Molecular dynamics simulation and electrical conductivity measurement of Na2O•3SiO2 melt under high pressure; relationship between its structure and properties

The relationship between structure and properties of the Na2O•3SiO2 melt was investigated using molecular dynamics (MD) simulations and electrical conductivity measurements under high pressure. The inter-atomic potential was newly developed using energy surfaces derived by quantum chemical calculations. In MD simulations, changes of the structure and properties were observed as a function of pressure. An increase in self-diffusion coefficients of network forming atoms is closely related to the distortion of the –Si–O– network and the changes in distributions of poly-membered rings which forms the –Si–O– network. In the electrical conductivity measurements, we found a negative pressure dependence at least up to 3 GPa. This suggests that electric conductivity in Na2O•3SiO2 melt is controlled by ionic conduction of sodium atoms.