Synthesis and characterization of SrFe12O19 powder obtained by hydrothermal process

We have synthesized strontium hexaferrite particles in an alkaline medium using a hydrothermal process at 180 °C. Our results show that to obtain a quasi-single SrFe12O19 phase, the Fe/Sr ratio in the initial solution must be equal to 8. However, the powders obtained contain traces of α-Fe2O3 and SrCO3. The SrFe12O19 hexaferrite particles are hexagonal-shaped platelets about 2 μm wide and 40 nm thick. When heated to 1000 °C, SrCO3 reacts with SrFe12O19 to give Sr4Fe6O13. According to XRD analysis, Mössbauer spectrometry and magnetic measurements, the magnetization axis of the single-phase SrFe12O19 particle is perpendicular to the platelets. For an Fe/Sr ratio higher than 8, the α-Fe2O3 phase becomes the major phase and for a ratio lower than 8, the amount of SrCO3 increases. For an Fe/Sr ratio equal to 5, the formation of the Sr3Fe2(OH)12 phase is also observed.