High-pressure and high-temperature laboratory experiments on the physical properties of mantle minerals provide a window into the Earth’s interior chemistry and geodynamics. The measurement of material density, compressibility, and elasticity at high P-T conditions provides thermoelastic parameters necessary to model seismic velocities in the Earth’s mantle at regional and global...
Thin film oxidation is investigated using two modeling techniques in the interest of better understanding the roles of space charge and non-equilibrium effects.
An electrochemical phase-field model of an oxide-metal interface is formulated in one dimension and studied at equilibrium and during growth. An analogous sharp interface model is developed...
While self-consolidating concrete (SCC) may no longer be considered a "new concrete", there are still significant challenges to overcome before there is broader acceptance of SCC. One of these challenges concerns the formwork pressure exerted by SCC. A major advantage of SCC is the accelerated casting process due to the...
This dissertation examines growth of platinum nanoparticles from vapor deposition on SrTiO3 using a characterization approach that combines imaging techniques and X-ray methods. The primary suite of characterization probes includes atomic force microscopy (AFM), grazing-incidence small-angle X-ray scattering (GISAXS), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and X-ray absorption spectroscopy...
The research reported in this dissertation covers the development of two high-performance concrete materials, Very-High-Strength Concrete (VHSC) and Frangible Concrete, and the philosophy of engineering the microstructure of these materials to produce their specific beneficial traits. The underlying problem addressed was how to optimize their design to maximize their desirable...
Motivated by performance requirements of future medical stent applications, experimental research addresses the design of novel TiNi-based, superelastic shape-memory alloys employing nanoscale precipitation strengthening to minimize accommodation slip for cyclic stability and to increase output stress capability for smaller devices. Using a thermodynamic database describing the B2 and L21 phases...
In recent years, research has expanded the uses of triblock copolymer gels to a wide variety of applications including everything from ceramics processing to regenerative medicine and drug delivery. The research presented in this dissertation focuses on a physically crosslinked, block copolymers gel system in a selective solvent. This system...
This dissertation demonstrates how self-assembly can direct nanoscale ordering and optimize electronic properties of organic semiconductors, as well as organic-inorganic hybrids. In excitonic solar cells, controlling the ordering and interfaces between electron-transporting (n-type) and hole-transporting (p-type) domains is crucial. In addressing this challenge, hybrid nanostructures were designed by mineralization of...
Dimensionally constrained material systems are at the forefront of current materials research because of their novel and often enhanced physical, chemical and biological properties. The dimensionality effects are pervasive through different classes of materials including ceramics, metals and polymers. Often times dimensionality effects are manifested as internal structure variations in...
This thesis examines the effects of micro-alloying additions to Al-Sc alloys on the microstructure, coarsening resistance and creep properties. The overarching goal of this research is to develop castable, creep-resistant aluminum alloys which can be used at temperatures in excess of 300?C. Successful high-temperature application of aluminum based alloys offers...
Structural dynamics in three polymer blend systems, differing largely with respect to morphology, have been investigated. The first system, composed of two immiscible homopolymers, exhibits a microstructure of micron-sized droplets dispersed in a matrix phase. We have examined small-angle x-ray scattering (SAXS) as a new approach for conducting in situ...
The optical and magneto-optical properties of the ferromagnetic semiconductors, InMnAs and its alloy InMnAsP were investigated to determine the band structure and nature of the ferromagnetism in these materials. Alloys were grown by metal-organic vapor phase epitaxy. Infrared absorption of InMnAs was investigated to determine the presence and properties of...
With the dual challenges of meeting global energy demand and mitigating anthropogenic climate change, significant effort is being applied to generating power from renewable sources. The dye-sensitized solar cell (DSC) is a photovoltaic technology capable of generating electricity from sunlight, but suffers losses in efficiency due to deleterious electron transfer...
Amorphous In-Ga-Zn-O (a-IGZO) and other amorphous oxide semiconductors are attracting increasing attention from the display industry for their high electron mobility, ease of large-area manufacture, and potential for future flexible electronics. However, such amorphous materials often show instability under gate voltage bias, temperature, and illumination stress, with extremely slow relaxation...
Data mining for materials discovery is concerned with representing materials science problems into a statistical framework, and learning models that describe observations about the processing, structure, and property of materials. The type of materials includes metals, ceramics, glass, polymers, and composites which are mixtures of multiple types. Observations come from...
Plasmonic nanostructures can confine light at their surface in the form of surface plasmon polaritons (SPPs) or localized surface plasmons (LSPs) depending on their geometry. SPPs are excited on nano- and micropatterned surfaces, where the typical feature size is on the order of the wavelength of light. LSPs, on the...