Electric Field Induced Patterns and their Temperature Dependence in a Bent-Core Liquid Crystal

TL;DR

This study investigates electroconvection patterns in a bent-core nematic liquid crystal, revealing their temperature dependence and the transition behaviors between different stripe patterns under varying frequency and voltage conditions.

Contribution

It provides new insights into the temperature-dependent behavior of electroconvection patterns in bent-core liquid crystals, highlighting an isotropic mechanism of pattern formation.

Findings

Longitudinal and oblique stripe patterns depend on frequency range.

Pattern contrast increases as temperature approaches Tc.

Onset voltages increase moderately with temperature, indicating an isotropic mechanism.

Abstract

Two kinds of electroconvection (EC) patterns in an ether-bridged bent-core nematic liquid crystal material (BCN), which appear in different frequency ranges, are examined and compared in this paper. One is a longitudinal pattern with the stripes parallel to the orientation of the BCN and with a periodicity of approximately the cell thickness, occurring in the high frequency range of several hundreds Hz; the other one is oblique stripes, which results in a zig-zag pattern, and appears in the low frequency range of several tens Hz. In addition, within an intermediate frequency range, transformations from oblique to longitudinal and then to normal stripes occur at increased ac voltages. In particular, we investigated the temperature behavior of longitudinal and oblique stripes: when the temperature T increases and approaches the clearing temperature Tc, the contrast of the domains is enhanced and the frequency range of existence becomes wider, while the onset voltages increase only moderately instead of diverging, thus suggesting an isotropic mechanism of pattern formation.