Evidence of existence of metastable SrFe12O19 nanoparticles

Abstract The existence of metastable hexaferrite is reported. Synthesis of strontium hexaferrite, SrFe 12 O 19 , at 400 °C was realized under controlled oxygen atmosphere. Such technique allows obtaining of SrFe 12 O 19 at lower temperatures than those by traditional methods (above 800 °C). Phase transformation occurred during a measurement of magnetization vs. temperature (heating up to 625 °C). The heat treatment induces a change from SrFe 12 O 19 to γ-Fe 2 O 3 (as the main phase), and SrFeO 2.74 to Sr 2 Fe 2 O 5 . Together with these phase transformations, an increment in the amount of SrCO 3 is detected. Magnetic study of the samples, before and after the heating, supports the structural analysis conclusions.