Dielectric Anisotropy in Liquid Crystal Phase ofp-Azoxyanisole

The dielectric constant ε' and the loss ε'' of p-azoxyanisole were measured under various magnetic field strengths and in the temperature range of 20 to 145°C. In the liquid crystal phase, both ε' and ε'' exhibited anisotropy produced by the magnetic field. Plots of ε' against θ under 2500 Gauss were fit by the experimental equation ε'=ε' 0 +(ε' 90 -ε' 0 ) cos 2 (θ-90), where θ is the angle between the electric and magnetic fields, and they were consistent with the Van Vleck theory. Under a weak magnetic field, however, they deviated from the Van Vleck theory. From these results, the mechanisms of the wall effect on the electrode are discussed. The relation between ε'' and θ is expressed as ε''=ε'' 90 +(ε'' 0 -ε'' 90 ) cos 2 θ.