Partial ordering of glass networks adjacent to simulated glass–crystal interfaces

Interfaces between sodium lithium borosilicate glasses and the (100) and (110) surfaces of MgO and CaO crystals were simulated using a melt-quench procedure, employing classical pair potentials and molecular dynamics. The density of network forming species within the glass at these interfaces was considered as a function of distance from the plane of the interface and the positions of network formers were calculated in relation to sites in the crystal surface.For each interface, a strong correlation was found between the position and orientation of borate and silicate coordination polyhedra within the glass and particular positions of ions in the crystal surface, indicating that different partial ordering of the glass had occurred. In addition, examination of oxygen density profiles revealed a sequence of consistently spaced layers of increased density extending into the glass for all interfacial systems.

Research highlights
► Molecular dynamics simulation of glass–crystal interfaces.
► Glass model is for technologically significant Na,Li mixed alkali borosilicate composition.
► Interfaces found to induce partial ordering of glass phase.
► Atomic density approach used to relate crystal-surface sites to glass species identifying epitaxy.
► Mechanism by which order at interface can be transmitted through glass is proposed.