A high-precision serial sectioning technique was used to study the isotope effect for 22Na and 24Na tracers, in single crystals, in the intrinsic range (table 16).

Isotope Effect of Diffusion of 22Na+-24Na+ in NaCl, KCl and KBr Single Crystals. F.Nicolas, F.Bénière, M.Chemla: Journal of Physics and Chemistry of Solids, 1974, 35[1], 15-23