Water-related defects and oxygen diffusion in albite: A computer simulation study

Computer simulation techniques have been used to investigate the energetics of defect formation in Albite and to calculate O and (OH) migration activation energies. We find that the Na Frenkel defect has the lowest formation energy, whilst interstitials associated with impurities are the most favourable O defects. Water can be accommodated in the albite structure as both OH groups and as H2O molecules with solution energy of 0.73 eV and 0.9 eV respectively. The activation energies for O migration is reduced by up to 50% when the O is migrating as part of an (OH) group. In addition, we find a marked diffusional anisotropy for both O and (OH) in albite.