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:
Sep. 30, 2025
Filed:
Sep. 29, 2020
The University of Tokyo, Tokyo, JP;
Dowa Holdings Co., Ltd., Tokyo, JP;
Shin-Ichi Ohkoshi, Tokyo, JP;
Asuka Namai, Tokyo, JP;
Hiroko Tokoro, Tokyo, JP;
Marie Yoshikiyo, Tokyo, JP;
Kazuhiro Yamaga, Tokyo, JP;
Yasuto Miyamoto, Tokyo, JP;
Yuki Mineyama, Tokyo, JP;
Kenji Sakane, Tokyo, JP;
Tetsuya Kawahito, Tokyo, JP;
DOWA HOLDINGS CO., LTD., Tokyo, JP;
THE UNIVERSITY OF TOKYO, Tokyo, JP;
Abstract
A raw material solution containing trivalent iron ions, or trivalent iron ions and ions of a metal element that partially substitutes Fe sites, and an alkaline aqueous solution for neutralizing the raw material solution are added to a reaction system to adjust the pH of the reaction system from 1.0 to 3.0 or lower. Hydroxycarboxylic acid is added to the obtained reaction solution and the pH of the reaction system is then neutralized from 7.0 to 10.0 or lower. The obtained precipitate of a substituent metal element-containing iron oxyhydroxide is coated with silicon oxide, followed by heating so as to form particles of ε-iron oxide in which Fe sites are partially substituted by other metal elements, and then, a slurry containing the particles is classified. The iron-based oxide magnetic powder has a particle shape close to a perfect sphere and is suitable for use in a magnetic recording medium.