Determination of Depth Profile of CuO+ and Cu+ in Superconductors by a Wet-Chemical Method Using Flow-Coulometry

摘要

Using a wet-chemical method based on flow-coulometry, an analytical method to measure unstable ions of copper, CuO+ and Cu+, in superconductors has been advanced. The distributions of these ions from the surface to inside of sample discs were determined by the developed method. The sample discs, which were prepared by the ceramic method, contained a lower CuO+/Cutotal ratio at the outermost surface, and gradually increased to a depth of 200 µm. On the contrary, the Cu+/Cutotal ratio in a YBa2Cu3O6 sample was almost homogeneous. The positively electrolyzed La2CuOy disc as an electrode exhibited a much higher oxidation state than that without electrolysis. It was confirmed that the CuO+/Cutotal ratio on the surface and in the bulk of the electrolyzed La2CuOy had an influence on the superconducting characteristics.