Characterization of oxygen-deficient perovskites as oxide-ion electrolytes

• Published in: Solid state ionics 1993-08, Vol.62 (3), p.225-234
• Main Authors: Manthiram, A., Kuo, J.F., Goodenough, J.B.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Diffusion in solids; Exact sciences and technology; Physics; Theory of diffusion and ionic conduction in solids; Transport properties of condensed matter (nonelectronic)
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/0167-2738(93)90376-E

Oxide-ion conduction in oxygen-deficient perovskites is analogous in several respects to that in oxygen-deficient fluorite structures. We report here an important difference: oxygen-deficient AMO 3− y perovskites containing M cations that are unstable in less than sixfold anion coordination may, at modest temperatures, capture oxygen and/or water from air to fill, at least partially, the oxygen vacancies. The insertion of water introduces mobile protons; the insertion of oxygen oxidizes the oxide-ion array in the presence of fully oxidized main group cations. We illustrate this insertion with the perovskite system BaZr 1− x In x O 3−0.5 x , M=Zr or Hf. The data suggest that any ordering of the oxygen vacancies so as to give planes of corner-shared MO 4 tetrahedra permits facile insertion of water and/or oxygen. In contrast, the oxygen-deficient fluorite structure has each cation in at least sixfold oxide-ion coordination, and the problem of water or oxygen insertion at modest temperatures does not arise.