| 简介 |
The magnetic powder and the sintered magnet of the invention comprise a primary phase of a hexagonal ferrite containing A, Co and R (where A represents Sr, Ba or Ca, and R represents at least one element selected from the group consisting of rare earth elements (including Y) and Bi), and have at least two different Curie temperatures, wherein the two different Curie temperatures are present within a range of from 400 to 480 DEG C, and an absolute value of a difference therebetween is 5 DEG C or more. As both the saturation magnetization and the magnetic anisotropy of the M type ferrite therein are increased, the magnetic powder and the sintered magnet have a high residual magnetic flux density and a high coercive force, which conventional M type ferrite magnets could not have, while having extremely excellent temperature characteristics of coercive force. In particular, they have excellent magnetic characteristics as their coercive force lowers little even in a low temperature region, and in addition, they have excellent squareness in the demagnetization curve. Moreover, they still have excellent characteristics even though having a reduced content of expensive Co. Further, the magnetic powder and the sintered magnet as produced in an aqueous system have a high degree of orientation that is comparable to the degree of orientation of those as produced in a solvent system. The invention also provides motors and magnetic recording media having excellent characteristics. |
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