Sensitivity of ionic thermocurrent spectra to the presence of divalent nickel in annealed NaCl crystals

Abstract

Ionic thermocurrent measurements were performed for solution-treated NaCl:Ni crystals additionally annealed in a wide temperature range. It has been shown that the decay of the impurity-vacancy (IV) dipoles at temperatures in the range 333 K ⩽ T an ⩽ 463 K is accompanied by the formation of some vacancy-rich clusters which are of metastable character. These clusters transform into the nuclei of the stable NiCl 2 phase. The decay of IV dipoles has been described in terms of an Avrami approach for precipitation of the dopant within stress fields of dislocations.