Spindle-shaped goethite particles, spindle-shaped hematite particles and spindle-shaped magnetic iron based alloy particles
US6183868A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 13, 1999 |
| Grant date | Feb 6, 2001 |
| Priority date | — |
| Expiry date | Sep 13, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2991
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The present invention relates to spindle-shaped goethite particles and spindle-shaped hematite particles, which have a narrow particle size distribution, include no dendrites, and have an appropriate particle shape and a large aspect ratio (major axial diameter/minor axial diameter); and spindle-shaped magnetic iron based alloy particles which are obtained from the spindle-shaped goethite particle or spindle-shaped hematite particles as a beginning material and which have a high coercive force and an excellent coercive force distribution. Such spindle-shaped goethite particles comprises: goethite seed containing 0.5 to 25 atm % of Co based on the total Fe in the spindle-shaped goethite particles, and goethite surface layer containing 0.5 to 15 atm % of Al based on the total Fe in the spindle-shaped goethite particles; and having an average major axial diameter of 0.05 to 1.0 .mu.m.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.