Mechanisms of defect migration

At temperatures when interstitial atoms and ions become mobile (typically, 20-30 K in both metals and insulators), they perform thermally-activated incoherent hops, the frequencies of which are exponentially dependent on reciprocal temperature  

From pair kinetics toward the many-reactant problem 

Many-phonon hopping processes could be treated as defect localization during some waiting time tq with further sudden and instant hop and new localization in a nearest lattice site for tq etc. The same situation takes place for solvated electrons in solutions and electron migration over impurities in 

During their diffusive walks, H centres can either approach their own F centres to within the distance r ro and recombine with them in the course of the so-called geminate (monomolecular) reaction or leave them behind in their random walks. Some of these H centres recombine with foreign F centres, thus participating in bimolecular reactions. The rest of the H centres become trapped by impurities, dislocations, or aggregate in the form of immobile dimer H2 centres thus going out of the secondary reactions as shown in Fig. 3.4. In other words, the survival probability of the geminate pairs (F centres) directly defines the defect accumulation efficiency and thus, a material s sensitivity to radiation. 

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