Hexaferrite magnetic materials prepared by mechanical alloying

The structure and properties of hexaferrites in the form of MFe₁₂O₁₉ with M = Ba, Sr and Pb prepared by mechanical alloying and heat treatment have been studied. Coercivities of 6–7 kOe were measured for Ba- and Sr-hexaferrite powders. The high values of coercivities have been associated with small particle sizes ( 0.1 μm) resulting from the mechanical alloying and subsequent heat treatment. High-coercivity anisotropic samples have been synthesized using hot-pressing, with remanences of 70–75% of the saturation magnetisation being obtained.