The Self-diffusion of Chloride Ions in Nickel Dichoride Crystallites and an Isotopic Exchange Reaction between Chlorine Gas and the Crystallites

Abstract

Abstract The self-diffusion of chloride ions in the bulk of nickel dichloride crystallites was studied in the temperature range of 180–340°C in a carefully-evacuated vacuum system; the isotopic exchange reaction between gaseous chlorine and the crystallites was also studied. The activation energy for the migration of chloride ions was determined to be 1.01 eV (=23.3 kcal/mol). The exchange reaction proceeded with activation energies of 3.6 and 9 kcal/mol for the active and the less-active part of the surface first layer, 13 and 16 kcal/mol for the active and the less-active one of the second layer, and 21 kcal/mol for the third layer. (These activation energies converge to the value of the self-diffusion in the bulk.) The Θ-rule nearly holds good in the present case.