High saturation magnetization in La–Ce–Zn–doped M-type Sr-hexaferrites

La–Ce–Zn-doped M-type Sr-hexaferries Sr0.7La0.3−xCexFe11.7Zn0.3O19−d (0≤x≤0.3) were synthesized by solid-state reaction in both air and nitrogen atmospheres. The increased saturation magnetization of ~78 emu/g, which is ~5% higher than that of La–Zn-doped Sr-hexaferrite (Sr0.7La0.3Fe11.7Zn0.3O19), could be obtained when the Ce-doped powder samples (x≥0.1) were either annealed in nitrogen at 1100 °C after calcination in air at 1200 °C or directly calcined in nitrogen at 1200 °C. The increased MS over the practical limit (~74 emu/g) is attributable to both the formation of magnetic composites with high-MS spinel phases and the MS increase of the M-type hexaferrite itself caused by oxygen vacancies.