对向列相液晶反转壁中+1缺陷处挠曲电效应的理论分析  

Theoretical analysis of the influence of flexoelectric effect on the +1 defect site in nematic inversion walls

作　　者：张辉[1,2] 郑桂丽[3] 田毅[3] 张志东[3] 

机构地区：[1]河北工业大学电子信息工程学院,天津300401 [2]天津市电子材料与器件重点实验室,天津300401 [3]河北工业大学理学院,天津300401

出　　处：《液晶与显示》2016年第8期740-747,共8页Chinese Journal of Liquid Crystals and Displays

基　　金：国家自然科学基金(No.11374087;No.11304074);河北省自然科学基金(No.A2014202123;No.A2016202282);河北省教育厅项目(No.QN2014130;No.QN2015260);河北省高校重点学科资助~~

摘　　要：基于Pramoda Kumar等人文章中关于向列相液晶反转壁中+1缺陷处挠曲电效应的实验现象,我们利用Landaude Gennes理论给出相应的理论分析。当对弱锚定的平行排列向列相液晶盒施加垂直基板的直流电压,在反转壁中的±1缺陷会发生旋转。对于其中的+1缺陷,我们给出了外加电场作用下液晶分子的自由能表达式并通过模拟描述指向矢的方位角和极角的变化情况给出相应的缺陷处电场驱动的结构变化。模拟结果给出的挠曲电效应引起的方位角的变化角度与Pramoda Kumar等人的实验得到的在+1缺陷处消光刷的变化情况是一致的。Based on the experimental phenomena of flexoelectric response at defect sites in nematic in- version walls conducted by Pramoda Kumar et al., we gave the theoretical analysis using the Landau- de Gennes theory. When a direct-current electric field normal to the plane of substrate is applied to theparallel aligned nematic liquid crystal cell with weak anchoring, the rotation of ＋ 1 defects in the nar- row inversion walls can be exhibited. The free energy of liquid crystal molecules around the ＋1 defect site was formulated and the electric field driven structural changes at the defect site characterized by polar and azimuthal angles of the local director were simulated. The results reveal that the deviation of azimuthal angle induced by flexoelectric effect are consistent with the switching of extinction brushes at the ＋1 defect obtained in the experiment conducted by Pramoda Kumar et al.

关 键 词：液晶 挠曲电效应 +1缺陷 Landau—de Gennes理论 

分 类 号：O753.2[理学—晶体学]