EFFECT OF FE2+ CONTENT ON THE INSTABILITY OF COERCIVITY OF COBALT-SUBSTITUTED ACICULAR IRON-OXIDES

The variation in coercivity was examined by annealing at 60°C cobalt-substituted acicular iron oxides with various Fe2+ and cobalt contents. Except for samples containing less than 1 wt%Fe2+, the coercivity increased by the annealing at 60°C, and samples containing more Fe2+ showed higher coercivity. The increase of coercivity was attributed to the magnetic anisotropy induced in cobalt-substituted acicular iron oxides, and the existence of Fe2+ was considered to facilitate the migration of cobalt ions. The dependence of coercivity on. © 1979 IEEE