The Dielectric Anomaly Near the Transition from the Smectic A* to Smectic C* Phase and Visco-Elastic Properties of Ferroelectric Liquid Crystals |
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| Authors: | E P Pozhidayev L M Blinov L A Beresnev V V Belyayev |
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| Institution: | 1. Organic Intermediates &2. Dyes Institute , Moscow, USSR;3. Institute of Crystallography , USSR Acad. Sci. , 117333, Leninsky prosp. 59, Moscow, USSR |
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| Abstract: | A pyro-electric technique is developed which allows the measurement of the dielectric response near the A*-C* phase transition in ferroelectric liquid crystals. The temperature dependence of the elastic modulus K θ(T) corresponding to the molecular tilt in smectic layers is calculated from the experimental data. Direct pyro-electric measurements of the relaxation time for the spontaneous polarization P s and the data on K θ(T) allow us to calculate the temperature behaviour of the twist-viscosity γ1(T) for the smectic C* phase. The curves γ1(T) are compared for the smectic C* and the nematic phase of the same compound and the dependence of the twist viscosity on the molecular tilt angle in the C* phase is investigated. The results of the dielectic measurements are discussed in terms of the mean-field approximation. |
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| Keywords: | nematic mesogens odd/even effets vinyl groups |
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