Three PhD students receive prestigious Rackham Fellowship

All three of MSE's nominees were selected to receive the highly competitive award.
Three PhD students receive prestigious Rackham Fellowship

2019-20 Rackham Predoctoral Fellowship winners: Kelsey Mengle, Bryan VanSaders, and Michael Wang

MSE is proud to announce that three Ph.D. candidates - Kelsey Mengle, Bryan VanSaders, and Michael Wang - have received Rackham Predoctoral Fellowships for the 2019-20 academic year.

The Rackham Predoctoral Fellowship is one of the most prestigious awards granted by the Rackham Graduate School. Each department (university-wide) can nominate up to three doctoral candidates, who are judged on the strength and quality of their dissertation abstract, publications and presentations, and recommendations.

 “The Rackham Predoctoral Fellowship is an extremely competitive and highly coveted award,” said MSE graduate program advisor Renee Hilgendorf. “Having all three of our nominees selected is a true testament to the extraordinary caliber of our students.”

Each of the winners is profiled below:

Kelsey Mengle

Dissertation title: First-Principles Calculations on the Electronic, Optical, and Vibrational Properties of High-Power-Electronic Materials

Abstract: Modern society relies heavily on electricity, but devices suffer from significant energy loss. Efficient power conversion is necessary to transform between voltages for use in all electronics, and higher efficiency LEDs are required for effective lighting. My research addresses these concerns by determining the viability of wide-band-gap-semiconductor materials for high-power electronic and deep-ultraviolet luminescence applications using density functional theory. My results for b-Ga2O3and h-BN provide hope for these indirect-gap materials to be used in light-emitting devices. I show how stacking faults in GaN structures impact its electronic properties, with the promise to improve LED efficiency. I calculate the first ab initioestimate of the breakdown field of b-Ga2O3, a value crucial the high-power electronics community. I propose a new material, r-GeO2, with a larger band gap and higher electron mobility as an alternative.

Bryan VanSaders

Dissertation title: Colloidal Crystal Microstructure Engineering

Abstract:Much like traditional metals, colloidal crystals display complex defect microstructures that have a significant impact on material properties. Due to the large length scale of colloidal particles (microns) novel approaches to microstructure engineering are possible. One promising approach which has seen little study is the application of specially designed active particles into colloidal crystals to impart local forces that drive microstructure evolution towards a desired configuration. This dissertation explores several methods of designing and employing such particles as agents of microstructural control. Throughout this work a heavy emphasis is placed upon interstitial particle-dislocation interactions. Also discussed is the use of swellable particles to create mobile defect species in colloidal crystals. Lastly, the impact of different defect species upon the optical properties of colloidal assemblies is explored through an experimental collaboration.

Michael Wang

Dissertation title: Enabling Thin-Film Li7La3Zr2O12 Electrolytes for High Energy Density All-Solid-State Li-Metal Batteries 

Abstract: Due to the potential of solid electrolytes to stabilize the Li metal-electrolyte interface, all-solid- state batteries not only improve the safety of, but can also drastically increase the energy density of Li- ion batteries. Although the ceramic Li7La3Zr2O12 (LLZO) electrolyte has emerged as a viable solid electrolyte, several challenges remain to achieve realistic operating conditions. In this work, the interfacial mechanics and kinetics at the Li-LLZO interface are analyzed, demonstrating cycling of Li-LLZO cells at rates relevant to electric vehicles (>1mA/cm2). Furthermore, by analysis of charge transport, a set of design criteria for composite cathodes are outlined. Finally, using novel manufacturing processes, thin-film LLZO films will be fabricated and assembled into prototypical Li metal all-solid-state batteries at realistic length scales. These results not only provide a guideline for the future design of all-solid-state batteries, but also provide a deeper understanding of electrochemistry and mechanics in the context of all-solid-state batteries.