Nonstandard electroconvection in a bent-core oxadiazole material
Nonstandard electroconvection in a bent-core oxadiazole material
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DOI：
10.1103/physreve.83.041704
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发表时间：
2011-04-08
影响因子：
2.4
通讯作者：
Gleeson, H. F.
中科院分区：
文献类型：
--
作者：
Kaur, S.;Belaissaoui, A.;Gleeson, H. F.
研究了具有负介电各向异性和随频率变化的电导率各向异性的弯芯恶二唑材料向列相中的电对流现象。在所研究的整个频率和电压范围内，纵向滚动(LR)图案的形成是观察到的主要特征之一。在远高于LR阈值的电压下，可以观察到各种复杂的图案，如“交错”图案、双峰曲张和湍流。不同寻常的是，这种材料中的非标准EC(ns-Ec)不稳定性是在测量介电各向异性和电导各向异性分别为负和正的区域内观察到的。另一个重要的观察结果是，EC在向列相的高、低温区域中显示出不同的特征，这支持了早期的报告，即EC模式可以区分已被报告为单轴和双轴向列相的区域。
Electroconvection (EC) phenomena have been investigated in the nematic phase of a bent-core oxadiazole material with negative dielectric anisotropy and a frequency dependent conductivity anisotropy. The formation of longitudinal roll (LR) patterns is one of the predominant features observed in the complete frequency and voltage range studied. At voltages much above the LR threshold, various complex patterns such as the "crisscrossed" pattern, bimodal varicose, and turbulence are observed. Unusually, the nonstandard EC (ns-EC) instability in this material, is observed in a regime in which we measure the dielectric and conductivity anisotropies to be negative and positive respectively. A further significant observation is that the EC displays distinct features in the high and low temperature regimes of the nematic phase, supporting an earlier report that EC patterns could distinguish between regions that have been reported as uniaxial and biaxial nematic phases.