Gas-release measurements were carried out on so-called wet (T7030, Vitreosil, T1030, Heralux, Suprasil II) and dry (T2030, GE214, SG25A, SG25SC, SG25SF, T7032, Suprasil W) vitreous silicas, at temperatures ranging from room temperature to 1000C, by using a constant heating-rate method. It was found that the principal gases which were released from the wet and almost-dry vitreous silicas were H2 and H2O, while those which were released from Suprasil W were CO and O2. Two clear maxima, at about 500 and 900C, were observed in the amount of H2 gas that was released from high OH-containing vitreous silica (T7030, T1030, Suprasil II). The low-temperature and high-temperature H2 releases were explained in terms of a diffusion process and a dissociation reaction process of SiOH and/or SiH, respectively. The molar extinction coefficients for infra-red stretching bands of SiOH and SiH were estimated and were found to be equal to 7.0 and 4.0m2/mol, respectively.

Y.Morimoto, T.Igarashi, H.Sugahara, S.Nasu: Journal of Non-Crystalline Solids, 1992, 139[1], 35-46