Dielectric and electrooptical responses of antiferroelectric liquid crystals in the Smectic-A phase

The Smectic-A (SmA) phases of the antiferroelectric liquid crystals (R)-MHPOBC, (R)-MHPOCBC and slightly racemized MHPOBC (R:S=17:3) have been studied by means of simultaneous measurements of the electric displacement and the tilt angle induced by the electric field. The SmA-SmCalpha* phase transition was observed in (R)-MHPOBC and (R)-MHPOCBC, while a phase transition similar to the SmA-SmC* one was observed in slightly racemized MHPOBC. In both cases, the Landau-type phenomenological theory explains well the critical behavior in the SmA phase, and the coefficients related to the theory can be determined.