Direct fabrication and characterization of metal doped magnesium ferrites from treated laterite ores by the solid state reaction method

Metal doped magnesium ferrites were directly synthesized from saprolite and limonite laterite ores by using an alkali fusion-solid state reaction method. Samples were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectrometer (FTIR), and Physical Property Measurement System (PPMS) to determine the structural and magnetic properties. The effects of the treated saprolite to limonite laterite ore mass ratio (MTSL/TLL, 4:6, 5:5 and 6:4 g g–1), calcination temperature (700, 900, 1000 and 1100 °C) and SiO2 content (2%, 3% and 5%) on the phase change and magnetic properties of as-prepared samples were investigated in detail. The results showed that single-phase cubic spinel ferrite could be obtained when the MTSL/TLL and calcination temperature were controlled at 6:4 and 1000 °C, respectively. With the calcination temperature increasing from 700 to 1100 °C, the saturation magnetization (Ms) value increased from 18.4 to 43.2 emu g–1 while the coercivity (Hc) value decreased from 165 to 60 Oe, which was mainly attributed to the improvement of crystallinity and purity of synthesized ferrites. In addition, increasing the SiO2 content from 2% to 5%, the Ms value decreased from 45.4 to 31.5 emu g–1 because of the occurrence of spin canting. And the decrease of Hc value from 120 to 75 Oe might be ascribed to the reduction of anisotropy energy.