Influence of Pressure on Smectic a-Nematic Phase Transition

Abstract

We propose a Landau-de Gennes phenomenological model to describe the pressure induced smectic A-nematic phase transition. The influence of pressure on smectic A-nematic phase transitions are discussed for varying coupling between orientational and translational order parameter with pressure. Increasing the pressure, the first order nematic-smectic A transition becomes second order at a tricritical point which agrees fairly well with available experimental results.

Neutrino Spin Relaxation in Medium With Stochastic Characteristics

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Binary mixtures of nCB and nOCB liquid crystals. Two experimental evidences for a smectic A–nematic tricritical point

“…To make this coupling stronger, McMillan thought that the ratio T AN /T NI , (where T NI is the nematic to isotropic transition temperature and T AN is the semectic-A to nematic transition temperature), called the McMillan ratio, should be near to one, its theoretical limit value being higher than 0.87. Experimental evidence for TCP can be found on phase diagrams of temperature versus pressure 4,5 or composition. [6][7][8][9][10] In fact, the most studied phase diagrams are the two-component systems at ordinary pressure for which the experimental results show tricritical points for a somewhat higher theoretical value of the McMillan ratio.…”

Pressure induced tricritical point at the cholesteric-smectic-A phase transition

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