Abstract
The variation of coercivity in annealing at 60°C and the printing effect of cobalt-substituted iron oxides with various contents of Fe2+ were examined. Except the samples containing Fe2+ less than 1 wt% the coercivity increased with annealing at 60°C, and the samples containing more Fe2+ showed higher coercivity. The increase of coercivity was attributed to the magnetic anisotropy induced in cobalt-substituted iron oxides by the spontaneous magnetic field of shape anisotropy. The existence of Fe2+ was considered to facilitate the migration of CO2+. The printing effect of cobalt-substituted iron oxides decreased with an increase of the annealing period at 60°C. The increase of Fe2+ content in samples resulted in the increase of printing effect. This printing effect was explained by the magnetic anisotropy induced in the direction of printing field.
