The Kinetics of Radiation-induced Point Defect Accumulation and Metallic Colloid Formation in Ionic Solids

Abstract A brief summary on the experimental methods of metal colloid formation and characterization in ionic solids, main results and theoretical approaches to the kinetics of this process is presented. We discuss in detail the results of a microscopic theory describing diffusion-controlled aggregation of primary radiation Frenkel defects- F and H centers- leading to colloid formation under low energy electron irradiation with further heating. We suggest the interpretation of relevant experimental data for the two ionic solids with different crystalline structures- LiF and CaF2- observed under electron irradiation. Theory successfully reproduces the main experimental observations including Ostwald ripening of small colloids into large colloids in the narrow temperature interval and suggests that radiation-enhanced F center diffusion occurs in CaF2 with as low activation energy as 0.4 eV. In contrast, the activation energy for a single F center diffusion in LiF is found to be as high as 1.5 eV. The key role of mutual defect elastic attraction in their aggregation is demonstrated. Another two examples are metal colloid formation during annealing of the thermochemically reduced MgO crystals with very high F center concentration, and F center aggregation in tracks of swift heavy ions in LiF.

KOTOMIN Eugene;  POPOV A.; 

2007-07-16

Springer

JRC31283

https://publications.jrc.ec.europa.eu/repository/handle/JRC31283,