Effect of interaction on magnetic properties of a particulate medium

Samples of magnetic particles were prepared in dry powder form, as well as in a plastic binder system. Magnetic measurements were made on the samples as function of the volumetric packing factor. Coercive force H
c
, squareness, and anhysteretic magnetization measurements are correlated with the uniformity of particle dispersion. It was found that the behavior of H
c
, squareness, and the initial anhysteretic susceptibility as a function of the packing factor are good indications of the degree of dispersion of the particles. It is shown that if the particles are well dispersed, H
c
increased with increased dilution, and the initial anhysteretic susceptibility increased at both high and low dilutions. A mathematical model is developed to explain the observed results. The model consists of a double distribution of interaction fields to account for the well-dispersed and the agglomerated particles.