Local crystal structure of Zn2+ impurity ions in LiF:U, Zn crystal

The structure of a uranium-activated lithium fluoride crystal LiF : U, Zn near Zn2+ local impurity center is calculated in the framework of the shell model in the pair potential approximation, the results are presented. The calculations indicate that radial displacements of orbits near Zn2+ impurity ion get stabilized starting from the eighth-ninth orbit, i.e. at a distance of ∼4-6 A from the central Zn2+ ion. It suggest that 116-122 ions in the Zn2+ impurity center close surrounding located on the eight or none orbits can be a nucleus of the impurity center. The orbits mentioned can be conditionally considered as an interface between the stable Zn2+ region and the region formed by (UO6)6- ion providing non-local compensation of the excess positive Zn2+ ion