Post-Recoil Annealing Effects

Green and Maddock (S3) subsequently found that the retention of chromium-51 in potassium chromate could be increased by heating the neutron-irradiated crystals. Thermal and radiation annealing have since been observed in a nmnber of systems (4, S, 9, 20, 21, 31, 35, 39, 4I, 50, 52, 53, 54, 60, 66, 67, 74, 77, 91). In general, annealing returns a part of the initially separable recoil atoms to the foim of the parent compound. 

The annealing of Szilard-Chalmers recoil atoms finds a striking parallel in the annealing of radiation damage produced in solids by neutron, charged-particle, or photon irradiation (25). In both cases one is dealing with solids which have been altered by the production of defects in a matrix of otherwise normal crystal. In both cases the defects are the 

The recombination of pairs of interstitials and vacancies has usually formed the basis of models for thermal annealing. It has sometimes been assumed that the vacancy is mobile (as in the vacancy model for self-diffusion) and sometimes that the vacancy is a fixed trap or sink, having a capacity of one interstitial atom, and the interstitial is mobile. The form of the kinetic equations is usually not dependent on the choice, and this is true even if both are mobile provided there is no initial correlation of interstitials and vacancies. 

Provided the annealing process described above leads to retention (the re-formation of the parent compound, or a species which produces the parent compound on chemical analysis), Eq. (3) can be expressed in terms of retentions as follows 

In order to simplify the equations we will consider only the increase in the number of recombined atoms on annealing. Although as we have seen in Section II the initial retention (fto) is usually not zero, and may 

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Ramsey theory, 22 201-204 Random-fragmentation model, Szilard-Chalmers reaction and, 1 270 Random-walk process, correlated pair recombination, post-recoil annealing effects and, 1 288-290 Rare-earth carbides, neutron diffraction studies on, 8 234-236 Rare-earth ions energy transfer, 35 383 hydration shell, 34 212-213 Rare gases... 

Correlated pairs, post-recoil annealing effects and, 283-290... 

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