Dielectric Relaxation in Nematic Liquid Crystals
Dielectric Relaxation in Nematic Liquid Crystals
复制标题
向列液晶中的介电弛豫
DOI：
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发表时间：
1966
期刊：
影响因子：
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通讯作者：
A. Saupe
中科院分区：
文献类型：
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作者：
G. Meier;A. Saupe
摘要 在向列型均匀有序液晶中，可以测量两个主要介电常数：平行于液晶对称轴的 ε1 和垂直于液晶对称轴的 ε2。两个介电常数可能表现出非常不同的弛豫行为。对于偶氮苯的烷氧基衍生物，仅观察到微波频率下的正常德拜色散区域。对于氧化偶氮苯的烷氧基衍生物，ϵ2 再次仅在微波频率下显示正常的德拜色散区域，但 ϵ1 在无线电区域中非常不寻常的低频处具有额外的色散。这种分散是由于氧化偶氮基团的永久电偶极矩，更准确地说是由于其平行于分子长轴的分量。由于分子间力，该组分在方向 1 上的重新定向受到势垒的阻碍。相应的弛豫时间增加了 g 倍。从德拜介电弛豫理论的修改开始，这......
Abstract In homogeneously ordered liquid crystals of the nematic type, two principal dielectric constants can be measured: ϵ1 parallel and ϵ2 perpendicular to the symmetry axis of the liquid crystal. The two dielectric constants may show a very different relaxation behavior. With alkoxy derivatives of azobenzene, only the normal Debye dispersion region at microwave frequencies has been observed. With alkoxy derivatives of azoxybenzene, ϵ2 shows again only the normal Debye dispersion region at microwave frequencies, but ϵ1 has an additional dispersion at very unusually low frequencies in the radio region. This dispersion is due to the permanent electric dipole momment of the azoxy group, more exactly to its component parallel to the long molecular axis. The reorientation of this component in direction 1 is hindered by a potential barrier due to intermolecular forces. The corresponding relaxation time is increased by a factor g. Starting from a modification of the Debye theory of dielectric relaxation, this...