Investigations of Defect Centres in Alkali Halides Doped with Trivalent Cations. Part 2: The NaCl:Cr³⁺Crystals

Abstract

On the basis of ITC studies, complemented by some spectroscopic and ionic conductivity measurements, it was stated that dielectric relaxations of the NaCl:Cr 3 + crystals are more complicated than those typical of AH:Me 2 + systems. The complexity of these phenomena concerns the number, shape and positions of the bands appearing in the ITC spectrum. The origin of the main peaks was discussed in terms of relaxations related with the chromium centres; substitutionally and off-center located Cr 3 + ions, accompanied by two cation vacancies at geometrically different positions, and Cr clusters distributed around dislocations were considered.