ChEMS Seminar: Understanding Interfacial Phase Behaviors to Help Decipher the Materials Genome

Professor Jian Luo

NanoEngineering and Materials Science and Engineering

University of California, San Diego

A piece of ice melts at 0 °C, but a nanometer-thick surface layer of the ice can melt at tens of degrees below zero. This phenomenon of stabilization of nanoscale liquid-like interfacial phases below the normal bulk melting temperatures, known as premelting, was first recognized by the physicist Michael Faraday in 1842. Since then, materials scientists have discovered that the surfaces and interfaces in engineered materials can exhibit more complex phase-like behaviors at high temperatures, which can affect the fabrication and properties of a broad range of metallic alloys and ceramic materials. Specifically, recent studies of grain-boundary interfacial phases (also called complexions) shed light on several outstanding scientific problems that have been puzzling the materials science community for decades, including the origins and atomic-level mechanisms of activated sintering, liquid metal embrittlement and abnormal grain growth.  Analogous surface phenomena have also been studied and utilized to improve the performance of batteries and supercapacitors. Since bulk phase diagrams are one of the most useful tools for materials design, it is conceived that interfacial phase diagrams can be developed as a useful materials science tool.   

Bio: Jian Luo graduated from Tsinghua University in 1994 with dual bachelor's degrees, one in materials science and engineering and another in electronics and computer technology. He received a master's degree in materials science and engineering in 1999, and a doctorate in ceramics in 2001, both from M.I.T. Luo joined the Clemson faculty where he served as an assistant/associate/full professor of materials science and engineering from 2003 to 2012.  In January 2013, he joined UCSD as a professor of nanoengineering and materials science and engineering. Luo received a National Science Foundation CAREER award (from the ceramics program) in 2005 and an Air Force Office of Scientific Research Young Investigator award (from the metallic materials program) in 2007. He was recently named as a National Security Science and Engineering Faculty Fellow (NSSEFF) by the U.S. Department of Defense in 2014.