Potassium self-diffusion in a K-rich single-crystal alkali feldspar

作者：Hergemoeller Fabian; Wegner Matthias; Deicher Manfred; Wolf Herbert; Brenner Florian; Hutter Herbert; Abart Rainer; Stolwijk Nicolaas A

来源：Physics and Chemistry of Minerals, 2017, 44(5): 345-351.

DOI：10.1007/s00269-016-0862-1

• Alkali feldspar
• Potassium diffusion
• Interstitialcy mechanism
• Correlation factor
• Haven ratio

The paper reports potassium diffusion measurements performed on gem-quality single-crystal alkali feldspar in the temperature range from 1169 to 1021 K. Natural sanidine from Volkesfeld, Germany was implanted with K-43 at the ISOLDE/CERN radioactive ion-beam facility normal to the (001) crystallographic plane. Diffusion coefficients are well described by the Arrhenius equation with an activation energy of 2.4 eV and a pre-exponential factor of 5 x 10(-6) m(2)/s, which is more than three orders of magnitude lower than the Na-22 diffusivity in the same feldspar and the same crystallographic direction. State-of-theart considerations including ionic conductivity data on the same crystal and Monte Carlo simulations of diffusion in random binary alloy structures point to a correlated motion of K and Na through the interstitialcy mechanism.

• 出版日期2017-5