LOW-FREQUENCY DIELECTRIC RESPONSE IN THE SMECTIC C-ASTERISK PHASE OF A FLC MIXTURE

Experimental studies of the dielectric response of a ferroelectric liq uid crystal (FLC) mixture having low spontaneous polarization at diffe rent temperature and frequency have been done in smectic C (Sm-C*) ph ase. The dielectric measurement were carried out on homogeneously alig ned samples. In the Sm-C phase the temperature dependent dielectric c ontribution of the Goldstone mode has been measured using two cells of thicknesses of 20 mu m and 100 mu m. Dielectric strength and correspo nding relaxation frequencies are determined. From the experimental res ults it has been observed that the variation of dielectric strength an d relaxation frequency with temperature are similar for the two cell, but the dielectric strength obtained for 20 mu m cell is higher than t hat obtained for 100 mu m cell at all temperatures. On the other hand the temperature dependence of relaxation frequency for both 20 mu m an d 100 mu m cell is almost the same. The mean field coupling coefficien ts between tilt and polarization are obtained from a fit of extended m icroscopic model for the interpretation of experimental results. The G oldstone mode rotational viscosity has been calculated from dielectric data. ?he results have been discussed.