Stone-Wales-type transformations in carbon nanostructures driven by electron irradiation

Kotakoski, Jani; Meyer, Jannik C.; Kurasch, Simon; Santos-Cottin, David; Kaiser, Ute; Krasheninnikov, Arkady V.

doi:10.1103/physrevb.83.245420

Cited by 246 publications

(290 citation statements)

References 39 publications

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“…Contrary to previously reported irreversible beam-induced dynamics [12][13][14][15][16][17][18][19][20][21][22] , here we report a beaminduced reversible conformational transformation of the trapped Si 6 cluster in a graphene nanopore. Density-functional calculations of an embedded Si 6 cluster are used to probe its bonding to the host graphene lattice and the energy barriers for the conformational transformation.…”

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confidence: 99%

“…Figure 1 shows a sequential set of annular dark field (ADF) Z-contrast images of a single Si 6 cluster trapped in a graphene nanopore. Electron-beam-induced ejection of carbon atoms and defect creation/migration has been actively studied in graphene and carbon nanotubes [12][13][14][15][16][17][18][19][20][21][22] . Contrary to these irreversible dynamics, we find that an oscillatory motion occurs in the trapped Si 6 cluster: one of the Si atoms executes a back-and-forth motion corresponding to the reversible conformational change of the Si 6 cluster in the graphene pore.…”

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Direct visualization of reversible dynamics in a Si6 cluster embedded in a graphene pore

et al. 2013

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Clusters containing only a handful of atoms have been the subject of extensive theoretical and experimental studies, but their direct imaging has not been possible so far, with information about their structure provided mainly by theory. Here we report a direct atomically-resolved observation of a single Si 6 cluster trapped in a graphene nanopore. Furthermore, though electron-beam-induced irreversible atomic displacements have been reported before, here we report a sequence of images that show a reversible, oscillatory, conformational change: one of the Si atoms jumps back and forth between two different positions. Density-functional calculations show that the embedded cluster is exploring metastable configurations under the influence of the beam, providing direct information on the atomic-scale energy landscape. The capture of a Si cluster in a graphene nanopore suggests the possibility of patterning nanopores and assembling atomic clusters with a potential for applications.

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Direct visualization of reversible dynamics in a Si6 cluster embedded in a graphene pore

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“…It is well known that in graphene, high-energy electron irradiation can induce sputtering of carbon atoms and bond rotations (so-called Stone-Wales transformations) 24 . In our experiment, we used an operating voltage of 80 kV, which is below the static sputtering threshold in graphene.…”

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Atomic scale study of the life cycle of a dislocation in graphene from birth to annihilation

et al. 2013

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Dislocations, one of the key entities in materials science, govern the properties of any crystalline material. Thus, understanding their life cycle, from creation to annihilation via motion and interaction with other dislocations, point defects and surfaces, is of fundamental importance. Unfortunately, atomic-scale investigations of dislocation evolution in a bulk object are well beyond the spatial and temporal resolution limits of current characterization techniques. Here we overcome the experimental limits by investigating the two-dimensional graphene in an aberration-corrected transmission electron microscope, exploiting the impinging energetic electrons both to image and stimulate atomic-scale morphological changes in the material. The resulting transformations are followed in situ, atom-by-atom, showing the full life cycle of a dislocation from birth to annihilation. Our experiments, combined with atomistic simulations, reveal the evolution of dislocations in two-dimensional systems to be governed by markedly long-ranging out-of-plane buckling.

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“…During such collision, kinetic energy is transferred from the high-energy electron beam to interstitial atoms, assisting them in overcoming the energy barrier to migration athermally. A similar mechanism had been previously proposed for radiation effects on vacancy diffusion in lead [28] and more recently also for defect transformation and migration on surfaces [29] and in mono-layer graphene [30][31][32][33]. However, until now radiation-induced diffusion of defect clusters in bulk had not been demonstrated.…”

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Radiation-induced mobility of small defect clusters in covalent materials

Jiang¹,

He²,

Morgan³

et al. 2016

Phys. Rev. B

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Although defect clusters are detrimental to electronic and mechanical properties of semiconductor materials, annihilation of such clusters is limited by their lack of thermal mobility due to high migration barriers. Here, we find that small clusters in bulk SiC (a covalent material of importance for both electronic and nuclear applications) can become mobile at room temperature under the influence of electron radiation. So far, direct observation of radiationinduced diffusion of defect clusters in bulk materials has not been demonstrated yet. This finding was made possible by low angle annular dark field (LAADF) scanning transmission electron microscopy (STEM) combined with non-rigid registration technique to remove sample instability, which enables atomic resolution imaging of small migrating defect clusters. We show that the underlying mechanism of this athermal diffusion is ballistic collision between incoming electrons and cluster atoms. Our findings suggest that defect clusters may be mobile under certain irradiation conditions, changing current understanding of cluster annealing process in irradiated covalent materials. Main textDefect clusters can form in covalent materials during ion implantation (e.g., in semiconductor applications) [1,2] or during irradiation (e.g., in nuclear reactor applications) [3][4][5][6]. Accumulation of such clusters is highly detrimental to electronic, optical, and mechanical properties of these materials [1,4,7]. While point defects can often be eradicated by mutual recombination or diffusion to defect sinks, clusters of defects in covalent materials are known to be immobile and resist annealing because of their high energy barriers to migration [8,9]. For SiC specifically, accelerated molecular dynamics (MD) simulations have shown that the barrier to migration of clusters as small as just three C interstitials is ~4.3 eV [8], which means that these clusters are immobile below 1,200 K on typical experimental annealing time scales (i.e., 1 hour whereas the cluster performs less than 1 hop/day). Such high barriers explain why models of defect evolution in SiC have assumed clusters to be immobile even at elevated temperatures (e.g., Ref. [10,11]) and why the nature of such clusters, their resistance to high-temperature annealing, and their effects on opto-electronic properties have been a subject of many discussions in the semiconductor literature [12,13].In this letter, we report a direct observation of interstitial clusters diffusion in bulk SiC under the influence of electron radiation at room temperature. Although it is known that in metals

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Stone-Wales-type transformations in carbon nanostructures driven by electron irradiation

Cited by 246 publications

References 39 publications

Direct visualization of reversible dynamics in a Si6 cluster embedded in a graphene pore

Direct visualization of reversible dynamics in a Si6 cluster embedded in a graphene pore

Atomic scale study of the life cycle of a dislocation in graphene from birth to annihilation

Radiation-induced mobility of small defect clusters in covalent materials

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