Magnetic materials square loop

Chem. Ges. 42,2248,1909). The ferrites are synthesized from Fe203 and the oxide, hydroxide, or carbonate of one or more divalent metals, e.g. Ba, Zn, Mn, Ni, Co, Mg or Cu. The firing process must be carefully controlled to maintain the required state of oxidation. Mg-Mn ferrites have a square hysteresis loop BaO-fiFejOj is a hard , or permanent, magnetic material. 

The hysteresis characteristics of soft magnetic materials may be enhanced for some applications by an appropriate heat treatment in the presence of a magnetic field. Using such a technique, a square hysteresis loop may be produced, which is desirable in some magnetic amplifier and pulse transformer applications. In addition, soft magnetic materials are used in generators, motors, dynamos, and switching circuits. 

The present most challenging problem of nanocomposite materials is their comparatively low coercivity. Recent values of the coercivities of isotropic magnets are presented in fig. 25. As seen, most of these magnets have coercivities less than 400 kA/m, except for some of the recently developed high-coercive powders. The values of coercivity are still comparatively small for industrial applications. Substitution of Dy or Tb for Nd is one way to increase the magnetic anisotropy of the main phase, and that has been tried by some groups (Coehoorn et al. 1989, Kanekiyo et al. 1993). These improvements, however, are at the expense of the magnetization and loop squareness. 

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