The crystalline structure and magnetic properties of chromium substituted hexagonal strontium ferrite, SrFe12−xCrxO19 (x = 0, 0.25, 0.5, 0.75, 1), nanoparticles have been investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM). These materials were prepared by the chemical sol–gel auto-combustion method. From the structural analysis, it was observed that the non-magnetic phase α-Fe2O3 appears after x ≥ 0.5 and remains to be a hexagonal magnetoplumbite phase for x <0.5. Various parameters such as lattice constants (a and c) were calculated from the XRD data. The coercively Hc initially decreases and then increases with increasing chromium concentration. The saturation magnetization exhibits an increase as the chromium content increases up to (x = 0.25) and then decreases with increase in the Cr content ion from 75.19 to 61.66 emu/g due to the substitution of Fe3+ ions by less magnetic Cr3+ ions. Furthermore, Mr continually decreases with increase in the Cr content.

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