Activation energies for impurity-vacancy dipole dimer formation in alkali halides

Abstract

We recently showed that the aggregation of impurity-vacancy dipoles in KCl and NaCl doped with divalent impurities followed initial second-order kinetics, by considering dimer dissociation as well as formation in the dipole-decay theory. Here, we present further proof that dimers form initially. We determine the activation energies for dimer formation in KCl:${\mathrm{Ba}}^{++}$, KCl:${\mathrm{Sr}}^{++}$, and NaCl:${\mathrm{Ca}}^{++}$, and they differ from those previously determined by others, who used incorrect theories.