Abstract
The electronic structure at surface of Y-doped BaCeO3 (BaCe1-xYxO3-δ) has been studied by soft-X-ray spectroscopy. The conduction band and valence band are mainly composed of Ce 4f state and the O 2p state hybridized with the Ce 4f state, respectively. The energy gap of BaCeO3, which corresponds to the energy separation between the top of the valence band and the bottom of the conduction band, is approximately 3.0 eV. The Fermi level in the surface state shifts to the valence band side with y concentration. The valence band consists of the mixed valence states of 4f0 (Ce4+) and 4f1 L. (Ce3+). The Ce4+ and Ce3+ states decrease with Y concentration. The existence of Ce3+ state disappears above x=0.08.
