(6el) Surface and Interfacial Properties in Ceramic and Inorganic Materials

Widgeon, S., University of California, Santa Barbara

Nano-scale materials have recently attracted great interest due to their ability to advance currently available materials to engineer next-generation technologies and devices.  This can lead to lower cost of production, reduced carbon foot print, higher energy efficiency, and improved performance in a variety of applications.   Since nanoparticles and nanocomposites have higher surface areas than their traditional micro-scale counterparts, it is becoming increasingly important to understand how surfaces and interfaces interact with their surrounding environments to contribute to the advanced properties and performances.  Using a variety of characterization tools, my research focuses on identifying the molecular-scale surface and interfacial structures to explain the mechanisms that control the observed macroscopic properties.  

My current and past research includes investigation of interfaces that exist in polymer-derived, nanocomposite ceramics and of surfaces of dicalcium silicate nanoparticles.  I completed my doctoral degree at the University of California, Davis under the advisement of Alexandra Navrotsky and Sabyasachi Sen, where I developed structural models for silicon-based polymer-derived ceramics that were synthesized from pyrolysis of a variety of preceramic polymers.  The nano-scale and micro-scale structures are highly tunable and have been proposed for a wide variety of high temperature applications.  It was found that the interfaces between the nano-scale domains in these ceramics contribute to high chemical and thermal stability that make these materials a desirable candidate for next generation high temperature ceramics.  Furthermore, it was determined that the morphology contains percolation networks that may also contribute to interesting transport and mechanical properties.  I am currently a University of California President’s Postdoctoral Fellow at the University of California, Santa Barbara, working under the advisement of Bradley Chmelka.  My postdoctoral research focuses on understanding the hydration mechanisms in dicalcium silicates, a minor component in anhydrous cement powders.  Sol-gel derived β-dicalcium silicate nanoparticles were recently synthesized to increase the hydration rate, with respect to conventionally prepared, micron sized β-dicalcium silicates.  Increasing the overall hydration rate of dicalcium silicate is considered to be an attractive option for replacing a portion of tricalcium silicate (the major component in anhydrous cement powders) to achieve similar mechanical strength properties with lower total calcium contents.  Correspondingly, this could reduce the carbon foot print of the cement manufacturing process due to the release of carbon dioxide during the refinement of calcium.  The molecular-scale surface structures of anhydrous and hydrated β-dicalcium silicates synthesized by the sol-gel and conventional methods are currently under investigation to identify the surfaces chemistry and interactions that cause the increased hydration rate.  

My future research interests include molecular-scale investigations on nanostructured ceramic and inorganic materials with applications in fuel cell electrodes and membranes, battery electrodes, supercapacitors, and high temperature ceramics.  My experimental approach to investigate these systems primarily involves the use of high-resolution, solid state nuclear magnetic resonance spectroscopy, which enables identification of molecular-scale structures in inorganic and ceramic materials.  Additionally, intermolecular interactions that occur at surfaces and interfaces can be elucidated to provide knowledge of the fundamental chemistry that is involved in the enhanced properties of next generation engineering materials.