Optical refracting properties, birefringence and order parameter in mixtures of liquid crystals: Direct smectic A - Isotropic and reverse isotropic - Smectic A phase transitions

Abstract

Due to the physical anisotropic and self-assembling nature, liquid crystalline materials holdvery important place in theoretical, experimental and applied physics. Besides, liquid crystals are important materials as working and active elements in various technical devices, optical and optoelectronic systems and technological processes.

In this work investigations of the thermo-optical properties of the monomorphic smectogens are presented. Homogeneous binary mixtures of 4-n-alkyl-4'-cyanobiphenyl mesogens were objects in these investigations. The optical refracting and birefringent properties, and behavior of the order parameter at the direct smectic A - isotropic and reverse isotropic - smectic A phase transitions are considered. Temperature dependences of the mean refracting index n refracting indices for the ordinary n(o) and extraordinary n(e) rays, and birefringence Delta n have been determined. Temperature dependences of the order parameter for the heating - cooling circular cycle at phase transitions are presented. (C) 2021 Elsevier B.V. All rights reserved.