High coercivity in Sm-doped SrFe12O19 powders with spherical morphology prepared by ultrasonic spray pyrolysis

SrFe12O19 is widely used due to its low cost, stability and corrosion resistance. In this study, Sm-doped porous SrFe12O19 powder with high coercivity was synthesized using KCl-assisted spray pyrolysis. The Sm doping, microstructure and magnetic properties were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). The results showed that when Sm-doping amount was 0.2, the ferrite powder prepared by KCl-assisted spray pyrolysis had high coercivity of 7.286 kOe and saturation magnetization of 56.422 emu/g. The coercivity of the Sm-doped samples increased by 39.23 % compared with that of the undoped samples. The significant increase in coercivity was associated with the improvement of super -exchange interaction between Fe3+ particles caused by Sm doping, and the size decrease of the hexagonal plate Sr -ferrite particle caused by KCl action. The influencing mechanism of coercivity was discussed in detail based on the analysis of crystal structure and microstructure observation.