Metal passivation effect on focused beam-induced nonuniform structure changes of amorphous SiOx nanowire

Passivation effect of heterogeneous Au nanoparticles (AuNPs) on the nonuniform structure changes of amorphous SiOx nanowire (a-SiOx NW) as athermally induced by focused electron beam (e-beam) irradiation is investigated in an in-situ transmission electron microscope. It is found that at room temperature the straight and uniform a-SiOx NW demonstrates an accelerated necking at the nanoscale along with a fast, plastic elongation and a local S-type deformation in the axial direction. However, once being modified with uniform AuNPs, the nanocurved sidewall surface of a-SiOx NW becomes intriguingly passivated and the processing transfers from a diffusion (or plastic flow)-dominated status to an evaporation (or ablation)-dominated status. As a result, the necking of the AuNPs-modified a-SiOx NW is greatly retarded without visible elongation and bending deformation. Two combined effects of nanocurvature and beam-induced soft mode and instability of atomic vibration are further proposed to elucidate the observed new phenomena.