Magnetite microcrystals for magneto-rheological fluids

We report a new synthetic method for the preparation of micrometric prismatic crystals of magnetite by means of a coprecipitation reaction of aqueous solutions of iron salts and ammonium oxalate, followed by thermal decomposition of the precipitate in an inert atmosphere. Magnetite prismatic crystals grown by this procedure are homogeneous in size and morphology. We also study the structure and orientation of the magnetic domains.