Measurement of atomic dispersion on buried Ag nanoparticles decomposed by Ne plus ion irradiation

The effects of room temperature 200 keV Ne + ion irradiation on Ag nanoparticles (NPs) embedded in a silicon nitride film have been studied via Medium Energy Ion Scattering (MEIS), Scanning Transmission Electron Microscopy (STEM), and the results are discussed in comparison with Monte Carlo TRI3DYN simulations. The experiment was designed to test the mechanisms controlling the room temperature irradiation-induced microstructure evolution of individual NPs and the overall system. We present an innovative MEIS approach capable of quantitatively determining Ag's content and spatial distribution in solution. The STEM observations demonstrate the nucleation of smaller Ag NPs distributed within the solute field. The TRI3DYN simulations suggest that a fraction of the solute content is reincorporated within the NPs. These results are discussed considering that room-temperature thermal diffusion processes are significantly retarded in silicon nitride substrates, which leads to an interpretation primarily based on the irradiation-induced atomic displacements that render a microstructure evolution driven by the minimization of chemical potential as an elemental thermodynamic force. Our findings are of applied interest concerning the application of ion beams to manipulate NP ensembles.