An investigation into hydrogen stability in synthetic, natural and air-swept synthetic quartz in air temperatures up to 1100 °C

Abstract

Systematic annealings, at increasing temperatures of up to 1100 °C in ambient air, of X, Y and Z-cuts of synthetic, natural and air-swept synthetic quartz crystals were performed. They show, after a first phase of rearrangements, an outdiffusion of hydrogen from the various bulk OH defects as controlled by their ir band absorptions. Outdiffusion is found to be virtually isotropic for (AlOH) defects in natural and swept quartz; it becomes evident at ~900-700 °C, respectively. Strong anisotropy appears for as grown OH defects in synthetic quartz where the Z-cuts outdiffuse before 550 °C. The relative S4/total OH concentrations reaches a maximum at ~800 °C. Results are quantified using a simple one dimensional classical theory of diffusion which allows diffusion coefficients (Dcm 2/s) to be attributed to these outdiffusions.