FIELD-INDUCED PHASE-TRANSITION IN SMECTIC-C-(BETA)ASTERISK PHASE OF ANTIFERROELECTRIC LIQUID-CRYSTALS

Electric field dependence of complex dielectric constant and temperatu re dependence of switching current were measured in antiferroelectric liquid crystals for various optical purities. A two-step change in the dielectric constant of bias field and current peaks representing SmC (alpha) phase were observed in high optical purity MHPOBC. A molecula r orientational model to explain results of the two-step change is pro posed. The first and the second decrease in the dielectric constant co rrespond to the reorientation to the ferroelectric and antiferroelectr ic orderings, respectively, and the two-step change in dielectric cons tant for electric field is related to the generation of antiferroelect ric ordering in SmC (beta) phase.