X-RAY PHOTOELECTRON SPECTROSCOPY STUDY OF THE SINGLE PHASE HIGH-T_c SUPERCONDUCTOR YBa₂Cu₃O_9-δ

X-ray Photcelectron Spectroscopy (XPS) was employed to study the single phase high-T_c superconductor YBa₂Cu₃O_9-δ. Comparison. Of the observed valence band spectrum with the theoretical spectrum of Mattheiss is given. The core level spectrum of Ba 3d_5/2 was examined. The results of Y₂Cu₂O₅ and Y₂BaCuO₅ are also reported.