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Anisotropic fracture dynamics due to local lattice distortions

DOI: 10.1021/acsnano.9b01071 DOI Help

Authors: Gang Seob Jung (Massachusetts Institute of Technology) , Shanshan Wang (University of Oxford; National University of Defense Technology, China) , Zhao Qin (Massachusetts Institute of Technology) , Si Zhou (University of Oxford) , Mohsen Danaie (Diamond Light Source) , Angus I. Kirkland (University of Oxford; Diamond Light Source) , Markus J. Buehler (Massachusetts Institute of Technology) , Jamie H. Warner (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Nano

State: Published (Approved)
Published: May 2019
Diamond Proposal Number(s): 19045

Abstract: A brittle material under loading fails by the nucleation and propagation of a sharp crack. In monatomic crystals, such as silicon, the lattice geometries front to the crack-tip changes the way of propagation even with the same cleavage surface. In general, however, crystals have multiple kinds of atoms and how the deformation of each atom affects the failure is still elusive. Here, we show that local atomic distortions from the different types of atoms causes a propagation anisotropy in suspended WS2 monolayers by combining annular dark-field scanning transmission electron microscopy and empirical molecular dynamics that are validated by first-principles calculations. Conventional conditions for brittle failure such as surface energy, elasticity, and crack geometry cannot account for this anisotropy. Further simulations predict the enhancement of the strengths and fracture toughness of the materials by designing void shapes and edge structures.

Journal Keywords: 2D materials; ADF-STEM; fracture mechanics; molecular dynamics; propagation anisotropy

Subject Areas: Materials

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