Improved properties of BaFe12O19 prepared by ammonium nitrate melt technique and washed in HCl

We have synthesized BaFe12O19 samples by ammonium nitrate melt technique (ANMT) at temperatures from 850 to 1200 degrees C. Calcinations at 850-1000 degrees C yield single domain grains having reasonably high coercive fields up to 4500 Oe. Higher temperature calcinations decrease the coercive fields due to multi-domain grain growth. Washing the samples in HCl is effective to reduce the impurities, especially the antiferromagnetic BaFe2O4. HCl-washing increases magnetization by about 50%; the saturation magnetization increases from 36-45 to 58-62 emu/g and the residual magnetization from 21-26 to 32-34 emu/g. (c) 2005 Elsevier B.V. All rights reserved.