Au nanowire junction breakup through surface atom diffusion

Abstract

Metallic nanowires are known to break into shorter fragments due to the Rayleigh instability mechanism. This process is strongly accelerated at elevated temperatures and can completely hinder the functioning of nanowire-based devices like e.g. transparent conductive and flexible coatings. At the same time, arranged gold nanodots have important applications in electrochemical sensors. In this paper we perform a series of annealing experiments of gold and silver nanowires and nanowire junctions at fixed temperatures 473, 673, 873 and 973 K (200 °C, 400 °C, 600 °C and 700 °C) during a time period of 10 min. We show that nanowires are especially prone to fragmentation around junctions and crossing points even at comparatively low temperatures. The fragmentation process is highly temperature dependent and the junction region breaks up at a lower temperature than a single nanowire. We develop a gold parametrization for kinetic Monte Carlo simulations and demonstrate the surface diffusion origin of the nanowire junction fragmentation. We show that nanowire fragmentation starts at the junctions with high reliability and propose that aligning nanowires in a regular grid could be used as a technique for fabricating arrays of nanodots.

The effect of heat-treatment on morphology and mobility of Au nanoparticles

“…Another important factor for heat-induced morphological changes overlooked by many other studies is annealing time. We believe it is rather surface effect resulting in rounding of NPs as an energy minimization via rearrangement of surface atoms similar to effect demonstrated recently by Vigonski et al [17] for heat-induced segmentation of Au nanowires at temperatures much below Au melting point. It was noticed that effect of rounding was more pronounced for NPs with five-fold twinned inner structure in comparison to single crystalline particles in the form of truncated triangles.…”

“…Simulations of NP rounding were carried out using the Kinetic Monte Carlo (KMC) code Kimocs [21], which is specifically designed for metal surfaces. The parameters for Au, developed in [17], used the tethering method for stabilization [22].…”

“…For already synthesized NPs morphology can be changed by giving additional energy to the NPs by laser treatment [16] or by heating the NPs in an oven. Partial melting can be achieved at significantly lower temperature than the melting temperature of bulk Au [17].…”

Imaging Beam‐Sensitive Materials by Electron Microscopy

“…The breakup dynamics of an ultrathin [111] grown Au nanowire due to Rayleigh instability can also be simulated using Kinetic Monte Carlo simulations under an elevated temperature, which results in more stable nanoclusters bounded by {111} facets through surface diffusion (Figure 4c). 146 On the other hand, as a typical 2D nanostructure system, ultrathin Au nanosheets with hexagonal close packing (hcp) structure are also subject to remarkable electron beam damage,147 which quickly lose their ultrathin nanosheet morphology and generate abundant pores with thicker pore walls (Figure 4d). Combining selected area electron diffraction (SAED) and HRTEM of individual pore walls (Figure 4e,f), this morphological evolution is accompanied with the hcp to fcc phase transformation and the formation of nanotwins and stacking faults 147.…”

The effect of heat treatment on the morphology and mobility of Au nanoparticles

“…For readily synthesized NPs, the morphology can be changed by adding energy to the NPs by laser treatment [16] or by heating the NPs in an oven. Partial melting can be achieved at a significantly lower temperature than the melting temperature of bulk Au [17].…”