Superplastic carbon nanotubes

Huang, Jianyu; Chen, S.; Wang, Ziqiang; Kempa, Krzysztof; Wang, Y. M.; Jo, Sung Ho; Chen, G.; Dresselhaus, M. S.; Z, Ren

doi:10.1038/439281a

Cited by 365 publications

(308 citation statements)

References 11 publications

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“…In situ TEM tension experiments showed that, at high temperatures, individual single-walled CNTs can undergo superplastic deformation (becoming nearly 280% longer than its original length, much larger than the theoretical strain of CNTs at room temperature). 48 Dramatically enhanced atomic diffusion was also observed for multiwalled CNTs under in situ TEM. 49 Second, the Si NWs in our experiments were synthesized using the CVD-VLS method, 34 while those in Han's experiments were synthesized using the thermal evaporation method.…”

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confidence: 91%

Mechanical Properties of Vapor−Liquid−Solid Synthesized Silicon Nanowires

et al. 2009

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The Young's modulus and fracture strength of silicon nanowires with diameters between 15 and 60 nm and lengths between 1.5 and 4.3 µm were measured. The nanowires, grown by the vapor-liquid-solid process, were subjected to tensile tests in situ inside a scanning electron microscope. The Young's modulus decreased while the fracture strength increased up to 12.2 GPa, as the nanowire diameter decreased. The fracture strength also increased with the decrease of the side surface area; the increase rate for the chemically synthesized silicon nanowires was found to be much higher than that for the microfabricated silicon thin films. Repeated loading and unloading during tensile tests demonstrated that the nanowires are linear elastic until fracture without appreciable plasticity.Silicon (Si) nanowires (NWs) are one of the key building blocks for nanoelectronic and nanoelectromechanical devices. 1 They exhibit excellent mechanical, 2,3 electrical, 4 and optical 5 properties, in addition to interesting multifunctional properties such as piezoresistivity 6 and thermoelectricity. [7][8][9] As such, Si NWs have been used in a broad range of applications including nanoelectronics, 10-12 nanosensors, 13 nanoresonators, 14 light-emitting diodes, 15 and thermoelectric energy scavengers. 7,8 The operation and reliability of these nanodevices depend on the mechanical properties of Si NWs, which are expected to be different from their bulk counterparts due to their increasing surface-to-volume ratio.Existing techniques for measuring the mechanics of individual NWs include observing the vibration (or resonance) of cantilevered NWs inside a transmission or scanning electron microscope (TEM/SEM), [16][17][18] measuring the lateral bending of suspended NWs with an atomic force microscope (AFM), 3,19-21 measuring uniaxial tension of suspended NWs in SEM or TEM, 2,22-26 and nanoindentation of NWs on a substate. 27 Available experimental results on Si NWs exhibit significant scatter including the following: (1) some reported a decrease in Young's modulus with decreasing size, 2,9,24,28 while others showed an opposite trend; 20,21 (2) the reported strength values of vapor-liquid-solid (VLS) grown Si NWs ranged from 500 MPa to 12 GPa; 3,28 (3) Han et al. 2 observed pronounced plastic deformation of Si NWs by in situ TEM tensile tests at room temperature, while Gordon et al. 21 reported linear elastic behavior followed by brittle fracture using AFM bending tests.Moreover the experimental data show large discrepancy with the simulation results. 29 For instance, the experimentally measured Young's moduli started deviating from the bulk value at diameters of about 200 nm; 28 conversely, computational studies using both density functional theory (DFT) and classical molecular dynamics (MD) indicated that the transition diameter for Young's modulus of Si NWs is less than 10 nm. [30][31][32] The experimentally observed plasticity at room temperature occurred for Si NWs with diameter less than 60 nm, while MD simulations 33 predicted a simi...

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confidence: 91%

Mechanical Properties of Vapor−Liquid−Solid Synthesized Silicon Nanowires

et al. 2009

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] It has been reported 12 that a mere 1 wt % of CNTs embedded into a polystyrene matrix would lead to significant increases in the overall elastic modulus and strength by approximately 35%-42% and 25%, respectively. In view of such potential applications, there is a strong motivation to understand their structural properties.…”

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Examining the effects of wall numbers on buckling behavior and mechanical properties of multiwalled carbon nanotubes via molecular dynamics simulations

Zhang

Wang

Tan

2008

Journal of Applied Physics

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Molecular dynamics simulations are performed on multiwalled carbon nanotubes ͑MWCNTs͒ under axial compression to investigate the effects of the number of walls and their van der Waals ͑vdW͒ interaction on the buckling behaviors and mechanical properties ͑Young's modulus and Poisson's ratio͒. The Brenner second-generation reactive empirical bond order and Lennard-Jones 12-6 potential have been adopted to describe the short-range bonding and long-range vdW atomic interaction within the carbon nanotubes, respectively. In the presence of vdW interaction, the buckling strain and Young's modulus of MWCNTs increase as the number of tubes is increased while keeping the outermost tube diameter constant, whereas Poisson's ratio was observed to decrease. On the other hand, when the MWCNTs are formed by progressively adding outer tubes while keeping the innermost tube diameter constant, Young's modulus and buckling strain were observed to decrease, whereas Poisson's ratio increases. The buckling load increases with increasing the number of walls due to the larger cross-sectional areas. Individual tubes of MWCNTs with a relatively large difference between the diameters of the inner and outer tubes buckle one at a time as opposed to simultaneously for MWCNTs with a relatively small difference in diameters.

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“…[13][14][15][16] We found recently that a carbon nanotube can be Joule heated to temperatures higher than 2000°C by passing a high current through it. [17][18][19][20][21] It was also discovered previously that carbon onions 22,23 and carbon nanotubes can be used as high-pressure cells to generate high pressures. 13,[24][25][26] The question then arises: can we generate high pressures and high temperatures simultaneously by using carbon nanotubes as heaters and carbon onions as pressure cells?…”

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In Situ Observation of Quasimelting of Diamond and Reversible Graphite−Diamond Phase Transformations

Huang¹

2007

Nano Lett.

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Because of technique difficulties in achieving the extreme high-pressure and high-temperature (HPHT) simultaneously, direct observation of the structures of carbon at extreme HPHT conditions has not been possible. Banhart and Ajayan discovered remarkably that carbon onions can act as nanoscopic pressure cells to generate high pressures. By heating carbon onions to ∼700°C and under electron beam irradiation, the graphite-to-diamond transformation was observed in situ by transmission electron microscopy (TEM). However, the highest achievable temperature in a TEM heating holder is less than 1000°C. Here we report that, by using carbon nanotubes as heaters and carbon onions as high-pressure cells, temperatures higher than 2000°C and pressures higher than 40 GPa were achieved simultaneously in carbon onions. At such HPHT conditions and facilitated by electron beam irradiation, the diamond formed in the carbon onion cores frequently changed its shape, size, orientation, and internal structure and moved like a fluid, implying that it was in a quasimelting state. The fluctuation between the solid phase of diamond and the fluid/amorphous phase of diamond-like carbon, and the changes of the shape, size, and orientation of the solid diamond, were attributed to the dynamic crystallization of diamond crystal from the quasimolten state and the dynamic graphite− diamond phase transformations. Our discovery offers unprecedented opportunities to studying the nanostructures of carbon at extreme conditions in situ and at an atomic scale.

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Superplastic carbon nanotubes

Cited by 365 publications

References 11 publications

Mechanical Properties of Vapor−Liquid−Solid Synthesized Silicon Nanowires

Mechanical Properties of Vapor−Liquid−Solid Synthesized Silicon Nanowires

Examining the effects of wall numbers on buckling behavior and mechanical properties of multiwalled carbon nanotubes via molecular dynamics simulations

In Situ Observation of Quasimelting of Diamond and Reversible Graphite−Diamond Phase Transformations

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