Effect of LaPr-Co co-substitution on microstructure and magnetic properties for Ca0.4Sr0.6-x(La0.8Pr0.2)xFe12-yCoyO19 hexaferrites

M-type hexaferrites with nominal composition of Ca0.4Sr0.6-x(La0.8Pr0.2)(x)Fe12-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 M-type 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 platelet-like, 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).