## Models of Water Diffusion in Silica Glass

**V.A. Kreisberg**
Proc. Int. Symposium on Glass Problems (Istanbul, Turkey, Sept. 4-6, 1996),
v. 1, p. 185-191 (1996)

**ABSTRACT**. The diffusive transport of water in silica glass affect many
important properties and working parameters of this material and its products.
The known models of water diffusion based only on kinetic scheme of water
interaction with silica matrix forming hydroxyl groups cannot explain the
concentration dependence of water diffusion coefficient and some other
features of diffusion behaviour of water in glass. The structural-geometric
factor should be taken into account as well. During the process of diffusion
into glass structure and fast hydroxylation, the breaking of silicon-oxygen
bonds occurs, the rings formed by silicon-oxygen tetrahedra disclose, the
mean effective diameter of the rings increases, and the water diffusion
coefficient rises. The structural-geometric model interprets why crystalline
quartz with more dense structure but with straight diffusion channels
possesses higher water diffusion coefficients at high temperatures than
silica glass.

Laboratory of Catalysis and Gas Electrochemistry