Radiotracer Experiments and Monte Carlo Simulations of Sodium Diffusion in Alkali Feldspar: Evidence Against the Vacancy Mechanism
- Author(s)
- F. Wilangowski, Rainer Abart, S.V. Divinsky, Nicolaas A. Stolwijk
- Abstract
Self-diffusion of sodium perpendicular to (001) in a potassium-rich alkali feldspar single crystal has been studied by self-diffusion experiments and by Monte Carlo simulations. Sodium diffusivities were measured with the radiotracer technique using the
22Na isotope in a temperature interval from 773 K to 1173 K. It was found that self-diffusion coefficients follow a linear Arrhenius relation with the pre-exponential factor of 1.2×10
-3 cm
2/s and an activation enthalpy of 1.3 eV. To study correlation effects in the monoclinic feldspar structure, a Monte Carlo method was applied assuming that the two cation species are randomly distributed on the common sublattice and are not influenced by the fixed sublattice of the silicate and aluminate anions. Correlation factors have been calculated assuming a vacancy mechanism and applying a developed four-frequency model for the nearest-neighbor vacancy jumps on the alkali sublattice. Our findings strongly indicate that vacancy diffusion provides only a minor contribution to sodium self-diffusion in potassium-rich feldspars.
- Organisation(s)
- Department of Lithospheric Research
- External organisation(s)
- Universität Münster
- Journal
- Defect and Diffusion Forum
- Volume
- 363
- Pages
- 79-84
- No. of pages
- 6
- ISSN
- 1012-0386
- DOI
- https://doi.org/10.4028/www.scientific.net/DDF.363.79
- Publication date
- 2015
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105116 Mineralogy, 105120 Petrology
- Keywords
- ASJC Scopus subject areas
- Condensed Matter Physics, Radiation, General Materials Science
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/23e534d1-c3f7-4a82-9cd1-3d09390e2bdf