Electric Field Effect on Chiral Smectic Phases of Antiferroelectric Liquid Crystal

Optical measurements using a photoelastic modulator and dielectric measurements under DC electric fields have been conducted on the chiral smectic phases of the antiferroelectric liquid crystal 4-(1-methyl heptyloxycarbonyl phenyl) 4′-octyloxy biphenyl-4-carboxylate (MHPOBC). The detailed electric field-temperature phase diagrams of MHPOBC have been obtained, in which a tricritical point was found on the SmA–SmCα* phase transition line. Furthermore, the soft mode condensation inducing the SmA–SmCα* phase transition was observed successfully in a very narrow temperature region in the SmA phase by dielectric measurements under DC electric fields.