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Pressure-induced stiffness of Au nanoparticles to 71 GPa under quasihydrostatic loading

Author(s): Hong, Xinguo; Duffy, Thomas S; Ehm, Lars; Weidner, Donald J

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Abstract: The compressibility of nanocrystalline gold (n-Au, 20 nm) has been studied by x-ray total scattering using high-energy monochromatic x-rays in the diamond anvil cell under quasi-hydrostatic conditions up to 71 GPa. The bulk modulus, K 0, of the n-Au obtained from fitting to a Vinet equation of state is ~196(3) GPa, which is about 17% higher than for the corresponding bulk materials (K 0: 167 GPa). At low pressures (<7 GPa), the compression behavior of n-Au shows little difference from that of bulk Au. With increasing pressure, the compressive behavior of n-Au gradually deviates from the equation of state (EOS) of bulk gold. Analysis of the pair distribution function, peak broadening and Rietveld refinement reveals that the microstructure of n-Au is nearly a single-grain/domain at ambient conditions, but undergoes substantial pressure-induced reduction in grain size until 10 GPa. The results indicate that the nature of the internal microstructure in n-Au is associated with the observed EOS difference from bulk Au at high pressure. Full-pattern analysis confirms that significant changes in grain size, stacking faults, grain orientation and texture occur in n-Au at high pressure. We have observed direct experimental evidence of a transition in compressional mechanism for n-Au at ~20 GPa, i.e. from a deformation dominated by nucleation and motion of lattice dislocations (dislocation-mediated) to a prominent grain boundary mediated response to external pressure. The internal microstructure inside the nanoparticle (nanocrystallinity) plays a critical role for the macro-mechanical properties of nano-Au.
Publication Date: 16-Nov-2015
Citation: Hong, Xinguo, Thomas S. Duffy, Lars Ehm, and Donald J. Weidner. "Pressure-induced stiffness of Au nanoparticles to 71 GPa under quasi-hydrostatic loading." Journal of Physics: Condensed Matter 27, no. 48 (2015): 485303. doi:10.1088/0953-8984/27/48/485303.
DOI: doi:10.1088/0953-8984/27/48/485303
ISSN: 0953-8984
EISSN: 1361-648X
Pages: 485303
Language: English
Type of Material: Journal Article
Journal/Proceeding Title: Journal of Physics: Condensed Matter
Version: Author's manuscript

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