ABSTRACTA combustion-synthesis method [Chick et al., Materials Letters 10, 6 (1990)] has been adapted for the efficient preparation of pure barium ferrite particles, BaFe12O19. Solutions of Ba(NO3)2 and Fe(NO3)3 · 9H2O were mixed in stoichiometric amounts and glycine (aminoacetic acid) was then added according to the desired glycine / nitrate ratio. The solution was heated to around 200°C, when combustion occured, yielding a highly magnetic ash, which XRD suggests consists of extremely fine-grained γ-Fe2O3 and Ba3Fe2O6. Subsequent heat-treatments of 1050°C for 1.5 hr or 1200°C for 1 hr converted the ash to pure barium ferrite, as determined by XRD and Mdssbauer spectroscopy. Single-crystal platelets of barium ferrite, identified by SEM, varied dramatically in size with heat-treatment (diameter ∼0.2 pm and 6 μm, respectively), as did coercivity, measured by VSM (∼5000 Oe and 2500 Oe, resp.), while magnetization was unaffected.
