Discovery of a novel ferrielectric phase of five-layer periodicity in binary mixtures of chiral smectic liquid crystals exhibiting unusual reversed phase sequence

Abstract

In a binary mixture system of ferroelectric and antiferroelectric liquid crystals whose major component shows an unusual reversed phase sequence of , a new phase with ferrielectric order of five layers has been discovered by the electric field-induced birefringence (EFIB) measurements. The EFIB was measured using a photo-elastic modulator (PEM) set-up and by applying an in-plane electric field to a homeotropic aligned cell filled with the binary mixtures of compounds with ferroelectric and antiferroelectric compounds. The contours of constant birefringence in the electric field–temperature (E–T) phase diagrams clearly indicate a distinct region corresponding to a new phase bordering the four-layer on the low temperature side and on the high temperature side. This new phase is unambiguously assigned to whose structure has been calculated by Osipov and Gorkunov.

Keywords:

• anti ferroelectrics
• chiral smectics
• ferrielectric phase of five layer periodicity
• unusual reversed phase sequence

Acknowledgements

The Science Foundation of Ireland is thanked for funding this research.

Notes

Two simplest biaxial subphases other than the ordinary 3- and 4-layer ones, the emergence of which have been established by our electro-optical studies, are expected to have the superstructures predicted by the Osipov group. For more details, see PRE 72, 041705 (2005), [15, 20, 8]. In our paper in this issue, we found one of the superstructure with (5 layer periodicity) even in the unusual case of the extraordinary phase sequence. These superstructures may soon be confirmed by resonant X-ray scattering technique using SOR (synchrotron orbit radiation).