Core–shell Fe-based nanoparticles in a carbon matrix: synthesis and magnetic properties

This study presents the synthesis, structural and magnetic characterization, as well as the evaluation of magnetic hyperthermia of Fe, Fe-Fe₃O₄, and Fe₃O₄ nanoparticles embedded in a carbon matrix. In the first stage, Fe@C nanoparticles with a core–shell architecture were synthesized by pyrolyzing iron phthalocyanine. In the second stage, these nanoparticles were gradually oxidized to produce Fe-Fe₃O₄ core–shell structures and Fe₃O₄ nanoparticles, all while preserving the integrity of the carbon shell. Among the samples, Fe exhibited the highest saturation magnetization, magnetic anisotropy constant, and the most efficient heating performance in an alternating magnetic field, achieving the highest specific loss power. This superior performance is attributed to the complex double-shell particle structure, which consists of an iron core, cementite (Fe₃C), and carbon shells that prevent metal oxidation and agglomeration of nanoparticles. These results highlight the potential of Fe-based core–shell nanoparticles for biomedical applications, particularly in magnetic hyperthermia therapy, due to their excellent magnetic properties and heating efficiency.