Atomic metastable point defects dominating the brittle-plastic transition process of fused silica: Self-trapped excitons

The inevitably processing-induced ∼μm brittle fractures on hard-brittle fused silica surfaces significantly degrade their mechanical-optical properties. Nevertheless, the key micro-structures dominating the brittle-plastic transition and corresponding regulation strategies were not determined. Herein, atomic self-trapped excitons (STEs) were found to play core roles during brittle-plastic transition. Based on molecular dynamics simulation and atomic characterization, it was found that STE was accumulated in brittle-plastic-mixing stages due to stress-induced intrinsic-structure modification. While fused silica cannot maintain steady states as STE density reaches its maximum. Meanwhile, metastable STE would be transformed into unstable “devastating” point defects, inducing brittle fractures. Accordingly, a regulation strategy was proposed to convert STE to stable intrinsic structures to put STE density away from the maximum, successfully inhibiting brittle fractures. Summarily, this work opens a convenient door to improve material plastic machinability through atomic regulation. It is meaningful for the high-performance application of fused silica and other agnate non-crystalline glass.