Landau Theory of Nematic-Smectic-A Transition in a Liquid Crystal Mixture

Abstract

Binary mixtures of HBAB {p-[(p-hexyloxy-benzylidene)-amino] benzonitrile} and CBOOA [N-p-cyanibenzylidene-p-n-octyloxyaniline] exhibit a two phase region where both smectic-A and nematic phase coexists. The reason for this two phase region is discussed by means of Landau formalism. The problem of the first or second order nature of the nematic-smectic-A phase transition is explored. General Landau theory for coupled orientational, translational order parameters and concentration is developed.

Key Words:

• Nematic phase
• smectic phase
• phase transition