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:
Mar. 05, 2002
Filed:
Apr. 26, 2000
Shoji Inoue, Chiba, JP;
TDK Corporation, Tokyo, JP;
Abstract
The invention aims to provide a manganese-zinc ferrite exhibiting a high initial permeability over a broad band and especially in a low-frequency region of about 10 kHz and a method for preparing the same. A method for preparing a manganese-zinc ferrite by firing is characterized in that the firing includes a main temperature holding step at 1,200-1,450° C. and a thermal ramp-down step prior to the main temperature holding step, and the lowest temperature reached by the mid-firing thermal ramp-down step is set in the range of 1,000-1,400° C. and lower by at least 50° C. than the hold temperature of the main holding step, thereby obtaining a manganese-zinc ferrite comprising 50-56 mol % calculated as Fe O of iron oxide, 22-39 mol % calculated as MnO of manganese oxide, and 8-25 mol % calculated as ZnO of zinc oxide as main components, and having a mean crystal grain size of more than 50 &mgr;m to 150 &mgr;m.