Dielectric anisotropy of nematic 4-pentil-4 '-cyanobiphenyl

The dielectric anisotropy and dispersion of the real part of permittivity o f 4-pentil-4'-cyanobiphenyl (5CB) were investigated in the relaxation frequ ency range from 10 MHz to 500 MHz. Two frequencies f(1) = 30 MHz and f(2) = 350 MHz characterizing the change of a sign of the dielectric anisotropy w ere obtained. The Debye relaxation fitting procedure showed that a quality of the fits was satisfactory in defining the frequency f(1), but there were discrepancies between the experimental and fitting results for the frequen cy f(2). It is due to the appearance of singularities on the dielectric spe ctrum around 300 MHz. The dielectric spectra are interpreted as a superposi tion of dielectric relaxation and resonance contribution. It was shown that isotropic phase and diluted solution of 5CB in benzene display the resonan ce dispersion region too.