Figure 1

Kink motion in a SWCNT. The SWCNT was tensile stressed at 2.8 V bias voltage. The current flowing in the SWCNT was reduced continuously from 100 to $0\mu \mathrm{A}$. The tensile strain was 17%, and the strain rate was $0.02\mathrm{nm}/\mathrm{s}$. Polarity: positive at the top and negative at the bottom of the SWCNT. Sketches in the figures show the change in the shape and position of the kinks. The velocity of the kink motion ranges from 0.2 to $1.7\mathrm{nm}/\mathrm{s}$. Arrowheads point to the kinks: (a)–(d) kink motion at the right side of the nanotube wall (movie M1 [20]); (e)–(h) kink motion at the left side of the nanotube wall (movie M2 [20]). In (f), kink multiplication occurred; (i)–(l) motion of a giant kink. The giant kink was dissociated into several smaller kinks in (k) and (l). Necking occurred in (k) and (l), leading to the failure of the carbon nanotube (m).Reuse & Permissions

Figure 2

Kink motion in a DWCNT under tensile stress at 2.3 V and $60\mu \mathrm{A}$. The tensile strain was 10% and the strain rate was $0.7\mathrm{nm}/\mathrm{s}$. Polarity: positive at top, negative at bottom. Arrowheads point to the kinks. The diameter of the initial DWCNT (a) was uniform. A kink was emitted from the middle-left wall at 2 s (b), and the kink then migrated with a velocity of $6\mathrm{nm}/\mathrm{s}$ upward (c)–(e). A second kink was emitted from the lower-right wall and migrated upward.Reuse & Permissions

Figure 3

Kink motion in a five-walled nanotube under tensile stress at 2 V and $100\mu \mathrm{A}$ (movie M3 [20]). The tensile strain was 3% and the strain rate was $0.04\mathrm{nm}/\mathrm{s}$. Polarity: positive at top, negative at bottom. The kink was emitted from the lower-right wall (a) and then propagated upward with a velocity of $0.7\mathrm{nm}/\mathrm{s}$ (b),(c). Note that the kink propagation directions changed from a longitudinal (a),(b) to a spiral way upward (c)–(e), as predicted by a dislocation glide mechanism [13, 14, 15]. Line sketches highlight the change of kink shapes and positions. The sketch in (d) shows the spiral motion of the kink.Reuse & Permissions

Figure 4

(a) The dislocations in a graphite sheet. $B_1$, $B_2$, and $B_3$ are the three sets of glide planes, and ${\mathbf{b}}_1$, ${\mathbf{b}}_2$, and ${\mathbf{b}}_3$ are the Burgers vectors of the three perfect dislocations. ${\mathbf{a}}_1$ and ${\mathbf{a}}_2$ are the basis vectors for the ($n$, $m$) indexing of the nanotubes. (b) An edge dislocation with a Burgers vector of ${\mathbf{b}}_2$ in a graphite sheet. The core of the edge dislocation is a $5/7$ pair. The edge dislocation was formed by removing half a row of atoms from the graphene sheet. (c) A nanotube junction was formed by wrapping up the graphene sheet in (b). Note the dislocation moves in a spiral way along the nanotube axis, as observed in Figs. 3c, 3d, 3e and sketched in the inset of Fig. 3d.Reuse & Permissions