Al substituted M-type hexaferrite samples, Sr0.1Ca0.6La0.3AlxFe12-xO19 (0 ≤ x ≤ 1.4), were synthesized by the ceramic process. The X-ray diffraction (XRD) was used to examine the phase composition of the magnetic powders. The XRD patterns of the magnetic powders at Al content (x) ≤ 0.8 show the M-type strontium hexaferrite phase with α-Fe2O3 as a second phase. At Al content (x) ≥ 1.0, there are single magnetoplumbite phase patterns. The images of the M-type hexaferrite magnets were observed by a field emission scanning electron microscopy (FE-SEM). The grain particles of the magnets are hexagonal platelet-like shape, and the grain size decreases with the increase of Al concentration (x). A permanent magnetic measuring system was used to measure the magnetic properties of the magnets. The remanence (B r) decreases with Al content (x) from 0 to 1.4. The intrinsic coercivity (H cj) increases with Al content (x) from 0 to 1.4. While the magnetic induction coercivity (H cb) first increases with Al content (x) from 0 to 0.6 and then decreases at Al content (x) ≥ 0.6.

Keywords: X-ray diffraction, Magnetic properties, Al doping, M-type hexaferrites