Dielectric response and phase transition measurements of nematic liquid crystals at various temperatures in the frequency range near 9.00 GHz

Abstract

Dielectric-response and phase-transition measurements of nematic liquid crystals at various temperatures in the frequency range near 9.00 GHz were made using a microwave cavity spectrometer. The liquid crystals chosen for study were pentyl-cyano-biphenyl (PCB) and heplyl-cyano-biphenyl (HCB). The relaxation times for these crystals were calculated using Slater's perturbation equations for a loaded resonant microwave cavity. The measured data for benziliclene butylaniline (MBBA) have also been incorporated into the analysis to compare the trend of variation of relaxation time for PCB and HCB. It is concluded that the cavity perturbation technique is a useful method for monitoring the phase changes in liquid crystals.<>