韩国能源技术研究院Oh, Sang Ho团队利用原位原子分辨电子显微镜监测无限层过渡金属氧化物的形成。相关研究成果发表在2024年8月27日出版的国际知名学术期刊《自然—化学》。

具有二维氧配位的无限层过渡金属氧化物，由于强烈的平面内轨道杂化而表现出有趣的电子和磁性。这种独特结构的合成主要依赖于，以三维多面体氧配位为特征的富氧相的动力学控制还原。

该文中，研究人员使用原位原子分辨率电子显微镜，仔细研究了导致SrFeO_2.5转变为无限层SrFeO₂的复杂的氧传导原子尺度机制。氧释放具有高度的各向异性，并受晶格重新取向的控制，使快速扩散通道朝向出口对齐，这是由铁离子和氧离子的协同而又混乱的位移所促进的。

伴随着氧的释放，FeOx多面体层的晶格灵活性促进了氧的三维到二维重构，采用了多个离散瞬态，遵循由最小能量消耗路径确定的顺序。类似的转变机制可能适用于与SrFeO₂同构的铜酸盐和镍酸盐超导体。

附：英文原文

Title: Monitoring the formation of infinite-layer transition metal oxides through in situ atomic-resolution electron microscopy

Author: Xing, Yaolong, Kim, Inhwan, Kang, Kyeong Tae, Byun, Jinho, Choi, Woo Seok, Lee, Jaekwang, Oh, Sang Ho

Issue&Volume: 2024-08-27

Abstract: Infinite-layer transition metal oxides with two-dimensional oxygen coordination exhibit intriguing electronic and magnetic properties due to strong in-plane orbital hybridization. The synthesis of this distinctive structure has primarily relied on kinetically controlled reduction of oxygen-rich phases featuring three-dimensional polyhedral oxygen coordination. Here, using in situ atomic-resolution electron microscopy, we scrutinize the intricate atomic-scale mechanisms of oxygen conduction leading to the transformation of SrFeO2.5 to infinite-layer SrFeO2. The oxygen release is highly anisotropic and governed by the lattice reorientation aligning the fast diffusion channels towards the outlet, which is facilitated by cooperative yet shuffle displacements of iron and oxygen ions. Accompanied with the oxygen release, the three-dimensional to two-dimensional reconfiguration of oxygen is facilitated by the lattice flexibility of FeOx polyhedral layers, adopting multiple discrete transient states following the sequence determined by the least energy-costing pathways. Similar transformation mechanism may operate in cuprate and nickelate superconductors, which are isostructural with SrFeO2.

DOI: 10.1038/s41557-024-01617-7

Source: https://www.nature.com/articles/s41557-024-01617-7