Preparation of acicular, ferrimagnetic iron oxides

US4497723A · kind A · utility

Assignee

• BASF SE

Inventors

• Manfred Ohlinger · Bischofswerda, DE
• Guenter Vaeth · Schifferstadt, DE
• Peter Rudolf · Ludwigshafen, DE
• Wilhelm Sarnecki · Schifferstadt, DE
• Helmut Jakusch · Bischofswerda, DE
• Eberhard Koester · Bischofswerda, DE
• Milena Melzer · Ludwigshafen, DE

Key dates

• Filing date: Jun 27, 1983
• Grant date: Feb 5, 1985
• Expiry date: Jun 27, 2003

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01P2006/42
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

A process for the preparation of acicular ferrimagnetic iron oxides by reducing gamma-iron(III) oxide hydroxide to magnetite, at from 280.degree. to 620.degree. C., by means of an organic compound which is decomposable at this temperature in the presence of iron oxide, and, optionally, a stream of reducing gas, and, if desired, then oxidizing the magnetite with oxygen-containing gases, at from 150.degree. to 450.degree. C., to acicular ferrimagnetic iron oxide of the formula FeO.sub.x, where x is from above 1.33 to 1.50, wherein the organic compound used for the reduction is a non-polar glycerol ester of a fatty acid which is introduced into the aqueous reaction suspension during the preparation of the gamma-iron(III) oxide hydroxide.