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

Effective static permeability mu(0,e) and effective resonance frequency f(R,e) have been studied for barium-ferrite/epoxy composites with various volume concentrations p. As compared to bulk material, effective mu(0,e) is significantly small and effective f(R,e) is shifted to higher frequency. Further, both mu(0,e) and f(R,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 mu(0,e) and f(R,e) on p, which is consistent with the experimental result for barium-ferrite composites with c-plane anisotropy. In addition, an important correlation (mu(0,e)-1)f(R,e)(2)=pC, which is similar to Snoek's law, is also obtained from the equations. (c) 2008 American Institute of Physics.