Dynamic Behaviour of the Local Layer Structure of Antiferroelectric Liquid Crystals under a High Electric Field Measured by Time-resolved Synchrotron X-Ray Microbeam Diffraction

Abstract

The local layer structure response to a triangular electric field in an antiferroelectric liquid crystal cell has been measured using synchrotron X-ray diffraction with 3 ms time resolution and a few µm spatial resolution. The initially coexisting vertical and horizontal chevron structures are irreversibly transformed to the layer structure with a rearranged molecular orientation at the surface (so-called vertical bookshelf structure). After the irreversible transformation, the rearranged layer structure shows a reversible transition between the horizontal chevron (high field, ferroelectric state) and the combination of the modified vertical and horizontal chevron (low field, antiferroelectric state) associated with the field-induced antiferroelectric-ferroelectric transition. The reversible layer structure has a smaller horizontal chevron angle (a few degrees) than that in the initial state (about 17°). The detailed microbeam diffraction revealed that the layer structure at a low electric field consists of a broad vertical chevron with a small chevron angle and a bent bookshelf in combination with a horizontal chevron, depending on the analyzing position. The stripe texture is related to the modified horizontal chevron structure.