Oxygen defect in YBa2Cu3Ox: An x-ray photoemission approach

Abstract

A combined x-ray photoemission and diamagnetic-susceptibility study of ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{\mathrm{x}}$ with x≃6 and 7 has been performed, with emphasis on the oxygen defect and the effect of heating in vacuum. By comparing spectra taken at these two oxygen contents, the core levels observed in the O 1s and Ba 4d spectral range are identified. Peak-intensity analysis indicates (1) that the oxygen released during the in situ heating is derived from or near the Cu-O-Cu-O chains of ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_7$ and (2) that there is a random distribution of oxygen defects in or near these chains leading to two chemically dissimilar barium atoms even in single-orthorhombic-phase samples.