Structural evolution of PVP@Ag nanowires induced by focused electron beam irradiation: The passivation effect of PVP

To explore the passivation effect of polyvinylpyrrolidone (PVP) on Ag nanowires (NWs), the structural evolution of PVP@Ag NWs was in situ induced under focused electron beam (e-beam) irradiation using transmission electron microscopy. Notably, interesting phenomena, including multiple necking and axial elongation, were observed at room temperature. By establishing a kinetic relationship, the passivation effect of PVP on the radial shrinkage of Ag NW was confirmed, with a determined surface energy index (b) of 0.2. The presence of PVP not only weakened the surface nanocurvature effect of Ag NW but also retarded the athermal activation effect of energetic e-beam irradiation. By taking into account two new concepts of nanocurvature effect and athermal activation effect, the structure evolution of PVP@Ag NW was well restored by COMSOL simulation. Additionally, the radial shrinkage of Ag NWs with and without PVP coating was compared extensively. The simulation vividly illustrated the evaporation and diffusion processes of atoms, showcasing how PVP effectively mitigates material loss.