Electro-optical and dielectric characterizations of the Goldstone mode relaxation in ferroelectric chiral smectic C liquid crystals

Abstract

We report structural (helical pitch), electro-optical (tilt angle and spontaneous polarization) and dielectric (Goldstone mode) investigations of ferroelectric liquid crystals (FLCs) exhibiting the chiral smectic C phase (SmC(*)). All these characterizations were performed on two pure FLCs showing the SmC(*)-SmA-N(*) phase sequence and having small pitch, high spontaneous polarization and a large relaxation frequency. We have determined the Goldstone rotational viscosity and the twist elastic constant in the SmC(*) phase from the helical pitch, tilt angle, polarization, dielectric strength experimental data and from the relaxation frequency of the Goldstone-mode relaxation. An Arrhenius-type behaviour of the Goldstone rotational viscosity was obtained and the corresponding activation energies were evaluated.