Application of the cBΩ model for the calculation of oxygen self-diffusion coefficients in minerals

The cB Omega model, which suggests the defect Gibbs energy is proportional to the isothermal bulk modulus and the mean volume per atom, is first introduced to predict self-diffusion coefficients of oxygen in various silicate and oxide minerals in terms of available elastic data. We develop a new approach to determine constant c in the cB Omega model on the basis of the observed compensation effect between the activation energies and pre-exponential factors, which is critical to the diffusivity prediction. Under anhydrous conditions, the validity of this model is tested by the experimentally determined oxygen self-diffusion coefficients. Our results show that the absolute oxygen diffusion rates derived from the cB Omega model are in agreement with experimental data in a variety of rock-forming minerals including olivine, MgSiO3 perovskite, spinet, and zircon. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3476283]