Enhancement of Saturation Magnetization and Remanence of BaFe12O19 Materials Prepared by NaCl–KCl and Hexamine as Flux

Abstract

Hexagonal platelet barium ferrite was produced through a two-step molten salt synthesis calcined at 850 °C for 5 h with NaCl–KCl as flux, followed by calcination at 400 °C for 5 h with hexamine. Influence of NaCl–KCl and hexamine on the structural, phase composition, surface morphology, and magnetic properties of BaFe12O19 was studied by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric/differential analysis, scanning electron microscopy, and a superconducting quantum interference device. The particles exhibited M -type barium hexaferrite nanoparticles with a product yield of 97.8% with a mean crystallite size of 81 nm for NaCl–KCl and 50 nm for hexamine. The infrared spectrum showed tetrahedral and octahedral positions in the absorption bands of hexagonal ferrite. As the atomic ratio of Ba:Fe:O is found to be 1:12.3:17.6, which is close to the stoichiometric ratio of BaFe12O19, it confirms the hexagonal structure of the sample. The plates are found to agglomerate, and variation in particle size was observed using scanning electron microscopy. The samples revealed better magnetic properties with a high saturation magnetization of 165.3 emu/g, higher remanence of 58 emu/g, coercivity of 929 Oe, and a squareness ratio of 0.35. This investigation was performed to examine the microstructure and the effect of crystallinity of the submicrometer BaFe12O19 powders on magnetic properties. This study also provides a promising method and total processing parameters to synthesize hard ferrite powders with improved hard magnetic properties and fine crystallite size.