Anisotropic Fracture of Two-Dimensional Ta₂NiSe₅

Anisotropic two-dimensional materials present a diverse range of physical characteristics, making them well-suited forapplications in photonics and optoelectronics. While mechanical properties play a crucial role in determining the reliability andefficacy of 2D material-based devices, the fracture behavior of anisotropic 2D crystals remains relatively unexplored. Toward this end,we herein present the first measurement of the anisotropic fracture toughness of 2D Ta2NiSe5 by microelectromechanical system-based tensile tests. Our findings reveal a significant in-plane anisotropic ratio (∼3.0), accounting for crystal orientation-dependentcrack paths. As the thickness increases, we observe an intriguing intraplanar-to-interplanar transition of fracture along the a-axis,manifesting as stepwise crack features attributed to interlayer slippage. In contrast, ruptures along the c-axis surprisingly exhibitpersistent straightness and smoothness regardless of thickness, owing to the robust interlayer shear resistance. Our work affords apromising avenue for the construction of future electronics based on nanoribbons with atomically sharp edges. Copyright © 2024 American Chemical Society