This book discusses the effect of the sintering temperature, sample temperature and frequency on the magnetic and dielectric properties and microstructure of the NixZn1-xFe2O4 with composition x=0.5 and 0.3 samples prepared by the conventional processing method. Complex-plane permittivity plots have been widely employed to reveal different types of dielectric polarization in polycrystalline ceramics. In this book we present a simple-manner adaptation of that technique to reveal magnetic polarization mechanisms using complex-plane permeability plots in a nickel-zinc ferrite material. The dielectric polarization was contributed by the interfacial and dipolar polarizations. Meanwhile the magnetization process was probably dominated by magnetic domain wall movement and magnetic spin rotation.