Reentrant nematic and tricritical behavior of the nematic to smectic-A phase transition in liquid crystal mixture

Abstract

We present an improved analysis of the reentrant nematic and tricritical behavior of the nematic to smectic A phase transition in liquid crystal mixture within phenomenological theory. To describe the nematic–smectic A–reentrant nematic phase sequence in binary mixture, nematic and smectic order parameters have been coupled with the concentration. We show that reentrant nematic and the tricritical point on the N–SmA phase transition line can be achieved in the same phase diagram under certain conditions. We predict two tricritical points. One corresponds to nematic to smectic A phase transition and other corresponds to reentrant nematic to smectic A phase transition. A comparison of the results with experimental phase diagrams is described in great details. The predictions of the theory are in good agreement with available experimental data.