Derivation of Transferable Pair Potentials and the Calculation of Intrinsic Defect Properties for Xenotime

Abstract

A new force field has been empirically derived that is transferable across the YPO4, Y2O3, and P2O5 phases, utilizing a reverse Monte Carlo method. This method employs a simulated annealing technique with a logarithmic quench to fit potential parameters to observed crystallographic and mechanical properties, producing a force field suitable for simulating radiation damage events in an atomistic molecular dynamics regime. These potentials are used to investigate the defect properties of xenotime, where a wide range of intrinsic defects including Schottky, Schottky-like, Frenkel pairs, and anti-site defects have been investigated, both at infinite dilution and as defect clusters. A common feature in the lowest energy defect configurations was the presence of polymerized phosphate tetrahedra, forming P2O7 units. The trend in the formation energies for the Frenkel pair defects at infinite dilution was in good agreement with previously published simulations. However, the binding energy associated with the aggr...