Development of La-Co Substituted Ferrite Magnets

Abstract

The effect of the simultaneous partial substitution of Co2+ for Fe2- and of La3- for Sr2+ ion in Sr ferrite on the magnetic properties of anisotropic Sr ferrite magnets was investigated. It was found that the coercive force iHc of Sr ferrite magnets is increased without significant decrease in residual flux density Br by La-Co substitution. The temperature coefficient of coercive force was found to be also improved by La-Co substitution. The residual orbital magnetic moment of Co2+ ion is considered to play a main role to increase the coercive force of La-Co substituted Sr ferrite magnets.Based on these results, the new grade (9B) Sr ferrite magnets were developed, whose typical magnetic properties are Br = 440 mT (4400 G), iHc = 350kA/m (4400 Oe).