Influence of ionic conductivity and interfacial charges on the relaxation dynamics of smectic phases of an antiferroelectric material

Abstract

The results, reported here, are on the dielectric relaxation spectroscopy and the switching current behavior at the SmC ⁎ and SmC A ⁎ phases of an antiferroelectric liquid crystal (AFLC) material. It has been observed that a large number of ions are generated due to thermal energy in the studied AFLC compound. The mobility of these charges destabilizing the SmC ⁎ phase for 2 μm cell, moreover such charges creates an interaction making non-linear behavior of soft mode in Sm A phase. In 2 μm thin cell we have observed the coexistence of the SmC ⁎ and SmC A ⁎ phases by extending SmC ⁎ phase into certain temperature region of SmC A ⁎ phase. It is clear from the dielectric data that the thin cell helps to promote super-cooled state during cooling. The observed Maxwell-Wagner-Sillars (MWS) mode in SmC ⁎ phase appears at around 100 Hz for 10 μm cell due to the inhomogeonity of thermally generated ions between the layer planes as well as at the electrode surface of cell. In 2 μm cell, the MWS mode is shifted to lower frequency and superimposing with DC loss. It is observed experimentally that a new phase seems to be emerged at super-cooled temperature region in the 2 μm cell that may be due to the confined geometry of thermally generated ions and high surface anchoring force.