Some aspects concerning dielectric behaviour of copper containing magnetic ceramics

Since the polycrystalline ferrites are very good dielectric materials, the dielectric constant ε_τ and the loss tangent tgδ in copper-zinc, copper-nickel and copper-manganese ferrites has been studied as a function of composition, frequency and temperature. Interesting results were obtained concerning the dependence of the dielectric parameters on frequency and temperature. We have found that in these ferrites the Cu⁺ ions which appear during the sintering process by reduction of Cu²⁺ ions have a great influence upon the dielectric properties. As a result of the presence of Cu²⁺ ions, the copper containing ferrites show a p-type electric conduction. This fact determines an abnormal behaviour of the dielectric parameters as a function of frequency and temperature