Preparation of magnetic alloy particles from metal and phthalate ions in dimethyl sulfoxide

Magnetic particles suitable for recording media are prepared by dissolving a metal salt (nickel, cobalt, iron, or their mixtures) in dimethyl sulfoxide to form a metal complex which is reacted with the phthalate ion (also dissolved in dimethyl sulfoxide) to produce the metal phthalate which precipitates with addition of water. The supernatant liquid is decanted, leaving the precipitate, which is washed with an aqueous solution to remove residual dimethyl sulfoxide. Reduction of the dried precipitate in the presence of hydrogen forms magnetic particles, cubic in structure, and of a particle size averaging between 0.03 and 1.5 microns.