Temperature-dependent dielectric characterization of 4-hexyl-4 0 -[2-(4-isothiocyanatophenyl)ethyl]-1,1 0 -biphenyl (HIEB), which exhibits smectic B and nematic phases, has been carried out over the frequency range of 1 Hz to 10 MHz for homeotropic and planar alignment of sample molecules. This compound shows positive dielectric anisotropy (Á" ¼ " k À " ? 40) in the nematic (N) phase. One mode of dielectric relaxation showing Arrhenius behaviour has been detected in the hexatic smectic B (SmB) phase. Various electrical parameters, namely, dielectric anisotropy, relaxation frequency and activation energy, have been determined in the N and SmB phases.

We report here some interesting optical textures and phase behavior exhibited by the binary mixtures of Cholestryl 5-(4-((4-hexylphenylimino) methyl)-3-hydroxyphenoxy) pentanoate (C74) and n-Butyloxybenzylidene-p-pentylaniline (BBPA). The samples with 1% to 30% of BBPA exhibit smectic and cholesteric phases. The intermediate concentrations ranging from 30% to 70% of BBPA exhibit smectic A, smectic C Ã , smectic G, smectic F and smectic B phases. The mixtures with higher concentrations from 71% to 99% of BBPA show Blue phase -N Ã -TGBA -TGBC -TGBC Ã -UTGBC Ã -Sm A phases, Sequentially. The phase behavior exhibited by the samples of different concentrations of BBPA has been studied using polarizing microscope and from the DSC recordings.