U.S. Philips Corporation

Johannen J Brondijk

Albert Huizing

Cornelis P Zegers

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.

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Eindhoven, Netherlands

Johannen J Brondijk