Structural and magnetic studies of Sn_xFe_3-2x/3O₄ nanoparticles

SnxFe3−2x/3O4 nanoparticles were synthesized using the precipitation under reflux method by Sn2+ doping (x = 0.000−0.150). The structural and magnetic properties of the prepared materials were characterized using a host of techniques. We demonstrate that Sn2+ doping increases the size of the nanoparticles (12−50 nm) and protects them from oxidation to the γ-Fe2O3 phase, making them useful for magnetic applications. Rietveld refinement data for the samples suggest that the dopant Sn2+ ions, while preferentially occupying the B sites at equilibrium, initially start with A-site occupation to maintain the charge balance. While the spin unsaturation at the surface of these nanoparticles, together with oxidation to maghemite, explains the observed decrease in magnetization of the Fe3O4 nanoparticles, it does not for the doped samples, for which spin canting in B sites was preferred.