The Self-Diffusion of Copper

The self-diffusion of copper has been measured with a radioactive isotope prepared by neutron bombardment of zinc. The isotope is electroplated in a thin layer upon the surface of a copper disk. By measuring the decrease in β-ray emission from the sample due to the penetration of the radioactive copper, the self-diffusion constant is determined within the limits of accuracy as 11 cm²/sec. exp(-57,200/RT). Methods of analyzing such data are given and the significance of the variation of activation energy between self-diffusion and heterogeneous diffusion is discussed.