| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a hexagonal magnetoplumbite type ferrite having a small average plate diameter, an appropriate coefficient of variation of the plate diameter, an appropriate platy mineral aspect ratio and appropriate coercive force, and its production method, and to provide a magnetic recording medium showing a high short-wavelength output and a low medium noise when replayed using an MR head, by using the ferrite in a magnetic layer. <P>SOLUTION: The hexagonal magnetoplumbite type ferrite is obtained by forming a coprecipitate having a desired hexagonal magnetoplumbite type ferrite composition through an inverse micelle method, exposing the obtained coprecipitate to a microwave irradiation and heating it at 150-300°C. The ferrite has an average plate diameter of 10-30 nm, a coefficient of variation of the plate diameter of 5-25%, a platy mineral aspect ratio of 1.5-4.5 and coercive force of 125-400 kA/m. The magnetic recording medium is obtained by adding the ferrite to the magnetic layer as a magnetic powder. <P>COPYRIGHT: (C)2007,JPO&INPIT |
