SOFT MODE DIELECTRIC-RELAXATION UNDER THE INFLUENCE OF BIAS ELECTRIC-FIELD OF A FERROELECTRIC LIQUID-CRYSTAL MIXTURE

Temperature dependent soft mode part of the complex dielectric constan t has been measured as a function of bias electric field both in the s mectic C and smectic A* phases for a ferroelectric liquid crystal (FL C) mixture. From the experimental data, soft mode relaxation frequency and dielectric strength have been determined both in smectic C and s mectic A phases. In smectic B* phase, relaxation frequency and invers e of dielectric strength of the FLC mixture does not follow the Curie- Weiss law. The critical exponent for the studied FLC mixture is 1.43. Dielectric results shows a dependence of soft mode dielectric strength and relaxation frequency with bias field near the transition temperat ure in smectic A phase to an extent of 1 degrees C above the transiti on temperature and above 1 degrees C bias field does not have any effe ct on relaxation frequency and dielectric strength It is observed that relaxation frequency increases with increasing bias held while the co rresponding dielectric strength decreases.