Oxygen self-diffusion in ThO₂ under pressure: connecting point defect parameters with bulk properties

ThO₂ is a candidate material for use in nuclear fuel applications and as such it is important to investigate its materials properties over a range of temperatures and pressures. In the present study molecular dynamics calculations are used to calculate elastic and expansivity data. These are used in the framework of a thermodynamic model, the cBΩ model, to calculate the oxygen self-diffusion coefficient in ThO₂ over a range of pressures (−10–10 GPa) and temperatures (300–1900 K). Increasing the hydrostatic pressure leads to a significant reduction in oxygen self-diffusion. Conversely, negative hydrostatic pressure significantly enhances oxygen self-diffusion. (paper)