Ruddlesden–Popper oxides, (AO)(ABO3) n , occupy a prominent place in the landscape of materials research because of their intriguing potential applications. Compositional modifications to the cation sublattices, A or B, have been explored in order to achieve enhanced functionalities. However, changes to the anionic sublattice have been much less explored. In this work, new oxygen-deficient manganese Ruddlesden–Popper-related phases, La0.5Ca2.5Mn2O6.5 and La0.5Ca2.5Mn2O6.25, have been synthesized by controlled reduction of the fully oxidized n = 2 term La0.5Ca2.5Mn2O7. A complete structural and compositional characterization, by means of neutron diffraction, electron diffraction and atomically resolved scanning transmission electron microscopy and electron energy-loss spectroscopy techniques, allows the proposition of a topotactic reduction pathway through preferential oxygen removal in the [MnO2] layers along [031] and [0{\bar 1}3] directions. The gradual decrease of the Mn oxidation state, accommodated by short-range ordering of anionic vacancies, reasonably explains the breaking of ferromagnetic interactions reinforcing the emergence of antiferromagnetic ones. Additional short-range order–disorder phenomena of La and Ca cations have been detected in the reduced La0.5Ca2.5Mn2O7−δ, as previously reported in the parent compound.

中文翻译：

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La0.5Ca2.5Mn2O7−δ Ruddlesden-Popper 相中氧缺陷的复杂结构排序

鲁德尔斯登-波普尔氧化物，（A哦)(AB氧3） n ，由于其有趣的潜在应用而在材料研究领域占据着重要地位。阳离子亚晶格的组成修改，A或者乙，已被探索以实现增强的功能。然而，对阴离子亚晶格的变化的探索却少得多。在这项工作中，新的缺氧锰 Ruddlesden-Popper 相关相 La0.5钙2.5锰2氧6.5和拉0.5钙2.5锰2氧6.25，通过完全氧化的受控还原合成n= 2 项 La0.5钙2.5锰2氧7。通过中子衍射、电子衍射和原子分辨扫描透射电子显微镜和电子能量损失光谱技术进行完整的结构和成分表征，允许通过优先去除[MnO2]中的氧来提出拓扑还原途径。2] 沿 [031] 和 [0{\bar 1}3] 方向层。Mn氧化态的逐渐降低，由阴离子空位的短程有序调节，合理地解释了铁磁相互作用的破坏，增强了反铁磁相互作用的出现。在还原的 La 中还检测到了 La 和 Ca 阳离子的其他短程有序无序现象0.5钙2.5锰2氧7−δ，如之前在母体化合物中报道的那样。