DIELECTRIC-RELAXATION STUDY OF 1-N XYL-4-(4-ISOTHIOCYANATOPHENYL)BICYCLO[2,2,2]OCTANE IN THE NEMATIC AND ISOTROPIC PHASES

Dielectric relaxation investigations on the mesogen 1-n-hexyl-4-(4-iso thiocyanatophenyl)bicyclo [2,2,2]octane in the nematic and isotropic p hases have been carried out in the frequency region from about 1 kHz t o 1 GHz. Two relaxation processes have been observed in both the isotr opic and nematic phases, when the measurements of the electric permitt ivity versus frequency are made parallel to the orientation axis of th e liquid crystal. The possible mechanisms responsible for these two pr ocesses are discussed. The height of the potential barrier which hinde rs the rotation of the liquid crystal molecules around the short axis in the nematic state, and the order parameter of the liquid crystal un der investigation have been estimated on the basis of the values for t he relaxation times in the nematic and isotropic phases.