Titre
Hydrogen diffusion mechanisms in quartz: insights from H–Li, <sup>2</sup>H–H and <sup>2</sup>H–H–Li exchange experiments
Type
article
Institution
UNIL/CHUV/Unisanté + institutions partenaires
Périodique
Auteur(s)
Jollands, Michael C.
Auteure/Auteur
Tollan, Peter M. E.
Auteure/Auteur
Baumgartner, Lukas P.
Auteure/Auteur
Müntener, Othmar
Auteure/Auteur
Liens vers les personnes
Liens vers les unités
ISSN
0026-461X
Statut éditorial
Publié
Date de publication
2022-02
Volume
86
Numéro
1
Première page
112
Dernière page/numéro d’article
126
Peer-reviewed
Oui
Langue
anglais
Résumé
The diffusivity and diffusion mechanisms of hydrogen together with with deuterium and lithium, parallel to the c axis of quartz, were investigated experimentally at 800°C, 0.1 GPa with the activity of H2O or 2H2O ≈ 1 [2H is used throughout this work to describe deuterium rather than D, to avoid confusion with the diffusion coefficient, D]. The pH was set using mixtures of H2O (or 2H2O) and HCl. Three types of experiment were conducted: (1) H-in/Li-out; (2) 2H-in/H-out; and (3) 2H-in/H + Li out, using three different natural quartz crystals as starting materials. Profiles of H, 2H and Li were measured using Fourier-transform infrared (FTIR) spectroscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). H, 2H and Li are charge-compensated by Al3+ replacing Si4+, or by excess O2–. The total atomic concentration of monovalent cations appears to remain constant over the duration of the experiments. The resulting diffusion profiles are different for the three experimental designs and three starting materials, and some show complex shapes inconsistent with simple diffusion. A multi-site diffusion–reaction model is developed, with the theory based on previous models that have been derived mainly on the basis of conductivity measurements. In these models, the monovalent cations move away from their charge-balancing ion then diffuse rapidly to another site. The mobility of the monovalent cations is described by both a diffusion coefficient and an equilibrium constant that enables dissociation of the immobile charge-balanced defects. This model can describe complex step-shaped profiles formed in H-in/Li-out experiments, profiles with local maxima ('humped’ profiles) in 2H-in/H + Li out experiments, and error function-shaped profiles in 2H-in/H-out and previously published Li-in/H-out experiments. Our data provide support for models previously proposed for quartz. Studies of the lengths and forms of diffusion profiles from such experiments provide a useful complement to assertions from conductivity experiments.
PID Serval
serval:BIB_988C498EBDF9
Open Access
Oui
Date de création
2022-04-08T12:47:07.445Z
Date de création dans IRIS
2025-05-21T02:21:29Z
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Nom
hydrogen-diffusion-mechanisms-in-quartz-insights-from-hli-2hh-and-2hhli-exchange-experiments.pdf
Version du manuscrit
published
Licence
https://creativecommons.org/licenses/by/4.0
Taille
986.83 KB
Format
Adobe PDF
PID Serval
serval:BIB_988C498EBDF9.P001
URN
urn:nbn:ch:serval-BIB_988C498EBDF97
Somme de contrôle
(MD5):663a09d8b8cfe2ebddb6838548f1327b