Improvement of the magnetic properties of barium hexaferrite nanopowders using modified co-precipitation method

Barium hexaferrite BaFe12O19 powders have been synthesized using the modified co-precipitation method. Modification was performed via the ultrasonication of the precipitated precursors at room temperature for 1 h and the additions of the 2% KNO3, surface active agents and oxalic acid. The results revealed that single phase magnetic barium hexaferrite was formed at a low annealing temperature of 800 deg. C for 2 h with the Fe3+/Ba2+ molar ratio 8. The microstructure of the powders appeared as a homogeneous hexagonal platelet-like structure using 2% KNO3 as the crystal modifier. A saturation magnetization (60.4 emu/g) was achieved for the BaFe12O19 phase formed at 1000 oC for 2 h with Fe3+/Ba2+ molar ratio 8 using 5 M NaOH solution at pH 10 in the presence of 2% KNO3. Moreover, the saturation magnetization was 52.2 emu/g for the precipitated precursor at Fe3+/Ba2+ molar ratio 12 in was achieved for the precipitated precursor ultrasonicated for 1 h and then annealed at 1200 oC for 2 h. Coercivities from 956.9 to 4558 Oe were obtained at different synthesis conditions. - Highlights: → Sonochemical assisted co-precipitation method improved the magnetic properties of barium hexaferrite. → Addition of 2% KNO3, 500 ppm CTAB, 500 ppm SDS and oxalic acid led to the formation of BaFe12O19 at low annealing temperature of 800 deg. C. → Microstructure of the pure BaFe12O19 appeared as hexagonal platelet-like structure. → Good saturation magnetization (60.4 emu/g) was achieved for the formed BaFe12O19 phase at 1000 deg. C for 2h with Fe3+/Ba2+ molar ratio 12 using NaOH at pH 10 in the presence of 2% KNO3. → Wide coercivities (956.9-4558 Oe) were obtained at different synthesis conditions.