SEMINAR
Growth Points in Ferroic Studies
Speaker L. Eric Cross
Evan Pugh Professor Emeritus of Electrical Engineering
Materials Research Institute
The Pennsylvania State University,
University Park, PA 16802, USA
时间：11月09日 （星期五）上午 9:00
地点： 4号楼14楼第一会议室
联系人：罗豪甦 研究员
Crystal research center, Shanghai Institute of Ceramics,
Chinese Academy of Sciences
中国科学院上海硅酸盐研究所晶体研究中心
Abstract
In the ferroic literature studies in special topic areas reoccur frequently and it is often in these areas one can identify growth points which strongly modify older ideas and generate a cascade of new innovation. In this talk I would like to focus on just two topic areas which have been of high interest to me:
The Topics of Relaxor Ferroics and of Extrinsic contributions to dielectric response in ferroelectrics.
In relaxors, I have been amazed at the tranquil passage into the literature of what I consider a major breakthrough. This is the work at National Institute for Material Science (NIMS) in Japan which reports relaxor FERROELASTIC behavior in a modified Martensite. Work showing clear Vogel:Fulcher behavior of the relaxing elastic compliance.
A second most important study in relaxors is that by the Blinc group in Slovenia on the drastic modification of the phase transition in lead magnesium niobate: lead titanate (PMN:PT) crystals at compositions close to the morphotropic phase boundary (MPB) by quite modest <111> oriented Electric fields. A study which underscores the massive fluctuations in the polarization and I believe calls into question our glib assignment of new phases in these highly inhomogeneous solids.
For more than 50 years I have been interested and excited by the role of extrinsic contributions to the weak field dielectric response in ferroelectrics. Two recent studies one on static domain wall arrays is barium titanate crystals at Tokyo Institute of Technology, and one on highly dynamic walls in rhombohedral BaTiO3 at Ecole Polytechnic Federal in Lausanne (EPFL) carry most interesting consequences I would like to discuss.
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