Abstract: The XPS spectra of superconducting(123-orthorhombic structure)and non-superconducting (123-tetragonal structure)YBa_2Cu_3O_(7-x)ceramics were obtained at room temperature and 130 K with RIBER LAS 3000 surface analysis system,in which a sample cooling stage and a surface cleaning scraper,both made by the authors,were installed.No evidence of Cu~(3+)was found.The O 1s shows double lines.They are attributed to O1 and O4 with higher binding en- ergy and to O2 and O3 with lower binding energy respectively,and it was confirmed by cal- culation of SW-X_α method.The differences and changes in valence states of Y,Ba,Cu and O in both samples were discussed.

Key words: YBaCuO, superconductor, low temperature, XPS