Dielectric investigation on some binary mixtures of hockey-stick-shaped liquid crystal and octyloxy-cyanobiphenyl. (2nd September 2019)

• Record Type: Journal Article
• Authors: Chakraborty, Susanta; Chakraborty, Anish; Das, Malay Kumar; Weissflog, Wolfgang
• Is Part Of: Phase transitions. Volume 92:Number 9(2019)
• Page Start: 806
• Page End: 815
• Publication Date: 2019-09-02
• Subjects: Hockey-stick-shaped liquid crystal -- binary mixture -- dielectric anisotropy -- dielectric permittivity -- phase transition -- critical behavior; Phase transformations (Statistical physics) -- Periodicals; 530.47405
• DOI: 10.1080/01411594.2019.1642476
• Languages: English
• ISSNs: 0141-1594

Abstract

ABSTRACT: We report the measurement of temperature-dependent dielectric parameters in some binary liquid crystal mixtures comprising of a hockey-stick-shaped mesogen 4-(3-decyloxyphenyliminomethyl) phenyl-4-decyloxycinnamate (SF7) and calamitic compound 4′-octyloxy-4-cyanobiphenyl (8OCB). All the investigated mixtures possess a large positive dielectric anisotropy (Δ ε ), although a noticeable reduction has been found by increasing the diverse-shaped dopant concentration. Investigation on the pretransitional behavior in the vicinity of isotropic to nematic ( I – N ) phase transition suggesting a tricritical character for all the studied mixtures. Parameterization of dielectric permittivity close to the nematic to smectic- A ( N –Sm- A ) phase transition exhibits non-universal values of the critical exponents describing a second-order nature of the transition. Systematic variation of critical exponents against dopant concentration and McMillan ratio reveals a well consistency with those obtained from the high-resolution optical birefringence measurements.