Phase evolution in synthesis of manganese ferrite nanoparticles

Physico-chemical equilibria that influence oxide powders' precipitation from an aqueous solution can be substantially altered when the process is carried out in a microemulsion system. To obtain nanosized MnFe2O4 and gain information about the physico-chemical characteristics of products, Mn2+ and Fe3+ metal ions were induced to precipitate in a toluene/water/sodium dodecylbenzenesulfonate microemulsion system. Portions of the precipitated powder were differently treated, both in solution and in the solid state, and the role of restricted aqueous domains in the obtained materials was investigated. X-ray diffraction profile-fitting methods and chemical analysis were applied to characterize the powder particles. Samples obtained from the selected microemulsion were identified as nanosized mixed hydroxide compounds. A low metal content and a limited matter exchange among aqueous nanodroplets appear to inhibit hydroxide to oxide transformation inside the selected micellar system. A calcination process of precipitated powder was required to obtain a manganese ferrite compound.