Dielectric properties of a surface stabilized ferroelectric liquid crystal in cells of various thickness

Abstract

Abstract Measurements of the complex dielectric permittivity have been performed in the frequency range of the collective director modes (101–106 Hz) in the vicinity of the S*C↔S*A phase transition of the compound 4-[(R)(-)-(2-chloro-3-methylbutanoyloxy)]-phenyl-[4n-decyloxy]benzoate and revealed that a dielectric relaxation process due to collective director fluctuations is active in the helically unwound S*C as well in the S*A phase, if the formation of the S*c helix is suppressed. A twisted and bent director configuration (splayed state) occurs in thin, planar oriented samples with various cell gaps (2–27 μm). The observed mode of Debye type was characterized as a function of temperature and cell thickness. By a decrease of the cell thickness the dielectric increment is lowered in the S*C phase but enhanced in the S*A phase. This Debye mode is only in part suppressed by the application of a bias electric field. With decreasing cell thickness its relaxation frequency decreases in the S*A phase, but incr...