Retardation of Molecular Relaxation in Highly Ordered Antiferroelectric Phase

Abstract

ABSTRACT Dielectric and DSC methods were used to study liquid crystalline compound MHPNBC exhibiting para-, ferro-, ferri-, antiferroelectric and a highly ordered antiferroelectric like phase. Two dielectric relaxation processes were revealed in the ferroelectric phase: typical Goldstone mode in the whole temperature range and the soft mode in the pre-transition region on both sides of the Curie temperature. In the antiferroelectric phase two relaxation processes were found: anti-phase fluctuations and reorientation around the short molecular axis. Using dielectric spectroscopy it has been found that the latter process is strongly retarded at the transition to the highly ordered phase. In this phase there is only one collective dielectric relaxation process left which may be due to anti-phase fluctuations.