Recovery of pure platinum and dilute platinum--gold alloy electron-irradiated at liquid-nitrogen temperature

Pure platinum, platinum-0.1-at.%-gold alloy and platinum with various supersatuations of vacancies were irradiated at approximately 90 °K by 3-MeV electrons. The production of damage for these samples did not follow the simple power law widely used. Isothermal annealing in 10 C° temperature intervals in the range - 150 to 100 °C revealed annealing peaks at - 75, 0, and 25 °C. The activation energies of these peaks were determined to be 0.48 ± 0.04, 0.74 ± 0.06, and 0.74 ± 0.06 eV. In addition, the annealing was continued to higher temperatures in 25 °C intervals to investigate the stage at 325 °C. From the dependence of the various peaks upon the preirradiation vacancy concentration, dose, and the results for the alloy samples along with the activation energies, it is suggested that the annealing process at 325 °C (activation energy of 1.45 ± 0.06 eV) associated with the migration of vacancies should be called stage III. In this way the physical phenomenon associated with this stage will correspond to that in other metals, such as Al and Au. The stage around - 75 °C is strongly impurity dependent, being completely suppressed in the 0.1-at.% alloy.