X-ray electron and Auger spectroscopy of Cu-La-Sr-O and Cu-Y-Ba-O superconductors

The stoichiometric composition and valence states of elements in the Cu-La-Sr-O and Cu-Y-Ba-O superconducting ceramics were investigated using X-ray photoelectron spectroscopy with an energy resolution of 1 eV at the 4f Ag line. Spectra were excited by Mg K-alpha (1253.6 eV) radiation. Information about the surface and internal composition of grains was obtained via O(+) and Ar(+) ion etching at an ion energy of 3.5 keV. It is shown that copper in the Cu(+), Cu(2+), and Cu(3+) states is present on the grain surfaces, while only Cu(2+) and Cu(3+) are present inside grains.