Finding optimal Fe/Ba ratio to obtain single phase BaFe12O19 prepared by ammonium nitrate melt technique

In the present work, the magnetic properties and the phase composition of barium ferrite BaFe12O19 powders prepared by the ammonium nitrate melt technique with Fe/Ba ratios varying from 2 to 13 was investigated. We observed that BaFe2O4 phase is formed at low values of Fe/Ba ratios (2–6) and α-Fe2O3 phase is formed at high values of Fe/Ba ratio as secondary phases. BaFe2O4 phase could be easily eliminated from the structure by washing the annealed powders with diluted HCl. HCl-washing is not effective for the elimination of α-Fe2O3 phase. Consequently, we succeed to obtain high quality single phase BaFe12O19 powders at low Fe/Ba ratios. Highest specific saturation magnetization Ms of the powders with Fe/Ba ratio of 2 was determined to be 66.7 emu/g.