Molecular dynamics simulation was used to investigate the kinetics of self-diffusion in the bulk and on the surface of pristine vitreous silica. Multibody potential functions were used to describe interatomic forces. Activation energies were found to be similar for Si and O self-diffusion and did not vary appreciably between self-diffusion in the bulk and on the surface. For both species in the bulk and on the surface, average activation energies ranged from 113-115 kcal/mol. Oxygen self-diffusivity was found to be only slightly higher than silicon self-diffusivity in the bulk and on the surface. Self-diffusion coefficients in the top 3-7 Å of the surface were found to be higher than those of bulk simulations by less than a factor of two. Self-diffusion on the surface was observed to occur by motion of SiO3 and SiO4 polyhedra over several angstroms while bulk self-diffusion involved significant neighbor exchange over similar length scales. Surface diffusion through a vapor phase (via desorption and re-adsorption at a distant location on the surface) was not included in the surface data.
|Number of pages||14|
|Journal||Journal of Non-Crystalline Solids|
|Publication status||Published - Sep 1997|
ASJC Scopus subject areas
- Ceramics and Composites
- Electronic, Optical and Magnetic Materials