Synthesis and characterization of nano-crystalline strontium hexaferrite using the co-precipitation and microemulsion methods with nitrate precursors

Nano-crystalline strontium hexaferrite (SrFe12O19) powder was synthesized using the classical co-precipitation and microemulsion methods. The precursors were obtained by precipitating Sr2+ and Fe2+ ions using tetramethylammonium hydroxide and calcinating at different temperatures ranging from 400 °C to 1000 °C in air. The influence of the Sr2+/Fe3+ mol ratio and the calcination temperature on the product formation and magnetic properties were studied. The formation of nanosized particles of SrFe12O19 with a relatively high saturation magnetization Ms = 64 Am2/kg, remanent magnetization of Mr = 39 Am2/kg and a coercitivity of Hc = 5.5 kOe was achieved at a Sr2+/Fe3+ mol ratio of 1:8 calcined at 900 °C. The formation of the SrFe12O19 was inspected using XRD analysis, thermogravimetric analysis (TGA), differential thermal analysis (DTA), TEM, and magnetic measurements.