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AssigneeU.S. Philips Corporation
InventorsAlbert Huizing, Cornelis P. G. M. Zegers, Johannen J. Brondijk
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The invention relates to a magnetic material for use in the magnetic recording and playback of information, which material consists of ferrite particles having the composition A.sub.1-y Zn.sub.y Fe.sub.2 O.sub.4, wherein A is one or more bivalent metal ions, which material is suitable for use in a recording medium having a high information density in that the magnetic material comprises monodisperse ferrite particles having an average particle size between 5 and 250 nm, preferably between 10 and 50 nm, and in that y is between 0.05 and 0.35. The magnetic material preferably is Co-Zn-ferrite. The material is manufactured by coprecipitation of a mixture of hydroxides succeeded by recrystallization at elevated temperature and pressure.
A magnetic material for use in the magnetic recording and playback of information, said material having a coercive force of from 10 to 150 k A/m and consisting of ferrite particles having the composition A.sub.1-y Zn.sub.y Fe.sub.2 O.sub.4, wherein A is one or more bivalent metal ions, characterized in that the ferrite particles have an average particle size between 5 and 250 nm, the ratio of the dimensions of the largest 10% of the particles to the dimensions of the smallest 10% is less than a factor of 2 and y is between 0.05 and 0.20.
Dependencies are inferred from the claim text.