Metal nanoparticles exhibit unique chemical, physical and optical properties that make them useful in a variety of sensor, catalysis, and electronic applications. Here, we investigate the effects of repeated deformation on the unique pseudoelastic shape recovery seen in gold nanospheres (Au-NS). Specifically, we pressurize small Au-NS in the gigapascal (GPa) regime in a diamond anvil cell and use changes in the surface plasmon to monitor deformation. The introduction of defects is indicated by a decrease in peak plasmon absorbance, an observation previously confirmed using in-situ X-ray diffraction. Previous research has established that single pressurization runs yield complete shape recovery accompanied by varying amounts of lasting internal defects introduced above a pressure threshold of approximately 2.5 GPa. However, a mechanistic model behind the introduction of structural defects has yet to be uncovered. Our investigation uses pressure cycling around the damage threshold to further our understanding of the conditions that cause defects to form. Cycling below the damage threshold causes an accumulation of defects, but only if the sample is not completely depressurized between cycles. On the other hand, exceeding the pressure even slightly (by about 0.5 GPa) in an early cycle causes the particles to accumulate damage in subsequent pressurizations, even under conditions that do not normally cause lasting damage. We propose that beyond a certain “point of no return”, large stacking faults prevent an effective recovery process during depressurization. Further investigations include post-recovery HRTEM analysis to evaluate changes at a single particle level and further compare high-pressure defects to cycling defects.

Damage through repeated low-level exposure: Defect accumulation in gold nanocrystals through non-hydrostatic pressure cycling

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.