Superconducting properties of the YBa2Cu3O7−δ perovskites are highly sensitive to the number of oxygen vacancies in the lattice. The vacancy concentration can be changed considerably by varying the sintering conditions of the ceramic pellets. We have used X‐ray Photoelectron Spectroscopy (XPS) and thermogravimetric analysis to examine the nature of the chemistry of Cu, Ba, and Y in a series of YBa2Cu3O7−δ samples of varying oxygen vacancy concentrations. XPS valence and core level spectra show the copper to be in different chemical environments. The data have been compared to the superconducting‐to‐insulating behavior observed in electrical resistivity measurements.
R. Budhani, Sing-Mo H. Tzeng, R. Bunshah
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