Novel metallic iron/manganese-zinc ferrite nanocomposites prepared by microwave hydrothermal flash synthesis

Graphical abstract: Metallic iron/manganese zinc ferrite nanocomposite crystal. Display Omitted Research highlights: → These nanocomposites were prepared for the first time by microwave flash synthesis. → XRD patterns exhibited a good crystallization despite no final heat treatment was carried out. → Composite grains structure was underlined by SAED and dark field imaging. → Magnetic properties were measured and compared with these of manganese zinc ferrite. - Abstract: Metallic iron (α-Fe)/manganese-zinc ferrite (Fe3-x-yMnxZnyO4) nanocomposites have been successfully synthesized for the first time using microwave hydrothermal treatment of alcoholic solutions of chloride precursors and sodium ethoxide. This new type of nanocomposites, never obtained by conventional synthesis, can now be produced in a short period (e.g. 15 s). The powders were characterized by X-ray diffraction, transmission electron microscopy and magnetic properties were measured. In most cases, three classes of crystallites were observed; one of them is composed of grains of about 100 nm in size where the metal is inserted into the oxide. For all samples, 20% of metallic iron was routinely obtained using the microwave flash synthesis. Consequently, the microwave heating appears to provide an efficient source of energy in producing metallic iron nanoparticles protected against oxidation by an oxide matrix.