Structural and topological properties of the interface between amorphous silica and sodium tetrasilicate glass studied by molecular dynamics simulation

Classical molecular dynamics simulations are used to study structural properties of a planar interface between amorphous silica and sodium tetrasilicate glass in a dry environment. The interface region is characterised by the change of the network connectivity. The effect of the interfacial microstructure on the diffusion of sodium is analysed within the framework of topological constraint theory. It is shown that the interface represents an elastic phase boundary where a transition to a stressed-rigid phase occurs. The onset of rigidity in the interface region makes the out-diffusion of sodium from the sodium silicate glass more difficult. The topological controlled diffusion kinetics provides an explanation for the barrier property of amorphous silica despite its open network structure.

Graphical abstract