Molecular Dynamics Study of the Mechanism of Ion Diffusion in an Na2O–ZnO–P2O5 Melt

Abstract

The specific features of the dynamics of structure-forming ions in an Na2O · ZnO · P2O5 melt are studied by the molecular dynamics method in the ion approximation of the interparticle interaction potential. It is shown that the oxygen diffusion mechanism in the pyrophosphate system is generally similar to that investigated previously for silicate systems. The main difference of the former mechanism is the absence of overcoordinated defect phosphorus–oxygen complexes. Owing to the use of long phase trajectories, the oxygen diffusion scenarios involving four tetrahedra are detected for the first time. It is demonstrated that the dominant movements of the zinc ion are long (no shorter than 0.25 nm) jumps, which makes it possible to retain a strong correlation of the relative positions of these ions over long (about 0.6 nm) distances.