Structural and magnetic properties of SrFe12O19 hexaferrite synthesized by a modified chemical co-precipitation method

M-type strontium hexaferrite (SrFe12O19) particles had been prepared by a modified chemical co-precipitation route. Structural and magnetic properties were systematically investigated. Rietveld refinement of X-ray powder diffraction results showed that the sample was single-phase with the space group of P63/mmc and cell parameter values of a=5.8751 A and c=23.0395 A. The results of field-emission scanning electronic microscopy showed that the grains were regular hexagonal platelets with sizes from 2 to 4 mum. The composition determined by energy dispersive spectroscopy is the stoichiometry of SrFe12O19. The ferrimagnetic to paramagnetic transition was sharp with Curie temperature TC=737 K, which further confirmed that the samples were single phase. However, it was found that the coercivity, saturation magnetization and the squareness ratio of the synthesized SrFe12O19 samples were lower than the theoretical values, which could be explained by the multi-domain structure and the increase of the demagnetizing factor.