Strained Metallic Surfaces

Levitin, Valim; Loskutov, Stephan

doi:10.1002/9783527626434

Cited by 3 publications

(3 citation statements)

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“…In a similar fashion, it has been shown, using a stochastic model, that the correlated motion of dislocations can lead to micron-sized surface protrusions, when persistent slip bands, caused by cyclic stress, break through the surface [23,24]. This was observed using SEM in fatigued samples exposed to high-cyclic stresses [25,26].…”

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confidence: 80%

Stochastic Model of Breakdown Nucleation under Intense Electric Fields

2018

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A plastic response due to dislocation activity under intense electric fields is proposed as a source of breakdown. A model is formulated based on stochastic multiplication and arrest under the stress generated by the field. A critical transition in the dislocation population is suggested as the cause of protrusion formation leading to subsequent arcing. The model is studied using Monte Carlo simulations and theoretical analysis, yielding a simplified dependence of the breakdown rates on the electric field. These agree with experimental observations of field and temperature breakdown dependencies.

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confidence: 80%

Stochastic Model of Breakdown Nucleation under Intense Electric Fields

2018

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“…In particular, the formation of surface features occurs at the surface-slip band intersection. [3][4][5][6][7] Even at stresses close to the yield point, a complete analysis of the dislocation dynamics must take into account the stochastic nature of mobile dislocation nucleation and depletion. 8 For instance, it was shown experimentally and through simulation that the compression of micropillars, which can be formed as single crystals with a low dislocation density, consists of a series of discrete slip events, in which applied stress unpins sessile dislocations and enables them to move to the surface of the crystal.…”

Section: Introductionmentioning

confidence: 99%

Theory of electric field breakdown nucleation due to mobile dislocations

Engelberg

Yashar

Ashkenazy

et al. 2019

Phys. Rev. Accel. Beams

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A model is described, in which electrical breakdown in high-voltage systems is caused by stochastic fluctuations of the mobile dislocation population in the cathode. In this model, the mobile dislocation density normally fluctuates, with a finite probability to undergo a critical transition due to the effects of the external field. It is suggested that once such a transition occurs, the mobile dislocation density will increase deterministically, leading to electrical breakdown. Model parametrization is achieved via microscopic analysis of OFHC Cu cathode samples from the CERN CLIC project, allowing the creation and depletion rates of mobile dislocations to be estimated as a function of the initial physical condition of the material and the applied electric field. We find analytical expressions for the mean breakdown time and quasistationary probability distribution of the mobile dislocation density, and verify these results by using a Gillespie algorithm. A least-squares algorithm is used to fit these results with available experimental data of the dependence of the breakdown rate on the applied strength of the electric field and on temperature. The effects of the variation of some of the assumptions of the physical model are considered, and a number of additional experiments to validate the model are proposed, which include examining the effects of the temperature and pulse length, as well as of a time-dependent electric field, on the breakdown rate. Finally, applications of the model are discussed, including the usage of the quasistatic probability distribution to predict breakdowns, and applying the predictions of the model to improve the conditioning process of the cathode material.

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“…[26,27] and references therein). For example, Kiejna and Pogosov [28] and Pogosov and Kurbatsky [29] have found a decrease of the work function in response to a uniaxial tensile strain using a modified stabilized jellium model, whereas Levitin and Loskutov [26] report positive values from theoretical calculations using different variants of the jellium model as well as from experimental determination of the variation of the work function with elastic deformation.…”

Section: Introductionmentioning

confidence: 99%

Sign-inverted response of aluminum work function to tangential strain

Michl

Weißmüller

Müller

2013

J. Phys.: Condens. Matter

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We have investigated the response of the work function, W, of low-index aluminum surfaces to tangential strain by using first-principles calculations based on density functional theory. This response parameter is a central quantity in electrocapillary coupling of metal electrodes relating to the performance of porous metal actuators and surface stress based sensing devices. We find that Al surfaces exhibit a positive response for all orientations considered. By contrast, previous studies reported negative-valued response parameters for clean surfaces of several transition metals. We discuss separately the response of W to different types of strain and the impact of the strain on the Fermi energy and the surface dipole. We argue that the reason for the abnormal positive sign of the Al response parameter lies in its high valence electron density.

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Strained Metallic Surfaces

Cited by 3 publications

References 0 publications

Stochastic Model of Breakdown Nucleation under Intense Electric Fields

Stochastic Model of Breakdown Nucleation under Intense Electric Fields

Theory of electric field breakdown nucleation due to mobile dislocations

Sign-inverted response of aluminum work function to tangential strain

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