Controllable synthesis and magnetization of Fe3O4 microspheres wrapped with amorphous carbon

A straightforward solvothermal methodology was employed to synthesize Fe 3 O 4 microspheres and Fe 3 O 4 @C hybrids, where amorphous carbon encapsulated Fe 3 O 4 microspheres. This encapsulation was achieved by meticulously controlling the reaction duration and glucose concentrations within the hydrothermal process. Analysis via X-ray diffraction and Raman spectroscopy confirmed that all specimens retained a homogeneous Fe 3 O 4 phase. Following encapsulation, the Fe 3 O 4 particles were uniformly distributed across the amorphous carbon spheres, with fine particle sizes in the hybrids measuring less than 20 nm. Magnetic characterization revealed that parameters such as saturation magnetization, remanent magnetization, and coercivity of the Fe 3 O 4 microspheres could be significantly adjusted by varying the hydrothermal reaction time. Notably, the hybrids exhibited a 5- to 10-fold increase in both coercivity and remanent magnetization when compared to the pristine Fe 3 O 4 microspheres. Nonetheless, the saturation magnetization of the hybrids reached up to 90% of that observed in bulk Fe 3 O 4 . These magnetic properties are predominantly influenced by the size effect associated with the nanostructured Fe 3 O 4 .