Patent Number: 6,309,479

Title: Spindle-shaped goethite particles, spindle-shaped hematite particles andmagnetic spindle-shaped metal particles containing iron as main component

Abstract: Spindle-shaped metal particles and a process for producing magneticspindle-shaped metal particle containing iron as a main component, whichcontains cobalt of 8 to 45 atm % calculated as Co, aluminum of 5 to 20 atm%, calculated as Al, and a rare earth element of 1 to 15 atm %, calculatedas rare earth element, wherein the particles have an average major axialdiameter of 0.05 to 0.15 .mu.m, an average minor axial diameter of 0.010to 0.022 .mu.m, an aspect ratio of 4:1 to 8:1, a particle sizedistribution of not more than 0.20, and an X-ray crystallite size D110 of12.0 to 17.0 nm. The spindle-shaped metal particles have a high coerciveforce, an excellent particle coercive force distribution, a largesaturation magnetization and an excellent oxidation stability, and areexcellent in a squareness (Br/Bm) of the sheet due to a gooddispersibility in a binder resin.

Inventors: Okinaka; Kenji (Ube, JP), Maekawa; Masaaki (Onoda, JP)


International Classification:

Expiration Date: 10/32013