Microwave-Assisted Solvothermal Controlled Synthesis of Fe-Co Composite Material

Syntheses of cobalt-iron oxide composites starting from cobalt acetate and iron acetylacetonate are carried out by microwave-assisted solvothermal process, using ethylene glycol as the solvent and (polyvinylpyrrolidone) PVP, as the stabilizer. Indeed, the reaction mechanism in the presence of ethylene glycol is well understood with the role of PVP being the inhibitor of nanoparticle growth. However, the control of the morphology of the synthetized nanoparticles is still a great challenge. Herein, it is demonstrated that by adding amines to the reaction mixture, it is possible to control the morphology of the prepared bimetallic cobalt-iron materials. Thus, different Fe-Co oxide micro-particles are synthetized by an innovative microwave-assisted solvothermal synthesis, which allows to considerably reduce reaction time from 12 h to 15 min, with respect to conventional methods. The procedure is optimized by varying several parameters, such as amount of PVP, in the presence or in the absence of amines, reaction temperature. The dark brown powders of the product are characterized by scanning electron microscopy, infrared spectroscopy, and thermal analysis, confirming the beneficial effect of the presence of the amine on the morphology of the obtained composites. These results open a new scenario for further studies on the possibility to control the morphology of composite materials.