Influence of hydroxyl group concentration on the structural relaxation rate of silica glass

Experimental data on the structural relaxation rate of silica glasses with varying OH-group content are presented. As the concentration of OH groups in silica glass decreased from 0.15 mol dm^--3 to values below the detection limit, the rate of structural relaxation at 910–930 °C decreased by a factor of about 5. This effect can be associated with the formation of molecular water in silica glass, its interaction with Si atoms through coordination bonds, and the accelerated formation of larger structural elements in the glass network with a change in the average Si–O–Si bond angle.