Cation distribution dependence of magnetic properties of sol–gel prepared MnFe2O4 spinel ferrite nanoparticles

MnFe2O4 nanoparticles have been synthesized with a sol–gel method. Both differential thermal and thermo-gravimetric analyses indicate that MnFe2O4 nanoparticles form at 400 °C. Samples treated at 450 and 500 °C exhibit superparamagnetism at room temperature as implied from vibrating sample magnetometry. Mössbauer results indicate that as Mn2+ ions enter into the octahedral sites, Fe3+ ions transfer from octahedral to tetrahedral sites. When the calcination temperature increases from 450 to 700 °C, the occupation ratio of Fe3+ ions at the octahedral sites decreases from 43% to 39%. Susceptibility measurements versus magnetic field are reported for various temperatures (from 450 to 700 °C) and interpreted within the Stoner–Wohlfarth model.