The Diffusion of Copper in Cuprous Oxide

Abstract

Cuprous oxide strips were prepared by the oxidation of copper at 1000°C. The diffusion of radiocopper in this material at 800 to 1050° gave a self-diffusion coefficient, D=0.0436 exp(−36100/RT). Virtually the same D is obtained from experiments in which radiocopper is plated on copper strips, and the distribution of activity measured in the cuprous oxide film formed on oxidation in air. The observed D values are in accord with a predicted relation k/D=4, where k is the parabolic rate constant for copper oxidation. It is suggested that parabolic rate constants with large negative entropies of activation and low heats of activation may be due to grain boundary diffusion.