Dielectric Relaxation and Order Parameters in the Nematic and Smectic Phases of 4-n-octyl-4′-cyanobiphenyl (8CB)

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Abstract
The dielectric properties of 8CB in the smectic and nematic phase over the frequency range up to 200 MHz are reported. Two relaxation processes are observed in samples where the director is aligned parallel to the measuring electric field and a broad relaxation process is observed in the perpendicular alignment. The relaxation times do not change significantly at the transition between the smectic and nematic phase, but the activation energy for dipole reorientation appears lower in the smectic phase than in the nematic phase. The results are interpreted to yield the dipole components responsible for the various relaxation processes and also the order parameters.