清华大学材料科学与工程研究院《材料科学论坛》
学术报告
报告题目：The Complex Structures and Useful Properties of Modern Ferroelectrics
报告人：Prof. Jacob L. Jones (Department of Materials Science and Engineering, North Carolina State University)
报告时间：2018年10月24日（周三）上午10:00
报告地点：清华大学逸夫技术科学楼A205报告厅
联系人：王轲老师 62786252
欢迎广大师生踊跃参加！
报告摘要：
The importance of structure-property relationships in materials research cannot be overstated. At the crystallographic level, the structure relates directly to nearly all physical properties ranging from thermal expansion and elastic compliance to dielectric polarization, piezoelectricity, and pyroelectricity. In ferroelectric crystals, in particular, there is great complexity in the crystal structures investigated today with examples including disordered atomic displacements, chemical disorder, octahedral tilting, and incommensurate modulations. A growing emphasis on in situ characterization, e.g. crystallographic study during application of electric fields or mechanical stress, further increases the opportunities for linking useful properties to structural features of interest.
In this talk, I will first introduce the concept of pseudosymmetry, a framework that is being increasingly used in the description of these complex structures. I will then describe the application of Pair Distribution Function (PDF) methods for characterizing local structures in dielectric, piezoelectric, and ferroelectric ceramics. PDFs can be determined from X-ray or neutron total scattering measurements and provide information about structure that is invisible to Bragg diffraction. The interesting local structures in a variety of compounds and solid solutions measured by our group and other researchers will be described. I will also present the development of in situ PDF for determining how insulating materials respond to an electric field, providing critical insight to understanding of dynamic structure-property relationships. The local structures of BaTiO3 (BT), Na0.5Bi0.5TiO3 (NBT), and solid solutions of BT-Bi(Me)O3, Pb(Zr,Ti)O3, and Pb(Mg1/3Nb2/3)O3-PbTiO3 will be presented and discussed. Different local structural responses to field will be shown and include piezoelectricity, polarization rotation, ionic polarizability, rearrangement of disordered dipoles, and phase transitions.
报告人简介：
Dr. Jacob L. Jones is a Professor of Materials Science and Engineering, Director and Principal Investigator of the Research Triangle Nanotechnology Network (RTNN), Director of the Analytical Instrumentation Facility (AIF), and a University Faculty Scholar at North Carolina State University. Jones is an interdisciplinary materials researcher with core expertise in areas of oxide materials, materials characterization, and structure determination. He established his career in the field of functional materials by developing new methods for characterization of electrostrain mechanisms in electrically active materials (e.g., piezoelectrics and ferroelectrics) using X-ray and neutron scattering. He continues to advance this field by developing new materials and new methods. As Director of the RTNN and AIF, he leads teams of faculty and staff that support academic and non-academic nanotechnology research and core nanotechnology facilities across the Research Triangle region of NC. The RTNN is the second largest site in the NSF-supported National Nanotechnology Coordinated Infrastructure (NNCI) and the AIF is the largest materials characterization facility in the Southeastern United States. In the past five years, Jones has diversified his research and scholarly contributions to include many new areas including but not limited to nanotechnology, water sustainability, and data science. Jones has published over 200 papers since 2004 and achieved an h-index of 42 (Google Scholar). Jones is a Fellow of the American Ceramic Society and Vice President for Ferroelectrics in the IEEE UFFC Society. He has received numerous awards for his research and education activities, including an NSF CAREER award, a Presidential Early Career Award for Scientists and Engineers (PECASE), the IEEE Ferroelectrics Young Investigator Award, a National Nuclear Security Administration (NNSA) Defense Program Award of Excellence, a UF-HHMI Science for Life Distinguished Mentor Award for his mentoring of undergraduate researchers, the NC State College of Engineering George H. Blessis Outstanding Undergraduate Advisor Award, and two Edward C. Henry “Best Paper” awards from the Electronics Division of the American Ceramic Society.