Stage-III Annealing in Gold after Electron Irradiation

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Abstract
Gold specimens of nominal 99.9999% purity were irradiated with 3-MeV electrons near liquid-nitrogen temperature. The damage production rate is found to depend on the purity of the specimen giving a lower value for the high-purity specimens. It is also found that the production rate is reduced remarkably by quenching the specimen before irradiation. For high-purity gold, a single large annealing peak is observed in stage III. The slope-change method and Primak analysis are employed to obtain the activation energy of stage-III annealing. Both methods give 0.85±0.02 eV for the activation energy in high-purity irradiated specimens. The activation energies for quenched and for quench-plus-irradiated specimens of comparable purity are found to be 0.85±0.03 and 0.86±0.02 eV, respectively, agreeing with the value for the irradiated specimens within the experimental error. Somewhat lower values are obtained for specimens of lower purity. Second-order kinetics are obeyed in the main part of the stage-III annealing for the irradiated, quench-plus-irradiated, and quenched specimens. Various models are discussed to explain stage-III annealing. It is concluded that vacancy migration in stage III with interstitial clusters acting as sinks can account for the observed results most satisfactorily in the case of gold.