Basf Aktiengesellschaft

Basf Aktiengesellschat

Udo Kullmann

Hartmut Hibst

Peter Rudolf

Werner Steck

Helmut Jakusch

Dieter Mayer

Werner Grau

Peter Heilmann

Guenter Vaeth

Rainer Feser

Christine Guttner

A process for the preparation of cobalt-containing isotropic magnetic iron oxides which are based on gamma-iron(III) oxide, contain from 2 to 7% by weight of cobalt(II) ions and less than 2% by weight of Fe(II) ions, the percentages in each case being based on the iron oxide, and have a particle length of from 0.08 to 0.30 .mu.m, a length/width ratio of from 1.5 to 3.5:1 and a specific remanent magnetization after saturation of not less than 60 nTm.sup.3 /g.

Preparation of cobalt-containing isotropic magnetic iron oxides

A process for the preparation of finely divided ferrites of the general formula

Preparation of finely divided ferrite powders

Magnetic recording media possess, on a dimensionally stable base which may or may not be provided with a non-magnetic lower layer, a thin ferromagnetic metal layer on which a protective layer consisting of a silicon monoxide/chromium dual coating is applied.

Magnetic recording media with a dual protective coating of silicon

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Dirmstein, Germany

Udo Kullmann