Distortion-sensitive insight into the pretransitional behavior of 4-n-octyloxy-4 %26apos;-cyanobiphenyl (8OCB)

作者：Rzoska Sylwester J^*; Drozd Rzoska Aleksandra; Mukherjee Prabir K; Lopez David O; Martinez Garcia Julio C

来源：Journal of Physics: Condensed Matter , 2013, 25(24): 245105.

DOI：10.1088/0953-8984/25/24/245105

Results of studies of the static and dynamic dielectric properties in rod-like 4-n-octyloxy-4%26apos;-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 tau(T) = tau(c)(T - T-C)(-phi). In the immediate vicinity of the I-N transition a novel anomaly has been found: Delta tau proportional to 1/(T - T*), where T* is the temperature of the virtual continuous transition and Delta tau is the excess over the %26apos;background behavior%26apos;. Experimental results are confronted with the comprehensive Landau-de Gennes theory based modeling.

• 出版日期2013-6-19