Collapse of double-walled carbon nanotube bundles under hydrostatic pressure

Abstract

We use classical molecular dynamics simulations to study the collapse of single (SWNT) and double-walled (DWNT) carbon nanotube bundles under hydrostatic pressure. The collapse pressure (p c ) varies as 1/R 3 , where R is the SWNT radius or the DWNT effective radius. The bundles show ∼ 30 % hysteresis and the hexagonally close packed lattice is completely restored on decompression.The p c of DWNT is found to be close to the sum of its values for the inner and the outer tubes considered separately as SWNT, demonstrating that the inner tube supports the outer tube and that the effective bending stiffness of DWNT, D DW N T ∼2D SW N T . We use an elastica formulation to derive the scaling and the collapse behavior of DWNT and multi-walled carbon nanotubes.

Stabilization of carbon nanotubes by filling with inner tubes: An optical spectroscopy study on double-walled carbon nanotubes under hydrostatic pressure

“…4(a)] the pressure-induced shifts show a steep increase at the critical pressures P c1 ≈3 GPa, P c2 ≈7 GPa, and P c3 ≈13 GPa, followed by a plateau. According to earlier results and theoretical predictions, 12,[22][23][24][25][26][27][28][29][30] we interpret the anomaly at P c1 in terms of a structural phase transition, where the tube is deformed from a circular to an oval shape. Above P c2 a more drastic change in the cross section from oval to race-track or peanut-type shape occurs.…”

“…According to molecular dynamics simulations by Gadagkar et al 30 the tubes cross sections remain nearly circular up to a critical pressure, where the tube cross sections are deformed to an elliptical shape. The critical pressure follows a 1/R 3 ef f dependence, 30 where the effective radius of the DWCNT R ef f is defined as 1/R…”

“…Several earlier experimental studies (mostly Raman) reported higher critical pressures for the structural transition of the outer tube in DWCNTs as compared to SWCNTs, and this was attributed to the structural support of the outer tube by the inner tube. 7,30,34 The enhanced structural stability of the outer tube was theoretically predicted by Yang et al 35 : For small-diameter (5,5)(10,10) DWCNT bundles (d inner ≈0.68 nm, d outer ≈1.36 nm) a small discontinuous volume change appears at the critical pressure P d =18 GPa, accompanied by a cross sections' change between two deformed hexagons; the collapse to peanut shaped cross sections, however, happens at higher pressure. In contrast, (7,7)(12,12) DWCNT bundles (d inner ≈0.95 nm, d outer ≈1.63 nm) undergo one structural phase transition and collapse at P d =10.6 GPa.…”

Radial deformation and stability of single-wall carbon nanotubes under hydrostatic pressure

“…21,22 The shape transition has also been directly observed in the diffraction experiments, by either x-ray 15,16 or neutron, 27 although there remains inconsistency in these experimental results. The radial deformation of carbon nanotubes under asymmetric ͑or local͒ stress was also examined with molecular dynamics ͑MD͒ simulations 30 and scanning probe microscope. 31 In contrast with these extensive investigations for bundles and crystals, the radial deformation of isolated nanotubes has been much less studied.…”

High Pressure Raman Spectroscopy in Carbon Nanotubes

“…Moreover, the theoretically predicted diameter dependence of the nanotube cross-section deformation is also verified experimentally for both bundled and individual SWCNTs [11,12]. On the other hand, theoretical calculations predict an enhancement of the structural rigidity of the nanotubes after the encapsulation of smaller diameter tubes in their interior and the formation of DWCNTs [13]. In line with this prediction, high pressure Raman studies on DWCNTs show that the presence of the internal tubes provide structural support to the externals against pressure application [14].…”