200 College St.
Abstract
Manipulating the structure and chemistry of grain boundaries and interphase interfaces in crystalline materials are crucial to obtain materials with desirable physical and functional properties. Although there are many experimental studies on grain boundary segregation in various alloys and ceramics, the study of the transformation from the initial solid solution structure at the atomic scale have not been explored. In this study, a novel bicrystal technique was developed to produce yttria stabilized zirconia (YSZ) bicrystal specimens without Y3+ segregation to the grain boundary. Scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS) characterization confirmed that the specimen is indeed free of Y3+ segregation. To trigger grain boundary segregation, the specimen was annealed at various temperatures and the structure and chemistry were tracked by atomic resolution STEM imaging and EDS mapping. The fundamental understanding of the segregation sequence, as well as the conditions that can activate solute segregation are important for tailoring the properties and behaviour for the specific applications of YSZ, including solid electrolyte for solid oxide fuel cells (SOFCs) and cutting tools.
Speaker Bio
Jason Tam is currently a postdoctoral researcher at The University of Tokyo. He received his B.A.Sc. and Ph.D. from the Department of Materials Science and Engineering, University of Toronto. During his graduate study, he was also a visiting scholar at Hokkaido University and The University of Tokyo. Prior to his current position in Japan, he took on several roles at the University of Toronto as a postdoctoral researcher, undergraduate course instructor, and research scientist supporting the operations of the electron microscopy facility in OCCAM. His research interests include physical metallurgy, specifically interfaces of materials, electrochemical synthesis of nanostructured materials, and electron microscopy.