Research on Ferrite Magnet Materials

Abstract

These experiments were carried out to investigate the effect of addition of various rare-earth oxides on the magnetic and physical properties of anisotropic or isotropic M-type (M=Ca, Sr, Pb, Ba) ferrites, and to make clear the effect of the use of a new manufacturing method and the additives on the properties of anisotropic W-type (W=Sr, Ba, Pb) ferrites.
In M-type ferrites, it was found the rare-earth oxide addition to these compounds (stoichiometric composition) was very useful in stabilizing the magnetoplumbite structure, and that these compound had excellent properties as a permanent magnet.
In M²⁺Zn₂-W-type ferrites, a new valuable manufacturing method which is characterized by the addition of M²⁺O(PbO, SrO, BaO) after semisintering treatment without atmosphere control was established. It was found that this process was very useful in stabilizing the W-type hexagonal structure, and in improving the magnetic properties of these compounds. It cleared that the effective additives for the W-type ferrites are CaO, SiO₂, Na₂O, La₂O₃, MgO, Al₂O₃.