Diffusion of Cd2+ Ions in Single-Crystal Sodium Chloride

Abstract

The diffusion of Cd+ + in commercial NaCl single crystals has been studied over the temperature range from 275° to 500°C by a radiotracer technique from CdCl2 vapor. From measurement of the concentration dependent diffusion coefficient the association energy was extimated to be 0.38 eV at 525°C and 0.52 eV at 376°C, between 376° and 275°; the entropy indicates more complex behavior than single species of cation—vacancy association. The saturated diffusion coefficient Ds is given by Ds=2.06×10−2 exp (−21 250 cal/RT) over this temperature range.