Extended Data Fig. 5: ITB transition and associated dislocation behaviours observed at the accelerating voltage of 200 kV.

a−c, HAADF-STEM images (each superimposed from five consecutive frames) measured during a continuous STEM observation. The ITB structural transition, nanocracking at the end of ITB, and the junction of SF and CTB were observed. The electron beam was turned off after c for 5 min before d was acquired. d−f, Continuously acquired single STEM frames from a separate continuous observation. In adjacent domains, additional lattice tearing (white arrow) and a dislocation loop (white box) were identified. The inset in f (also the insets in g and h) shows the enlarged inverse fast Fourier filtering (IFFT) image of the selected area, clearly revealing the dislocation loop. g, A single STEM frame aquired after f with a 10 min interval of electron beam shutoff. The dislocation loop was observed to react with the CTB, resulting in dislocation multiplication and a step at the CTB. At the same time, a full dislocation was created at the position of lattice tearing (see the red arrow in f). h, A superimposed image from five consecutive STEM frames obtained with the electron beam turned off for 30 min between g and h. The dislocation loop was annihilated, along with the elimination of the CTB step. Meanwhile, the nanocracks were healed, and the previously created full dislocation evolved into an extrinsic SF (cyan box). i, A superimposed image from five consecutive STEM frames, obtained with the electron beam turned off for 30 min between h and i. Multiple dislocations and CTB steps were generated in addition to the extrinsic SF observed in h. In the panels, solid red lines: CTBs; dashed yellow lines: SFs; white arrow: nanocrack; ⊥: dislocation.