Hydrogen formation observed during high pressure treatment of silica glass

Silica glass treated at high pressures and temperatures (1–3 GPa, 1100–1250 °C) in a solid-media pressure apparatus incorporated observable quantities of hydroxyl and hydride. The FTIR absorbance signals for these species appeared only when the glass sample was pressurized in the presence of water together with graphite at a high temperature, and the hydroxyl signal disappeared completely when the glass was heat-treated at 1000 °C in air for 1 h. These results indicate that hydrogen diffused into and reacted with the silica glass during the high pressure–temperature treatment. Reduction of H2O by graphite at high pressure/temperature conditions is the probable source of hydrogen.