Oxide magnetic material, ferrite particle, sintered magnet, bonded magnet, magnetic recording medium and motor
US6139766A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 26, 1998 |
| Grant date | Oct 31, 2000 |
| Priority date | — |
| Expiry date | Oct 26, 2018 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B2235/96
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The invention aims to provide a ferrite magnet having a high remanence and a high coercivity which are unachievable with prior art hexagonal ferrite magnets, by realizing a hexagonal ferrite whose saturation magnetization and magnetic anisotropy are both high; a ferrite magnet having a high remanence and a high coercivity as well as significantly improved temperature properties of coercivity and experiencing a minimized drop of coercivity even in a low temperature range; a ferrite magnet having a high remanence and a high coercivity using relatively coarse ferrite particles with a particle diameter in excess of 1 .mu.m; and a magnetic recording medium having a high remanence and thermal stability. To achieve these objects, an oxide magnetic material comprising a primary phase of ferrite with na hexagonal structure and having a composition containing A, R, Fe, and M wherein A is at least one element selected from Sr, Ba, Ca and Pb, with Sr being essentially contained in A, R is at least one element selected from Bi and rare earth elements inclusive of Y, with La being essentially contained in R, and M is Co or Co and Zn, the proportions in total of the respective elements relative t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.