Crystal structure and magnetic properties of Ga-Mn cosubstituted M-type strontium ferrite synthesized by sol-gel method

Abstract

The M-type hexagonal strontium ferrites substituted by Gd-Mn ions were synthesized by the sol-gel self-combustion method. The synthesized samples were researched by X-ray diffraction (XRD), Fourier transform infrared spectroscopy analysis (FT-IR), scanning electric microscopy (SEM), and vibrating sample magnetometer (VSM). The XRD and the FT-IR results show that the pure M-type hexagonal ferrites phase is successfully obtained in the samples with the substitution amount (x) from 0.00 to 0.09 of Gd-Mn. The VSM results show that, as the substitution amount (x) of Gd-Mn increases, the remanent magnetization (Mr) and saturation magnetization (Ms) of the Sr1-xGdxFe12-xMnxO19 gradually increase, and the maximum values of 39.53 emu/g and 23.73 emu/g were obtained when x = 0.09. When x continues to increase, Mr and Ms decrease slightly, but they are still higher compared with those of the unsubstituted one. The coercivity (Hc) of the samples after doping is much higher than the coercivity of the pure sample, but as the substitution amount x increases, the coercivity first increases and then decreases, while the maximum value of Hc is 6738 Oe at x = 0.06.