In situ three-dimensional observation of plasticity onset in a Pt nanoparticle

imaging of the complete dislocation network, coupled with multi-reflection BCDI, enabled us to determine the Burgers vectors of the defects revealing sessile dislocations. Finally, by measuring the elastic field inside the crystal during indentation, we estimate that the shear stress required to generate defects is 6.4 GPa, representing the upper theoretical limit of elasticity and setting an unprecedented standard for Pt nanoparticles. Our findings provide fundamental insights into defect dynamics in nanoscale systems, offering invaluable knowledge for advanced materials design and engineering.