讲座题目：Domain Engineered Relaxor Based Single Crystals and the New Role of Domain Walls
报告人：曹文武（教授）
时 间：1月21日（周五） 下午4:00
地 点：廖凯原楼2-102
主持人：董蜀湘（教授）
报告内容摘要：
Domain engineering is an effective method in fabricating multidomain ferroelectric materials that possess ultrahigh piezoelectric properties, such as [001]c polarized Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) and Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) single crystals. Recent experimental results demonstrated that the piezoelectric property enhancement in multidomain ferroelectric crystals depends strongly on the size of domains, or the density of domain walls. This means that domain walls do contribute to the effective macroscopic piezoelectric responses, although it might not be in terms of domain wall motions as in conventional PZT ceramics. In a simplified model, one may treat the domain wall as a separated thin layer material sandwiched in between two domains that have different material properties. Traditionally, domain wall region had been considered to have much higher electrical conductivity, but using conductive domain walls leads to contradictions with experimental results. We have explored a new theoretical treatment by assuming domain wall region as a thin layer insulating piezoelectric material. Through fitting the experimental results of BaTiO3 and PZN-6%PT multidomain single crystals, we were able to extract the corresponding set of effective material properties for domain walls. This simple piezoelectric domain wall model can provide satisfactory explanations to the domain size dependence of piezoelectric property enhancement in domain engineered ferroelectric crystals.
报告人简介：
曹文武教授于1982年1月获吉林大学理论物理学士学位（77级），1987年5月获美国宾州州立大学凝聚态物理学博士学位。先后在宾州州立大学材料研究所及康奈尔大学物理系固体物理及原子分子所做了三年博士后。1990年受聘于宾州州立大学材料研究所及材料系。历经助理教授兼助理研究员，副教授兼副研究员。1995年加入数学系任副教授，并与2001年荣获美国宾州州立大学数学系和材料研究院共聘终身教授，同时还兼任生物工程系和材料工程系研究生导师。
曹文武教授的主要科研方向是鉄电材料物理的理论及应用，特别是压电器件和医用超声换能器的设计和制造。他的有关铁电畴和铁电相变理论方面的研究成果被国际同行广泛引用并被收入多部经典专著。已发表SCI学术论文280余篇、包括Nature Materials 和Physical Review Letters 等高端杂志。 合著学术专著3部、主持过十几次大型国际会议、在各种国际学术会议上做过百余次大会特邀报告。2006年入选教育部讲座教授，2009年受聘为中组部“”国家特聘专家。