Electroconvection with and without the Carr-Helfrich effect in a series of nematic liquid crystals.
Electroconvection with and without the Carr-Helfrich effect in a series of nematic liquid crystals.
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DOI：
10.1103/physreve.70.011711
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发表时间：
2004-07
期刊：
影响因子：
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通讯作者：
Elżbieta Kochowska;S. Németh;G. Pelzl;A. Buka
中科院分区：
文献类型：
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作者：
Elżbieta Kochowska;S. Németh;G. Pelzl;A. Buka
报道了四种具有负介电各向异性ε和不同符号的电导率各向异性σ a（相对σ a; a= σ a/σ（垂直）范围为-0.6至+0.3）的同系物的电对流实验研究。具有正电导率各向异性的同系物遵循标准理论模型的预测，而具有负sigmaa的同系物则显示出一种现象，即，非标准的电对流，不是由Carr-Helfrich机制描述的，而是以主要平行于初始指向矢的条纹的形式表现出来，因此具有与标准EC的辊的形态相似性。其余两个同系物改变其电导率各向异性的标志与温度，导致一个双重的字符，从标准到非标准的电对流交叉。标准和非标准EC的模式进行了表征和比较。
Experimental electroconvection (EC) investigations on four homologs with negative dielectric anisotropy epsilona and conductivity anisotropies sigmaa of various signs (the relative sigma; a=sigmaa/sigma(perpendicular) ranges from -0.6 to +0.3 ) are reported. The homolog with positive conductivity anisotropy follows the predictions of the standard theoretical model, while the homolog with negative sigmaa shows a phenomenon, i.e., nonstandard electroconvection, not described by the Carr-Helfrich mechanism but manifesting in forms of stripes mainly parallel to the initial director, thus having a morphological similarity to the rolls of the standard EC. The remaining two homologs change the sign of their conductivity anisotropy with temperature that leads to a twofold character by crossing over from standard to nonstandard electroconvection. The patterns of both the standard and nonstandard EC have been characterized and compared.