on the fundamentals from many areas of corrosion science, electrochemistry, metallurgical engineering, and chemical and analytical engineering, etc., and the integration of several submodels, including a water-oil surfactant distribution submodel, the aqueous cmc prediction submodel, and the modified Langmuir adsorption (MLA)/ modified quantitative structure activity relation (MQSAR) submodel. Software is developed based on the ICI model and the use of computational and programming resources. The phenomena and processes integrated into the ICI model include surfactant partitioning between oil and water, micellization and precipitation, adsorption/desorption at surfaces and interfaces, surfactant-solvent interactions, surfactant-counterion pairing, lateral interactions between surfactant molecules, and fluid flow. These phenomena are incorporated into three main processes and associated modeling: partitioning between oil and water, micellization/precipitation, and effective adsorption on metal substrate and water/oil interface. The framework of multiphysics ICI model is intended to serve as a basic framework in the understanding of mixed surfactant inhibitor performance with a focus on the application in salt-containing WOS environments. Beyond this, other potential applications may be extended to the design of surfactants, selection of optimal surfactants for specific applications, experimental validation of developed models, simulation of conceivable processes and phenomena, and the integration into more comprehensive lifetime prediction models in which all the surfactant efficiency-affecting factors may be evaluated.

Recently, a new technology termed the controllable photochromic has emerged within the field of chromogenic technology. This technology represents a novel approach to the control of solar heat gain and adjustable transmission by utilizing a combination of chromogenic and radiation sensitive technologies. By harnessing solar energy for coloration, these systems represent a low-energy approach to controllable transmission glazings when compared to other chromogenic technologies available today. The zero external power required to reduce the glazing transmission and to maintain that state will provide opportunities for applications where today's chromogenic technologies are not well suited. One emphasis of this work was the rationalization of a general framework through which present and future controllable photochromic systems can be discussed. This framework discusses the roles and properties of the system components, necessary and desired for the function of the system, including a radiation sensitive electrode, a chromogenic electrode, and an electrolyte. The framework was also examined through a detailed case study of a system involving an anatase TiO₂ radiation sensitive electrode and a WO₃ chromogenic electrode. While this study involved a particular implementation of the technology, it exposed a great many attributes of this system including kinetics, wavelength sensitivity, influence of construction parameters, sensitivity to non-uniform incident radiation, and control over the photochromic response. While the general framework is useful for discussion of the principles involved in device operation, the detailed mechanisms occurring in a particular implementation will generally be more complex. Through careful study of the example system described in this thesis, the primary mechanisms occurring in the device were identified, and a model is proposed which is consistent with the observed findings. The source of degradation occurring due to prolonged cycling in the devices was studied through investigation of changes occurring in individual device components. While only one implementation of the technology was studied in detail in this investigation, three configurations were discussed in terms of the general framework. These systems exhibit an impressive array of desirable properties; however, it is clear that there is still much to be done to bring the technology to full fruition.

<p> Thin films (~100 nm) have been prepared of the prototypical spin-crossover complex Fe(phen)₂(NCS)₂ (phen = 1,10-phenanthroline). Initial attempts to prepare these films by direct vapor deposition yielded films of a different material. Through extensive FT-IR, Raman, UV-Vis, and x-ray photoelectron spectroscopy it is shown that these as-deposited films are the ferroin-based tris complex [Fe(phen)₃](SCN)₂. Structural characterization by AFM and powder XRD reveals them to be smooth and amorphous. When heated, the [Fe(phen)₃](SCN)₂ films are converted first to Fe(phen)₂(SCN)₂ and then to a third species postulated to be Fe(phen)(NCS)₂ which is likely a one-dimensional coordination polymer. On the other hand, deposition from Fe(phen)₂(NCS)₂ onto heated substrates produces a mixture of these three materials. The identity of the Fe(phen)₂(NCS)₂ films is proved by additional spectroscopic, structural, and magnetic characterization. Magnetometry reveals them to remain spin-crossover active albeit with a more gradual and incomplete spin-transition than the bulk material. The films are found to be granular in nature and deep crevices were observed at the grain boundaries. Within the optical microscope, the coloring of the grains is seen to be dependent upon sample orientation. Powder XRD indicates texturing of crystalline domains where the crystallographic c-axis is parallel to the surface normal. This represents a new process for production of Fe(phen)₂(NCS)₂ films.</p><p> With the aim of realizing the potential for spin-crossover materials to modulate electrical conduction and vise versa, electrical characterization has been performed as a function of temperature on vertical junction devices incorporating the prepared Fe(phen)₂(NCS)₂ films. In order to prevent penetration of the top electrode through the cracks and crevices in the organometallic layer, a multiple sequential deposition and annealing process was developed to produce films with a continuous surface topography. A small change in the weak electrical conductivity of these devices appears at the spin transition temperature, demonstrating for the first time in this important material a coupling of the electrical conductivity and magnetic spin state. Here, the HS state has a higher electrical conductivity. Incorporation of LiF interfacial layers between the Fe(phen)₂(NCS)₂ and the metal electrodes improves conduction slightly but tunneling still appears to be the current-limiting mechanism. Electrical measurements were also performed on devices made with the related complex [Fe(phen)₃](SCN)₂. Such films were much more conductive&mdash;as good as other typical organic semiconductor materials. All together, this work establishes the potential for this family of complexes to be incorporated into thin-film based electrical devices whose operation is based on the spin-crossover effect or otherwise.</p>

Use of electroless nickel plating for self-regulating low temperature induction heating of tumors (hyperthermia) was investigated. The desired magnetic properties for the material were: (1) a Curie temperature, T(C), in the range of about 52-62°C, (2) high induced power above T(C), and (3) an abrupt drop in induced power at the Curie temperature. An amorphous ferromagnetic material would provide the highest corrosion resistance and superior magnetic properties, while cylindrical geometry is necessary for clinical considerations and for maximum heating. Electroless Ni-P containing near 11-12 atomic percent phosphorus (Curie temperature 45-60°C) was plated to thicknesses exceeding three skin depths (calculated for nickel) onto 1 mm diameter wires. Power produced by the plated wires was low and no sharp drop in power was seen in the range of 20-80°C. High internal stress, which decreases magnetic permeability, and thus reduces power, can be reduced by annealing at 150°C. The lack of a sharp temperature drop was attributed to inherent inhomogeneity in the plating, determined by x-ray microanalysis. Stainless steel tubes filled with amorphous high permeability material heated well in a magnetic field, while no heating was obtained using the same amount of amorphous material packed into plastic tubing or using empty stainless steel tubing. The heat produced per unit length by the composite implants was greater than that produced by solid 1 mm diameter NiSi, but less than that estimated for stranded NiSi implants, which are comprised of optimum diameter strands to maximize eddy current heating. Electroless Ni-P alone cannot be used to provide high power implants, but it or other biocompatible conductive coatings could possibly be used on the outside of a flexible implant filled with high permeability material. This would allow the possibility of producing a flexible, biocompatible device which is thermally self-regulating and produces high induced power. It also opens up the possibility of using induction heating and radiotherapy sequentially or simultaneously if the radiation sources could be loaded with the high permeability material.

Novel unidirectional crystallization was tested in glasses of the Bi-Sr-Ca-Cu-O system to produce highly oriented microstructures. Some evidence of liquid-liquid phase separations on cooling melts of Bi₂Sr₂Ca₁Cu₂Oₓ and Pb₀ͺ₃₂Bi₁ͺ₆₈Sr₁ͺ₇₅Ca₂Cu₃Oₓ is found for the first time from Differential Thermal Analysis (DTA), X-ray Diffraction (XRD), and Transmission Electron Microscope (TEM). This made it difficult to produce highly oriented microstructures through the present route because one of the phases in the phase separated structure is likely close to "R"-phase composition and lead to copious nucleation of "R"-phase on heating. This also resulted in sequential crystallization of the current liquids, first to "R"-phase and then to the Bi₂Sr₂Ca₁Cu₂Oₓ phase. Theoretical modelling was performed to understand general questions in the present route. The model suggests that a liquid with high interfacial energy is a good candidate for the present route to produce highly oriented microstructures. The model was tested in lithium diborate glass and showed a highly oriented microstructure. Thus, unidirectional crystallization is generally an attractive processing option for a liquid free of phase separation.

The behavior of cemented sands is examined experimentally and theoretically in this study. The first segment of the investigation involves an extensive laboratory program to examine the effects of slenderness ratio, effects of cementation, and effects of confining pressure on the stress-strain curves of cemented sands. Results show that specimens with slenderness ratio of 1.5 or greater exhibit lower strength, higher dilatation rates, and relatively brittle behavior when compared to samples with slenderness ratio of 1. Furthermore, cemented sands have an essentially straight line Mohr-Coulomb failure envelope, whose cohesion intercept increases with the degree of cementation of the soil. The effective friction angles measured for cemented sands with various cementation levels are in the same ranges as the effective friction angle evaluated for uncemented sands. Moreover, failure modes of the material varies from brittle to ductile depending upon the level of cementation and the degree of confinement. In general, as cementation increases, cemented sand exhibits a brittle failure behavior; while increasing the confining pressure causes a ductile failure response. The second portion of the project includes development of a constitutive model for cemented sands. Cemented sand is viewed as a multi-phase material comprising three phases: sand, cement, and pore water. The elastoplastic behavior of cemented sands is the consequence of the behavior of the individual phases plus the interaction of the phases. The individual phases (sand and cement) are modeled using the theory of plasticity. Mixtures theory is used to assemble the individual phases to simulate the overall behavior of cemented sands. The gradual damage of the internal structure of cemented sands is also incorporated within the model. The agreement between experimental data and model predictions is very good. In summary, mixtures theory using simple plasticity models for the individual phases is capable of capturing the complex behavior of cemented sands.

The magnitude and temperature dependence of both the nucleation and crystal growth rates in lithium diborate glass were determined in the temperature range, 490 to 520°C. Comparison of the nucleation rates predicted by Classical Nucleation Theory and those found experimentally shows that the predicted classical nucleation rates are about 95 orders of magnitude smaller than the experimentally determined values. In addition, Classical Nucleation Theory does not predict the temperature dependence found experimentally. Comparison is also made with silicate glass systems which have been shown to exhibit homogeneous nucleation. Crystal nucleation in the lithium diborate glass almost certainly proceeds by a homogeneous mechanism. Comparisons are made between experimentally obtained values of the crystal growth rate in lithium diborate glass and those computed using surface nucleated crystal growth theory. Although the temperature dependence of the experimental growth rates at large undercoolings appears to be described well by the latter model, the computed values of the growth rates are about 60 orders of magnitude too small. Using a temperature dependent surface tension (obtained from fitting crystal nucleation data) in the surface nucleated crystal growth model partially reduces the discrepancy between the experimental and calculated magnitudes of the growth rate, but produces an incorrect prediction for the temperature dependence of the growth rate.

Alkaline solutions based on ammonium hydroxide and quaternary ammonium hydroxides such as choline (hydroxyethyl trimethyl ammonium hydroxide) and TMAH (tetramethyl ammonium hydroxide) are used widely in the wet processing of silicon wafers for the control of ionic and particulate impurities. The Wilhelmy plate technique was used in characterizing the ability of alkaline solutions to alter the wettability of wafers. Choline improved the water wettability of wafers, and at concentrations greater than 1000 ppm, rendered the wafers very hydrophilic. Ellipsometric and XPS analyses showed that the exposure of choline-treated surfaces to air resulted in the oxidation of Si to SiO₂. The increase of wettability of wafers in TMAH solutions was due to the roughness introduced by the high etch rate of TMAH solutions. Ammonia solutions without the addition of H₂O₂ did not increase wettability. The addition of H₂O₂ and a non-ionic surfactant to alkaline solutions significantly increased the wettability of wafers, decreased the etch rate, and resulted in smoother surfaces. The use of isopropyl alcohol (IPA) in the drying of wafers has been considered by the semiconductor industry. The addition of IPA to water resulted in a decrease in surface tension at the solution/vapor interface. The surface excess of IPA molecules at the solution/air interface was calculated to have a maximum value of 8.5 x 10⁻¹⁰ moles/cm² at a solution composition of 25% IPA and 75% water. IPA solutions with less than 25% IPA were very effective in removing PSL particles on hydrophilic wafers. Hydrophilic particles such as alumina and glass were difficult to remove from wafers in DI water and IPA solutions, however, hydrophobic particles such as silicon were slightly removable in DI water and IPA solutions. The wettability of particles (θ) and substrate (α) in solutions played important roles in removing particles on substrates. Leenaars' equation for the calculation of magnitude of surface tension force which balance adhesion force, F(A), did not seem to hold for solutions containing less than 25% IPA. Modification to this equation by adding a surface pressure term, π*, was considered in explaining the experimental results.

A uniform coating of precursors of various metal oxides on individual alumina particles was achieved by controlled hydrolysis of metal alkoxides in a slurry of alumina. Heterogeneous deposition of the precursors on the surface of the alumina particles was attributed to the electronegative character of alkoxy groups of the metal alkoxides. The powder coating techniques provided superior microstructures with homogeneous size and spatial distribution of secondary phases. It also lowered the sintering temperature of alumina in certain systems. In order to characterize microstructure development of the coated alumina during heating, powder compacts were rapidly quenched from elevated temperatures into liquid nitrogen and their interfaces and microstructures were examined by analytical TEM and FE-SEM. The EM studies revealed that the alumina particle surfaces act as sites for heterogeneous nucleation. The final structure of the alumina simultaneously doped with precursors of cupric oxide and titania was reached in the presence of a liquid phase but a large shrinkage occurred before the liquid formed. This phenomenon was explained from the viewpoints of superplasticity of the precursors and of a solid state reaction during heating. This speculation was supported by the similar accelerated sintering behavior with an addition of bismuth oxide and titania. The sintering behavior of alumina coated with a precursor of titania or zirconia, oxides of group 4 elements, was very different. The solid solution between alumina and titania after the nucleation of rutile on the surface of alumina resulted in sintering rate enhancement, while the slow self-diffusion characteristics of zirconia resulted in "droplets" on the surface of alumina particles which impeded the grain boundary migration.