Influence of surfactants on co-precipitation synthesis of strontium ferrite

► Three surfactants SDS, nonionic surfactant (PEG-6000), CTAB, were applied. ► The ferrite precursors were calcinated with KCl and NaCl in order to lower the calcination temperature. ► The effects of Fe 3+/Sr 2+ mole ratio were first verified and annealing temperatures were then discussed. Strontium ferrite (SrFe 12O 19) particles were prepared by co-precipitation method. The ferrite precursors were produced from aqueous mixtures of ferric chloride and strontium nitrate by co-precipitation, using 3 mol/L sodium hydroxide aqueous solutions as precipitant. Three surfactants sodium dodecyl sulfate (SDS), polyethylene glycol 6000 (PEG-6000), cetyltrimethylammonium bromide (CTAB), were applied and the influence of surfactants on the properties of the strontium ferrite particles was studied. The ferrite precursors were first precalcined in a muffle furnace at 400 °C and then mixed with KCl and NaCl using a planetary milling machine in order to lower the calcination temperature. Subsequently the mixtures were calcined at various temperatures. Structure and magnetic properties of the particles were characterized by X-ray powder diffraction, transmission electron microscopy and vibrating sample magnetometer. In this paper, effects of Fe 3+/Sr 2+ mole ratio were first verified and annealing temperatures were then discussed. The results show the strontium ferrite phase begins to form at 650 °C and complete at 800 °C after calcination, and the particles prepared using CTAB exhibit the best properties with respect to particle size and dispersibility.