Materials Science Distringuished Lecture/Physics Colloquium
Presented jointly by the Colorado School of Mines and the National Renewable Energy Laboratory
Peter K. Davies
Professor and Chair, University of Pennsylvania, Materials Science & Engineering and Class of 1942 Professor
"Modulated Perovskites: Frustration and Hidden Nanoscale Order"
Abstract: Perovskites constitute one of the most widely studied and technologically important families of inorganic oxides. The flexibility of the structure in accommodating multiple substitutions of cations has enabled a myriad of functional responses both in film and bulk form. Their complex chemistries can lead to many frustrations in their local bonding and to ordering phenomena and defect formation that are often critical in mediating the property response. This talk will focus on families of alkali-based perovskite oxides where the multiple occupancy of the “A-site” position in the ABO3 structure induces the formation of unusual nanoscale “checkerboard” modulations. Studies of their local atomic structures using aberration corrected TEM indicate these modulations produce unusual periodic ferrielectric nanodomain structures. The factors responsible for the formation of these unique structures and their remarkable sensitivity to small changes in bulk stoichiometry will be discussed.
Bio: Peter K. Davies is the Class of 1942 Professor in the Department of Materials Science and Engineering in the School of Engineering and Applied Science at the University of Pennsylvania. He received his B.A. degree in Chemistry from New College, Oxford University and his Ph.D. in Solid State Chemistry from Arizona State University. His primary interests lie in the synthesis, stability, crystal chemistry and properties of electronic ceramic materials. Areas of focus have included the role of cation ordering reactions in enhancing the resolution of microwave resonators in wireless communication systems, the preparation of new lead-free ferroelectric and piezoelectric materials, development of crystal chemical models for PMN-type relaxors, the formation of nanoscale modulated perovskite oxides and the stabilization of semiconducting ferroelectrics for photovoltaic applications. Dr. Davies is a Fellow of the American Ceramic Society and a recipient of the National Science Foundation Creativity Award. He serves on the editorial and advisory boards of several ceramic and solid-state science journals and has received multiple teaching awards from the University of Pennsylvania. He has authored or co-authored over 175 publications, holds 3 patents and co-edited 5 books, and advised more than 50 graduate students and post-docs. Dr. Davies also served as Chair of the Materials Science Department at Penn for 14 years and headed the University Materials Council of North America.
To full the full schedule, visit: http://physics.mines.edu/PH-physics-colloquia