Molecular dynamics simulation and electrical conductivity measurement of Na ₂O•3SiO ₂ melt under high pressure; Relationship between its structure and properties

The relationship between structure and properties of the Na ₂O•3SiO ₂ 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 Na ₂O• 3SiO ₂ melt is controlled by ionic conduction of sodium atoms.