Magnetic Properties of Ba-Zn-System W-Type Hexagonal Ferrite Magnets

Ba-Zn system W-type hexagonal ferrite magnets were prepared by a new manufacturing method in which BaO was added after semisintering treatment, and without atmosphere control. This process was found to be very useful in stabilizing the W-type hexagonal structure. The optimum conditions for making magnets, and some properties of typical specimens, are as follows: chemical analysis Ba<inf>1.092</inf>Zn<inf>1.725</inf>-Fe<sup>2+</sup> <inf>0.410</inf>Fe<sup>3+</sup><inf>15.848</inf>O<inf>27</inf>; semisintering conditions 1275°C×1.0 hr in air; sintering conditions 1225°C×0.5 hr in air; magnetic and physical properties J<inf>m</inf>=0.405 T, J<inf>r</inf>=0.364 T, H<inf>cJ</inf>=86.0 kA/m, H<inf>cB</inf>=82.0 kA/m, (BH)<inf>max</inf>=18.5 kJ/m<sup>3</sup>, T<inf>C</inf>=330°C, H<inf>A</inf>=987.0 kA/m, K<inf>A</inf>=1.87×10<sup>5</sup>J/m<sup>3</sup>, and n<inf>B</inf>=33.7¿<inf>B</inf>.

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