Application of the cBΩ model to the calculation of diffusion parameters of Si in silicates

Silicon diffusion in major mantle minerals plays an important role in understanding a number of physical and chemical processes in the Earth's interior. Inspection of existing experimental data reveals linear compensation law between the preexponential factors and the activation energies for Si diffusion in various minerals by focusing on those of geophysical interest. On the basis of the observed compensation relationship, here we propose a thermodynamic model, the so-called cB model that interconnects point defect parameters with the bulk properties to reproduce the Si self-diffusion coefficients in different rock-forming minerals. When the uncertainties are considered, the predicted results show that the temperature and pressure dependences of self-diffusion coefficients concur with existing experimental data and theoretical calculations in most cases.