Structural and magnetic properties of Ni substituted M-type Ca-Sr hexaferrites synthesized by solid-state reactions

In this study, we have prepared the M-type Ca-Sr hexaferrites with composition of Ca0.2Sr0.8Fe12.0-xNixO19 (0.0 <= x <= 0.8) by the solid-state reactions. The phase compositions of the samples were confirmed by X-ray diffraction analysis. The results of X-ray diffraction patterns show that for the M-type hexaferrite magnetic powders with the Ni content (x) from 0.0 to 0.4, the XRD patterns belong to the M-type strontium hexaferrite; when Ni content (x) >= 0.6, Sr4Fe6O13 is detected. It is observed that lattice parameter c first increases with the increase of Ni content (x) from 0 to 0.4, and then decreases when Ni content (x) = 0.4, while lattice parameter a basically keeps constant. Magnetization properties were measured at room temperature by a permanent magnetic measuring system. The remanence (B-r) first increases with increasing Ni content (x) from 0.0 to 0.2, and then decreases when Ni content (x) >= 0.2. The the intrinsic coercivity (H-cj), magnetic induction coercivity (H-cb) and maximum energy product [(BH)(max)] decrease with the increase of Ni content (x) from 0.0 to 0.8.