Frequency dispersion of dielectric permittivity-voltage hysteresis during field driven ferroelectric-antiferroelectric-ferroelectric transition in antiferroelectric liquid crystal (SmC_A~*)

摘要

Dielectric permittivity at different polarizing states during field driven ferroelectric-ferroelectric (F-F) transition and the dielectric relaxation spectra in the antiferroelectric liquid crystal (AFLC) phase have been studied to elucidate the interaction processes involved during the transition. The unwinding process of antiferroelectric helix has been found to be governed by the polar coupling between the applied field and the antiferroelectric polarization vector followed by nonpolar interaction with the dielectric anisotropy of the tilted molecules. Frequency dependence of the permittivity-voltage hysteresis behavior observed during the F-F transitions is concluded to be due to different relaxation processes involved in the AFLC phase.