Abstract
A consistent model of the intrinsic and hydrogen-related defects of amorphous (a-)SiO2 is presented. The author shows that the identical to Si-Si identical to bond is the diamagnetic precursor of the E' defect. The intrinsic defects can now be considered as the products of two equilibria: fluctuations in chemical order producing Si-Si and O-O bonds, and the breaking of Si-O bonds. The broken bond defects are converted to hydroxyl groups in 'wet' silica while the Si-Si and O-O (peroxyl) groups dominate in dry silicas. Peroxyl groups participate in a second equilibrium with H2, forming pairs of OH groups.