Probing the Mechanical Properties of Porous Nanoshells by Nanoindentation

In this contribution, we present a study of the mechanical properties of porous nanoshells measured with a nanoindentation technique. Porous nanoshells with hollow designs can present attractive mechanical properties, as observed in hollow nanoshells, but coupled with the unique mechanical behavior of porous materials. Porous nanoshells display mechanical properties that are dependent on shell porosity. Our results show that, under smaller porosity values, deformation is closely related to the one observed for polycrystalline and single-crystalline nanoshells involving dislocation activity. When porosity in the nanoparticle is increased, plastic deformation was mediated by grain boundary sliding instead of dislocation activity. Additionally, porosity suppresses dislocation activity and decreases nanoparticle strength, but allows for significant strain hardening under strains as high as 0.4. On the other hand, Young's modulus decreases with the increase in nanoshell porosity, in agreement with the established theories of porous materials. However, we found no quantitative agreement between conventional models applied to obtain the Young's modulus of porous materials.

Automated summary

This study investigates the mechanical properties of porous nanoshells using nanoindentation technique. The results show that the mechanical properties of porous nanoshells are closely related to the shell porosity. When the porosity is low, deformation is similar to polycrystalline and single-crystalline nanoshells involving dislocation activity. However, with the increase in porosity, plastic deformation is mediated by grain boundary sliding instead of dislocation activity. Porosity suppresses dislocation activity, decreases nanoparticle strength, but allows significant strain hardening. Young's modulus decreases with the increase in nanoshell porosity, but conventional models fail to quantitatively predict it.