MSE Seminar: Yipeng Gao, Crystallographic Analysis of Pathway and Microstructures in Ferroic Transitions

PhD Candidate advised by Dr. Yunzhi Wang, Department of Materials Science and Engineering, The Ohio State University

All dates for this event occur in the past.

264 MacQuigg Labs
105 W. Woodruff Ave.
Columbus, OH 43210
United States

Abstract

Structural transformations with symmetry reduction underpin extraordinary properties of ferroic materials, including piezoelectricity, magneto-striction, and superelasticity. Recent experiments have shown that these properties could be enhanced dramatically under specific conditions, but a fundamental theoretical framework has not yet been established. We use graph theory to connect crystal symmetry, transformation pathway network topology, domain and defect structures, and functional properties of these smart materials, through which not only the reversibility, but also the giant responses and functional fatigue associated with both transformation and non-transformation pathways can be analyzed and predicted. In the graph approach, global symmetry and topology of transformation pathways can be characterized, which is beyond the reach of Landau’s Theory on phase transformations. Using examples of a typical ferroelectric and a typical ferroelastic system, we discuss potential transformation pathway engineering to obtain giant functional response and prevent fatigue in smart materials.

Bio

Yipeng Gao received his Bachelor and Master Degrees in Shanghai Jiao Tong University. He was working in one of the best research groups specialized on martensitic transformation, which is led by Prof. Zuyao Xu. In 2006, Yipeng Gao got Bao Steel Corp. Elite Student Scholarship during his master study, and then came to OSU to pursue a PhD degree in 2008. He is currently working with Prof. Wang and focused on crystallographic modeling of ferroic transitions to provide insight for the fundamental relationship among crystal structure, transformation pathway and material properties.