Dielectric Properties of Strongly Polar Nematogens with Cyano and Fluoro Substituents
Dielectric Properties of Strongly Polar Nematogens with Cyano and Fluoro Substituents
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DOI：
10.1080/15421400903065762
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发表时间：
2009-01-01
影响因子：
0.7
通讯作者：
Dabrowski, Roman
中科院分区：
文献类型：
--
作者：
Czub, Joanna;Urban, Stanislaw;Dabrowski, Roman
在1 kHz - 3 GHz频率范围内研究了几种氰基和氟取代化合物的介电性能。大多数化合物在较宽的温度范围内呈现出非晶中间相。研究了各向同性相和非均匀相的介电常数主分量和弛豫过程。分析了分子的偶极结构。确定了表征主要分子运动的弛豫时间和活化能垒。这些物质的介电各向异性对频率有很强的依赖性：它在高频下改变其符号。这类化合物可用于配制双频寻址系统的混合物。
Dielectric properties of several compounds with cyano and fluoro substituents were studied in the frequency range of 1 kHz - 3 GHz. Most of compounds exhibit nematic mesophase in a broad temperature range. The principal permittivity components and the relaxation processes were studied in the isotropic and the nematic phases. The dipole structure of molecules was analysed. The relaxation times and the activation barriers characterizing the principal molecular motions were determined. The substances show strong dependence of the dielectric anisotropy upon frequency: it changes its sign at high frequencies. Such compounds are useful to formulation of nematic mixtures for double frequency addressing system.