High performances boron doped γ-Fe2O3particles prepared from oxalic precursors

γ-Fe₂O₃ particles (L≈0.15 to 0.2 μm, L/D≈2 to 5) with coercivity up to 400 Oe have been prepared from oxalic precursors. To preserve the particle form, the oxalates were doped with boron. The effects due to this element was studied during the different thermal treatments which effect the pseudomorphous transformation of oxalate particles into spinel ferrite. ESCA spectroscopy, and X-ray measurements could point out the presence of a Fe₃BO₅ phase at the surface of γ-Fe₂O₃ particles. In spite of the important mass losses (H₂O, CO, CO₂) and the important crystallographic structure modifications occurring during the transformation of oxalate into magnetic oxide, γ-Fe₂O ₃ particles obtained by this method have very good textural characteristics. Boron-doped γ-Fe₂O₃ particles were used to make 3.5-in diskettes with standard formulation. In these conditions, media properties were comparable to trading diskettes properties