Atom to Application
My research broadly seeks to understand how atoms are arranged in solid materials, and then to apply this insight to either improve these materials or our understanding of them. To journey from the Pico meter sizes of atoms to the centimeter or meter sizes of most material applications, I use a variety of spectroscopic and computational techniques. A great challenge of this style of research is connecting the ideal laboratory environment--where we discover most exciting phenomena--with the “messy” environments and cruel practicalities of the real world.
Research directionsResearch Tools
Nanomaterials and Solid Acid Fuel Cells
Nanomaterials have demonstrated some fantastic energy harvesting properties, and many forward looking technologies like fuel cells hinge on these materials. However, tiny things are often difficult to make in anything other than tiny amounts, a common problem in scaling up many of these promising technologies. My research efforts in nanomaterials focus on high volume production (for a research setting) of Solid Acid Fuel Cell (SAFCs) materials, especially finding approaches that can scale practically to meet modern energy demands.
A "high" volume 93 kV electrospinner designed and constructed for an ARPA-E Caltech-Industry collaboration Electrostatic effects cause material to be pulled from the liquid surface into micron sized threads, which are then whipped (and stretched) into nanometer sized fibers.
Geologic mineralogy
In contrast to the high purity of an engineering environment, the Earth presents a messy and dynamic workspace for studying matter. With the eyes of an experimentalist, I see the Earth as a large chemistry project that has been running for 4.6 B years. In addition to the shear variability and variety of natural materials present at the surface, Earth also provides materials from conditions that are unreasonable to replicate in a typical laboratory setting. Given the complexity of geologically-relevant questions, it is a perfect test ground to develop spectroscopic and analysis approaches. My work in geologic mineralogy has used NMR to identify possible mechanisms for incorporating trace elements into mantle minerals including forsterite, clinoenstatite, and periclase.
Optical microscopy on crushed synthetic forsterite grains.
The exchange between engineering-focused sciences (materials science, mechanical engineering, ceramics) and the Earth sciences (geology and environmental sciences) happens too seldom, and some of my current geological research involves developing and testing synthesis methods that I believe will be useful to future experimental petrologists.
Cements
Despite cement's widespread use and the enormous greenhouse gas emissions related to its production, the materials and methods used to produce cement have seen relatively minimal improvements over the last 190 years. The insight needed for creating the greener cements of tomorrow may actually come from a deeper understanding of the crystal structures and atomic species found in current and historic cements. My research in this area includes directed studies of key cement minerals, such as B-belite, as well as the application of computer algorithms to increase the capacity of spectroscopic techniques for studying these minerals.
Electron microscopy of B-belite grains.The thermodynamics of phase stability can often be influenced by minor changes in composition. In the above image, B-belite grains are stabilized by adding 0.3 wt% Al.
Optical materials
Studying optical materials from new perspectives. My research has introduced paramagnetic NMR as powerful method for studying solid-state laser materials.
Optical materials play many key roles in the technological progress of our world, from enabling self-driving cars to detect pedestrians to reflecting the beam of light that enabled the observation of gravity waves. These materials' usefulness often depends on subtle changes to chemical composition and atomic arrangement; tailoring this composition can affect optic qualities. Additionally, many of the qualities that make optical materials great for optics also make them fascinating playgrounds for learning more about the complex nature of chemical bonding and distribution.
The majority of spectroscopic research in this field uses (with little surprise) optical spectroscopy. While it is a powerful and aptly suited technique, it is, like all spectroscopy techniques, only able to observe part of the picture. My research has presented an efficient NMR spectroscopic approach that uses the effects of unpaired electronic spins to observe atomic distribution in optical grade materials such as laser, scintillators, and phosphors. In future work I intend to merge my expertise with low concentration NMR to investigate the formation and minimization of grain boundary defects in optical materials, a current problem limiting the application and effectiveness of multicrystalline solid-state laser materials.
Research Tools
Solid-state Nuclear Magnetic Resonance
Within Solid State NMR, most of my focus is in improving our ability to detect trace elements. This includes both analysis software and more sensitive hardware. There are already many remarkable mathematical tools for increasing sensitivity and the analysis of NMR data. While these tools are often only found in scientific publications, I've created a user friendly tutorial on how to use these tools (available on SolidStateNMR.com). In regards to NMR hardware, my research includes “tiny lines”, small diameter transmission line probes, with a specific interest in low gamma nuclides.
Computational chemistry
My work in computational chemistry primarily studies diamagnetic and paramagnetic non-periodicity in otherwise periodic systems. Computational approaches enable both a prediction and possible interpretation of experimental results, in many cases enabling and extending conclusions drawn initially from expensive or difficult to obtain experimental NMR spectra. In most of my simulations, a single atomic species with unpaired electron spins is contained within a large diamagnetic oxide crystal, from which the Fermi-contact interactions and localized effects on the magnetic field can be estimated. Often, large probabilistic calculations paired with additional simulations are necessary to bridge the insight of the highly homogeneous computational simulations with the complex atomic distribution found in synthesized materials.
Electron probe micro analysis
EPMA explains the crystallization history of this ceramic. As this ceramic cooled, zircon rich particles (in green) provided nucleation sites for long aluminum rich crystals (in purple). The remaining composition could not crystallize fast enough, and remains as a magnesium rich intergranular glass.