Strain Evolution in Nanocrystals under High Pressure Tracked with Bragg Coherent X-ray Diffraction Imaging

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Physics

Background:

• Understanding atomic-scale stress accommodation in nanocrystals is vital for their performance in extreme environments.
• Nanocrystals are increasingly used in demanding applications, necessitating knowledge of their mechanical limits.

Purpose of the Study:

• To investigate stress accommodation mechanisms in individual platinum nanoparticles under high pressure.
• To track the evolution of strain and defects within nanoparticles using advanced imaging techniques.

Main Methods:

• Utilized high-pressure Bragg Coherent Diffraction Imaging (BCDI) within a diamond anvil cell (DAC).
• Tracked three-dimensional strain and defect evolution in individual platinum nanoparticles up to 6.7 GPa.
• Employed elastic finite-element modeling to correlate stress concentrations with observed plasticity.

Main Results:

• Observed an interfacial Shockley partial dislocation up to 2.7 GPa.
• Detected nucleation of a dense dislocation network at 5.0 GPa, signifying plasticity, followed by relaxation.
• Documented the reappearance and transformation of the interfacial partial into a perfect dislocation upon unloading, with further glide events.

Conclusions:

• High-pressure BCDI effectively captures dislocation activity and plasticity in nanocrystals.
• The study links reciprocal-space (Bragg peak broadening) and real-space (dislocation imaging) signatures of plasticity.
• Findings provide atomic-scale insights into nanocrystal deformation mechanisms under extreme pressure conditions.