Electron Diffraction Studies on the Oxidation of Pure Copper and Pure Zinc Between 200 ~ and 500~

Previous workers identified an oxide CuO ' in addition to Cu20 and CuO during the oxidation of copper. Studies on pure copper, clectrodeposited copper, and evaporated copper show that the extra reflections characteristic of CuO ' may/)e interpreted as due to an oxide of lead or zinc. These impurities, although present in trace amounts, concen-trate in the surface layer during oxidation or are picked up from the surrounding at-mosphere. Cu:O is found to be the essential oxide in the surface layer for oxidations in the tem-perature range of 200 ~ to 40O ~ with CuO forming during longer oxid'~tion times a 400 ~ 9 rod 500 ~ In high vacua the CuO disappears by the solid phase reaction of cof)per to form CuxO. These observations show t at at temperatures of 200 ~ to 500 ~ the cuprous ion diffuses through the Cu..,O structure. Finch and Quarrell, in a study of the Oxides formed on molten zinc a devaporated zinc films, propose an oxide pseudomorphic with zinc in thatits cell is distorted slightly to match that of the underlying metal. This pseudomorphic oxide changes to thenormal form at higher temperatures. The present oxidation studies using super-pure zinc rods and evaporated zinc specimens give electron diffraction patterns of zinc and normal ZnO but no evidence for the pseudolnorphic oxide