FT-IR study on the effect of OH content on the damage process in silica glasses irradiated by hydrogen

Abstract

Hydrogen retention in H + irradiated silica was investigated by FT-IR spectroscopy using silica glasses with different OH contents. Quantitative analyses of FT-IR spectra indicated that almost all the implanted hydrogen atoms were trapped in the form of SiO–H or Si–H in the high-OH (800 ppm) silica glass up to the fluence of 5 × 10 16 H + cm −2. The implanted hydrogen atoms started to form H 2 gaseous molecules above this irradiation dose, and eventually surface blistering occurred. The low-OH (ca. 1 ppm) silica glass, by contrast, had a tendency to trap less hydrogen in the form of SiO–H or Si–H bonds, compared to the high-OH sample. Such a difference in the hydrogen retention between the two silica glasses could be attributed to different silica network structures depending on the amount of intrinsic OH content. With increasing OH content, the silica network structure has more open spaces in an atomic scale, as suggested in our previous XAFS analyses, resulting a larger amount of H retention.