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Title: 

Understanding the Effect of Surfaces on the Mechanical Behavior of Metal Nanoparticles Using In-Situ Transmission Electron Microscopy 

  

ABSTRACT: 

  

Metal nanoparticles are widespread in applications from biomedical sensing to solar energy to catalysis; the performance in these applications depends on the reliability and mechanical integrity of these nanoparticles. The purpose of this project is to achieve fundamental understanding of the mechanical behavior of small–size (<20 nm) metal nanoparticles by using in situ nanoindentation inside of a transmission electron microscope (TEM). This approach combines atomic-scale characterization of nanoparticle’s size, shape and crystal structure with nanonewton-scale force resolution to probe mechanical properties of individual metal nanoparticles.  

Prior work had established that metal nanoparticles show size–sensitive “smaller is stronger” mechanical strength due to defect starvation, and ultrasmall particles (~5–20 nm) show a “smaller is much weaker” trend, which is commonly attributed to surface-diffusion assisted deformation. However, critical questions remain about the deformation mechanism governing the mechanical behavior of metal nanoparticles, and also about the role of the surface in nanoparticle deformation. Prior and ongoing work in this project is aimed at examining the role of thermal energy in governing nanoparticle shape, the effect of particle morphology, and loading conditions on nanoparticle strength. If it is successful, this project will establish the role of surfaces in nanoparticle deformation, and enable the tuning of mechanical strength of small nanoparticles by controlling size, shape, and surface termination.

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