Atomic-Scale In-situ Observation of Carbon Nanotube Growth from Solid State Iron Carbide Nanoparticles

Yoshida, Hideto; Takeda, Seiji; Uchiyama, Tetsuya; Kohno, Hideo; Homma, Yoshikazu

doi:10.1021/nl080452q

Cited by 531 publications

(562 citation statements)

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“…Although the VLS model reasonably explains the phase separation dynamics between carbon and iron, it is still controversial whether SWNT growth always requires the formation of metal carbide or not. Indeed, it is likely that this depends on the type of the metal catalyst employed (see for instance two environmental transmission electron microscopy (ETEM) studies where cap nucleation was observed, one where bulk iron carbide was formed [27] and another where nickel did not form carbide in bulk [28]). Since the VLS model is a concept mainly based on thermodynamic reasoning, it does not promote per se an understanding of the atomistic details of the SWNT nucleation and growth processes.…”

Section: Introductionmentioning

confidence: 99%

Milestones in molecular dynamics simulations of single-walled carbon nanotube formation: A brief critical review

et al. 2009

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We present a brief review of the most important efforts aimed at simulating single-walled carbon nanotube (SWNT) nucleation and growth processes using molecular dynamics (MD) techniques reported in the literature. MD simulations allow the spatio-temporal movement of atoms during nonequilibrium growth to be followed. Thus, it is hoped that a successful MD simulation of the entire SWNT formation process will assist in the design of chirality-speciÀ c SWNT synthesis techniques. We give special consideration to the role of the metal catalyst À particles assumed in standard theories of SWNT formation, and describe the actual metal behavior observed in the reported MD simulations, including our own recent quantum chemical MD simulations. It is concluded that the use of a quantum potential is essential for a qualitatively correct description of the catalytic behavior of the metal cluster, and that carbide formation does not seem to be a necessary requirement for nucleation and growth of SWNTs according to our most recent quantum chemical MD simulations.

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Section: Introductionmentioning

confidence: 99%

Milestones in molecular dynamics simulations of single-walled carbon nanotube formation: A brief critical review

et al. 2009

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“…An interface between carbon nanotubes and metal particles was also observed during the growth of nanotubes from catalytically active metals (11). However, the structure of the interface and the nature of bonding between metal and carbon remained unclear.…”

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confidence: 99%

Heterojunctions between metals and carbon nanotubes as ultimate nanocontacts

Rodríguez–Manzo

Banhart

Terrones

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

111

100

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We report the controlled formation and characterization of heterojunctions between carbon nanotubes and different metal nanocrystals (Fe, Co, Ni, and FeCo). The heterojunctions are formed from metal-filled multiwall carbon nanotubes (MWNTs) via intense electron beam irradiation at temperatures in the range of 450 -700°C and observed in situ in a transmission electron microscope. Under irradiation, the segregation of metal and carbon atoms occurs, leading to the formation of heterojunctions between metal and graphite. Metallic conductivity of the metal-nanotube junctions was found by using in situ transport measurements in an electron microscope. Density functional calculations show that these structures are mechanically strong, the bonding at the interface is covalent, and the electronic states at and around the Fermi level are delocalized across the entire system. These properties are essential for the application of such heterojunctions as contacts in electronic devices and vital for the fabrication of robust nanotube-metal composite materials.nanoelectronics ͉ interfacial interactions ͉ conductivity ͉ electron microscopy ͉ composites H eterojunctions between different materials are of increasing interest in nanotechnology. For creating devices at the nanoscale, different structures have to be joined so as to obtain junctions with predefined properties. Junctions between carbon nanotubes (CNTs) and metals (1-3) or semiconducting (1, 4) nanowires are highly desirable to exploit the excellent electronic and mechanical properties of CNTs. In electronic devices, conductive contacts between the graphitic network of CNTs and metallic electrodes need to be established to link the nanotubes with each other and their periphery. To date, most results indicate that the properties of such a device are dominated by the electronic behavior at the nanotube-metal contact. For instance, the resistance of the ohmic contact (1, 3, 5) or Schottky barrier effects (6) are influenced by the type of interface between metal and the graphitic structure. In some previous studies, multiwall carbon nanotube (MWNTs) interconnections with metal electrodes only occurred with the outermost wall of MWNTs (7). A robust mechanical connection in such a junction cannot be expected, nor can the inner walls of MWNTs participate considerably in charge transport (5). Therefore, detailed knowledge regarding the nature and strength of bonding as well as the morphology and electrical properties of contacts is important because it is vital to connect all concentric cylinders of a MWNT, across the entire cross-section of the nanotube, to a metal particle. In particular, a covalent nanotube-metal junction would allow one to attach nanotubes firmly to metal pieces, which is useful for achieving well-defined electrical contacts and also for attaching nanotubes firmly to metal supports for the realization of ultrastrong nanotube ropes in mechanical systems.Recent studies have reported examples of graphitic material interfaces with metal particles for Co crysta...

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“…41,[50][51][52][53] Hence, E-TEM enabled the direct measurement of CNT growth kinetics of individual CNTs growing from a single catalyst nanoparticle, as shown in Fig. 6.…”

Section: Catalytic Activation and Cnt Nucleationmentioning

confidence: 99%

Data-driven understanding of collective carbon nanotube growth by in situ characterization and nanoscale metrology

Bedewy

2016

J. Mater. Res.

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Aligned carbon nanotubes (CNTs) possess great potential for transforming the fabrication of advanced interfacial materials for energy and mass transport as well as for structural composites. Realizing this potential, however, requires building a deeper understanding and exercising greater control on the atomic scale physicochemical processes underlying the bottom-up synthesis and self-organization of CNTs. Hence, in situ nanoscale metrology and characterization techniques were developed for interrogating CNTs as they grow, interact, and self-assemble. This article presents an overview of recent research on characterization of CNT growth by chemical vapor deposition (CVD), organized into three categories based on the growth stage, for which each technique provides information: (I) catalyst preparation and treatment, (II) catalytic activation and CNT nucleation, and (III) CNT growth and termination. Combining all three categories together provides insights into building the process-structure relationship, and paves the way for producing tailored CNT structures having desired properties for target applications.

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Atomic-Scale In-situ Observation of Carbon Nanotube Growth from Solid State Iron Carbide Nanoparticles

Cited by 531 publications

References 32 publications

Milestones in molecular dynamics simulations of single-walled carbon nanotube formation: A brief critical review

Milestones in molecular dynamics simulations of single-walled carbon nanotube formation: A brief critical review

Heterojunctions between metals and carbon nanotubes as ultimate nanocontacts

Data-driven understanding of collective carbon nanotube growth by in situ characterization and nanoscale metrology

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