Molecular theory of proper ferroelectricity in bent-core liquid crystals.
Molecular theory of proper ferroelectricity in bent-core liquid crystals.
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弯芯液晶中固有铁电性的分子理论。
DOI：
10.1140/epje/i2014-14079-0
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Osipov MA
中科院分区：
文献类型：
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作者：
Osipov MA
摘要在由非手性弯芯分子组成的正交近晶相中发现了反铁和铁电有序。到目前为止，这些系统是实验证实的唯一合适的流体铁电材料。我们考虑了各向同性、向列相和近晶A相铁电有序的分子理论，得出结论：分子电偶极子和空间偶极子的局域平行和反平行有序化趋势之间的微妙平衡在受限几何中发生了强烈的位移。这就是为什么偶极有序更有可能发生在近晶层中的原因。我们推导了极性弯芯分子的模型相互作用势，并给出了考虑分子双轴性的近晶正交相中铁电有序化的平均场理论结果。数值计算了有序参数分布，给出了相图，使人们能够分析极性弯芯分子形状调制的偶极-偶极相互作用和分子间引力的相对重要性。
AbstractAntiferro- and ferro-electric ordering has been discovered in orthogonal smectic phases composed of nonchiral bent-core molecules. These systems are the only proper fluid ferroelectrics confirmed experimentally so far. We consider a molecular theory of proper ferroelectric ordering in isotropic, nematic and smectic A phases and conclude that the delicate balance between the tendencies for local parallel and antiparallel ordering of molecular electric and steric dipoles is strongly shifted in restricted geometries. This is a reason why dipolar ordering is more likely to occur within a smectic layer. We derive model interaction potentials for polar bent-core molecules and present the results of the mean-field theory of ferroelectric ordering in the orthogonal smectic phase taking into account also the molecular biaxiality. Order parameter profiles have been calculated numerically and phase diagrams are presented which enable one to analyze the relative importance of dipole-dipole interaction and intermolecular attraction modulated by polar bent-core molecular shape.Graphical abstract