Phase Transition between the Cholesteric and Twist Grain Boundary C Phases

TL;DR

This paper investigates the phase transition between the Cholesteric and Twist Grain Boundary C phases in liquid crystals, revealing a split transition with a novel superposed phase near the critical temperature.

Contribution

It introduces a mean field approach to determine the critical temperature and uncovers a new superposed TGB2q phase with degenerate layer inclinations.

Findings

The phase transition splits into two with the appearance of TGBA or TGB2q phases.

The TGB2q phase is a superposition of two degenerate TGBct phases.

The critical temperature Tc2 is determined for the phase transition.

Abstract

The upper critical temperature Tc2 for the phase transition between the Cholesteric phase (N*) and the Twist Grain Boundary C phase with the layer inclination tilted to the pitch axis (TGBct) in thermotropic liquid crystals is determined by the mean field Chen-Lubensky approach. We show that the N*-TGBct phase transition is split in two with the appearance of either the TGBA or the TGB2q phase in a narrow temperature interval below Tc2. The latter phase is novel in being superposed from two degenerate TGBct phases with different (left and right) layers inclinations to the pitch axis.