Electric field effect on dielectric constant of antiferroelectric liquid crystal (MHPOBC)

Abstract

A phenomenological model is elaborated for better understanding of the ferrielectric phase of the MHPOBC type antiferroelectric liquid crystals under an external electric field. The antiferroelectric phase stabilized by the two layer pairing interaction was found to become unstable as the electric field was increased above a threshold value E_c = 2JP₀ , where J is the nearest neighbor interaction constant of the molecular dipoles in the adjacent smectic layers and P ₀ the molecular dipole moment. When the applied electric field brings about the instability of the antiferroelectric phase, the three layer pairing interaction is assumed to stabilize the system at a different configuration corresponding to the ferrielectric ordering. The observed dielectric constant data of the antiferroelectric (R)-MHPOBC as a function of electric field could be understood in terms of the model within the acceptable range of parameters.