Tricritical behavior of the smectic-A to smectic-C~* transition

摘要

A phenomenological Landau-like theory is presented, which describes the tricritical behavior of thesmectic-A to smectic-C~* transition in a liquid crystal mixture. The influence of the concentration onthis transition is discussed by varying the coupling between the concentration variable and the orderparameters. It was observed from the theoretical calculations that for a particular value of theconcentration, the first order smectic-A to smectic-C~* transition becomes second order at a tricriticalpoint. Calculations based on this model agree qualitatively with experiment.