Substitution effects of La3+ and Zn2+ ions on the microstructural and magnetic properties of Sr2-x Lax Ni2 Fe12-x ZnxO22 Y-type hexaferrite synthesized by sol-gel auto-combustion method

Strontium hexaferrite nanoparticles with composition Sr2-xLaxNi2Fe12-xZnxO22 (for x= 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) have been synthesized by auto combustion sol-gel method. The samples were characterized by X-ray diffraction (XRD), high resolution field emission scanning electron microscopy (FESEM), and vibrating sample magnetometer (VSM).The XRD analysis confirms the single phase at 1000 ˚C and various parameters such as lattice constant, cell volume and crystallite size have also been calculated from XRD data. FE-SEM patterns showed that all of the particles had a hexagonal platlet shape and with the increase of La3+, Zn2+ contents, the size of particles reduced. This reduction is relative on the inhibitor properties of additional elements. The VSM measurements were used to determine the saturation magnetization (Ms), retentivity (Mr) and coercivity (Hc) of the samples. This results showed that by increasing the La3+ and Zn2+ contents, the saturation magnetization and retentivity were increased from 37.94 to 44.14 emu/g and 18.46 to 20.56 emu/g, respectively, whereas coercivity was decreased from 1199.95 to 898.6 Oe. The reduction in coercivity revealed that this material is suitable for high frequency applications, such as electromagnetic devices, because of its soft magnetic properties.