Complex permeability and permittivity spectra of polycrystalline Ni–Zn ferrite samples with different microstructures

Abstract: Polycrystalline Ni–Zn ferrite samples with different microstructures have been prepared by the conventional ceramic technique, and their complex permeability and permittivity spectra have been studied. The permeability spectra have been resolved into contributions of domain wall resonance and spin rotation relaxation. The fitting results of permeability dispersion have revealed the relationships between domain wall resonance, spin rotation relaxation mechanisms, and microstructures. With increasing average grain size, the permittivity also gradually increased. However, extremely big grain size led to an uneven permittivity–frequency curve. These results may be rationalized in terms of the modifications of the microstructures brought about by the different sintering temperatures. [Copyright &y& Elsevier]