Metals that are strained past their elastic limit typically undergo permanent deformation. It has been recently observed that sub-10nm metal nanocrystals compressed to large strains will recover their initial shape and microstructure when load is removed. Here, we explore the size-dependence of this pseudo-elastic behavior by compressing colloidal Au nanocrystals in a diamond anvil cell. Spherical Au nanocrystals ranging 4-41nm in size were compressed to 10GPa under either hydrostatic and non-hydrostatic pressure while, taking advantage of the sensitivity of plasmon resonances to nanocrystal size and shape, optical absorbance was used to monitor nanocrystal structural changes. Finite element modeling was used to correlate the applied pressure to nanocrystal structural changes. We find that 4nm Au nanocrystals recover their original size and shape when load is removed, even when compressed by ~20%. In contrast, 41nm Au nanocrystals show permanent deformation upon compression as expected for bulk metals.

Size-dependent pseudo-elasticity in gold nanocrystals

255th National Meeting (2018)

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