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:
Aug. 02, 2022
Filed:
Dec. 04, 2019
Dowa Electronics Materials Co., Ltd., Tokyo, JP;
Fujifilm Corporation, Tokyo, JP;
Hirohisa Omoto, Tokyo, JP;
Shuji Kaneda, Tokyo, JP;
Hiroyuki Suzuki, Kanagawa, JP;
Toshio Tada, Kanagawa, JP;
DOWA ELECTRONICS MATERIALS CO., LTD., Tokyo, JP;
FUJIFILM CORPORATION, Tokyo, JP;
Abstract
Provided is a hexagonal ferrite magnetic powder for a magnetic recording medium, containing hexagonal ferrite magnetic particles having aluminum hydroxide adhered on the surface thereof, the hexagonal ferrite magnetic powder having an Al/Fe molar ratio of 0.030 to 0.200, a Co/Fe molar ratio of 0.002 to 0.030, and a Nb/Fe molar ratio of 0.005 to 0.050, and having an Fe site valence Aof 3.015 to 3.040 as calculated by A=(3+2×[Co/Fe]+5×[Nb/Fe])/(1+[Co/Fe]+[Nb/Fe]) wherein [Co/Fe] represents the Co/Fe molar ratio and [Nb/Fe] represents the Nb/Fe molar ratio, and preferably having an activation volume Vact of 1400 to 1800 nm. This magnetic powder simultaneously achieves an increase in magnetic characteristics including SNR of a magnetic recording medium and a further increase in durability thereof.