Anisotropic mechanical properties of α-MoO₃ nanosheets

Abstract

The mechanical behaviors of 2D materials are fundamentally important for their potential applications in various fields. α-Molybdenum trioxide (α-MoO3) crystals with unique electronic, optical, and electrochemical properties, have attracted extensive...

Anisotropic Fracture of Two-Dimensional Ta2NiSe5

“…34,35 In addition, the standard deviation of modulus and strength here exhibits a relatively high level, which may be attributed to 37 MoO 3 , 24 BCN, 38 graphene, 36 h-BN, 39 TMDs, 40 t-Se, 22 b-As, 23 variations in material thickness, sample width, prestress, as well as edge defects. The consequent anisotropic ratio (Section S5) for Young's modulus is approximated to be 1.3, similar to MoO 3 24 and b-As, 23 but lower than that documented for As 2 S 3 11,12 and BP. 9 Another anisotropic mechanical response lies in the discrepancy between failure strain along two different directions.…”

“…This is because the interlayer slip-induced mechanical softening is more pronounced for a few layers − (typically <10 layers) but indiscernible for thick layers. , In addition, the standard deviation of modulus and strength here exhibits a relatively high level, which may be attributed to variations in material thickness, sample width, prestress, as well as edge defects. The consequent anisotropic ratio (Section S5) for Young’s modulus is approximated to be 1.3, similar to MoO 3 and b-As, but lower than that documented for As 2 S 3 , and BP . Another anisotropic mechanical response lies in the discrepancy between failure strain along two different directions.…”

“…Such a high strain limit among other 2D materials endows TNS with great potential for flexible/stretchable electronics. Comparatively, we summarize the anisotropic ratio of failure strain of various 2D materials in Figure g, among which TNS shows a more significant mechanical anisotropy than graphene family (graphene, C–B–N compounds − ) and oxide-based materials . Although comparable to most TMDs, such an anisotropic ratio is lower than that for elemental materials with puckered lattice structure. ,, There is no doubt that the observed mechanical anisotropy of TNS originates from its anisotropic structures, where linear chains and zigzag chains are formed along the a -axis and c -axis, respectively.…”

“…(e) Young’s modulus and (f) fracture strength in different crystallography orientations. (g) Summary of anisotropic ratio of failure strain for 2D materials including B 4 N, MoO 3 , BCN, graphene, h-BN, TMDs, t -Se, b-As, and b-P …”

“…Nonetheless, foreseeing the development of fracture remains a daunting challenge, which hinges on the precise characterization of anisotropic fracture toughness. In this regard, most of studies so far focused on the anisotropic fracture of isotropic 2D materials, such as graphene, hexagonal boron nitride (h-BN), and high-symmetry TMDs, primarily based on in situ scanning electron microscopy (SEM) tensile tests, − dynamical observations of crack tips in transmission electron microscopy (TEM), − and identification of edge orientations by mechanical cleavage. − Although several works reported the fracture of anisotropic 2D materials, − there is a dearth of quantitative understanding on nanoscale failure mechanism.…”