Structural origin of hot-compression-enhanced mechanical properties of aluminosilicate glass

Abstract

Hot-compression treatment has emerged as an effective method for improving mechanical properties of oxide glasses. However, the pressure-induced structural changes that are responsible for the enhanced mechanical properties have remained elusive. Using molecular dynamics simulations, we find that increasing pressure significantly improves the fracture toughness and nano-ductility of a calcium aluminosilicate, consistent with experiments. The enhanced mechanical properties can be traced back to the increase of atomic coordination numbers, decrease of oxygen-centered bond angles, as well as reorganization of medium-range structure as seen from the change of network topology. Moreover, our simulations highlight oxygen tri-clusters (⁽³⁾O) as critical sites for enhancing fracture toughness and nano-ductility, as they are active for dynamic bond rupturing and reformation. These findings help to understand how hot compression alters the structure and mechanical properties of oxide glasses, insights that are crucial for improving mechanical performance of network-forming materials.