Microscopic understanding of exceptional orientation-dependent tensile and fracture responses of two-dimensional transition-metal carbides

[Display omitted] •MXene has isotropic stiffness with remarkable stretchability for all directions.•These properties render MXene 2D ceramics suitable to flexible/wearable applications.•MXene fractures into zigzag-atomic-edged fragments regardless of tensile direction.•These mechanical features rema...

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Veröffentlicht in:Applied surface science 2022-05, Vol.585, p.152557, Article 152557
Hauptverfasser: In Jhon, Young, Ki Han, Il, Lee, Ju Han, Jhon, Young Min
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Sprache:eng
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Zusammenfassung:[Display omitted] •MXene has isotropic stiffness with remarkable stretchability for all directions.•These properties render MXene 2D ceramics suitable to flexible/wearable applications.•MXene fractures into zigzag-atomic-edged fragments regardless of tensile direction.•These mechanical features remain unchanged for surface termination existence/absence.•The fracture mechanism of MXene can be generalized to other hexagonal 2D materials. Two-dimensional (2D) materials have exceptional mechanical properties that are absent in conventional bulk materials due to their ultra-thin structure with ultra-high surface-to-volume ratio. Despite their great potential both for basic research and applications, however, deep understanding of fundamentally important orientation-dependent mechanical responses of 2D materials have rarely been achieved. In this work, for the first time, we investigate the tensile mechanical response of 2D transition-metal carbides (MXenes) as gradually varying tensile direction by using reactive molecular dynamics simulations. Despite its highly bonded multi-atom-thick structure, MXene proves significantly stretchable (11–17%) for all directions with isotropic stiffness desirable for flexible/wearable applications, while exhibiting unusual characteristic fracture anisotropy. Noticeably, these mechanical features remained qualitatively the same regardless of presence/absence of surface termination. We discover that MXene has always fractured into zigzag-atomic edged fragments regardless of tensile direction and/or surface termination. We reveal the detailed fracture mechanism and propose its generalization to other hexagonal 2D materials with validation for both pristine and surface-hydrogenated graphene nanosheets. Based on these findings, we finally present a physically robust, computationally efficient framework for fast and reliable prediction of MXenes’ unique fracture anisotropy, showing excellent agreement with time-consuming simulation results and suggesting broad applicability to 2D material mechanics.
ISSN:0169-4332
1873-5584
DOI:10.1016/j.apsusc.2022.152557