fig4

Figure 4. SEM surface morphologies of the composite film with (A) 10 wt% MWCNTs and (B) 20 wt% MWCNTs; (C) Cross-sectional SEM image of the composite film with 20 wt% MWCNTs; (D) SEM image of the composite material before sintering, showing MWCNTs in a loose, free random entanglement state around matrix particles; (E) Morphology at the early stage of Joule heating pulse annealing, with local thermodynamic driving and binder carbonization shrinkage causing MWCNTs to gradually adhere to matrix particle surfaces; (F) Surface morphologies of the composite material after sintering completion, with high-density MWCNTs tightly wrapping Bi_0.5Sb_1.5Te₃ particles; (G) Physical model schematic of interface reconstruction and 3D interconnected network formation between Bi_0.5Sb_1.5Te₃ particles and MWCNTs driven by the thermal field. SEM: Scanning electron microscopy; MWCNTs: multi-walled carbon nanotubes.