The M-type hexaferrite Ca0.4Sr0.3(La0.8Pr0.2)0.3Fe11.76Co0.24O19 was synthesized by the solid-state reaction method. The effects of calcination temperature and sintering temperature on the microstructural and magnetic properties have been carefully investigated. The X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and a permanent magnetic measuring system were used to investigate the microstructure and magnetic properties of the samples. Single-phase hexaferrite patterns are observed for the hexaferrite magnetic powders at different temperatures from 1210 to 1270 oC for 2 hrs. The FESEM images of the magnets show that the hexagonal structures have been formed in the magnets, and the grains in the magnets are distributed evenly. With the increase of calcination temperature, the remanence (B r) and maximum energy product [(BH)max] increase from 1210 oC to 1270 oC, while the magnetic induction coercivity (H cb) and intrinsic coercivity (H cj) increase from 1210 oC to 1250 oC, and then decrease when the calcination temperature ≥ 1250 oC. With the increase of sintering temperature, the remanence (B r) and maximum energy product [(BH)max] increase from 1180 to 1200 oC, while the magnetic induction coercivity (H cb) and intrinsic coercivity (H cj) increase from 1180 to 1195 oC, and then decrease when the calcination temperature ≥ 1195 oC.

Keywords: M-type hexaferrite, Calcination temperature, Sintering temperature, X-ray diffraction, Magnetic properties