X-Ray photoelectron spectroscopic studies of the Fermi edge and oxygen stability of 1-2-3 superconducting systems
Review articleOpen access
L.M. Chen - No affiliation found
1995/03/01 Full-length article DOI: 10.1016/0927-6513(94)00076-8
Journal: Microporous Materials
AbstractX-ray photoelectron spectroscopy (XPS or ESCA) has been employed to investigate the compositional behavior of YBa2Cu3Ox (6.3<x<6.9) or 1-2-3 superconducting systems (in both bulk-ceramic and thin-film form) at room temperature. Several questions are addressed that relate to the oxygen stability of these materials and the corresponding attributes of the resulting Fermi edges. First, it is demonstrated that subjecting these materials to ultra-high vacuum conditions extracts oxygen from these systems (i.e., reduces x). We then show that this degradation may be substantially mitigated by the by-product layer that forms on the surface of all air-exposed 1-2-3 systems. As a result we have generated the first view of the above Tc (normal conductive) finite Fermi density for 1-2-3. We then show that this density may be removed by the destructive force of a direct focus X-ray system. All of these features may be cycled back and forth merely bt alternating exposures of the 1-2-3 systems to air and vacuum.
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