Molecular dynamics simulation of the structure of soda silica

In this work five soda silica glasses containing 5, 10, 15, 20 and 33 mole per cent of soda are simulated by using the molecular dynamics method. The calculated structures of these systems are compared with recent neutron diffraction and EXAFS results. As in pure silica glass, a network of silicon-oxygen tetrahedra exists in these systems. The sodium ions are connected to this network through non-bridging oxygen ‘bonds'. The ratio of bridging to non-bridging oxygen ions depends on the composition of the system. In low soda containing systems, microclusters rich in soda are formed. From the hole analysis in these systems, it appears that the sodium ions tend to occupy holes in the silica network.