Using isotope-exchange techniques, it was found that the self-diffusion of Sr ions in type-A zeolite at 21 to 100C could be described by:

D(cm2/s) = 5.7 x 100exp[-21(kcal/mol)/RT]

The diffusion obeyed the conversion function of an homogeneous diffusion process, indicating that all six Sr+ ions per unit cell occupied structurally similar positions.

Isotope Exchange Studies on Silicate Ion-Exchangers. Self-Diffusion of Sr Ions in Synthetic Zeolite. E.Hoinkis, H.W.Levi: Zeitschrift für Naturforschung A, 1969, 24[10], 1672-3