The work presented in this dissertation focuses on ceramic anode materials for solid oxide fuel cells (SOFCs). The primary goal was to characterize the anode and relate the electrochemical behavior to the microstructure. The anode that was most extensively studied in this work was a composite of Gd0.10Ce0.90O1.95 (GDC) and...
For bone regeneration, there is need for biodegradable, synthetic scaffolds that direct the formation of <em>de novo</em> mineralized tissue. Orthopaedic implants additionally require mechanical function. The work described herein attempts to address both of these needs. The general strategy involves integrating molecularly designed tissue engineering scaffolds with porous metallic foams...
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...
Aluminum alloys strengthened with coherent (L1<sub>2</sub>), nanosize Al<sub>3</sub>Sc precipitates may be used as structural materials at elevated temperatures. They are creep resistant at 300°C and exhibit a threshold stress, below which creep is not measurable. Introducing ternary alloying additions, such as rare-earth elements (RE=Y, Dy, Er), that segregate within Al<sub>3</sub>Sc...
A series of investigations was undertaken to explore the processing and properties of porous titanium with 6 wt% Al and 4 wt% vanadium (Ti-6Al-4V) and an equiatomic nickel-titanium alloy (NiTi). In this study, porous materials were created in the solid state by entrapping argon in a powder compact, and subsequently...
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...
In this dissertation, the Tg behavior of nanoconfined polymer films and 1-dimensional (1-D) patterned polymer nanostructures was studied. Using a novel fluorescence method, a reduction in Tg was observed upon confinement in PS films supported on silica, where free-surface (polymer-air interface) effects are dominant in modifying Tg. In contrast, Tg...
Because soft materials, particularly polymer gels, are playing a greater role in industrial and biotechnological applications today, the exploration of their mechanical behavior over a range of deformations is becoming more relevant in our daily lives. Understanding these properties is therefore necessary as a means to predict their response for...
Gradient copolymers are novel materials that possess a gradual variation in composition along the chain, thereby forming an intermediate structure between random and block copolymers. As such, they are a model system to investigate the effect of molecular structure on fundamental properties of copolymers and may be useful in many...
In this work, the processing of the superconductor MgB<sub>2</sub> was studied to create a fundamental scientific background for the production of superconducting composite wires. The synthesis of MgB<sub>2</sub> from Mg and B powders was investigated in situ to determine reaction rates and kinetic parameters for the application of powder-in-tube technology...
Oxide surface structures play a key role in many technological processes, including catalysis, thin film growth, and layered structures, and a thorough understanding of surface structures and surface structure dynamics is required in order to better engineer materials systems for these processes. This research works towards understanding these fundamental principles...
Over the past two decades photonic crystals (PhCs) have emerged as a promising new class of materials which offers unprecedented control of light in materials. Recently, atomic layer deposition (ALD) has been shown to be a powerful tool for the infiltration of 3D templates with dielectric or semiconducting materials, which...
In high power density transmission systems, Ni-Co secondary hardening steels have shown great potential for next-generation gear applications due to their excellent strength, toughness and superior fatigue performance.
Study of residual stress generation and evolution in Ferrium C61 and C67 gear steels revealed that shot peening and laser peening processes...
Novel self-healing alloy composites have been designed to address the need for self-repairable high-strength structural materials. A systems-based materials design approach using computational design tools was used to design a multifunctional biomimetic composite that can repair structural damage. The self-healing composite consists of a controlled-melting alloy matrix reinforced by thermodynamically...
Polymers and polyelectrolytes are ideal tools for the development of novel self-assembled materials. The ability to control the length-scales of self-assembly, and thus the properties, for soft materials lies in the understanding and subsequent manipulation of competing intermolecular interactions, such as hydrophobicity, hydrogen bonding, van der Waals, electrostatics. In this...
Supramolecular chemistry has proven to be an effective strategy for bottom-up fabrication of monodisperse, functional nanostructures. However, most applications require these nanostructures to be spatially or orientationally ordered. This thesis investigates patterning and spatial confinement as tools for controlling order in self-assembling systems.
We first look to improve the ordering...
Using ab initio calculations, we discovered a quasi two-dimensional copper–bismuth nano sheet, which we call cubine. According to our predictions, single layers of cubine can be isolated from the recently reported high-pressure CuBi bulk material at an extremely low energetic cost, comparable to values to separate single layers of graphene...
Ceramic matrix composites are known for their low density, high strength and high stiffness, but lower fracture toughness compared to metal matrix composites. The addition of a reinforcing agent within the matrix can increase the toughness of the composite via many strain energy absorption mechanisms such as plastic deformation. This...
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...
Fundamental investigations on the origins of friction at the nanoscale were carried out using both theoretical and experimental approaches. A model was developed that analytically solves for friction by the motion of dislocations at atomically flat crystalline interfaces. It combines known concepts from dislocation drag, grain boundary theory, and contact...