Experimental study of dielectric relaxation in 4-cyano-4-n-hexyl biphenyl nematic liquid crystal

Microwave cavity spectrometer has been used to measure the width of resonan t profile and the shift of the resonant frequency. The observed data are an alyzed to determine permittivity, dielectric loss and relaxation time. The relative variation of dielectric loss and permittivity at different tempera tures has been studied for the purpose to monitor the phase changes in the range 282 degrees K to 314 degrees K and to identify the transition tempera tures. We have used two frequencies 9.0 GHz and 29.867 GHz to see the frequ ency dependence for the purpose to compare relaxation mechanism. The techni que used is useful as it needs if small quantity (< 0.001 cm(3)) of the sam ple and provides fruitful information about the macroscopic structure of th e liquid crystal. The transition temperatures are TC -->N = 287.6 degrees K and TN -->I = 301.9 degrees K.