Properties of Sm–Mn substituted M-type strontium ferrites synthesized by the sol-gel method

Abstract

M-type strontium ferrites Sr1-xLnxFe12-xMxO19 (Ln: Sm; M: Mn; x = 0, 0.03, 0.06, 0.09, 0.12) doped with equivalent Sm-Mn ions were synthesized via the sol-gel method. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electric microscopy (SEM) and vibrating sample magnetometer (VSM). The samples with x from 0.00 to 0.12 were confirmed to the single-phase M-type strontium ferrite, and the impurity phases Fe2O3 and SmFeO3 were detected when the content of dopants x ≥ 0.09. When x = 0.09, the saturation magnetization (Ms) and the remanent magnetization (Mr) of strontium ferrites Sr1-xSmxFe12-xMnxO19 reached to the maximum values of 37.19 emu/g and 22.48 emu/g, respectively. When x = 0.06, the coercive force (Hc) of strontium ferrites Sr1-xSmxFe12-xMnxO19 reached to the maximum values of 6224 Oe. Acid-treatment reduces the magnetic properties of the Sr1-xSmxFe12-xMmxO19 (x = 0.03). Compared to 950 °C preparation, preparation at 1200 °C decreases its magnetic properties and the Hc drop is very significant.