The serial sectioning technique was used to investigate diffusion and the isotope effect (22Na and 24Na) in single crystals which contained 2000ppmK, 1500ppmCs and 50ppmNa (tables 149 and 150). At temperatures ranging from 377 to 707C, the diffusivity of 22Na in intrinsic material could be described by:

D (cm2/s) = 1.03 x 103 exp[-2.06(eV)/kT]

The data for extrinsic material indicated an activation energy of 0.593eV. The temperature dependence of the correlation factor, as deduced from isotope-effect measurements, was 0.19eV in the intrinsic region and -0.05eV in the extrinsic region.

Diffusion of Sodium in Rubidium Chloride. N.L.Peterson, S.J.Rothman: Physical Review, 1969, 177[3], 1329-33

Table 150

Isotope Effect for 22Na/24Na Diffusion in RbCl