Structural and magnetic properties of Cr doped strontium spinel ferrite SrFe2O4 by sol-gel auto-combustion method

Chromium doped strontium ferrites with composition SrFe2-xCrxO4 (x = 0.00, 0.25, 0.50, 0.75) were prepared by the sol-gel auto-combustion method. The techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) are employed to examine the effect of variation of Cr3+ ion substitution and also its impact on crystal structure, crystallite size, lattice parameter and magnetic properties of the synthesized magnetic powders. XRD results reveal that with the increasing Cr-substitution the crystallite size and lattice parameter increases. The SEM images demonstrate inhomogeneous grains distribution with agglomeration which is due to dipole-dipole interactions. The grain size was observed from 0.68 to 1.11 μm and no secondary phase was found in the synthesized magnetic samples. VSM technique is used to analyze the soft magnetic behavior of the samples. The value of coercivity reveals the soft magnetic action. It is observed that the values of saturation magnetization (Ms) and remanence (Mr) decreases with increasing the chromium substitution. The results and discussion suggest that the synthesized samples are favorable for microwave absorbing purposes.