One-Dimensional Metallofullerene Crystal Generated Inside Single-Walled Carbon Nanotubes

Hirahara, Kaori; Suenaga, Kazu; Bandow, Shunji; Kato, H.; Okazaki, Toshiya; Shinohara, Hisanori; Iijima, Sumio

doi:10.1103/physrevlett.85.5384

Cited by 508 publications

(400 citation statements)

References 13 publications

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“…In addition to metal atoms, fullerenes have also been encapsulated inside single walled carbon nanotubes. [6][7][8][9][10][11][12] High-resolution transmission electron microscopy ͑HR-TEM͒ images clearly show the encapsulations of various fullerenes, e.g., C 60 , C 70 , C 80 , and C 84 , as well as metallofullerenes, e.g., Gd@ C 82 and Sc 2 @C 84 inside single-walled nanotubes. These unusual structures occasionally called carbon peapods, can be classified as a new class of crystalline carbon with novel structural hierarchy: The structure of the peapods is characterized by an interesting combination of one-and zero-dimensional constituent units, i.e., carbon nanotubes and fullerenes.…”

Section: Introductionmentioning

confidence: 99%

Energetics of carbon peapods: Elliptical deformation of nanotubes and aggregation of encapsulatedC60

Okada

2008

Phys. Rev. B

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The energetics of large diameter carbon nanotubes encapsulating C 60 molecules ͑peapods͒ have been studied by using the local density approximation in the density-functional theory ͑DFT͒. We find that the energy gain ascribed to the encapsulation of C 60 increases under the elliptical deformation of the nanotubes compared to that for the nanotubes with circular cross section. The energy cost of the deformation of nanotubes is found to be less than 10 meV per atom and is found to be the largest for the ͑20,20͒ nanotube. We also explore the energetics of the aggregation of encapsulated C 60 in the nanometer-scale space of the ͑10,10͒ nanotube. The total energy of the dimerized C 60 encapsulated in the ͑10,10͒ nanotube is lower by 0.2 eV per atom than that of the isolated C 60 indicating that the dimerization reaction is exothermic. The activation barrier for the dimerization of C 60 is about 1.4 eV, so that the spontaneous dimerization of C 60 is unlikely to take place without any external stimuli such as electron irradiation.

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Section: Introductionmentioning

confidence: 99%

Energetics of carbon peapods: Elliptical deformation of nanotubes and aggregation of encapsulatedC60

Okada

2008

Phys. Rev. B

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“…It has been shown that the lumen of SWNTs can be filled with fullerenes [1] and metallofullerenes [2][3][4]. Even in the weakly interacting C 60 @SWNT case, SWNT properties are modified due to the encapsulated fullerene chains [5].…”

Section: Introductionmentioning

confidence: 99%

Single Wall Carbon Nanotubes Filled with Metallocenes: a First Example of Non-Fullerene Peapods

et al. 2001

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We report the synthesis and analysis of metallocenes (ferrocene, chromocene, ruthenocene, vanadocene, tungstenocene-dihydride) encapsulated in single wall carbon nanotubes (SWNTs). In the case of ferrocene, efficient filling of the SWNTs was accomplished from both the liquid and the vapor phase. The other two metallocenes were filled from the vapor phase. High resolution transmission electron microscopy reveals single molecular chains of metallocenes inside SWNTs. Molecules move under the electron beam in the SWNTs indicating the absence of strong chemical bonds between each other and the SWNT wall. Their movement freezes after short illumination as a result of irradiation damage. Energy dispersive X-ray spectrometry confirms the presence of iron, chromium, ruthenium, vanadium and tungsten.

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“…The high fraction is associated with the exothermic encapsulating process [12,13]. Depending on preparation methods, the various fullerene species can be C 60 , C 70 , C 82 , and metallofullerenes [3,9,10,11].Electron-beam irradiation [9] or heat treatment [10] on these carbon composites induces coalescence of core fullerenes into an inside single-wall nanotube, of which diameter is 0.71 nm smaller than that of the outer 'vessel' tube. Since the electron beam in this case is irradiated for hundreds of seconds and its energy is about 0…”

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Dynamics of Fullerene Coalescence

et al. 2003

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Fullerene coalescence experimentally found in fullerene-embedded single-wall nanotubes under electron-beam irradiation or heat treatment is simulated by minimizing the classical action for many atom systems. The dynamical trajectory for forming a (5,5) C120 nanocapsule from two C60 fullerene molecules consists of thermal motions around potential basins and ten successive StoneWales-type bond rotations after the initial cage-opening process for which energy cost is about 8 eV. Dynamical paths for forming large-diameter nanocapsules with (10,0), (6,6), and (12,0) chiral indexes have more bond rotations than 25 with the transition barriers in a range of 10-12 eV. and "Y" and "T" junctions [4] have attracted much attention from scientists for last two decades due to their unique structural, mechanical, and electrical properties [5]. In particular, carbon nanotubes and related junctions have great potential for applications on nanometric electronic devices such as quantum functional transistors and rectifiers since nanotubes can be semiconductors or metals depending upon their chiralities and diameters [6]. At the moment, however, development of the nanotubebased technology is limited because delicate control of their structures is not yet feasible.Recently, merging processes between carbon nanostructures have been proposed as a new synthesis technique to construct more complicate functional structures: (1) Two nanotubes coalesce into diameter-doubled one in a high-energy (1.25 MeV) electron beam condition [7]. (2) In the same condition, initially crossed nanotubes are found to form some functional junctions shaped like "Y" and "T" characters [4]. Since each carbon atom is displaced approximately every 100 sec by knock-on collisions with the high-energetic electrons, the irradiationinduced vacancies may play a crucial role in these merging processes. Terrones and his coworkers [4,7] studied the vacancy-related merging mechanism utilizing the ordinary molecular dynamics technique. Though introducing various functional structures, this high-energy process may be not appropriate for nanometric device application because of the uncontrollable defect formation. (3) A low energy growth technique for nanotube bundles, where the chiral indexes of all individual nanotubes are almost perfectly mono-dispersed, was proposed in the mixture of C 60 molecules and catalyst Ni pillars with a help of a ∼1.5 T magnetic field [8]. The annealing temperature is just 950 • C. (4) In another low energy situation, a single-wall nanotube can be synthesized by merging fullerene molecules inside a nanotube vessel in nano-peapod systems [9,10]. Of special importance is the last technique of fullerene coalescence because it is a catalyst-free and bottom-up process, having a potentiality for diameter and chirality control of single-wall nanotubes.Nano-peapods [3] consist of array of fullerene molecules (inner peas) and a single-wall carbon nanotube (an outer pod), and all components are separated from the others by the van der Waals distance. Th...

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One-Dimensional Metallofullerene Crystal Generated Inside Single-Walled Carbon Nanotubes

Cited by 508 publications

References 13 publications

Energetics of carbon peapods: Elliptical deformation of nanotubes and aggregation of encapsulatedC60

Energetics of carbon peapods: Elliptical deformation of nanotubes and aggregation of encapsulatedC60

Single Wall Carbon Nanotubes Filled with Metallocenes: a First Example of Non-Fullerene Peapods

Dynamics of Fullerene Coalescence

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