Dielectric relaxation studies in n-(4-octyloxy-2-hydroxybenzylidene)-4-carbethoxyaniline

Abstract

Temperature dependent dielectric spectroscopy of a newly synthesized compound N-(4-octyloxy-2-hydroxybenzylidene)-4-carbethoxyaniline, having a wide temperature range ($70 C) Smectic A (SmA) phase has been carried out in the frequency range 100 Hz-10 MHz. Dielectric permittivity and loss in the homeotropic (" 0 k and " 00 k ) and planar (" 0 ? and " 00 ? ) alignments of the molecules have been determined. Relaxation frequencies corresponding to the rotation of the molecules about their short axes have been found to lie below 1 MHz and exhibit Arrhenius behaviour. Relaxation frequencies corresponding to the rotation of the molecules about their long axes are expected to lie above 10 MHz. Dielectric anisotropy (Á" 0 ¼ " 0 k À " 0 ? ) has been found to be negative throughout the range of the SmA phase.

Dielectric relaxation study of a H shaped liquid crystal dimer

“…The small difference in the magnitude of the relative permittivity for planar and homeotropic alignment in the SmC phase indicates that this liquid crystal dimer has less anisotropic nature in the smectic phase as compared to other conventional nematic liquid crystal [14]. The anisotropic properties of the liquid crystals are important in determining the optical response of the liquid crystals [15]. The dielectric anisotropy of liquid crystals is manifested as a difference in the value of dielectric permittivity measured along the parallel direction to the long molecular axis " || and perpendicular to the long molecular axis " ?…”

Dielectric Relaxation of Dye-Doped Ferroelectric Liquid Crystal Mixture: A Comparative Study of Smectic C* and Smectic A Phase

“…The Cole-Cole equation is given by: [22][23][24][25][26]) Here " 0 is the dielectric strength of the relaxation and is the distribution parameter. On separating real and imaginary part of the above equation one may get after adding high and low frequency correction parameters.…”

“…12) The A f m term is added in (7) for the high frequency effect due to the ITO resistance and lead inductance. 25,26) By the best fitting of above equations into the experimental data we have removed the low and high frequency problems.…”