Effects of La doping on the structural and magnetic properties of Sr1−xLaxFe11.75Co0.10Zn0.15O19 hexagonal ferrites

The M-type hexaferrite Sr1−xLaxFe11.75Co0.10Zn0.15O19 (0 ≤ x ≤ 0.7) magnetic powders and magnets were synthesized by the ceramic process. The phase constituents of the magnetic powders were analyzed by x-ray diffraction. There is a single magnetoplumbite phase in the magnetic powders with La content (0.2 ≤ x ≤ 0.4). For the magnetic powders containing La content (0 ≤ x ≤ 0.1) or (0.5 ≤ x ≤ 0.7), magnetic impurities coexist in the structure. The microstructures of the magnets were characterized by field emission scanning electron microscopy. The magnets consist of homogenously distributed ferrite particles with the hexagonal structures. The magnetic properties of the magnets were measured by a permanent magnetic measure equipment. The remanence, maximum energy product, and Hk/ Hcj ratio of the magnets at x = 0.3 reach the maximum values. However, the intrinsic coercivity and magnetic induction coercivity of the magnets at x = 0.2 reach the maximum values.