Dielectric Dispersion in 4′-n-Alkyl-4-Cyanobiphyenyls

The dispersion of ϵ∥ in the frequency range of 1-10 MHz has been studied for 4′-n-alkyl-4-cyanobiphenyls (pentyl to octyl) at different temperatures in teh nematic phase. It is established for the first time that the relaxation frequency at a common relative temperature (TNI - T) for the successive homologues shows an alternation similar to that exhibited by the nematic-isotropic transition point or the orientational order parameter. The activation energy evaluated from the Arrhenius plot is found to be the same (∼ 0.56 eV) for the compounds.