Variations of coercive force with packing densiy in fine magnetic oxide powder

Abstract

The variation of coercive force (iHc) with packing density in acicular and granular gamma ferric oxides, acicular and cubic cobalt doped gamma ferric oxides and hexagonal and granular barrium ferrite (BaO⋅6Fe2O3) was studied.The iHc of these samples was measured at room temperature by a ballistic method in the low packing range (P=0.08-0.7g/cc/p).The variation of their iHc with packing density depended on the morphological properties of their particles; In case of the acicular particles, the Me was remarkably or slightly decreased with increasing packing density. (b) the granular and cubic paticles, the iHc did not change with packing density. and (c) the hexagonal particles, the Me was increased with increasing packing density. In case of mixture of magnetic oxides and non magnetic oxides, the change of the iHc was the same as that of magnetic oxides only.Hitherto, the variation of the iHc with packing density had been supposed to be affected by the interaction among particles and by the crushing of particles. In this paper, the variation of the Me with packing density was suggested to be due to the effect of the orientation of particles as well as the morphologic properties.