| Abstract Scope |
While metal nanoparticles are foundational to many advanced technologies, the instability of small particles limits their performance and lifetime. Extensive prior work has demonstrated size-dependent behavior. However, mechanistic understanding of deformation processes has been hampered by the difficulty of characterizing nanoparticles as they fail. Here, we have compressed nanoparticles to failure with in situ transmission electron microscopy, linking strength to direct observation of failure mechanisms. More than 250 tests, conducted on particles of Au, Ag, and Pt with sizes ranging from 3 to 130 nm, reveal a complex, non-monotonic dependence of strength on particle size. Larger particles showed a size-dependent competition between displacive plasticity and diffusive mechanisms, with non-monotonic strength. The ultrasmall particles, with single-digit-nanometer sizes, exhibit homogeneous diffusive deformation that contradicts recent theories, and is instead well described by a fundamental thermodynamic energy balance. Overall, this work reveals the regimes and mechanisms underlying nanoparticle failure, across sizes and materials. |