Materials Science & Engineering Seminar Series: Professor Jian Luo

UW-Madison Department of Materials Science and Engineering welcomes this week’s seminar speaker, Professor Jian Luo. The seminar on “Decipher the Materials Genome via Understanding 2D Interfacial Phases and Beyond” will be on Thursday, Sept. 19 in MS&E 265 from 1 p.m. to 2 p.m.

Abstract

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, known as “premelting,” was first recognized by physicist Michael Faraday. Materials scientists have discovered that 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. Studies of 2D interfacial phases (also named as “complexions”) shed light on several long-standing mysteries in materials science, including the origins and atomic-level mechanisms of “solid-state” activated sintering, as well as liquid metal embrittlement in Ni-Bi and grain boundary (GB) embrittlement in Ni-S. Since phase diagrams are arguably one of the most useful materials science tools, a focus of this seminar is to discuss a series of studies to compute GB “phase” diagrams via thermodynamic models, atomistic simulations, and machine learning [see a perspective, Interdisciplinary Materials 2:137 (2023) and references therein]. Analogous 2D surface phases have also been studied and utilized to improve the performance of batteries and other materials for energy-related applications. After briefly discussing two other ongoing studies on (i) ultrafast sintering (in seconds) with vs. without electric fields and field effects on microstructural evolution and (ii) 5- to 21-component high-entropy and compositionally complex ceramics, nascent topics at the intersections of these emergent areas and interfacial science will be discussed. Here, recent collaborative studies within the UCI MRSEC CCAM investigated disordered GBs in refractory high-entropy alloys and compositionally complex perovskite oxides and their roles in activated sintering and ionic conduction, respectively. In addition, we demonstrated that applied electric fields can induce GB phase-like transitions via electrochemical coupling, thereby opening a new window to tailor microstructures.

Bio

Jian Luo graduated from Tsinghua University with dual Bachelor’s degrees: one in Materials Science and Engineering and another in Electronics and Computer Technology. After receiving his M.S. and Ph.D. degrees from M.I.T., Luo worked in the industry for more than two years with Lucent Technologies Bell Laboratories and OFS. In 2003, he joined the Clemson faculty, where he served as an Assistant/Associate/Full Professor of Materials Science and Engineering. In 2013, he moved to the University of California San Diego as a Professor of Chemical and Nano Engineering and Professor of Materials Science and Engineering. Luo group’s current research focuses on interfaces in metals and ceramics, high-entropy and compositionally complex ceramics, ultrafast sintering and other novel ceramic processing technologies, and advanced materials for energy-related applications and sustainability. Luo received a National Science Foundation CAREER award in 2005 (from the Ceramics program) and an AFOSR Young Investigator award in 2007 (from the Metallic Materials program). He was a Vannevar Bush Faculty Fellow (2014) and a Minerals, Metals & Materials Society Brimacombe Medalist (2019). Luo is a Fellow of the American Ceramic Society (2016), a Fellow of the ASM International (2022), and an Academician of the World Academy of Ceramics (2021).