Pseudoelasticity in metal nanocrystals allows for shape recovery from strains much larger than their bulk counterparts. This fascinating property could be used to engineer self-healing or reconfigurable materials, but to take full advantage of its possibilities a deeper understanding of its mechanism and limitations is needed. For instance, it is unknown whether room-temperature pseudoelasticity can occur in all metal nanocrystals without the introduction of plastic damage. Here we report the use of non-hydrostatic compression of gold nanocrystals in a diamond anvil cell to a range of maximum pressures, up to 11.4 GPa. Optical absorbance spectroscopy of the localized surface plasmon resonance is used to non-invasively monitor changes in particle shape and crystallinity, as indicated by the plasmon resonance peak position and intensity, respectively. We find that while complete shape recovery occurs following compression to all pressures tested, irreversible crystalline defects are only introduced above a threshold of approximately 2.5 GPa. In this way, we establish the capacity of gold nanocrystals to undergo complete pseudoelastic shape recovery following compression under moderate loads, as well as the onset of limited pseudoelastic behavior at higher loads. This work lays a foundation for future investigations of the limits of pseudoelastic deformation in a wide variety of metal nanocrystals.

Limits of pseudoelasticity in gold nanocrystals

ACS Spring 2022

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