Dielectric and electro-optic behavior of pure ferroelectric liquid crystal material and the isomeric mixtures

We report here the dielectric relaxation spectroscopy and electro-optical properties of a ferroelectric liquid crystal (FLC) CB470 (R) and isomeric mixtures containing CB470 (R) and its optical isomer CB480 (S) in two different concentrations. We have studied with two isomeric mixtures: mixing CB470 (R) and CB480 (S) in the ratio 95:5 (w/w) and 90:10 (w/w). With increase of percentage of 08480 (S) in the mixture the spontaneous polarization (P-S) value has been decreased due to cancellation of a part of the dipolar contribution, since the direction of P-S of the two isomers are in opposite direction. The tilt angles of the pure FLC materials anti the isomeric mixtures remain almost unchanged. The dielectric strength of Goldstone mode is almost proportional to the spontaneous polarization (P-S). An additional collective mode has been observed in the SmC* phase due to the formation of domain with large periodicity in pure FLC material and in one of the isomeric mixtures by unwinding the helical Structures, which is known as domain mode. The existence of domain mode has been studied extensively with the variation of P-S in the isomeric mixtures. The result has been discussed. (C) 2008 Elsevier B.V. All rights reserved.