Oxidation of ferrous hydroxides with nitrate: A versatile method for the preparation of magnetic colloidal particles

► Ferrous hydroxide oxidation with NO3- is a versatile synthesis method. ► It permits the synthesis of nano- and micrometric magnetite particles. ► It enables the preparation of magnetite particles with increasing surface roughness. ► Superposition of a magnetic field results in the formation of rod-like particles. ► Particles of various ferrites can be obtained by addition of divalent cations other than Fe2+.