Philosophical Magazine B, 65(3), 463-471 (1992)

Molecular-diffusion of oxygen and water in crystalline and amorphous silica

M. I. Heggie (a), R. Jones (b), C. D. Latham (a), S. C. P. Maynard (a), P. Tole (a)

(a) Department of Computer Science, The Old Library, University of Exeter, Exeter, EX4 4PT, UK

(b) School of Physics, University of Exeter, Exeter, EX4 4QL, UK

Abstract

The hydrolytic weakening of quartz requires diffusion of water to dislocation cores, while the oxidation of silicon requires diffusion of oxygen and/or water through amorphous silica (a-SiO₂).  Perfect alpha-quartz channels and larger dislocation channels are used to model the diffusion in alpha-quartz and a-SiO₂ in conjunction with a classical interatomic potential for SiO₂.  Our results show that water and oxygen molecules are heavily compressed in perfect channels and much less so in the dislocation channel.  The diffusion of these molecules through enlarged channels involves much lower activation energies and such channels will be preferred paths over the perfect channels.

• Next abstract . . .
• List of published work . . .
• About the Aimpro Group at Exeter . . .
• About the School of Physics . . .
• Index of publications by the Aimpro Group . . .