Oxygen nonstoichiometry in SrCeO3-based high-temperature protonic conductors evaluated by Raman spectroscopy

Raman spectra of Yb-doped strontium cerate SrCe1−xYbxO3−δ were measured to evaluate their defect structure, which is much expected to influence their physical properties, such as solubility and diffusivity of protons in these oxides. In spectra, a signal showing existence of oxygen vacancies was observed at about 630 cm−1 for doped samples. The intensity of this band increased with oxygen vacancy formation by Yb-doping and by annealing at high temperatures in dry [low P(H2O)] or reducing [low P(O2)] conditions. Since a clear relationship between a peak intensity of the oxygen vacancy band and dopant concentration was obtained, it was found oxygen nonstoichiometry in SrCe1−xYbxO3−δ system could be evaluated using this relationship.