Phase Behawour and Birefringence Studies of a Liquid Crystal Binary Mixture

Abstract

The phase diagram of binary system of 4-n-pentyl 4′-cyanobiphenyl (5CB) and 4-Pentyl Phenyl trans-4 pentyl cyclohexane carboxylate (D55) is presented, which shows the presence of an injected smectio-A phase and a higher order smectic phase (SmG). Refractive indices (n0, ne) and densities for different compositions of this mixture and for one pure compound (D55) are measured. The orientational order parameters <P2> are determined from the polarizability values (αoαe) which are calculated using both Vuks' as well as Neugebauer's internal field models. The experimental order parameter values for the samples having smectic A phase have been compared with McMillan's theory and with Maier-Saupe theory for the nematic cases.