Two Types of Dielectric Polarization

The real part of the dielectric constant, ε′, of a material having a polarizability due either to dipoles or to heterogeneity should be a decreasing function of frequency while the imaginary part, ε″, should have a maximum, a type of behavior usually designated as anomalous dispersion. The frequency at which anomalous dispersion occurs is determined by the time of relaxation, τ, of the polarization. For dipole polarizations changes of τ with temperature are due largely to changes in viscosity while for Maxwell‐Wagner polarizations the value of τ depends upon the dielectric constant and conductivity of the components of the dielectric. It is shown that for glycerine anomalous dispersion is observed at 30 cycles as well as at 98 × 10 6 cycles with no apparent discontinuity at intermediate frequencies. The value of ε″ max . increases with decreasing temperature as predicted for dipole polarizations. For halo‐wax and paper anomalous dispersion is also observed, but with the distinct difference from glycerine that the values of ε″ max . decrease with decreasing temperature. This behavior is predicted for Maxwell‐Wagner polarizations in a heterogeneous dielectric, one component of which has a considerably greater conductance than the other. It is indicated that the anomalous dispersion in halowax and paper is due to Maxwell‐Wagner polarizations while that in glycerine is due to dipoles.