2001 Volume 42 Issue 11 Pages 2242-2246
We have performed molecular dynamics (MD) simulations for vitreous P2O5 using isotropic pair potentials composed only of coulombic and repulsive interactions. The P–O pair distribution function obtained had the two distinguishable peaks expected from the results of neutron diffraction experiments, in the nearest-neighbor P–O correlation. The neutron-weighted real-space correlation function was also in semi-quantitative agreement with that obtained from the experimental results. The distribution of the coordination number for O around P and P around O showed that most P atoms form tetrahedral PO4 units in the glass, and that three-fifths of O atoms are bridging oxygen atoms, OB, and the remaining are terminal oxygen atoms, OT. The pair distribution functions for P–OB and P–OT show that the PO4 units have three long P–OB bonds and one short P–OT bond. We have concluded that the short-range structure obtained for vitreous P2O5 agrees well with the picture derived from many experiments. This fact indicates that the short-range structure of vitreous P2O5 can be described mainly by both charge ordering and packing based on the differences in ionic charge and size between cation and anion.