Air-stable magnetic cobalt-iron (Co7Fe3) bimetallic alloy nanostructures via co-digestive ripening of cobalt and iron colloids

Phase pure Co7Fe3 alloy magnetic nanostructures were successfully synthesized by co-digestive ripening of Fe/Co-toluene nanoparticles in mesitylene in the presence of hexadecyl amine (HDA). Controlled heat treatment of as-synthesized samples under anaerobic conditions showed a transformation of disordered-to-ordered crystal structure, which was confirmed by PXRD and TEM measurements. This also resulted in carbonization of HDA over the nanoparticles surface rendering them air-stable. Magnetic measurements of these carbon-encased samples revealed enhanced saturation magnetization (MS) values compared to the as-prepared samples. The zero field cooling (ZFC) and field cooling (FC) curves demonstrated that Co7Fe3 nanoparticles exhibit ferromagnetic behaviour at room temperature. These air-stable Co–Fe magnetic nanostructures have immense potential for applications as soft magnets.