Low-frequency dispersion in carrier-dominated dielectri

Abstract

Some dielectric materials with large densities of low-mobility charge carriers show an anomalous low-frequency dispersion of the real and imaginary components of the complex dielectric permittivity, both varying as ω ⁿ⁻¹ , with n close to or equal to zero. This behaviour is likely to be found in any dielectric material at sufficiently low frequencies, but is seen in particular in the presence of sufficiently high densities of charge carriers. With non-zero values of n, the behaviour is linear and the proposed interpretation involves strong dipolar interactions within the framework of a recently proposed ‘universal’ model of dielectric response. With n = 0, the process is non-linear and is interpreted in terms of the formation of Schottky barriers at electrodes which are blocking to the charge carriers in question. Neither response is readily understandable in terms of Maxwell-Wagner and similar circuit-simulation mechanisms.