The measurement of weak adhesive energies has previously been difficult to obtain. To measure these energies, I designed a technique that uses the combined sensitivities of both a quartz crystal resonator and the inflation of an elastomeric polymer membrane. The surfaces of the quartz crystal and/or the membrane are modified...
Liquid metal melt-lubrication of high-power and high-speed sliding electrical contacts improves electrical current collection and reduces friction. However, armature material loss may cause transition to arcing or plasma contact. Boundary lubrication of the sliding contact with low melting-point alloys can provide comparable improvement in current collection at reduced temperatures. Bismuth,...
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...
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...
Increasing interest in long-life bone implants with reduced mechanical properties reducing the stress-shielding effect and a structure mimicking bone porous architecture has encouraged study and development of fabrication methods for porous NiTi. The main objective of this work was to advance these goals by developing new processing procedures for porous...
In this work, electron beam induced current (EBIC) and scanning photocurrent microscopy (SPCM) were used to quantitatively investigate the electronic properties of silicon nanowire devices. For the first time, it was shown that minority carrier diffusion lengths in phosphorous-doped silicon nanowires are significantly reduced from their bulk values because of...
A multicomponent bimodal poly(vinyl acetate) (PVAc) polymer composite has been scientifically designed to increase biaxial plastic flow stabilization for the achievement of large biaxial deformations. For this, a systems-based approach was used for the computational materials design of a high performance bubblegum whose mean in-vivo bubble diameter exceeds that of...
Recent assessment of material property requirements for blast resistant applications, especially for the naval ship hulls, has defined the need to design steels with high stretch ductility and fragment penetration resistance, along with high strength and adequate toughness. Using a system based computational materials design approach, two series of austenitic...
Characterizing the interaction of light and matter has become increasingly important in recent decades, as devices scale down, data transfer speeds up, and the use of photon-based technology (photonics and optoelectronics) becomes widespread. Copper chloride (CuCl) thin films and zinc oxide (ZnO) inverse opal photonic crystals are the two material...
Subsolidus phase relationships within the ZnO-In<sub>2</sub>O<sub>3</sub>-SnO<sub>2</sub> system at 1275 <sup>o</sup>C were established by conventional solid state reaction methods. No new compounds or structures were observed within the ternary diagram. Equilibrium in the ZnO-corner, between the homologous compounds and the spinel phase, was found difficult to achieve. This problem was overcome...
Wood-derived ceramics and composites have been of interest in recent years due to their unique microstructures, which lead to tailorable properties. The porosity and pore size distribution of each wood type is different, which yields variations in properties in the resultant materials. The thermal properties of silicon carbide ceramics and...
ZnO is a member of the unique class of materials known as transparent conducting oxides (TCOs). TCOs are currently used for many applications including flat panel displays, solar cells, and energy efficient windows. Of particular interest is the possibility of developing materials that have high electron mobilities, such that conductivities...
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...
This thesis demonstrates the use of dual-beam focused ion beam - scanning electron microscopy (FIB-SEM) for making complete three-dimensional reconstructions of SOFC electrodes in order to better understand the links between processing and performance with respect to microstructure. Sufficient compositional contrast, with nano-scale resolution, between Ni and LSM with respect...
The morphological evolution due to coarsening is analyzed for two distinctive types of microstructure. First, the feasibility of characterizing spatial correlations of interfacial curvature in topologically complex structures is demonstrated with the analysis of bicontinuous two-phase mixtures produced using phase field modeling. For structures produced with both conserved and nonconserved...
High performance structural materials are needed for Naval applications which require an excellent combination of yield strength, low-temperature impact toughness, ductility, ballistic-resistance, and weldability. This research investigates precipitation-strengthened HSLA-115 steels and ballistic-resistant 10 wt. % Ni steels, which have emerged as promising alternatives to the widely used HSLA-100 steels for...
Carbonate minerals are integral to life on earth, as reservoirs for CO2 in the earth’s natural carbon cycle and as the skeletal elements of abundant organisms like corals and plankton. Because of its relevance, availability, and low toxicity, calcium carbonate is also an important model system for phase transformations in...
Atom probe tomography (APT) was used to analyze doping and alloying in low-dimensional electronic materials including thin film heterostructures, van der Waals materials, and colloidal quantum dots (QDs).
Firstly, APT was used to reveal structure-property relationship for low-dimensional thin film semiconductors used in electronic and opto-electronic devices. APT was shown...
Over the last 20 years a new field of amorphous transparent conducting oxides (a-TCOs) has developed. The amorphous nature of these films makes them well suited for large area applications. In addition, a-TCOs can be made at low temperatures and through solution processing methods. These assets provide promising opportunities to...
Supported metal catalysts find many important uses in areas including chemical production, petroleum refining and emission control. The catalytic behavior of a supported metal catalyst is influenced by size and type of reaction sites on metal nanoparticles. For many structure insensitive reactions catalyzed by the supported metal catalysts, smaller metal...