A sol-gel auto combustion approach was used to synthesize Co2+ substituted M-type strontium hexagonal ferrite with the chemical formula Sr1-xCoxFe12O19 (x=0.0, 0.25, 0.50 and 0.75). X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Raman Spectroscopy and Vibrating Sample Magnetometer (VSM) have been used to investigate the structural and magnetic properties as a function of cobalt ions substitution in Sr-hexaferrite. XRD pattern disclosed a single M-type hexagonal crystalline phase at x=0, while a desired phase of the strontium M-type hexaferrite with undesired phase appeared with the increase of the cobalt contents. FE-SEM images showed that the particles have irregular distribution and non-uniform shape. Generally, the cobalt ions substitution does not alter the surface morphology. The Raman spectra measurement proved the formation of magnetoplumbite structure of Sr1-xCoxFe12O19 system. The pure strontium hexaferrite compound showed sharp and intense peaks. The intensity of the peaks decreased when the Co2+ ions contents increased. VSM measurements showed ferromagnetic properties for all synthesized samples. The magnetic properties such as saturation magnetization (Ms), remanence magnetization (Mr), coercive field (Hc), effective anisotropy constant (Keff), anisotropy field (Ha), and squareness ratio (S) showed a progressive decrease with the increase of the cobalt ions substitution in the M-type strontium hexaferrite system. Replacement of strontium (Sr) by cobalt (Co) ions weakens the super-exchange interactions among particles.
