Si diffusion : Why DSiLat ∝ CH2O1/3 ?
–Si diffusion is driven through vacancies in Si sites
• Also DSiLat ∝ [VO･･]
–Jump of VSi”” associated with VO･･ should dominate
• Si is surrounded by O, which makes a barrier
• If one neighbor oxygen ion is missing, VSi”” can jump more easily.
–VSi”” and VO･･ attract with each other due to Coulomb force
• Significant proportions of VSi”” and VO･･ will coupled in a crystal even though [VSi””] and [VO･･] are both low
–This hypothesis should be examined.
• ∴ DSiLat ∝ [VSi””][VO･･]
O diffusion: Why no water-content dependence on DOLat?
Fei, H.-Z., and T. Katsura, Si and O self-diffusion in hydrous forsterite and iron-bearing olivine from the perspective of defect chemistry, Phys. Chem. Miner. 43, 119-126, 2016.