Anisotropy of hydrogen diffusion in tourmaline

Oxygen and Hydrogen Diffusion in Minerals

“…Diffusion within the basal plane is isotropic (D a = D [120] ). In addition, Desbois and Ingrin (2007) found that the hydrogen diffusion rates in their elbaite-composition tourmaline are one order of magnitude greater than those reported for schorlite-composition tourmaline (Jibao and Yaqian 1997).…”

“…The stated purpose of their study was to investigate the anisotropy of hydrogen diffusion in tourmaline and the effect of composition. The results of Desbois and Ingrin (2007) indicate that hydrogen diffusion rates are two to three times faster along the c-direction than along directions parallel to the basal plane. The Arrhenius relation for transport along the c-direction has an activation energy of 106.3±36.8 kJ/mol, and along the a and [120] directions it has an activation energy of 66.8±19.6 kJ/mol.…”

“…Hydrogen-deuterium exchange in elbaite-composition tourmaline natural single crystals has been studied by Desbois and Ingrin (2007) at 0.1 MPa and 700-800 °C. The isotope exchange was determined by micro-FTIR analysis.…”

Iron redox reactions in the tourmaline structure: High-temperature treatment of Fe3+-rich schorl

“…The published experiments were almost exclusively performed under oxidizing conditions (i.e., in air); however, different structural aspects might appear under reducing conditions. Only the high-temperature experiments of Desbois and Ingrin (2007), which were performed to evaluate H diffusion in nearly Fe-free tourmaline, were done under a reducing atmosphere of argon-deuterium/hydrogen mixed gases (10% of D 2 or H 2 in Ar) and at temperatures up to 800°C where no decomposition of tourmaline was observed.…”

Preparation and Properties of Tourmaline/Chitosan Composite Powder

“…[1,2]. Tourmaline, (Tourmaline, Tour) chemical general formula can be written as NaR 3 Al 6 [Si 6 O 18 ][BO 3 ] 3 (OH,F) 4 , with piezoelectricity and pyroelectricity and other unique physical and chemical properties, possess ability of production of anion, reduction of the water molecular beam, emission of far infrared ray, in recent years is widely applied in functional fiber, textiles, clothing, coating materials, water purification and other fields [3][4][5]. If tourmaline is compounded in chitosan matrix, is expected to get a new composite powder that possess good biological compatibility and biological activities, at the same time possess the capacity to produce anion and far infrared emission, the composite powder will have a good application prospect in the field of biomedical and cosmetics field.…”