The random networks of non-crystalline forms of this oxide, such as fused silica or film that was grown on a Si substrate in a dry O atmosphere, were investigated in terms of the transport properties of H (fused silica) or O (oxide layer). It was proved that the diffusion of both H and O were anomalous in the sense of percolation theory. Representative experimental results concerning the annealing kinetics of atomic H in Suprasil glasses, and the growth of oxides on Si, were explained by considering transport in a percolation cluster. Transport coefficients with related activation energies and (random-) fractal-like parameters were obtained. Their numerical values permitted a deeper understanding to be obtained of structural features which were related to the non-homogeneous SiO2 network. In particular, the disordered network of the latter was found not to be a continuous random lattice, but rather a granular random lattice that contained grains and percolation pathways which were connected to relaxed bonds.

L.Verdi, A.Miotello: Philosophical Magazine B, 1995 71[4], 741-50