Studies of some material constants of a SmC* ferroelectric liquid crystal mixture

Abstract The material constants, (1) the tilt angle (θ), (2) the helical pitch (Zo), (3) the spontaneous polarization (Ps), (4) the critical fields (Ec) to unwind the helix and (5) the switching time of ferroelectric liquid crystal mixture, FCS 101, in its SmC* phase have been studied. Our experimental data show that Ps∝ t0.5 and θ ∝ t0.3 at lower temperatures, where, t = (Tc−T)/Tc . The dependence of both the critical fields Ec and E'c on temperature are obtained experimentally. Ec , ΔE'c show the temperature relation as (Tc − T)0.53±0.04 and (Tc − T)0.59±0.01 respectively. The ratio of these critical fields, 0.71, is found to be temperature independent. The switching time is found to be of the same order (≃ 2 ms) as electro-optic response time. The agreement between the experimental and calculated P ko values is found to be poor. This discrepancy shows the inadequency of the theory so far developed. The differences between the real and ideal situations are discussed.