Effects of crystallographic and geometric orientation on ion beam sputtering of gold nanorods

Abstract

Nanostructures may be exposed to irradiation during their manufacture, their engineering and whilst in-service. The consequences of such bombardment can be vastly different from those seen in the bulk. In this paper, we combine transmission electron microscopy with in situ ion irradiation with complementary computer modelling techniques to explore the physics governing the effects of 1.7 MeV Au ions on gold nanorods. Phenomena surrounding the sputtering and associated morphological changes caused by the ion irradiation have been explored. In both the experiments and the simulations, large variations in the sputter yields from individual nanorods were observed. These sputter yields have been shown to correlate with the strength of channelling directions close to the direction in which the ion beam was incident. Craters decorated by ejecta blankets were found to form due to cluster emission thus explaining the high sputter yields.

Evolution of Gold Nanoparticles in Radiation Environments

“…These experimental results contradict the classic Monte Carlo-based simulations of sputtering effects [57]. A more catastrophic image of radiation damage in various sizes and morphologies of gold nanoparticles is predicted by molecular dynamic simulations of heavy ion irradiation [20,26,27,56,58]. An example of these types of simulations comparing the expected sputtering from a flat surface versus significantly increased sputtering from a nanoparticle can be seen in Figure 6 [58].…”

“…An example of these types of simulations comparing the expected sputtering from a flat surface versus significantly increased sputtering from a nanoparticle can be seen in Figure 6 [58]. The recent work has correlated the in-situ TEM observation of nanorod evolution and sputtering with molecular dynamic simulations that provide greater insight into the role of local crystal orientation on the effects of individual ion strikes relative to the nanoparticle orientation [26,56]. The sputtering of the nanoparticles has also been tied to sintering of clustered gold nanoparticles, which is not surprising due to the work imparted into such a small volume.…”

“…Clearly, the response of both freestanding and embedded gold nanoparticles is drastically different than gold in bulk or thin-film morphologies and is highly dependent on the radiation environment, particle morphology, and surface conditions. Additional work is needed to elucidate the underlying physics governing the increased sputtering and other scaling effects observed in gold nanoparticles [26,27,56]. Without a detailed understanding of the mechanisms active when the displacement damage length scale of the radiation event approaches that of the size of the nanoparticle exposed, it will be challenging to employ gold nanoparticles in most radiation environments.…”

“…Put simply, instead of diffusing into organized defect structures, the generated point defects tend to annihilate at the particle surface, or material is ejected from the particle volume, as a result of the energetic collision [24,25]. This can drastically alter the shape of individual particles and cause agglomeration of closely spaced particle groupings [26][27][28]. Such morphological changes have the potential to adversely affect their efficacy in applications where the high surface-to-volume ratio and local structure are essential for performance.…”

Highly Self-Organized Materials: Formation Mechanism and Electrochemical Synthesis

“…Materials scientists are focused on advanced techniques that afford the self-assembly and selforganization of nanoscale species into systems. Several researches have been undertaken and different methods were used for the fabrication of organized nanostructures: lithography techniques [11,12], ion sputtering [13,14], bottom-up approach [15], i.e. building up nanostructures, electrochemical methods [16,17], template synthesis [18,19] etc.…”