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キーワード:
Annihilation; Density functional theory; Ab initio; Atomic configuration; Condition; Field ion microscope; Field ion microscopy; Formation kinetics; High electric fields; Metal surfaces; Microscope images; Vacancy formation energies; Electric fields
要旨:
Recording field ion microscope images under field-evaporating conditions and subsequently reconstructing the underlying atomic configuration, called three-dimensional field ion microscopy (3D-FIM), is one of the few techniques capable of resolving crystalline defects at an atomic scale. However, the quantification of the observed vacancies and their origins are still a matter of debate. It was suggested that high electrostatic fields (1-5 V/Å) used in 3D-FIM could introduce artifact vacancies. To investigate such effects, we used density functional theory simulations. Stepped nickel and platinum surfaces with kinks were modeled in the repeated-slab approach with a (971) surface orientation. An electrostatic field of up to 4 V/Å was introduced on one side of the slab using the generalized dipole correction. Contrary to what was proposed, we show that the formation of vacancies on the electrified metal surface is more difficult compared to a field-free case. We also find that the electrostatic field can introduce kinetic barriers to a potential "vacancy annihilation"mechanism. We rationalize these findings by comparing to insights from field evaporation models. © 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by the Max Planck Society.
