Sodium-potassium interdiffusion in potassium-rich alkali feldspar II
- Autor(en)
- Anne-Kathrin Schäffer, Elena Petrishcheva, Gerlinde Habler, Rainer Abart, Dieter Rhede, Gerald Giester
- Abstrakt
Na-K interdiffusion in disordered potassium-rich alkali feldspar was studied experimentally using cation exchange between gem quality sanidine from the Eifel and alkali-halide melt at temperatures of 800 °C to 1000 °C and at close to ambient pressure. Sodium-potassium interdiffusion coefficient DNaK was determined for potassium mole fractions in the range 0.65 < XOr < 0.99. At 0.65 < XOr < 0.95 the sodium-potassium interdiffusion coefficient is largely independent of composition. At XOr > 0.95, it rises sharply with increasing potassium mole fraction. Diffusion perpendicular to (001) is about one order of magnitude faster and less strongly temperature dependent than perpendicular to (010). The parameters of the Arrhenius equation describing the temperature dependence of the sodium-potassium interdiffusion coefficient DNaK D0Exp (EA/RT) were estimated as D0 (001)(0.92) 5.18 108 m2/s, EA (001)(0.92) 179kJ/mole D0 (001)(0.98) 1.82 107 m2/s, EA (001)(0.98) 182kJ/mole D0 (010)(0.92) 5.81 105 m2/s, EA (010)(0.92) 272kJ/mole D0 (010)(0.98) 1.34 104 m2/s, EA (010)(0.98) 269kJ/mole. The results of our direct determinations are compared with theoretical calculations using the corresponding sodium- and potassium tracer-diffusion coefficients, and the processes underlying the observed composition- and temperature dependence of sodium-potassium interdiffusion are discussed.
- Organisation(en)
- Department für Lithosphärenforschung, Institut für Mineralogie und Kristallographie
- Externe Organisation(en)
- Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum
- Journal
- American Journal of Science: an international earth science journal
- Band
- 314
- Seiten
- 1300-1318
- Anzahl der Seiten
- 19
- ISSN
- 0002-9599
- DOI
- https://doi.org/10.2475/09.2014.03
- Publikationsdatum
- 11-2014
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105116 Mineralogie, 105113 Kristallographie, 105120 Petrologie
- Schlagwörter
- ASJC Scopus Sachgebiete
- Allgemeine Erdkunde und Planetologie
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/7a49776e-79d1-440d-83cd-1adab6c1de02