Sreenilayam S P, Panarin Yu P, Vij J K, Torgova S I, Lehmann A, Tschierske C
Department of Electronic and Electrical Engineering, Trinity College, University of Dublin, Dublin 2, Ireland.
School of Electrical and Electronic Engineering, Dublin Institute of Technology, Dublin 8, Ireland.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Aug;92(2):022502. doi: 10.1103/PhysRevE.92.022502. Epub 2015 Aug 24.
The flexoelectric polarization (Pf) of four bent-core nematic liquid crystals (LCs) has been measured using the pyroelectric effect. Hybrid aligned nematic cells are fabricated for measuring the pyroelectric response over the entire range of the nematic phase. It is found that the magnitude of flexoelectric polarization Pf and the sum of the flexoelectric coefficients |e1+e3| for the bent-core LCs studied here are three to six times higher than for the calamitics. Pf is found to depend on the transverse dipole moment of LC molecules. However, |e1+e3| values are by no means giant as |e3| alone had been reported for a bent-core nematic system previously. The dependence of the sum of "splay and bend flexoelectric coefficients" is discussed in terms of the shape of the molecule and of the dipole moment directed normal to the molecular axis.
利用热释电效应测量了四种弯曲核向列型液晶（LCs）的挠曲电极化（Pf）。制备了混合取向向列型盒，用于测量向列相整个范围内的热释电响应。结果发现，本文研究的弯曲核液晶的挠曲电极化Pf的大小以及挠曲电系数之和|e1+e3|比普通液晶高3至6倍。发现Pf取决于液晶分子的横向偶极矩。然而，|e1+e3|的值远非巨大，因为之前报道的一个弯曲核向列型体系仅|e3|就已很大。从分子形状和垂直于分子轴方向的偶极矩方面讨论了“展曲和弯曲挠曲电系数之和”的依赖性。
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