We investigated the dielectric dispersion of two homologous series: n-alcylcyanobiphenyls (7CB, 8CB) and n-alcyloxy- cyanobiphenyls (70CB, 80CB) both in the isotropic phase and crystal states in the frequency range from 100 MHz to 1000 MHz. For each substance the dielectric spectra can well be described by the Debye equation with one relaxation time. It has been established that additional peaks at about 170, 280, 360, 450, 550 and 600 MHz exist in all spectra. Comparative analysis of the dielectric spectra has shown when the oxygen is disposed in the mesogenic core of the molecule his effect on frequencies of the peaks is absent. But in n-alcyloxy-cyanobiphenyl substances the peaks splitting and increasing in their strength are observed. The dispersion spectra were interpreted as a sum of Debye relaxation process and of resonance type.

Date Published: 27 June 2002
PDF: 4 pages
Proc. SPIE 4759, XIV Conference on Liquid Crystals: Chemistry, Physics, and Applications, (27 June 2002); doi: 10.1117/12.472161

Published in SPIE Proceedings Vol. 4759:
XIV Conference on Liquid Crystals: Chemistry, Physics, and Applications
Jolanta Rutkowska; Stanislaw J. Klosowicz; Jerzy Zielinski, Editor(s)