Thermal annealing synthesis of Fe₄N/Fe nanocomposites from iron oxide (Fe₃O₄) nanoparticles

A facile sono-thermal approach using inexpensive and non-toxic chemicals was applied for the large-scale synthesis of iron nitride/iron (Fe₄N/Fe) nanocomposite. The as-synthesized iron oxide (Fe₃O₄) nanoparticles by sonochemical method were treated in a thermal annealing chamber in presence of hydrogen (H₂) and ammonia (NH₃) gases to obtain Fe₄N/Fe nanocomposite. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analyses revealed that the Fe₄N/Fe nanocomposite had been successfully synthesized using this simple method. Transmission electron microscopy (TEM) data demonstrated that the sizes of the as-synthesized Fe₄N/Fe nanocomposite were larger compared to the sizes for the initial Fe₃O₄ NPs. The magnetization curve obtained using vibrating sample magnetometer (VSM) measurements showed that the magnetization had been significantly increased in the synthesized Fe₄N/Fe nanocomposite compared to that in the freshly-prepared Fe₃O₄ magnetic NPs.