Structural and mechanical properties of densified (Li2O)0.2(SiO2)0.8 glasses: A molecular dynamics simulations study

Molecular dynamics (MD) simulations have been carried out to study the structural and mechanical properties of densified (Li2O)(0.2)(SiO2)(0.8) glasses under uniaxial tension. Fractions of SiOx (x = 4 -6) and LiOy(y = 3 - 8) units change with the density. There is a relationship between the changes in Q(n) species and in SiOx unit with increasing density. The sample of 2.28 g cm(-3) exhibits brittle behavior, at which fraction of SiO4 units is almost maintained and the breakages of Li-O bonds cause the transformation of LiOy units from higher- to lower- fold Li coordination. Big-voids are formed during the tension process. Li-O voids play important roles in the evolution and coalescence of voids causing the crack propagation. The densified samples of 2.96 and 3.81 g cm(-3) exhibit ductile behavior, at which the transformations of SiOx and LiOy occur. Shear transformation zones (STZs) and shear bands (SBs) are formed during plastic deformation.