Proton diffusion mechanism in amorphous SiO2.
We study proton diffusion in amorphous SiO2 from the atomic scale to the long-range percolative regime. Ab initio molecular dynamics suggest that the dominant atomic process consists in cross-ring interoxygen hopping assisted by network vibrations. A statistical analysis accounting for the disorder in amorphous SiO2 yields relations between transition energies and interoxygen distances for both cross-ring and nearest-neighbor hopping. The percolative regime is then addressed through large-size model systems reproducing these relations. Cross-ring hopping is confirmed as the dominant diffusion mechanism and supported by a good agreement with experiment for the activation energy.
Godet
Julien
J
Ecole Polytechnique Fédérale de Lausanne, Institute of Theoretical Physics, CH-1015 Lausanne, Switzerland.
Pasquarello
Alfredo
A