Figure 5. Origins of the enhanced ductility in densified a-silica.

(a) Fracture surface energy and shear banding energy of a-silica versus quenching pressure; (b) Fraction of 4- and 5-fold Si as a function of strain during uniaxial tension test for densified samples (0, 4, 8 and 15 GPa). (c) Snapshots of the 8 GPa sample at different times at 35% strain in the uniaxial tension test. Note: red for 4-fold Si, green for 5-fold Si, O atoms are omitted for clarity. Inside the dashed circle, two 5-fold Si atoms appear then disappear, indicating the migration of 5-fold Si atoms inside the sample while maintaining a constant population as seen in (b).