Strain-induced structural modifications and size-effects in silica nanowires

This study investigates the structural transformations and properties of silica glass nanowires under tensile loading via molecular dynamics simulations using the BKS (Beest-Kramer-Santen) interatomic potential. Surface states of the elongated nanowires were quantified using radial density distributions, while structural transformations were evaluated via ring size distribution analysis. The radial density distributions indicate that the surface states of these silica nanowires are significantly different than those of their interior. Ring size analysis shows that the ring size distributions remain mainly unchanged within the elastic region during tensile deformation, however they vary drastically beyond the onset of plastic behavior and reach plateaus when the nanowires break. The silica nanowires undergo structural changes which correlate with strain energy and ring size distribution variations. It is also found that the ring size distribution (and strain energy) variations are dependent on the diameter of the silica nanowires. Interestingly, for ultrathin nanowires (diameters < 5 .0 nm), the variation of ring size distributions shows a distinct trend with respect to tensile strain, indicating that the surface states play a key role in both modifying the mechanical properties and structural characteristics. These results for ultrathin nanowires are consistent with prior theoretical and simulation predictions. The overall findings in this study provide key insights into the novel properties of nano-sized amorphous materials, and are aimed to inspire further experiments.