题目: Phase Transitions and Domain Structures in Ferroelectric Thin Films
报告人:Prof. Long-Qing Chen(陈龙庆，美国宾州州立大学)
Department of Materials Science and Engineering,Pennsylvania State University
时间：6月5日上午9:30
地点：曹光彪大楼617室
报告内容简介：
This presentation will discuss the applications of thermodynamic theories and phase-field method to predicting phase transitions, domain structures and switching in nanoferroelectrics. The emphasis is on the role of strain in the phase transition temperatures, domain stability, and switching and piezoelectric responses of in ferroelectric thin films and islands under an external electrical field. Examples to be discussed include several important oxide systems, PbTiO3, BaTiO3, SrTiO3, PbZrxTi1-xO3, BiFeO3 and superlattices. It is shown that ferroelectric transition temperatures in thin films can be shifted by hundreds of degrees as compared to the corresponding bulk crystals. It is also demonstrated that strain can drastically modify the domain structures of a thin film as well as its properties such as coercive field, spontaneous polarization, dielectric constant and piezoelectric responses. Examples of domain stability diagrams, stability as a function of temperature and strain, will be presented, which can potentially provide guidance for achieving desirable ferroelectric properties by choosing appropriate substrate and growth temperature of thin films.
报告人简介：
Prof. Long-Qing Chen received his B.S. in Materials Science and Engineering from Zhejiang University in China in 1982, a M.S. in Materials Science and Engineering from State University of New York at Stony Brook in 1985, and a Ph.D. in Materials Science and Engineering from MIT in 1990. He held a postdoctoral fellowship at Rutgers University from 1990 to 1992. Prof. Chen joined the Department of Materials Science and Engineering at Penn State as an assistant professor in 1992. He was promoted to associate professor in 1998 and to professor in 2002. Prof. Chen’s main research interest is in developing computational models for predicting mesoscale microstructure evolution in advanced materials. Prof. Chen is the author or co-author of more than 200 papers and has delivered more than 150 invited presentations. He received the ONR Young Investigator Award in 1995 and a NSF special research creativity award in 1999. In 2000, Prof. Chen received the Wilson Award for Excellence in Research from his college, and he was awarded the Penn State University Faculty Scholar Medal in Engineering in 2003. Prof. Chen was selected as one of the Outstanding Overseas Young Scholars by the Chinese Natural Science Foundation in 2004 and was named a Changjiang Chair Professor at Beijing University of Science and Technology through the Chinese Ministry of Education. He received a Guggenheim Fellowship and a Royal Society Kan Tong Po Fellowship for 2005-2006. He is the recipient of 2006 ASM Materials Research Silver Medal.
