Abstract
Some magnetic properties of γ-Fe2O3 powders for magnetic recording have been measured as a function of packing density.
The samples were prepared by the methods in the previous reports, all having different particle size and shape. Histeresis loop, coercive force BHC and induction Bm were measured on these samples by a ballistic method at the coefficient of packing density over the range from 10% to 60%.
The results were as follows : (1) The coercive forceBHC was strongly influenced by the average length to diameter ratio of the particle. (2) The BHC values of single domain particles decreased with increasing packing density and the changes were almost linear. The slope of BHC packing density curves increased with increasing axial ratio. The decrease. of BHC with the compression was supposed to be affected by the interaction among nearby particles and by the crushing of the particles. (3) The induction Bm increased with increasing packing density, and the these relations being almost linear.
