Tailoring of Structural and Magnetic Properties of Nanosized Lithium Ferrites Synthesized by Sol–gel Self-Combustion Method

In this study, we report the influence of Co2+ on structure and magnetic properties of nano-sized Li0.5−x/2Fe2.5−x/2CoxO4(where x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) synthesized using sol–gel auto-combustion method. The X-ray diffractometric analysis of samples confirmed the formation of pure Li0.5−x2Fe2.5−x2CoxO4 nanoparticles ranges crystallite size from 36 to 43 nm with co-doping. There is a structural transformation from ordered P4332 to random Fd3m observed, which is caused by the localization of cobalt ions. RT-Mössbauer the showed presence of 57Fe in both sublattices. Position identification was performed based on the distribution of the over exchange fields and isomeric shift data. Magnetic measurements showed that the saturation magnetization increases to x ≤ 0.8 and then decreases with Co-content due to the change in cationic distribution. The cobalt substitution turns Li–Co ferrite from soft-magnet to hard-magnet.