Dielectric relaxation spectra of a liquid crystalline (LC) material showing blue-phase-III (BPIII) for a considerably large temperature regime consisting of T-shaped molecules are investigated. A low frequency relaxation mode is observed in the isotropic phase ($I$) as well as in BPIII of the investigating material which is attributed to the short axis rotation of the T-shaped molecules. The outcome of the temperature and dc bias field variation of dielectric strength (Δε) and relaxation frequency (${\nu }_c$) in the vicinity of the $I$-BPIII transition is also discussed. The temperature dependence of ${\nu }_c$ in BPIII with a minor deviation from Arrhenius activities in the fluctuation-dominated nonlinear region (FDNLR) is found to follow the unusual thermal behavior of the activation energy ($E_A$). The growth of pretransitional fluctuations is found to be nonlinear in the vicinity of the $I$-BPIII transition. A moderate growth of transition fluctuation commences from the value of the exponent ${\alpha }_{\mathrm{eff}}=0.38$/°C, which is obtained by an exponential variation of ${\nu }_c$ with respect to temperature in BPIII. Observed dynamic phenomenon in the vicinity of the $I$-BPIII transition regions is explained on the basis of the Landau–de Gennes and Maier-Saupe Theories.

• Received 27 November 2012

DOI:https://doi.org/10.1103/PhysRevE.88.012502