Specific features of the approximation of the dielectric spectra of alkylcyanobiphenyl liquid crystals

Abstract

The frequency dependences of the longitudinal and transverse permittivities of oriented nematic liquid crystals belonging to the alkylcyanobiphenyl group n CB ( n =5–8) are measured in the relaxation region in the meter and decimeter wavelength ranges. It is established that the dispersion of the longitudinal permittivity is well approximated by the sum of two Debye processes with different relaxation times. The frequency dependence of the transverse permittivity is represented by the dispersion relation with a continuous distribution of relaxation times in a specified time range. It is demonstrated that, in the high-frequency range ( f >200 MHz), in which the dielectric spectra exhibit a number of weakly pronounced dispersion features, the total dispersion of the permittivity is adequately described by the sum of relaxation and resonance processes.