Structure and Magnetism of Fe/Fe₃C Nanoparticles in Carbon Spheres

Iron-cementite (Fe/Fe₃C) nanoparticles in carbon spheres were synthesized by a solid-phase pyrolysis of iron phthalocyanine. The morphology, sizes and composition of the synthesized nanocomposite were studied by high-resolution transmission and scanning transmission electron microscopes (HRTEM, STEM), Mossbauer spectroscopy, X-ray diffraction and extended X-ray absorption fine structure (EXAFS). The M-T dependence shows a significant increase of magnetization at temperatures slightly below 10 K. Apparently, such behavior at low temperatures can be associated with the magnetic properties of the carbon matrix. The heating efficiency of samples under study was evaluated by forming aqueous solutions of 10 mg/mL and exposing them in AC magnetic field 375 kHz/60 mT. Fe-content is a determinant of heating efficiency quantification as expressed by the Specific Loss Power Index. Thus, we surmise that with facile synthetic steps, currently underway, SLP value may enhance even further and render such nanoparticles biomedically exploitable.