A novel Ruddlesden–Popper-related compound, Gd₃Ba₂Fe₄O₁₂, 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. Gd₃Ba₂Fe₄O₁₂ belongs to the tetragonal system P4₂/ncm, with a = 5.59040 (10) Å and c = 35.1899 (10) Å. The A-site ions in the Ruddlesden–Popper structure, i.e. Gd³⁺ and Ba²⁺, 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⁻b⁰c⁰/b⁰a⁻c⁰. 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.

中文翻译：

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缺氧的 Ruddlesden-Popper 化合物 Gd3Ba2Fe4O12 中独特的八面体旋转模式

发现了一种新型的 Ruddlesden-Popper 相关化合物 Gd ₃ Ba ₂ Fe ₄ O ₁₂，并通过单晶 X 射线衍射确定了其晶体结构。该结构沿c轴具有八面体和棱锥体的有序结构。Gd ₃ Ba ₂ Fe ₄ O ₁₂属于四方晶系P 4 ₂ / ncm，a = 5.59040 (10) Å 和c = 35.1899 (10) Å。Ruddlesden-Popper 结构中的A位离子，即Gd³⁺和 Ba ²⁺，表现出沿c轴的排序。在适当的 Ruddlesden-Popper 结构中的 GdO 层中适应了完美的缺氧。使用键价和方法，FeO ₆八面体和FeO ₅金字塔中的Fe 离子分别代表+3 和+2.5 的价态，证明了二维电荷歧化。角共享的 FeO ₆八面体和 FeO ₅金字塔向相反的方向倾斜，相邻的简单钙钛矿配置的一个轴周围，使用 Glazer 的符号，可以表示为a ⁻ b ⁰ c ⁰ /b ⁰ a ^- c ⁰。在钙钛矿块中，面向Gd 层的FeO ₅金字塔以相同的方向旋转，这是与缺氧相关的独特旋转特征。