Thermodynamic calculations of Fe–Mg interdiffusion in (Mg,Fe)₂SiO₄ polymorphs and perovskite

In this study, we show that the temperature and pressure dependence of Fe–Mg interdiffusion in (Fe,Mg)₂SiO₄ polymorphs (olivine, wadsleyite, and ringwoodite) and perovskite can be successfully reproduced in terms of bulk elastic and expansivity data through a thermodynamic model (so-called cBΩ model) that interconnects point defect parameters with bulk properties. Under dry and wet conditions, our calculated Fe–Mg interdiffusion coefficients D_calc^Fe-Mg (particularly for anisotropic diffusivity in olivine), activation enthalpy h^act, and activation volume υ^act over a wide range of geologically relevant temperatures (1000–2400 K) and pressures (0–100 GPa) are consistent with the experimental ones when the uncertainties are considered