Magnetic properties of Ce–Mn substituted M-type Sr-hexaferrites

Ce–Mn substituted M-type Sr-hexaferrites (SrM) of Sr1−xCexFe11−xMnxO19 and Sr1−xCexFe11−2xMn2xO19 (0≤x≤0.2) were synthesized by solid-state reaction routes. Ce–Mn doped SrM exhibited an increased coercivity (HC) of ~5 kOe, which is 37% higher than that of non-substituted SrM (x=0). This high HC could be obtained without reducing the saturation magnetization (MS) when the optimally doped (x=0.1) powder samples were calcined at 1200 °C. The Ce–Mn doped SrM samples also showed enhanced thermal stability of HC, characterized by ~60% lower temperature coefficient for HC compared to the undoped SrM. The increased HC and the higher thermal stability of HC are attributable to both the grain refinement and the enhancement of magneto-crystalline anisotropy in the Ce–Mn SrM.