Microstructure and magnetic property of M-type SrRe(x)Fe(12-x)O19 by sol-gel method

Magnetoplumbite-type (M-type) SrRE(x)Fe(12-x)O19 (RE = La and Ce, x = 0-1.0) powders were prepared by a citric acid sol-gel technique and subsequent heat treatment. The crystal structure, grain size and magnetic properties were investigated by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and vibrating sample magnetometer (VSM). The XRD patterns show that SrRE(x)Fe(12-x)O19 (RE = La and Ce) are mainly hexagonal magnetic plumbite structure, and the average grain size of 30-40 nm was calculated using the Scherer's equation based on the XRD spectrum. Substitution of Fe ion by the rare earth La ion causes a significant decrease in intrinsic coercivity (Hc) and a slight decrease in saturation magnetization (Ms) as shown in the magnetization hysteresis loops. However, the Hc rises gradually in a small wave pattern with the increase of doping content of the rare earth Ce. The relation between the crystal structure and magnetic properties was also studied in this work.