Experiments on Stage III Annealing in the Noble Metals

Abstract

High purity copper, silver, and gold specimens have been irradiated with 10-MeV protons near 80°K. An integrated flux of 1× ${10}^{17}$ p/${\mathrm{cm}}^2$ produced a resistivity increase of 3.3×${10}^{-8\mathrm{}}$ Ω-cm in copper, 7.4×${10}^{-8\mathrm{}}$ Ω-cm in silver, and 16.6×${10}^{-8\mathrm{}}$ Ω-cm in gold. The specimens were isothermally annealed in steps of 20°K for 64 min at each temperature from 143 to 363°K. The recovery in stage III follows second-order kinetics with an activation energy of 0.71±0.04 eV for copper, 0.67±0.03 eV for silver, and 0.80±0.04 eV for gold. Distribution curves of the fractional concentration of defects annealing with a given activation energy have been calculated. In the case of copper and silver they show a complex structure followed by a large broad maximum at 0.71 eV for copper and 0.67 eV for silver. In gold there is only one large peak at 0.80 eV. The relationship of these results to the various models is discussed.