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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 the restraint of the substrate on the domain change in the epitaxial ferroelectric thin films, the stress function method is used to solve the intrinsic stress in the domain change of the epitaxial ferroelectric thin films. Combining with the phase field method, the domain structures and polarities of the ferroelectric thin films under different electrical boundary conditions Intensity. The calculation of the domain structure of PbTiO3 epitaxial ferroelectric thin films under the short-circuited electrical boundary shows that the film thickness at the transition from a-domain to a / c / a domains is very close to that obtained by the finite element method. By analyzing the domain structure of the ferroelectric thin films under the open-circuit electrical boundary, the film thickness at the transition from a-domain to a / c / a domain is found to be much larger than that under short-circuit conditions. The change of the stress caused by the matrix restraint causes the delamination of a domain and a / c / a domain in the domain structure of the film. The average spontaneous polarization of ferroelectric thin films increases with the increase of thickness, and the polarization intensities increase significantly from a-domain to multi-domain.