Phase Sequence in Smectic Liquid Crystals Having Fluorophenyl Group in the Core

The phase sequence of a new family of chiral smectic liquid crystals, represented by 4-(1-methylhepthyl-oxycarbonyl) 3-fluorophenyl 4'-dodecylbiphenyl-4-carboxylate (MHFPDBC), were investigated by measurements of dielectric dispersion under various bias field strengths. Three phases, ferrielectric smectic C-gamma(*) phase (Sm-gamma(*)), antiferroelectric phase (AF) and ferrielectric phase (FI), were confirmed between ferroelectric SmC* phase and antiferroelectric SmCA* phase. In the dielectric measurements around the ferrielectric phases, an opposite bias treatment prior to the application of the target bias field strength is important. Observed dielectric relaxation modes were discussed together with the results of electrooptical and conoscopic observations.