DISCRETE-LATTICE THEORY FOR FRENKEL-DEFECT AGGREGATION IN IRRADIATED IONIC SOLIDS

A microscopic theory of diffusion-controlled aggregation of radiation Frenkel defects-called in ionic solids H and F centers-is presented. T his is based on a discrete-lattice formalism for the single defect den sities (concentrations) and the coupled joint densities of similar and dissimilar defects treated in terms of a modified Kirkwood superposit ion approximation. The kinetics of defect aggregation is studied in de tail; the cooperative character of this process for both types of comp lementary defects is shown. The theory is applied to the description o f the kinetics of metal colloid formation during heating of electron-i rradiated CaF2 crystals.