Synthesis and characterization of Fe and Fe₃O₄ nanoparticles by thermal decomposition of triiron dodecacarbonyl

Magnetic nanoparticles possess numerous potential applications, e.g., hyperthermia, magnetic resonance imaging (MRI), catalytic applications, etc. Decomposition of iron pentacarbonyl is one of the most common methods for preparation of magnetic iron oxide and iron nanoparticles. However, Fe(CO)₅ is severely toxic and alternative precursors should be used. The present manuscript presents a new simple method for preparation of iron oxide and iron nanoparticles, by thermal decomposition of Fe₃(CO)₁₂ in diethylene glycol diethyl ether with oleic acid as a stabilizer. The obtained magnetite (Fe₃O₄) nanoparticles were annealed at 300, 700 and 900 °C under inert atmosphere. The annealing temperature allowed control of size and size distribution of the nanoparticles, as well as their composition, crystallinity and magnetic properties. The as-prepared nanoparticles and the nanoparticles annealed at 300 °C are superparamagnetic with blocking temperatures of 22 and ∼140 K, respectively, while the nanoparticles annealed at 700 and 900 °C are ferromagnetic. The nanoparticles annealed at 900 °C are composed of pure Fe as the major phase (90%) and Fe₃O₄. Characterization of the obtained nanoparticles has been accomplished by routine methods such as transmission electron microscopy, powder X-ray diffraction, superconducting quantum interference, elemental analysis and Mössbauer spectroscopy.