Dielectric relaxation, dipole-moment components and order parameters in nematic mixtures of p-methoxybenzylidene-p-n-butyl- aniline and 4-n-heptyl-4′-cyanobiphenyl

Abstract

The dielectric relaxation spectrum of mixtures of p-methoxybenzylidene-p-n-butylaniline (MBBA) and 4-n-heptyl-4′-cyanobiphenyl (7CB) are reported in samples aligned parallel and perpendicular to the applied measuring field. Two dispersion processes are observed in the parallel aligned samples and a single broad dispersion in the perpendicular aligned samples. The experimental results show that the dielectric dispersion is a co-operative process and there is no evidence (on the time scale of the experiment) of the formation of any molecular complexing. The intensities are analysed to give give dipole-moment components parallel and perpendicular to the rotational axis of the polar entity involved in the dispersion process as well as the nematic order parameters.