Characteristics of effective permeability and resonance frequency for barium-ferrite∕epoxy composites

Effective static permeability μ0,e and effective resonance frequency fR,e have been studied for barium-ferrite∕epoxy composites with various volume concentrations p. As compared to bulk material, effective μ0,e is significantly small and effective fR,e is shifted to higher frequency. Further, both μ0,e and fR,e show nonlinear dependence on p. To understand these characteristics, a model that considers two-particle system and the demagnetizing interaction between the two particles in composites is proposed. Based on the model, two equations have been derived to predict the dependence of μ0,e and fR,e on p, which is consistent with the experimental result for barium-ferrite composites with c-plane anisotropy. In addition, an important correlation (μ0,e−1)fR,e2=pC, which is similar to Snoek’s law, is also obtained from the equations.