Microstructural and magnetic studies on the Cr substituted M-type CaSrLa hexaferrite magnets

A series of Cr substituted M-type hexaferrite Ca0.30Sr0.35La0.35CrxFe12-xO19 (0 ≤ x ≤ 1.05) magnets were prepared by theconventional solid state reaction method. The properties of the samples were characterized by X-ray diffraction (XRD), fieldemission scanning electron microscopy (FE-SEM) and a permanent magnetic measuring system. At Cr substitution (x) ≤ 0.60,XRD patterns of the magnetic powders show the M-type strontium hexaferrite phase with α-Fe2O3 as a second phase. WhenCr substitution (x) ≥ 0.60, there are magnetoplumbite phase patterns with only a small trace of α-Fe2O3 phase. The images ofthe magnets show that the hexagonal structures are formed, and the particle size keeps unchanged with increasing Crsubstitution (x). The remanence (Br) decreases with Cr substitution (x) from 0.00 to 1.05. The intrinsic coercivity (Hcj) increaseswith Cr substitution (x) from 0.00 to 1.05. While the magnetic induction coercivity (Hcb) first increases with Cr substitution(x) from 0 to 0.75 and then decreases at Cr substitution (x) ≥ 0.75.