Synthesis of (Ca, Sr)-based W-type hexagonal ferrite

This investigation has examined the synthesis conditions and magnetic properties of (Ca, Sr)-based W-type hexagonal ferrite. Substituting Ca for Sr in Ca x Sr 1 − x Zn ₂Fe ₁₆O ₂₇ (where 0 ≤ x ≤ 1 ) resulted in the formation of the W-type structure at x ≤ 0 . 7 sintered at T S = 1250 and 1300°C. However, these W-type samples were accompanied by secondary spinel and hematite phases, making it necessary to modify the initial composition to form a single W-type phase. Eliminating the potential compositions of these secondary phases resulted in the optimal single-phase-forming condition of Ca: Sr: Zn: Fe = 0.55: 0.45: 0.88: 11.6 and T S = 1200°C. The magnetization of this sample at 5 K was 130.7 A m ² /kg at 7 T, consistent with a model of a collinear magnetic structure. The Curie temperature of this sample was found to be 350°C.