Structural and Magnetic Properties of La-Substituted M-Type Hexagonal Sr-Ni Ferrites Synthesized by Ball-Milling-Assisted Ceramic Process

Sr0.5Ni0.5LaxFe12 - xO19 (x =0, 0.08, 0.16, and 0.24) hexaferrites have been synthesized by ball-milling-assisted ceramic process. The calcined samples are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and vibrating sample magnetometry (VSM). XRD reveals that all samples consist of the main M-type hexagonal Sr ferrite phase and a low amount of rhombohedral Fe2O3 as secondary phase, and a continuous increase of the hexagonal lattice parameters with substitution content (x). Magnetic characterization indicates that all Sr0.5Ni0.5LaxFe12 - xO19 samples have a hard magnetic property. Substitution of Fe3+ ions by La3+ ions can obviously improve the specific saturation magnetization, remanence, magnetic moment, and effective anisotropy constant. Specific saturation magnetization, remanence, and the magnetic moment reach a maximum at x= 0.24 and calcination temperature of 1050 C-degrees.