Low Frequency Dielectric Response in the Smectic C* Phase of a FLC Mixture

Abstract

Experimental studies of the dielectric response of a ferroelectric liquid crystal (FLC) mixture having low spontaneous polarization at different temperature and frequency have been done in smectic C* (Sm-C*) phase. The dielectric measurement were carried out on homogeneously aligned samples. In the Sm-C* phase the temperature dependent dielectric contribution of the Goldstone mode has been measured using two cells of thicknesses of 20μm and 100 μm. Dielectric strength and corresponding relaxation frequencies are determined From the experimental results it has been observed mat the variation of dielectric strength and relaxation frequency with temperature are similar for the two cell, but the dielectric strength obtained for 20μm cell is higher than that obtained for l00μm cell at all temperatures. On the other hand, the temperature dependence of relaxation frequency for both 20μm and l00μm cell is almost the same. The mean field coupling coefficients between tilt and polarization are obtained from a fit of extended microscopic model for the interpretation of experimental results. The Goldstone mode rotational viscosity has been calculated from dielectric data. The results have been discussed.