Structural and mechanical properties of Al2O3.2SiO2 glass: Insights from molecular dynamics simulations

Abstract The Al2O3.2SiO2 glass sample was constructed by using the molecular dynamics method. The structural characteristics were analyzed by the pair radial distribution function, bond angle distribution, coordination number, simplex analysis and local configuration entropy responsible for their mechanical behavior. The AS2 glass exhibits brittle behavior, at which most SiO4 units are maintained and the breakages of Al-O bonds cause the transition of AlOy units from higher- to lower-fold Al coordination. The big simplexes, with the radii ≥ 2.6 A, tend to gather to form the clusters, where the large pores locate. Big simplexes are formed under the tensile deformation. Most atoms belonging to these big simplexes have the highest configurational entropy, which are considered as liquid-like atoms. These atoms play important roles in the evolution and coalescence of the big simplexes causing the crack propagation. Most of them are O atoms, which belong to the big simplexes.