Sumitomo Special Metals Co., Ltd.

Hitachi Metals, Ltd.

Shuji Anamoto

Isamu Furuchi

Sachio Toyota

Seiichi Hosokawa

The ferrite magnet powder of the present invention is magnet powder having, as the major phase, a La&mdash;Co magnetoplumbite ferrite where La and Co are substituted for Sr and Fe, respectively, represented by (1&minus;x)SrO.(x/2)La O .(n&minus;y/2)Fe O .yMO wherein x, y, and n represent mole ratios and satisfy 0.22&minus;0.02&lE;x&lE;0.22&plus;0.02, 0.18&minus;0.02&lE;y&lE;0.18&plus;0.02, and 5.2&lE;n&lE;6.0, where x>y.

Ferrite magnet powder and magnet using the magnet powder, and method for preparing them

An La&mdash;Co ferrite magnet powder, in which Sr and Fe are replaced with La and Co, respectively, is made by carrying out a calcination process at a temperature higher than 1300&deg; C. and equal to or lower than 1450&deg; C. Fe has a magnetic moment oriented upwardly with respect to a crystal c-axis at a number of sites thereof, and also has an opposite magnetic moment oriented downwardly with respect to the crystal c-axis at another number of sites thereof. And Fe is replaced with Co at the greater number of sites thereof. As a result, high coercivity is attained. In this manner, coercivity can be increased while suppressing decrease in saturation magnetization &sgr; .

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Osaka, Japan

Shuji Anamoto