Static and dynamic magnetic properties of CoZn substituted Z-type barium ferrite Ba3 Cox Zn2 - x Fe24 O41 composites

Abstract

The static and dynamic magnetic properties were studied for Z-type barium ferrites Ba3 Cox Zn2 - x Fe24 O41 with x = 0-2.0 and the corresponding composites, and the attenuation spectra of the composite materials were calculated from the complex permittivity and permeability. The anisotropy of Ba3 Cox Zn2 - x Fe24 O41 is modified from easy c-axis to easy c-plane at x = 0.4-0.8. The resonance and reflection characteristics of the composites are significantly different for c-axis and c-plane anisotropy. For c-plane anisotropy, only natural resonance exists, while for c-axis anisotropy, two resonances, the natural resonance and wall resonance, are observed. The static permeability μ0 ′ and the maximum imaginary permeability μmax ″ are increased, while the resonance is shifted to lower frequency, as the Co substitution is decreased. The predicted frequency response of reflection loss showed that Ba3 Cox Zn2 - x Fe24 O41 composites are good electromagnetic materials with low reflectivity and broad bandwidth at microwave frequency. © 2006 Elsevier B.V. All rights reserved.