Improvements in or relating to magnetic recording powders

Abstract

Abstract A magnetic recording powder is prepared by co-precipitating cobalt and iron hydroxides from an alkaline medium, heating the resultant precipitate in its mother liquor to convert it to a crystalline precipitate, preferably by heating under pressure to a temperature of at least 100 DEG C., especially 130 DEG C.-170 DEG C., separating the crystals, and heating them in a reducing atmosphere, preferably at 350 DEG C.-400 DEG C. for example in an atmosphere of hydrogen, carbon monixide, or city gas. The product may then be reoxidized by heating, for example to 200 DEG C. to 550 DEG C. in air. The mol. ratio of cobalt oxide to ferric oxide in the product is preferably not greater than 1:1 and especially from 0,2% to 3%.

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