Simulations of electromechanical shape transformations of Au nanoparticles

Metallic nanocrystals can exhibit intriguing properties due to large surfaces specific for low-dimensional objects. Recent experimental observation showed an interesting shape transformation of Au nanoparticle during simultaneous mechanical and electrical load. By applying finite element methods extended to include nanosize effects, we study the mechanisms of such transformations. We utilize fully coupled electro-thermal calculations with the nanoscale correction to the electric and thermal conductivities. The mechanical response of the material is simulated using the elastoplastic material model while the nanoscale mechanical interaction between gold and tungsten particles is simulated using adhesive contact modelling. We observe that Joule heating due to high electric currents increases the temperature of the nanoparticle to the value close to the melting point. In combination with the mechanical stress, this causes significant plastic deformations within the nanoparticle, which can explain the observed shape modification of the latter.