The fracture stabilities of ultrathin gold nanowires

The fracture and corresponding failure of ultrathin gold nanowires have attracted much attention due to its applicable reliability of nanoelectromechanical devices, so understanding the fracture stability is critical especially when the width reduces to ultrathin scale. Here, we studied the fracture stabilities of ultrathin gold nanowires subjected to uniaxial tension. The statistical mechanical properties show that the stabilities result from size effects, in which, the width of 4.5a (“a” means lattice constant, 0.408 nm for gold) is shown as a critical and transitional size. Less than 4.5a, the strong mechanical strength is obviously unstable, attributing to surface dislocation nucleation; Larger than 4.5a, the mechanical stabilities have been enhanced. However, the fracture stabilities are demonstrated to be extrinsic at large sizes because of the dominated action of small aspect ratios. With macro-broken position distributions at the effects of sizes and atomic vacancies, the intrinsic and extrinsic fracture stabilities are further found to be related with the damaged degrees of crystalline lattices and propagated styles of the tensile waves. Lastly, the atomic vacancy sensitivities show the extrinsic fracture stabilities of large sizes are from a competition of bulk atoms and the strong shock induced by small aspect ratio.