Nucleation of Dislocations in 3.9 nm Nanocrystals at High Pressure

TL;DR

This study demonstrates that dislocations can form and cause permanent plasticity in 3.9 nm gold nanocrystals under high pressure, challenging assumptions about their stability at such small scales.

Contribution

It provides experimental and simulation evidence that dislocations nucleate at nanometer scales, showing their activity and impact on plasticity in ultra-small metal crystals.

Findings

Dislocations nucleate within 3.9 nm gold nanocrystals under high pressure.

Surface-nucleated partial dislocations are observed.

Dislocations can lead to permanent plastic deformation at nanometer scales.

Abstract

As circuitry approaches single nanometer length scales, it is important to predict the stability of metals at these scales. The behavior of metals at larger scales can be predicted based on the behavior of dislocations, but it is unclear if dislocations can form and be sustained at single nanometer dimensions. Here, we report the formation of dislocations within individual 3.9 nm Au nanocrystals under nonhydrostatic pressure in a diamond anvil cell. We used a combination of x-ray diffraction, optical absorbance spectroscopy, and molecular dynamics simulation to characterize the defects that are formed, which were found to be surface-nucleated partial dislocations. These results indicate that dislocations are still active at single nanometer length scales and can lead to permanent plasticity.