The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 09, 1979
Filed:
Dec. 16, 1977
Masakazu Oshimura, Ibaraki, JP;
Kenichi Yokoyama, Ibaraki, JP;
Yukihiro Hayashi, Ibaraki, JP;
Akira Miyake, Ibaraki, JP;
Hitachi Maxell, Ltd., Ibaraki, JP;
Abstract
Acicular ferromagnetic metal particles having a particle size of 0.1 to 1 .mu.m and a dimension of crystallite-size of not more than about 215 A in the effective thickness of the crystallite in the direction perpendicular to the reflecting plane (110), which have a high coercive force, preferably not less than 1,400 oersteds and are useful for a high-density magnetic recording tape, video mother tape, or permanent magnet material, and a method for the preparation of the ferromagnetic metal particles comprising reducing with heating goethite particles which are prepared by treating a ferrous salt with a large amount of a basic agent, particularly an alkali metal hydroxide.