开路和短路电学边界外延铁电薄膜的畴结构及铁电性能

(厦门大学 材料学院,福建省特种先进材料重点实验室,福建 厦门 361005)

应力函数; 开路电学边界; 短路电学边界; 相场法; 铁电畴结构

Domain Structures and Ferroelectric Property Under Open and Short Circuit Electrical Boundary in Epitaxial Ferroelectric Thin Films
LEI Lisha,LIN Xiaohui,ZHOU Zhidong*

(Fujian Key Laboratory of Advanced Materials,College of Materials,Xiamen University,Xiamen 361005,China)

stress function; open circuit electrical boundary; short circuit electrical boundary; phase field method; ferroelectric domain structures

DOI: 10.6043/j.issn.0438-0479.201703044

备注

考虑基体对外延铁电薄膜内畴变的约束,采用应力函数方法求解外延铁电薄膜畴变时的本征应力,并结合相场法分析了不同电学边界条件下铁电薄膜的畴结构与极化强度.对短路电学边界下PbTiO3外延铁电薄膜畴结构的计算表明,由a畴到a/c/a畴转变时的薄膜厚度与采用有限元方法模拟的结果十分接近.通过对开路电学边界下铁电薄膜畴结构的分析发现,由a畴到a/c/a畴转变时的薄膜厚度远大于短路条件下的转变厚度.基体约束引起的应力变化使得薄膜内畴结构出现a畴和a/c/a畴的分层.铁电薄膜的平均自发极化强度随厚度的增加而增加,从a畴向多畴转变后,极化强度有显著的增加.

Considering constraints on the domain switching of epitaxial ferroelectric thin films with the substrate,we use the stress function method to calculate the eigenstress of epitaxial ferroelectric thin films.Further,according to the phase field method,the domain structures and polarization intensity of PbTiO3 epitaxial ferroelectric thin films under different electrical conditions are analyzed.The present results with the short circuit electrical boundary show that the critical thickness,in which a domain switches to a/c/a domain in epitaxial ferroelectric thin films,is very close to that using the finite element method under the same condition.The numerical results with the open circuit electrical boundary show that the critical thickness of a domain switching to a/c/a domain is much greater than that with the short circuit electrical boundary.The substrate,which affects the eigenstress in thin films,leads to two layers of a domain and a/c/a domain in thin films.With the increase in thickness,the polarization intensity increases.When domain structures switch from a domain to a/c/a domain,the polarization intensity has an obvious increase.