Molecular dynamics simulations of near-surface Fe precipitates in Cu under high electric fields

Vigonski, Simon; Djurabekova, Flyura; Veske, Mihkel; Aabloo, Alvo; Zadin, Vahur

doi:10.1088/0965-0393/23/2/025009

Cited by 10 publications

(3 citation statements)

References 42 publications

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“…Because of the high stress required to create dislocations in a perfect crystal, various imperfections have been introduced into the simulations. Simulations of subsurface voids [1] and precipitates [13] have shown that these sites can generate plateaus or protrusions on the surface when sufficient external stress is applied.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Spontaneous Surface Modifications on Polycrystalline Cu Due to Electric Fields

et al. 2021

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We present a credible mechanism of spontaneous field emitter formation in high electric field applications, such as Compact Linear Collider in CERN (The European Organization for Nuclear Research). Discovery of such phenomena opens new pathway to tame the highly destructive and performance limiting vacuum breakdown phenomena. Vacuum breakdowns in particle accelerators and other devices operating at high electric fields is a common problem in the operation of these devices. It has been proposed that the onset of vacuum breakdowns is associated with appearance of surface protrusions while the device is in operation under high electric field. Moreover, the breakdown tolerance of an electrode material was correlated with the type of lattice structure of the material. Although biased diffusion under field has been shown to cause growth of significantly field-enhancing tips starting from initial nm-size protrusions, the mechanisms and the dynamics of the growth of the latter have not been studied yet. In the current paper we conduct molecular dynamics simulations of nanocrystalline copper surfaces and show the possibility of protrusion growth under the stress exerted on the surface by an applied electrostatic field. We show the importance of grain boundaries on the protrusion formation and establish a linear relationship between the necessary electrostatic stress for protrusion formation and the temperature of the system. Finally, we show that the time for protrusion formation decreases with the applied electrostatic stress, we give the Arrhenius extrapolation to the case of lower fields, and we present a general discussion of the protrusion formation mechanisms in the case of polycrystalline copper surfaces.

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Section: Introductionmentioning

confidence: 99%

Mechanism of Spontaneous Surface Modifications on Polycrystalline Cu Due to Electric Fields

et al. 2021

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“…There are many indications in the literature that metal surfaces behave differently under the influence of a high electric field [2,5,[23][24][25][26][27][28][29][30]. For example, the surface diffusion of adatoms has been found both computationally [31][32][33] and experimentally [34][35][36] to vary depending on the magnitude of the applied field and even become biased when a non-uniform field is present [25,37].…”

Section: Introductionmentioning

confidence: 99%

Atomistic behavior of metal surfaces under high electric fields

et al. 2019

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Combining classical electrodynamics and density functional theory (DFT) calculations, we develop a general and rigorous theoretical framework that describes the energetics of metal surfaces under high electric fields. We show that the behavior of a surface atom in the presence of an electric field can be described by the polarization characteristics of the permanent and field-induced charges in its vicinity. We use DFT calculations for the case of a W adatom on a W{110} surface to confirm the predictions of our theory and quantify its system-specific parameters. Our quantitative predictions for the diffusion of W-on-W{110} under field are in good agreement with experimental measurements. This work is a crucial step towards developing atomistic computational models of such systems for long-term simulations. arXiv:1808.07782v3 [cond-mat.mtrl-sci]

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“…The triggering mechanism of vacuum breakdowns is not entirely clear yet, but experiments have shown a significant field enhancement near copper surfaces, that could lead to breakdown events via positive feedback effect [5]. Such an enhancement could be caused, for instance, by Cu nanotips with aspect ratio of 30-140 [5] whose formation mechanisms have been studied in [6]- [10]. However, such tips have not yet been directly observed on Cu surfaces [5], although there is a report about the formation of field emitters with aspect ratio 3.5-15 on Nb surfaces [11].…”

Section: Introductionmentioning

confidence: 99%

Electrodynamics—molecular dynamics simulations of the stability of Cu nanotips under high electric field

Veske¹,

Parviainen²,

Zadin³

et al. 2016

J. Phys. D: Appl. Phys.

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The shape memory effect and pseudoelasticity in Cu nanowires is one possible pair of mechanisms that prevents high aspect ratio nanosized field electron emitters to be stable at room temperature and permits their growth under high electric field. By utilizing hybrid electrodynamicsmolecular dynamics simulations we show that a global electric field of 1 GV/m or more significantly increases the stability and critical temperature of spontaneous reorientation of nanosized <100> Cu field emitters. We also show that in the studied tips the stabilizing effect of an external applied electric field is an order of magnitude greater than the destabilization caused by the field emission current. We detect the critical temperature of spontaneous reorientation using the tool that spots the changes in crystal structure. The method is compatible with techniques that consider the change in potential energy, has a wider range of applicability and allows pinpointing different stages in the reorientation processes.

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Molecular dynamics simulations of near-surface Fe precipitates in Cu under high electric fields

Cited by 10 publications

References 42 publications

Mechanism of Spontaneous Surface Modifications on Polycrystalline Cu Due to Electric Fields

Mechanism of Spontaneous Surface Modifications on Polycrystalline Cu Due to Electric Fields

Atomistic behavior of metal surfaces under high electric fields

Electrodynamics—molecular dynamics simulations of the stability of Cu nanotips under high electric field

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