Kinetics of correlated annealing of radiation defects in alkali halide crystals

Abstract

Kinetics of the correlated annealing of pairs of neutral (F-H) Frenkel defects in the KBr crystal is treated theoretically, taking into account defect diffusion, and annihilation at short distances stimulated by an elastic interaction. It is shown that an elastic interaction affects the annealing kinetics and the survival probability of close geminate detects considerably. The widespread description of the correlated annealing in terms of a first-order reaction fails for close defects yielding effective energies which in fact differ essentially from an activation energy of diffusion. Ea, even if it is corrected by an interaction energy. The effect of the initial distribution of defects over relative distances is studied. It is concluded that the several-stage annealing of defect concentrations often observed in thermostimulated experiments in alkali halides does not necessarily mean recombination of close Frenkel defects which differ in initial distances.