...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Physical Review X >Fréedericksz-Like Transition in a Biaxial Smectic- A Phase
【24h】

Fréedericksz-Like Transition in a Biaxial Smectic- A Phase

机译：弗雷德里克斯斯在双轴偏见中的过渡 - 一个阶段

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The two main classes of liquid-crystal (LC) phases of rodlike molecules are nematics, where the rods align in the same direction (the nematic director n ), and smectics, where the rods not only are aligned but also form layers. The electro-optic effects in LC devices that are a backbone in today’s display industry mainly use the Fréedericksz transition, which is the bulk reorientation of a surface-anchored nematic by an electric field. Conventional (uniaxial) smectics do not present a Fréedericksz transition, because, due to their layered structure, the director reorientation would distort the layers, which would cost too much energy. In a worldwide ongoing effort to extend the variety of LC compounds suitable for applications in the display industry, bent-shaped molecules have recently raised much attention, since they present multiple new LC phases with unusual properties. In this paper, we report on a structural and electro-optic study of the LC phases of a bent-shaped dimer. On cooling from the isotropic liquid, this compound shows a usual nematic ( N ), a twist-bend nematic ( N TB ), and a biaxial smectic- A phase ( Sm A b ). Quite surprisingly, contrary to usual smectics, Sm A b presents a remarkable electro-optic response, with low ( 4 V ) voltage threshold, no reorganization of the smectic layers, and low ( 1 ms ) response time (i.e., 30 times faster than the N phase at higher temperature). We interpret this unexpected electro-optic effect as a Fréedericksz transition affecting the secondary director m of the Sm A b , and we model it by analogy with the usual Fréedericksz transition of the n director of the uniaxial N phase. Indeed, a Fréedericksz transition affecting only m in this biaxial fluid smectic does not alter its layered structure and costs little energy. From the point of view of applications, thanks to its low relaxation time, this “biaxial” Fréedericksz transition could be exploited in electro-optic devices that require fast switching.
机译：棒状分子的两个液晶（LC）阶段的两个主要类别是Nematics，其中杆在相同的方向（旨在的方向（Nematic Director N）和椎体上对齐，其中杆不仅对准而且形成层。 LC设备中的电光效应是当今展示业中骨干的主要使用Fréedericksz过渡，这是由电场锚固的围绕围绕的料理重新定向。常规（单轴）椎体没有呈现Fréedericksz过渡，因为由于它们的分层结构，导演重新定向将扭曲层，这会花费太多的能量。在全球范围内持续努力扩展适合于显示行业中应用的LC化合物，最近弯曲的分子非常关注，因为它们存在多种新的LC阶段具有不寻常的性质。在本文中，我们报告了弯曲形二聚体的LC相的结构和电光研究。在从各向同性液体中冷却时，该化合物显示出通常的向列（n），扭曲弯曲向列（N TB）和双轴偏相 - 一个相（Sm A B）。非常令人惊讶的是，与通常的椎间目相反，SM A B呈现出显着的电光响应，低（＆LT; 4V）电压阈值，无重组近晶层，并且低（＆ 1ms）响应时间（即，比在较高温度下的N相时间快30倍）。我们将这种意想不到的电光效应解释为影响SM A B的次要主任M的FréederickSz转换，我们通过类别N阶段N阶段的通常Fréedericksz转换来模拟它。实际上，在这种双轴流体中仅影响M的Fréedericksz过渡不会改变其层叠结构并成本很少。从应用程序的角度来看，由于其低放松时间，这种“双轴”FréederickSz过渡可以在需要快速切换的电光器件中利用。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号