Patent · US Expired

Production of cobalt-doped ferrimagnetic iron oxides

US4297395A · kind A · utility

14Cited by

7References

2Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Gunter Buxbaum · Krefeld, DE
Heinrich-Christian Schopper · Krefeld, DE
Lutz Leitner · Krefeld, DE
Volker Hahnkamm · Krefeld, DE

Key dates

Filing date	Jan 10, 1980
Grant date	Oct 27, 1981
Priority date	—
Expiry date	Jan 10, 2000

Classification

Technology area (CPC G)Physics
CPC primaryG11B5/70694
WIPO fieldAudio-visual technology
WIPO sectorElectrical engineering

Abstract

A cobalt-doped, acicular ferrimagnetic iron oxide having an FeO content of about 16 to 24%, by weight, and a cobalt content of about 0.7 to 2.4%, by weight, the coercive force amounting to at least about 425 Oe+175 Oe/%, by weight, of Co is produced by precipitating and oxidizing a cobalt-containing aqueous iron (ii) salt solution, reducing the precipitate to Fe.sub.3 O.sub.4, partially reoxidizing to adjust the FeO content and heat treating under inert conditions at a temperature from about 600.degree. to 800.degree. C.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.