Reorientation and degrees of binding of X2+-vacancy complexes in KCl

Abstract

The reorientation of impurity-vacancy complexes in KCl crystals doped with Mg²⁺, Ni²⁺, Mn²⁺, Ca²⁺, Sr²⁺, Pb²⁺and Ba²⁺was studied using the ITC method. These results are analysed together with those obtained by other authors by ITC, EPR and optical methods on Cd²⁺, Be²⁺, Eu²⁺, Sm²⁺and Yb²⁺ions. For the first series of ions and Cd²⁺, it was concluded that the most favoured vacancy position is the NNN site, and that it increasingly dominates the NN site as one proceeds from Mg²⁺to Ba²⁺. The observed reorientation of complexes is mainly governed by the vacancy jump from the NNN to the NN position. In the case of Be²⁺it was found that the majority of vacancies are in the NN position and the special behaviour of the Eu²⁺, Sm²⁺and Yb²⁺rare earth ions is discussed.