Title :
Dielectric response and phase transition measurements of nematic liquid crystals at various temperatures in the frequency range near 9.00 GHz
Author :
Johri, G.K. ; Johri, M. ; Roberts, J.A.
Author_Institution :
Dept. of Phys., North Texas Univ., Denton, TX, USA
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
Keywords :
dielectric measurement; liquid crystal phase transformations; microwave measurement; nematic liquid crystals; 9 GHz; Slater´s perturbation equations; benziliclene butylaniline; cavity perturbation technique; dielectric response; frequency range; heplyl-cyano-biphenyl; loaded resonant microwave cavity; microwave cavity spectrometer; nematic liquid crystals; pentyl-cyano-biphenyl; phase charge monitoring; phase transition measurements; relaxation times; Dielectric liquids; Dielectric measurements; Electrochemical impedance spectroscopy; Equations; Frequency measurement; Liquid crystals; Microwave measurements; Phase measurement; Resonance; Temperature distribution;
Conference_Titel :
Conduction and Breakdown in Dielectric Liquids, 1990. ICDL 1990. Conference Record., 10th International Conference on
Conference_Location :
Grenoble
DOI :
10.1109/ICDL.1990.202904
