Aqueous synthesis of non-superparamagnetic MnFe2O4 nanoparticles and their magnetic properties

Nanocrystalline MnFC2O4 particles with average particle diameters 50 mu and less were synthesized by using the oxidation method. The superparamagnetic behavior, which is influenced by the particle size, was controlled by varying the concentration of the oxidant. The Mossbauer spectrum showed only sextets corresponding to the A- and B-sites of the ferrite, when the particle size is larger than 50 mn. However, the appearance of superparamagnetic doublet was recorded for the manganese ferrite particles synthesized using higher concentration of oxidant. The saturation magnetization of the particles larger than 50 nm was almost equal to their bulk counter part.