Magnetic properties of a new family of rare-earth substituted ferrites

The magnetic properties of substituted hard-magnetic M-type ferrites are surveyed. A combined La-Co substitution leads to magnets of compositions Ba 1-xLa xFe 12-xCo xO 19 and Sr 1-xLa xFe 12-xCo xO 19 (x = 0, 0.1, 0.2, 0.3, 0.4). Due to this substitution, the anisotropy as well as the coercivity increases. The effect of the ion size was studied on the system (Sr 1-yCa y) 1-xLa xFe 12-x Co 0.75xFe 2+ 0.25xO 19 (x= 0.2, 0.4; y = 0, 0.33, 0.66, 1). Additionally, Sm substitution which leads to a strong increase of the coercivity was studied, but the effect on the anisotropy is small (1%)