(Sr 1-xBa x)FeO 2 (0.4 ≤ x ≤ 1): A new oxygen-deficient perovskite structure

Takafumi Yamamoto, Yoji Kobayashi, Naoaki Hayashi, Cédric Tassel, Takashi Saito, Shoji Yamanaka, Mikio Takano, Kenji Ohoyama, Yuichi Shimakawa, Kazuyoshi Yoshimura, Hiroshi Kageyama

Research output: Contribution to journalArticle

22 Citations (Scopus)


Topochemical reduction of (layered) perovskite iron oxides with metal hydrides has so far yielded stoichiometric compositions with ordered oxygen defects with iron solely in FeO 4 square planar coordination. Using this method, we have successfully obtained a new oxygen-deficient perovskite, (Sr 1-xBa x)FeO 2 (0.4 ≥ x ≥ 1.0), revealing that square planar coordination can coexist with other 3-6-fold coordination geometries. This BaFeO 2 structure is analogous to the LaNiO 2.5 structure in that one-dimensional octahedral chains are linked by planar units, but differs in that one of the octahedral chains contains a significant amount of oxygen vacancies and that all the iron ions are exclusively divalent in the high-spin state. Mössbauer spectroscopy demonstrates, despite the presence of partial oxygen occupations and structural disorders, that the planar-coordinate Fe 2+ ions are bonded highly covalently, which accounts for the formation of the unique structure. At the same time, a rigid 3D Fe-O-Fe framework contributes to structural stabilization. Powder neutron diffraction measurements revealed a G-type magnetic order with a drastic decrease of the Néel temperature compared to that of SrFeO 2, presumably due to the effect of oxygen disorder/defects. We also performed La substitution at the Ba site and found that the oxygen vacancies act as a flexible sink to accommodate heterovalent doping without changing the Fe oxidation and spin state, demonstrating the robustness of this new structure against cation substitution.

Original languageEnglish
Pages (from-to)11444-11454
Number of pages11
JournalJournal of the American Chemical Society
Issue number28
Publication statusPublished - 2012 Jul 18

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Fingerprint Dive into the research topics of '(Sr <sub>1-x</sub>Ba <sub>x</sub>)FeO <sub>2</sub> (0.4 ≤ x ≤ 1): A new oxygen-deficient perovskite structure'. Together they form a unique fingerprint.

  • Cite this

    Yamamoto, T., Kobayashi, Y., Hayashi, N., Tassel, C., Saito, T., Yamanaka, S., Takano, M., Ohoyama, K., Shimakawa, Y., Yoshimura, K., & Kageyama, H. (2012). (Sr 1-xBa x)FeO 2 (0.4 ≤ x ≤ 1): A new oxygen-deficient perovskite structure. Journal of the American Chemical Society, 134(28), 11444-11454. https://doi.org/10.1021/ja3007403