Effects of La-Co Substitution and Ratio of Ba and Sr on Anisotropic Magnetic Field of Fe₂-W Ferrites

Abstract

It is known that the anisotropic magnetic fields are improved by La and Co substitutions for M-type ferrite sintered magnets, and the coercive forces are significantly improved. On the other hand, since W-type ferrites have a crystal structure similar to that of M-type ferrites, it is expected that La-Co substitution would improve magnetic properties in the same way. However, evaluations of the effects of La and Co substitution are difficult because sintered bodies with a single phase of W-type has not been obtained and sintering at high temperatures is required. Recently, a method to determine the anisotropic magnetic fields using the saturation asymptotic law was proposed by T. Kuno et al., J. Jpn. Soc. Powder Powder Metallurgy 63 (2016) 1053, which makes it possible to evaluate the anisotropic magnetic fields. In this study, La-Co substituted W-type ferrite powders in the Ba, Sr and (Ba-Sr) based systems were prepared, and the effects of La-Co substitution and the ratio of Ba and Sr on the anisotropic magnetic fields were investigated.