Sol–gel synthesis of Cr3+ substituted Li0.5Fe2.5O4: Cation distribution, structural and magnetic properties

Li0.5CrxFe2.5−xO4 powders with fine sized particles were successfully synthesized by sol–gel auto combustion, using lithium nitrate, ferric nitrate, chromium nitrate, and citric acid as the starting materials. The process takes only a few minutes to obtain as-prepared Cr-substituted lithium ferrite powders. The resultant powders were annealed at 600 °C for 4 h and investigated by thermogravimeter/differential thermal analyzer (TG/DTA), X-ray diffractometer (XRD) and vibrating sample magnetometer (VSM). Lattice parameter, bulk density and particle size are found to decrease with increasing Cr concentration, whereas X-ray density and porosity showed an increasing trend with the Cr content. Cation distribution indicates that the chromium ion occupy octahedral B-site. The magnetic moments calculated from Neelʹs molecular field model are in agreement in the experiment result, which indicates that the saturation magnetization decreases linearly from 37.36 to 4.27 emu/g with increasing Cr3+ content. However, coercivity, it increases with the Cr3+ substitution.