Dielectric properties and conductivity of zinc ferrite and zinc ferrite doped with yttrium

The electrical properties of spinel ferrites are determined by the different factors, of which synthesis method, chemical composition and grain size have the most important role. In this paper we investigate dielectric behavior and conductivity of the nanosized ZnFe2O4 and Y0.15Zn0.85Fe2O4 powders obtained by the coprecipitation method. The frequency dependence of the dielectric permittivity, the loss factor, and the conductivity of the samples are determined in the frequency range from 1 Hz to 100 kHz, at temperatures from 300 to 350 K. The dielectric behavior of ferrites is explained by the interface polarization, arising from the heterogeneous nature of its structure. Increasing trend of electrical conductivity (σ) and decreasing trend of the dielectric permittivity (ɛ) with increasing frequency are explained by the Koops model. The maximum values of tan δ are noticed in the frequency range from 1 to 10 kHz.