Hydrogen solubility in amorphous Mg0.6SiO2.6 at high pressure

The solubility of hydrogen in amorphous Mg 0.6 SiO 2.6 at a temperature of 250°C and pressures up to 75 kbar is studied using a quenching technique. The molar ratio H 2 /formula unit is found to nonlinearly increase with pressure from x = 0.12 at P = 10 kbar to x = 0.303 at P = 75 kbar. An investigation of the quenched samples by Raman spectroscopy demonstrated that hydrogen dissolves in amorphous Mg 0.6 SiO 2.6 in the form of H 2 molecules. X-ray diffraction and Raman studies showed that the hydrogenation of the samples is likely to be accompanied by a phase transition in the amorphous lattice of Mg 0.6 SiO 2.6 at P ≈ 52.5 kbar to a denser amorphous modification.