AN INVESTIGATION OF THE FIELD-INDUCED FERRIELECTRIC SUBPHASES IN ANTIFERROELECTRIC LIQUID-CRYSTALS

We report results of detailed investigations of the dielectric response of two antiferroelectric liquid crystal materials over a wide range of frequencies as a function of bias voltage and of temperature. On the basis of extensive measurements of the tilt angle, the spontaneous polarization, and the optical transmittance as a function of voltage, we conclude that there appears to exist a previously undetected, new field-induced phase (referred to as the X phase) with uniform monodomain structure. This new phase seems to be stable over a wide range of applied voltages and possesses effective values of spontaneous polarization and tilt angle within 70-80% of their maximum values. Although the results appear to rule out the presence of the SmCalpha* phase, nevertheless, the new phase has some characteristics similar to those of the SmCalpha* phase. The differences between the characteristics of the two phases are detailed.