Molecular Dynamics Study of the Mechanism of Ion Diffusion
in an Na₂OZnOP₂O₅ Melt

G. G. Boiko and A. V. Parkachev

Grebenshchikov Institute of Silicate Chemistry, Russian Academy of Sciences,
ul. Odoevskogo 24/2, St. Petersburg, 199155 Russia

Received September 20, 2002

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 investi-
gated previously for silicate systems. The main difference of the former mechanism is the absence of overco-
ordinated defect phosphorus–oxygen complexes. Owing to the use of long phase trajectories, the oxygen diffu-
sion 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.

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