Fabrication of SrFe_12-xNi_xO₁₉ nanoparticles and investigation on their structural, magnetic and dielectric properties

SrFe_12-xNi_xO₁₉ nanoparticles (x = 0–1) were synthesized by a combustion sol–gel method. Their structure, dielectric and magnetic properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), an LCR metry, and vibrating sample magnetometry (VSM).The results reveal that all samples of Ni doped compounds (SrFe_12-xNi_xO₁₉) with x < 0.2 are single phase. It appears that the Fe³⁺ ions are substituted by Ni²⁺ ions on the crystallographic sites of the SrFe₁₂O₁₉ structure; however, for x ≥ 0.2, the secondary Ni phase ferrite (NiFe₂O₃) appears, which reduces the saturation magnetization and coercivity. In addition, Ni doping reduces the dielectric constant, dielectric loss, and alternating current (ac) electrical conductivity of the samples. The variation in ac conductivity (σ_ac) with frequency shows that the electrical conductivity in these ferrites is mainly attributed to the electron hopping mechanism.Therefore; all the single-phase Ni doped samples are suitable for use in magnetic recording media and microwave devices.