报告题目：Structure and properties of PbZrO3-based antiferroelectrics
报告人：Xiaoli Tan（Department of Materials Science and Engineering, Iowa State University）
报告时间：2019年4月12日（周五） 下午 3:00
PbZrO3-based perovskite oxides represent the most extensively studied and technologically important antiferroelectric ceramics. The reversible antiferroelectric (AFE) – ferroelectric (FE) phase transition under electric field makes them promising for energy storage capacitors and solid state cooling devices. To facilitate and manipulate the phase transition, Sn and Ti, together with minor amounts of La or Nb, are often incorporated. These chemically modified compositions are featured with nanoscale incommensurate modulations (IM) in their microstructures. In this study, several techniques are employed to uncover the atomic and domain structures and their transitions under applied electric fields in representative compositions. Using the STEM-HAADF technique, the Pb-cation displacements are mapped out. It is found that they are not in the traditionally believed antiparallel arrangement. Instead, an almost orthogonal pattern is formed. Such a macroscopically AFE but microscopically FE phenomenon is described by a special term, “quasi-antiferroelectric.” In addition, ideas for future research on AFE will be discussed.
Professor Tan has been actively conducting research on the structure-property relationship in ferroelectric and piezoelectric ceramics, with the electric field in-situ transmission electron microscopy (TEM) technique as the main characterization tool. He joined Iowa State University as an Assistant Professor of Material Science and Engineering in 2002, was promoted to Associate Professor in 2008, and to Professor in 2013. He has so far advised eight PhD students and four MS students to graduation. Professor Tan has been involved in 30 research projects with a total of $~8M in research funds. In particular, he has served as the lead PI on five NSF research projects. He has delivered 70 invited talks at universities and international conferences around the world and published 150 articles in refereed technical journals. According to Web of Science, Professor Tan’s articles have received a total of 4,000 citations as of March, 2019, and his h-index is 35.