fig5

Figure 5. Morphology evolution of Fe₃O₄@RF and Fe₃O₄@C microspheres under MIH. (A) TEM image of an Fe₃O₄@RF microsphere after MIH curing; (B) TEM image of an Fe₃O₄@C microsphere obtained after calcination of the MIH-cured precursor under nitrogen; (C) High-magnification TEM image of the Fe₃O₄@RF microsphere (MIH-cured) showing the core-shell interface; (D) High-magnification TEM image of the resulting Fe₃O₄@C microsphere confirming the solid core-shell structure. RF: Resorcinol-formaldehyde; MIH: magnetically inductive heating; TEM: transmission electron microscopy.