Evidence of O-H Bond in the Bulk State of Protonic Conductor Y-Doped SrCeO3by Soft-X-Ray Spectroscopy

The electronic structure in the band-gap region of protonic conductor Y-doped SrCeO 3 has been investigated by soft-X-ray emission spectroscopy (SXES) and X-ray absorpiton spectroscopy (XAS), which reflect the electronic structure in the bulk state. The O 1 s SXES spectrum exhibits three O 2 p states, which correspond to the top of the valence band, near the Fermi level, and the botttom of the conduction band. The O 1 s XAS spectrum exhibits the existence of hydrogen structures whose energy positions match with those of the three O 2 p states. These findings are direct evidence of the O-H bond in the bulk state.