Concentration of thermal vacancies in metallic nanoparticles

The influence of particle size on the concentration of thermal vacancies in metallic nanoparticles is investigated. By analyzing the contributions of surface energies and surface stresses to the vacancy formation energy, a particle size-dependent model is derived. The vacancy concentration in metallic nanoparticles is predicted to be smaller than the bulk value. The results are verified by Monte Carlo simulations using the broken bond model and by molecular statics calculations with embedded atom method potentials. The combination of both methods allows to study the influence of surface energies and stresses, separately, and to verify the proposed model description.