MAGNETIC-PROPERTIES AND CRYSTAL-STRUCTURE OF COMPOSITE BA-FERRITE PARTICLES CONTAINING ALPHA-FE

Composite Ba-ferrite particles containing alpha-Fe were prepared by re ducing Co-Ti-Sn substituted Ba-ferrite platelet particles in a hydroge n gas atmosphere. The coercivity of the composite particles increased to about three times that of the starting Ba-ferrite, and a magnetic e asy cone appeared when the saturation magnetization grew larger than 6 2 emu/g. The substitution cations, particularly the Ti ions; were show n to inhibit the transformation of the crystal structure through Seduc tion. The enhanced coercivity observed in the composite particles was due to the decrease of both Co ions as the substitution element and ir on ions at the 12k site. The magnetic easy cone seemed to be caused by the formation of paramagnetic iron ions in the particles, which inter rupted the superexchange interaction between magnetic iron ions.