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 n o and extraordinary n e refractive indices has been investigated. The principal polarizabilities α 0 and α e , effective geometry parameter α eg and average polarizability α ave were calculated using the internal field model (Vuks approach). Behavior of the birefringence Δ n and the anisotropy of polarizability Δ α 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. [ABSTRACT FROM AUTHOR]