title: Distortion-sensitive insight into the pretransitional behavior of 4-n-octyloxy-4'-cyanobiphenyl (8OCB).
abstract: Results of studies of the static and dynamic dielectric properties in rod-like 4-n-octyloxy-4'-cyanobiphenyl (8OCB) with isotropic (I)-nematic (N)-smectic A (SmA)-crystal (Cr) mesomorphism, combined with measurements of the low-frequency nonlinear dielectric effect and heat capacity are presented. The analysis is supported by the derivative-based and distortion-sensitive transformation of experimental data. Evidence for the I-N and N-SmA pretransitional anomalies, indicating the influence of tricritical behavior, is shown. It has also been found that neither the N phase nor the SmA phase are uniform and hallmarks of fluid-fluid crossovers can be detected. The dynamics, tested via the evolution of the primary relaxation time, is clearly non-Arrhenius and described via τ(T) = τ(c)(T-T(C))(-φ). In the immediate vicinity of the I-N transition a novel anomaly has been found: Δτ is proportional to 1/(T - T*), where T* is the temperature of the virtual continuous transition and Δτ is the excess over the 'background behavior'. Experimental results are confronted with the comprehensive Landau-de Gennes theory based modeling.
authors.affiliation: Institute of Physics, University of Silesia, Katowice, Poland. sylwester.rzoska@gmail.com
authors.forename: Sylwester J
authors.initials: SJ
authors.lastname: Rzoska
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Drozd-Rzoska
authors.forename: Prabir K
authors.initials: PK
authors.lastname: Mukherjee
authors.forename: David O
authors.initials: DO
authors.lastname: Lopez
authors.forename: Julio C
authors.initials: JC
authors.lastname: Martinez-Garcia
mesh_terms: D001713:Biphenyl Compounds / Q000737:chemistry*; D017097:Electric Impedance; D050866:Liquid Crystals / Q000737:chemistry; D044367:Phase Transition; D013696:Temperature
chemical_list: D001713:Biphenyl Compounds; C010574:biphenyl