Preparation of Sr-based hexagonal ferrite by controlling the oxidation state of Fe

抄録

We have investigated synthesis conditions and magnetic properties of Sr₂Fe²⁺₂Fe³⁺₁₂O₂₂ (Sr₂Fe₂Y). The main Y-type phase was observed for the sample synthesized with the initial composition of Sr:Fe²⁺:Fe³⁺=1.5:2:8 sintered at T_S=1200℃ and P_O2=10 Pa. The Curie temperature of Sr₂Fe₂Y was 643 K. The magnetization was 45.0 Am²/kg at T= 5 K and μ₀H=7 T. The difference in magnetization from the ideal collinear spin arrangement of Sr₂Fe₂Y is due to the existence of a minor Fe₃O₄-like spinel phase. The yield of Sr₂Fe₂Y phase was estimated to be 83 wt.%, suggesting successful synthesis of the Sr₂Fe₂Y hexaferrite.