How Do Gold Nanowires Break?

Abstract

Suspended gold nanowires have recently been made in an ultrahigh vacuum and were imaged by electron microscopy. Using realistic molecular dynamics simulation, we study the mechanisms of formation, evolution, and breaking of these atomically thin Au nanowires under stress. We show how defects induce the formation of constrictions that eventually will form the one-atom chains. We find that these chains, before breaking, are five atoms long, which is in excellent agreement with experimental results. After the nanowire's rupture, we analyze the structure of the Au tip, which we believe will be universally present due to its highly symmetric nature.

The uniaxial tensile deformation of Ni nanowire: atomic-scale computer simulations

“…With the strain up to 39.12%, those atoms at the 'tip' of the neck rearrange themselves into an one-atom thick, about three-atoms long necklace (see Fig. 5(b)) which is some similar to what happened in the gold nanowire [18,21]. However, this is not observed for Ni nanowire simulated by Sorensen et al [17].…”

“…However, measuring the mechanical and electrical properties of a nanowire is a difficult task due to the small dimensions [11]. In recent years, the deformation of nanowires have been studied by molecular dynamics simulations using either embodied-atom-method (EAM) [12][13][14][15] or effective-medium theory (EMT) [16,17] potentials as well as first-principles method based on the density functional theory (DFT) [18][19][20][21]. These studies focus on the correlation of the force (associated with the changes in the bonding of the nanowire) and the conductance for the metallic Au, Ni, and Na nano-contacts [17,22] and Au, Ni, Al, Na, and SiSe 2 nanowire [12,16,20,23].…”

“…These studies focus on the correlation of the force (associated with the changes in the bonding of the nanowire) and the conductance for the metallic Au, Ni, and Na nano-contacts [17,22] and Au, Ni, Al, Na, and SiSe 2 nanowire [12,16,20,23]. The structural transformation takes place in nanoscale metallic wires under uniaxial strain [12,14,[17][18]23]. At lower strain rates, the Ni nanowire shows superplasticity [12,13], and at sufficiently high strain rates, it can transform continuously to an amorphous metal at constant temperature [13,14,23].…”

“…At lower strain rates, the Ni nanowire shows superplasticity [12,13], and at sufficiently high strain rates, it can transform continuously to an amorphous metal at constant temperature [13,14,23]. The Au nanowires, before breaking under tensile stress, can get as thin as one-atom chains, and as long as five suspended atoms [18,21]. Sorensen et al [17] have simulated the mechanical deformation of atomic-scale metallic contacts under tensile strain, and found that various defects such as intersecting stacking faults, local disorder, and vacancies were created during the deformation.…”

Alternating starvation of dislocations during plastic yielding in metallic nanowires

“…Due to the unique mechanical, thermal, electrical and optical properties, materials with nanometer-sized structure have attracted a great deal of interest as potential building blocks in nanoelectronic and nanoelectromechanical devices [1]. Many researchers have demonstrated, through both experiments and analysis, that the structure and properties of nanowires can be quite different from those of bulk materials due to the effect of the large surface to volume ratio [2][3][4][5][6][7][8][9][10][11][12][13][14].Recently, Uchic et al [15,16] and Greer et al [17,18] reported that the plastic deformation behavior of single-crystalline sub-micropillars is dependent on the size of the pillar, even without a deformation gradient. More recently, a ''mechanical annealing" test was used to demonstrate that dislocations can be swept out of the samples through the progressive activation and exhaustion of dislocation sources [19].…”