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The doping element and morphology are important factors for improving the magnetic properties of M-type hexaferrite powder. As the demand for electromagnetic absorber and magnetic sensors increases in the market, it is required to develop hexaferrite powder with a homogenous shape and excellent magnetic properties. In this study, Ca substituted strontium hexaferrite powders were synthesized by the molten salt method under various calcination conditions. The morphology and magnetic properties of the synthesized powders were successfully controlled according to the Ca content and calcination conditions. As a result, single-crystalline Sr0.90Ca0.10Fe12O19 powders with an average thickness of 0.4 µm were successfully obtained by calcining at 950 °C for 1 h. The synthesized powders had a magnetic saturation of 74.9 emu/g and a coercivity of 3397 Oe.

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Electro-magnetic devices, such as motors and inductors, have been continuously required to increase their operation frequency for high efficiency. To satisfy this requirement, Fe-Si powder cores with high electrical resistance have been attracted much attention although they have lower permeability than Fe-Si electrical steels. With increasing the Si content, the ductility of Fe-Si alloy sharply decreases, which further lowers the density and magnetic properties of cores. In this study, we aimed to fabricate Fe-Si powder cores with higher saturation magnetization and lower loss in 1 ∼ 10 kHz range compared with commercial products. As a result, fabricated Fe-1.5wt% Si@Fe3(PO4)2 cores reached a 98% theoretical density and showed a magnetic flux density of 1.65 T at 10000 A/m and a core loss of 176.8 W/kg at 1 T @ 2 kHz.

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