The Ideal Strength of Two-dimensional Stanene May Reach or Exceed the Griffith Strength Estimate

Ideal strength is the maximum stress a material can withstand, and it is an important intrinsic property for structural applications. A Griffith strength limit of ∼E/9 is the best known upper bound of this property for a material loaded in tension. Here we report that stanene, a recently fabricated two-dimensional material, could approach and possibly exceed this limit from a theoretical perspective. Utilizing first-principles density functional theory, we investigated the nonlinear elastic behavior of stanene and found that its strength could reach ∼E/7.4 under uniaxial tension in both armchair and zigzag directions without incurring phonon instability or mechanical failure. The unique mechanical properties of stanene are appreciated by comparison with other Group-IV 2D materials.