Synthesis and magnetic characterization of Sr-based Ni2X-type hexaferrite

We have investigated the synthesis conditions, and the magnetic properties of the Sr2Ni2X-type hexagonal ferrite, Sr2Ni2Fe28O46. The Sr2Ni2X-type hexaferrite was synthesized at 1240∘C. The spontaneous magnetization at 5 K was 44.2 μB/f.u., suggesting that most of the Ni2+ ions are at the up-spin octahedral sites in the spinel-structure blocks within the model of a Néel-type collinear ferrimagnetic structure. The Curie temperature of the Sr2Ni2X-type hexaferrite was estimated to be TC[Sr2Ni2X] = 472∘C. This is consistent with the difference of the block stacking structures of SrM-type, Sr2Ni2X-type, SrNi2W-type, and nickel spinel ferrites.