Abstract

Well dispersed and fine barium ferrite (BaFe₁₂O₁₉) powders have been successfully prepared by mechanically activating co-precipitated precursors, followed by calcination at 700 and 800 °C. When mechanically activated in a sodium chloride matrix for 20 hours, nanocrystallites of BaFe₁₂O₁₉, α-Fe₂O₃ and a spinel (γ-Fe₂O₃) phase of <10 nm in size were triggered in the co-precipitated precursor. Single phase barium ferrite platelets 50–100 nm in size were developed upon subsequent calcination at 800 °C for 1 hour. The resulting barium ferrite powder exhibits an intrinsic coercivity (_iH_c) of 436.7 kA m⁻¹ and a saturation magnetization (M_s) of 67.8 A m² kg⁻¹. These magnetic properties compare favorably with those of the materials derived from conventional calcination of the co-precipitated precursor without prior mechanical activation, which led to very poor powder characteristics.