Construction of Theoretical Models of Layered Ferroelectrics

层状铁电体理论模型的构建

基本信息

批准号：
16540295
负责人：
ISHIBASHI Yoshihiro
金额：
$ 1.92万
依托单位：
Aichi Shukutoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

To investigate the domain structures and the interface structures between different materials and between different phases of a material, we proposed, based on the Landau theory, a one-dimensional model, where two semi-infinite materials contact at the interface, interacting by bi-linear coupling.Using this model, we obtained the polarization profiles and the interface energies for more realistic cases of ferroelectrics undergoing the first order transition. Followings are found.(1)In the case of small interaction constant at the interface, two materials are just placed independently, and therefore the gap of the polarization values at the interface is large and the interaction energy at the interface is small.(2)In the case of large interaction constant at the interface, and the polarization of the softer material is "pulled" towards the one of the harder material, with the gap of the polarizations at the interface decreasing with increasing the interaction parameter.(3)The interface energy becomes maximum at a certain magnitude of the interaction parameter.By the present model the extrapolation length, assumed a priori in the thin film model proposed by Tilley and Zeks, turned out not to be a material constant, but rather to be obtained in a natural way, depending upon the combination of two materials concerned.Since two materials are assumed to be semi-infinite, the effect of the formed interface on the extensive quantities like polarization is not significant, but the one on the intensive quantities like the coercive field can be remarkable. In fact the interface triggered polarization reversals are found to occur with a reduced coercive field.

为了研究不同材料之间和材料不同阶段之间的域结构和界面结构，我们根据Landau理论（一个一维模型）提出，在界面处的两个半infinite材料接触，通过双线性耦合进行交互。我们使用此模型进行了偏极和界面能量的转换，以实现更现实的效率。（1）在界面处的相互作用常数较小的情况下，两种材料仅独立放置，因此，界面处的极化值的间隙很大，界面的相互作用能量很小。（2）在界面处的较大相互作用常数，而界面的差异和距离的极化为偏离的层面是划线的，而划线的界限则是界限的层次。相互作用参数。（3）界面能量在相互作用参数的一定程度上最大化。根据本模型的外推长度，假定在Tilley和Zeks提出的薄膜模型中是先验的，事实证明不是材料恒定，而是以一种自然的方式获得的材料，取决于两种材料的组合。就像极化不是显着的，但是强化量（例如强制场）的偏振化可能是显着的。实际上，发现触发极化逆转的界面是在降低的强制场中发生的。