Unique octahedral rotation pattern in the oxygen‐deficient Ruddlesden–Popper compound Gd3Ba2Fe4O12. Issue 6 (26th May 2021)

• Record Type: Journal Article
• Authors: Urushihara, Daisuke; Nakajima, Kenta; Nakamura, Ariki; Fukuda, Koichiro; Sugai, Hodaka; Konishi, Shinya; Tanaka, Katsuhisa; Asaka, Toru
• Is Part Of: Acta crystallographica. Volume 77:Issue 6(2021)
• Page Start: 286
• Page End: 290
• Publication Date: 2021-05-26
• Subjects: Ruddlesden–Popper phase -- iron oxide -- gadolinium -- barium -- iron -- crystal structure; Crystallography -- Periodicals; Crystals -- Periodicals; 548.3
• DOI: 10.1107/S2053229621005258
• Languages: English
• ISSNs: 2053-2296

Abstract

Abstract : A novel Ruddlesden–Popper‐related compound, Gd3 Ba2 Fe4 O12, has been synthesized. The crystal structure was determined via single‐crystal X‐ray diffraction. The compound shows the unique octahedral rotation scheme related to the oxygen‐deficient structure. Abstract : A novel Ruddlesden–Popper‐related compound, Gd3 Ba2 Fe4 O12, was discovered and its crystal structure was determined via single‐crystal X‐ray diffraction. The structure has an ordered structure of octahedra and pyramids along the c axis. Gd3 Ba2 Fe4 O12 belongs to the tetragonal system P 42 / ncm, with a = 5.59040 (10) Å and c = 35.1899 (10) Å. The A ‐site ions in the Ruddlesden–Popper structure, i.e. Gd 3+ and Ba 2+, exhibit an ordering along the c axis. The perfect oxygen deficiency is accommodated at the GdO layers in the proper Ruddlesden–Popper structure. Using the bond‐valence‐sum method, the Fe ions in the FeO6 octahedra and FeO5 pyramids represent valence states of +3 and +2.5, respectively, demonstrating a two‐dimensional charge disproportionation. The corner‐sharing FeO6 octahedra and FeO5 pyramids are tilted in opposite directions, with the neighbours around one axis of the simple perovskite configuration, which, using Glazer's notation, can be represented as a − b 0 c 0 / b 0 a − c 0 . In the perovskite blocks, the facing FeO5 pyramids across the Gd layer rotate in the same sense, which is a unique rotation feature related to oxygen deficiency.