First Principles Suggestions of Targeted Diffusion Experiments on SiO₂

In this paper we propose a couple of experimental lines in order to probe specific features of oxygen and silicon diffusion in -quartz and SiO2 in general. We start from the results of atomistic first principles calculations and from their predictions concerning point defects formation free enthalpies; we suggest that measurements with variable oxygen partial pressure could confirm that, in well defined regimes, oxygen diffusion is controlled by doubly negative oxygen interstitials. Along similar lines, for silicon diffusion, one should check the real equilibrium conditions of samples, with gaseous oxygen or bulk silicon, or closed conditions. We discuss our predictions for silicon diffusion, that could clarify some discrepancies between experimental results. Another possible probe would be to perform measurements under hydrostatic pressure, in order to measure the formation volume of the migrating species and to compare it to the theoretical values.