Thermotropic, refracting and birefringent properties in homogeneous mixtures of 4-n-alkyl-4′-cyanobiphenyl mesogens

In this work, studies of the thermotropic and thermo-optical properties in five homogeneous mixtures of 4-n-alkyl-4′-cyanobiphenyl mesogens have been carried out. Temperature behavior of the mean refractive index n, ordinary no and extraordinary ne refractive indices has been investigated. The principal polarizabilities α0 and αe, effective geometry parameter αeg and average polarizability αave were calculated using the internal field model (Vuks approach). Behavior of the birefringence Δn and the anisotropy of polarizability Δα as a function of temperature, and the order parameter in regions of the smectic A-nematic, nematic-isotropic liquid and smectic A-isotropic liquid phase transitions are discussed.