The Influence of the Interaction Potential on the Diffusion of Neutral Particles in Oxyfluoride Glasses

A systematic study of the effects of the interaction potential upon the diffusion coefficients of neutral particles (P0s) and ions in the 60GeO2–40PbF2 glass has been performed using molecular dynamics simulations. The P0–P0 and P0–ions pair potentials were described by a Lennard–Jones potential with two parameters: the well depth (e) and the size (σ). These parameters were varied in the ranges: (σ) = 0.1-1.0 eV and σ=1.0−4.0 A. The diffusion coefficients were calculated for several combinations at several temperatures (300–1200 K). The estimated glass transition temperature (T g) presented a slight dependence upon the potential parameters, but it is near the crystallization temperature of a glass of similar composition. Whereas, the diffusion coefficients of the P0s presented a strong dependence with the potential parameters, where increasing e and σ causes a decrease of their diffusion coefficients. These results suggest that the atoms should be responsible for forming any surface film, since neutral particles larger than atom, such as, nanoparticles, should have negligible diffusion.