COMPLEX IMPEDANCE AND DIELECTRIC-PROPERTIES OF AN MG-ZN FERRITE

Complex impedances of a sintered polycrystalline Mg0.5Zn0.5Fe2O4 ferri te in the frequency range of 15 mHz to 13 MHz were measured at several temperatures in the range of 273-373 K. The complex-plane impedance s pectra indicate that the material can be represented by a two-layer le aky capacitor which corresponds to the bulk and the grain boundary phe nomena at high and low frequencies respectively. A series resistance o f about the same value at all temperatures is observed. This resistanc e is believed to be due to the external contacts and the electrodes. A greement between experimental and simulated data is established by ass uming a frequency-dependent capacitive element. The results for the re lative dielectric constant epsilon'(r) and dielectric loss epsilon'(r) at low frequencies are discussed as being attributed to the interfaci al polarization; at high frequencies a Debye-like relaxation from orie ntational polarization is dominant. The dependence of impedance and di electric properties on temperature and frequency are discussed.