M-type hexaferrites with nominal composition of Ca0.4Sr0.6-x(La0.8Pr0.2)xFe12-yCoyO19 (0.00 ≤ x ≤ 0.50, 0.00 ≤ y ≤ 0.40) were prepared by the solid-state reaction method. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and a permanent magnetic measuring system were used to investigate the microstructural and magnetic properties of the Mtype hexaferrites. All the LaPr-Co substituted M-type hexaferrites are in single-phase with hexagonal structure and no impurity phase is observed in the structure. The FE-SEM images of the magnets show that the grains are hexagonal plateletlike, and the grain size of the magnets basically keeps unchanged with increasing LaPr-Co content. The remanence (B r), first decreases, and reaches to the minimum value at x = 0.20, y = 0.16, and then increases with the increasing substitution content of LaPr (0.20 ≤ x ≤ 0.50) and Co (0.16 ≤ y ≤ 0.40). The intrinsic coercivity (H cj) increases with the increase of LaPr-Co content (0.00 ≤ x ≤ 0.40, 0.00 ≤ y ≤ 0.32), and then decreases with the increasing substitution content of LaPr (0.40 ≤ x ≤ 0.50) and Co (0.32 ≤ y ≤ 0.40). Magnetic induction coercivity (H cb) and maximum energy product [(BH)max] increase with increasing LaPr- Co content (0.00 ≤ x ≤ 0.50, 0.00 ≤ y ≤ 0.40).

Keywords: M-type hexaferrites, LaPr-Co co-substitution, X-ray diffraction, Magnetic properties.