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:
Apr. 08, 1986
Filed:
Jun. 28, 1984
Applicant:
Inventors:
Assignee:
Fuji Photo Film Co., Ltd., Kanagawa, JP;
Primary Examiner:
Int. Cl.
CPC ...
H01F / ; C01G / ;
U.S. Cl.
CPC ...
427127 ; 252 6256 ; 427129 ;
Abstract
A process for preparing cobalt-modified ferromagnetic iron oxide by modifying ferromagnetic .gamma.-Fe.sub.2 O.sub.3 particles with cobalt, wherein prior to cobalt modification treatment, the ferromagnetic .gamma.-Fe.sub.2 O.sub.3 is heat treated at a temperature in the range of from about -200.degree. C. to +30.degree. C. of the critical temperature at which partial transition of .gamma.-Fe.sub.2 O.sub.3 into .alpha.-Fe.sub.2 O.sub.3 occurs and which reduces the saturation magnetization to 99% of the saturation magnetization measured before the heat treatment, and the atomic ratio of Fe.sup.++ /Fe.sup.+++ after the cobalt modification is 0.00 to 0.10.