Microscopic mechanism of fullerene fusion

Han, Seungwu; Yoon, Mina; Berber, Savaş; Park, Noejung; Ōsawa, Eiji; Ihm, Jisoon; Tománek, David

doi:10.1103/physrevb.70.113402

Cited by 82 publications

(100 citation statements)

References 40 publications

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“…8,[10][11][12][13][14] It is well established that that rotation of a C-C bond in a sp 2 carbon network, known as the Stone-Wales ͑SW͒ transformation, is the key step of such a transformation. 10,12,13 The calculated barrier of such a bond rotation is as high as 5-9 eV ͑Refs. 11 and 15͒ which explains the requirement of high temperature for the formation of peapod-derived DWNTs.…”

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confidence: 99%

Formation mechanism of peapod-derived double-walled carbon nanotubes

Ding

Yakobson

et al. 2010

Phys. Rev. B

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Atomistic simulations and a dislocation-based analysis reveal the mechanism of carbon peapod fusion into double-walled nanotubes. They explain the trend of diameter increase for the emerging inner wall, driven by the reduction in its strain energy and the interwall van der Waals energy. Surprisingly, this is also accompanied by the systematic bias in the nanotube chirality, changing from zigzag toward armchair. This prediction agrees well with our experimental data and is further supported by the analysis of earlier observations. [5][6][7][8][9] where the encapsulated fullerenes coalescence into an inner tube at high temperature. The peapod route is the preferred method for preparing relatively pure DWNTs with welldefined structures. 1 There has been considerable effort to understand the mechanism of fullerene coalescence and the transformations of sp 2 carbon networks. 8,[10][11][12][13][14] It is well established that that rotation of a C-C bond in a sp 2 carbon network, known as the Stone-Wales ͑SW͒ transformation, is the key step of such a transformation. 10,12,13 The calculated barrier of such a bond rotation is as high as 5-9 eV ͑Refs. 11 and 15͒ which explains the requirement of high temperature for the formation of peapod-derived DWNTs. 9 Because of the high barrier, it is impossible to simulate a defect-free DWNT structure by conventional molecular-dynamics simulation due to the limited simulation time ͑time scale from picosecond to nanosecond͒. 8,14 Although a full route from two fullerenes to a short SWNT has been demonstrated in previous studies, the final SWNT formation was predetermined and thus information about the inner-tube chiral angle cannot be determined correctly by these methods. [10][11][12][13] In this Rapid Communication, we study the formation of peapod-derived DWNTs. An atomic simulation successfully reproduces the transformation from peapods into a defectfree DWNT through the SW mechanism. It is found that most of the simulated inner tubes have large chiral angles ͑e.g., Ͼ 20°͒ and detailed theoretical analysis has shown that the preference for large chiral angles is dominated by the driving force of the SW transformation during tube fattening. Through careful analyzing experimental data, we have confirmed that the abundance of large chiral-angle tubes is in agreement with most experimental observations.It is well established that the kinetic Monte Carlo ͑KMC͒ method can simulate a long-time process by neglecting the thermal vibrations of atoms and considering the process of overcoming barriers directly. In mimicking the KMC method, we propose a similar method to study the coalescence of fullerenes but by considering instead the energy change in the barrier between two states. In detail, the sp 2 carbon network is described by the most used second generation Tersoff-Brenner potential in which the van der Waals interactions have been properly incorporated 15 and the energy of the relaxed initial structure is denoted as E i . A C-C bond is then selected randomly and rotated by 90°. Th...

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confidence: 99%

Formation mechanism of peapod-derived double-walled carbon nanotubes

Ding

Yakobson

et al. 2010

Phys. Rev. B

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“…Two mechanisms have been suggested for inner tube growth: (i) from di-or polymerized encapsulated fullerenes [3][4][5] through Stone-Wales transformations [6], (ii) from completely disintegrated fullerenes [7].…”

Section: Introductionmentioning

confidence: 99%

The effects of inhomogeneous isotope distribution on the vibrational properties of isotope enriched double walled carbon nanotubes

Zólyomi

Simón

Rusznyák

et al. 2007

Physica Status Solidi (b)

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The radial breathing mode in the Raman spectrum of 13 C isotope enriched single walled carbon nanotubes is inhomogeneously broadened due to the random distribution of isotopes. We study this effect theoretically using density functional theory within the local density approximation and compare the result with experiments on isotope engineered double walled carbon nanotubes in which the inner tubes were grown from a mixture of 13 C enriched fullerenes and natural fullerenes. As explained by the calculations, this synthesis procedure leads to an increased inhomogeneity compared to a case when only enriched fullerenes are used. The good agreement between the measurements and calculations shows the absence of carbon diffusion along the tube axis during inner tube growth, and presents a strong support of the theory that inner tube growth is governed by Stone -Wales transformations following the interconnection of fullerenes.

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“…However, as pointed out in early works, 4,12,14 there is a wide gap between experimental observations and theoretical predictions in coalescence of fullerenes and nanotubes in terms of the energy barriers for these structural rearrangements. Under thermal treatment only, the fullerenes begin to merge with one another around 800°C and complete coalescences below 1200°C.…”

Section: Introductionmentioning

confidence: 99%

“…4 Two nanotubes can also form a larger one by electron beam irradiation 5 or under thermal treatments without high energy particles, such as an electron beam. 6,9 With the aid of computational resources, the process of fullerene fusion has been simulated by many researchers, including Zhao et al, 10 Kim et al, 11 and Han et al 12 For the coalescence of two nanotubes, López et al 9 suggested a "patching and tearing" mechanism, wherein many initial defects like vacancies are presumed. Yoon et al 13 proposed a "zipping" mechanism, wherein two nanotubes can be merged only by successive generalized Stone-Wales ͑GSW͒ transformations of which the activation energy barriers are 5-6 eV.…”

Section: Introductionmentioning

confidence: 99%

“…The merging and junction formation mechanism of carbon nanostructures, which can broaden our understanding of the fabrication and manipulation of complex nanoscale devices and their components, have been widely investigated experimentally [3][4][5][6][7][8] and theoretically. [9][10][11][12][13][14][15] In experiments, the merging of fullerenes in a nanopeapod has been observed in electron beam irradiation 3 and studied under heat treatments. 4 Two nanotubes can also form a larger one by electron beam irradiation 5 or under thermal treatments without high energy particles, such as an electron beam.…”

Section: Introductionmentioning

confidence: 99%

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Coalescence and T-junction formation of carbon nanotubes: Action-derived molecular dynamics simulations

et al. 2006

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The mechanisms of coalescence and T-junction formation of carbon nanotubes are analyzed using actionderived molecular dynamics. The control of kinetic energy in addition to the total energy leads to the determination of the minimum-energy atomistic pathway for each of these processes. Particularly, we find that the unit merging process of two carbon nanotubes consists of four sequential generalized Stone-Wales transformations occurring in four hexagon-heptagon pairs around the jointed part. In addition, we show that a single carbon atom may play the role of an autocatalyst, which significantly reduces the global activation energy barrier of the merging process. For T junction formation, two different models are chosen for simulation. One contains defects near the point of junction formation, while the other consists of two perfect nanotubes plus two additional carbon atoms. Our results indicate that the coalescence and junction formation of nanotubes may occur more easily than theoretically predicted in the presence of additional carbon atoms at moderate temperatures.

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Microscopic mechanism of fullerene fusion

Cited by 82 publications

References 40 publications

Formation mechanism of peapod-derived double-walled carbon nanotubes

Formation mechanism of peapod-derived double-walled carbon nanotubes

The effects of inhomogeneous isotope distribution on the vibrational properties of isotope enriched double walled carbon nanotubes

Coalescence and T-junction formation of carbon nanotubes: Action-derived molecular dynamics simulations

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