Abstract
A series of non-acicular particulate media with coercivity of up to 2150 Oe, residual magnetization of up to 50 emu/g and squareness ratio of up to 0.72 has been developed based on γ-Fe2O3, modified with Mn, Co and Zn. They were prepared by coprecipitation of Fe, Mn, Co, and Zn ions from an aqueous solution, using an organic alkali, such as triethylamine, to adjust the pH, followed by suitable annealings. The fine particle size of around 50 nm, strong magnetocrystalline anisotropy and annealed directional ordering are possible causes of high coercivity. These media are potential candidates for high density recording.