Structural and magnetic properties of La–Co substituted Sr–Ca hexaferrites synthesized by the solid state reaction method

• Sr0.7 − xCa0.3LaxFe12 − yCoyO19 hexaferrites were synthesized by the solid state reaction method.
• Br continuously increases with increasing dopant contents.
• Hcb, Hcj and (BH)max for the magnets first increases and then decreases with an increase in the La–Co contents.

Hexagonal ferrite Sr0.7 − xCa0.3LaxFe12 − yCoyO19 (x = 0.05–0.50; y = 0.04–0.40) magnetic powders and magnets were synthesized by the solid state reaction method. X-ray diffraction was employed to determine the phase compositions of the magnetic powders. There is a single magnetoplumbite phase in the magnetic powders with the substitution of La (0.05 ≤ x ≤ 0.15) and Co (0.04 ≤ y ≤ 0.12) contents. For the magnetic powders containing La (x ≥ 0.20) and Co (y ≥ 0.16), magnetic impurities begin to appear in the structure. A field emission scanning electron microscope was used to characterize the micrographs of the magnets. The magnets have formed hexagonal structures. Magnetic properties of the magnets were measured by a magnetic properties test instrument. The remanence continuously increases with increasing dopant contents. Whereas, the magnetic induction coercivity, intrinsic coercivity and maximum energy product for the magnets first increases and then decreases with an increase in the La–Co contents.

The change of the remanence (Br) and intrinsic coercivity (Hcj) with La content (x) and Co content (y) of hexagonal ferrite Sr0.7 − xCa0.3LaxFe12 − yCoyO19 magnets.Figure optionsDownload as PowerPoint slide