How interfacial thermodynamics revolutionizes the design of nanostructured oxides

Ricardo H.R. Castro is the Chancellor’s Leadership Professor of Materials Science and Engineering at the University of California-Davis. Castro leads the Nanoceramics Thermochemistry Laboratory in the Department of Materials Science and Engineering, focused on the fundamental understanding of nanomaterials and their behavior under processing and service in extreme environments, such as high temperatures, complex chemistries, and radiation. Castro holds a B.Sc. in molecular sciences and a Ph.D. in metallurgical and materials engineering from the University of Sao Paulo in Brazil. He has received several national and international awards, including the NSF CAREER Award, DOE Early Career Program Award, the Young Investigator Award from the Society of Professional Hispanic Engineers (SHPE), the Sosman Award by the Calorimetry Conference, the Robert L. Coble Award from the American Ceramic Society (ACerS), among others. Castro is a fellow of ACerS, Principal Editor for the Journal of Materials Research, and Editor-in-Chief of the International Journal of Ceramic Engineering and Science published by ACerS/Wiley.

Ricardo H. R. Castro
University of California, Davis

RESUMO

Crystal size refinement down to the nanoscale results in unique properties and phenomena in oxide-based materials. With properties ranging from unprecedented hardness, high ionic exchange rates, and radiation damage tolerance, the nano-dimension offers diverse technological opportunities to address current societal challenges. However, after decades of nanotechnology, the limited fundamental understanding of the origins of those nano-induced features still refrains a comprehensive design and optimization of devices. In those systems, a significant fraction of the atomic volume belongs to the interfacial regions, a complex chemical environment that governs the system interactions in both positive and negative ways. While interfaces are responsible for phenomena such as the above-mentioned improved ion exchange rate in nano-cathodes, the intrinsic interface excess energies trigger coarsening even at moderate temperatures, limiting service time. This talk discusses how interfacial thermodynamics and its relationships with nanoscale properties offer an effective strategy to understand and design oxides nanomaterials. The first part will discuss how interfacial segregation reduces excess energies in nano-LiMn2O4 and causes increased stability against coarsening and improved capacity retention in Li-ion batteries. In the second part, we briefly address the connection between grain boundary energies and the mechanics of nanoceramics, highlighting how selected dopants affect fracture behavior to improve mechanical performance. These two representative cases demonstrate the power of interfacial thermodynamics in controlling the nano-world as we envision further developments in other more complex interfacial environments.