A Correlated STEM/APT Study of Multidimensional and Interconnected Multi-element Nanostructures Derived from a Complex Concentrated Oxide
A Correlated STEM/APT Study of Multidimensional and Interconnected Multi-element Nanostructures Derived from a Complex Concentrated Oxide
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复杂浓缩氧化物衍生的多维和互连多元素纳米结构的相关 STEM/APT 研究
DOI：
10.1093/micmic/ozad067.948
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发表时间：
2023
影响因子：
2.8
通讯作者：
Abdul-Aziz, Kandis Leslie
中科院分区：
文献类型：
--
作者：
Guo, Huiming;Mead, Christopher;Balingit, Marquez;Shah, Soham;Wang, Xin;Xu, Mingjie;Tran, Ich;Aoki, Toshihiro;Samaniego, Jack D;Abdul-Aziz, Kandis Leslie
络合浓缩氧化物（CCOs）是一种新兴的材料类别，包括高熵氧化物（HEOs）和熵稳定氧化物（ESOs），其前所未有的性能源于稳定许多阳离子（通常是> 5）固溶体[1][2]引起的电子结构和化学的无序分布。将这些材料集成到具有纳米级可调性的复合材料中，将使定制（多）功能超越单相[3]。在这里，我们展示了一种新颖的、高度可扩展的方法来实现具有复杂多元素纳米结构的cco基纳米复合材料。所谓的杂化脱溶自组装合成应用于由lafeo3（一种通常通过化学掺杂改性的钙钛矿）激发的CCO，用于未来的电化学、传感和电/光催化应用[4]。利用脉冲激光沉积，我们选择性地还原了6-阳离子钙钛矿氧化物中的阳离子，诱导缺陷相互作用驱动的析出和金属纳米棒和金属氧化物核壳纳米颗粒的同时自组装，这取决于薄膜的生长条件。纳米复合材料的合成是在保持竞争性电子导电性的同时实现的，两种机制都是通过相关的亚纳米级电子和原子探针来阐明的。利用像差校正扫描透射电子显微镜（STEM）成像、能量色散x射线光谱（EDS）、电子能量损失光谱（EELS）、几何相位分析（GPA）应变图、原子探针断层扫描（APT）三维质谱和x射线光发射光谱（XPS）进行相关分析，阐明了高度定制合成方法背后的基本纳米结构形成机制。我们表明，该方法实现均匀的体溶在短的工艺时间，并通过调整易于访问的PLD条件进行操作。详细的表征解决了氧空位浓度增加和阳离子还原性变化对纳米结构自组装的影响。为例。金属纳米棒从薄膜底部向顶部生长，生长受到基体在平面方向上施加的压应力的限制。金属氧化物核壳纳米颗粒通过种子生长效应嵌入基体中，这种种子生长效应是由金属纳米颗粒形成引发的，随后是额外的移动阳离子的减少。这项工作表明，通过纳米复合材料设计的功能薄膜，可以实现巨大的形态可调性和成分复杂性。由于这种新兴的材料类别包括heo和eso，本研究还为可调构型熵[5]产生的额外合成控制和材料功能奠定了基础。
Complex concentrated oxides (CCOs) are an emerging material class that includes high-entropy oxide (HEOs) and entropy-stabilized oxides (ESOs), whose unprecedented properties stem from disorder-induced distributions in electronic structure and chemistry caused by stabilizing many-cation (typically> 5) solid solutions [1][2]. Integrating these materials into composites with nanoscale tunability will enable tailored (multi) functionality beyond what is possible in a single phase [3]. Here, we demonstrate a novel, highly extensible approach to realize CCO-based nanocomposites with intricate multi-element nanostructures. So-called hybrid exsolution self-assembly synthesis is applied to a CCO inspired by LaFeO3—a perovskite commonly modified through chemical doping for use in future electrochemical, sensing, and electro/photocatalysis applications [4]. Using pulsed-laser deposition, we selectively reduce cations in a 6-cation perovskite oxide, inducing defect-interaction-driven exsolution and simultaneous self-assembly of metal nanorods and metal-oxide core-shell nanoparticles, depending on film growth conditions. Nanocomposite synthesis is achieved while maintaining competitive electronic conductivity, and both mechanisms are elucidated via correlated sub-nanoscale electron and atom probes.A correlated analysis using aberration-corrected scanning transmission electron microscopy (STEM) imaging, energy dispersive X-ray spectroscopy (EDS), electron energy-loss spectroscopy (EELS), geometric phase analysis (GPA) strain mapping, atom probe tomography (APT) with 3D mass spectrometry, and X-ray photoemission spectroscopy (XPS) was performed to elucidate the fundamental nanostructure formation mechanisms underlying the highly tailorable synthesis approach. We show that the method achieves uniform bulk exsolution with short process time and is manipulated by tuning readily accessible PLD conditions. Detailed characterization resolved the impact of increasing oxygen vacancy concentration and varying cation reducibility on nanostructure self-assembly. For example. Metal nanorods grow from bottom of the thin film to top surface, with growth restricted by compressive stress exerted by the matrix in the in-plane direction. Metal-oxide core-shell nanoparticles embedded in the matrix form via seed growth effect triggered by metal nanoparticle formation followed by subsequent reduction of additional mobile cations. This work demonstrates a route towards vast morphological tunability and compositional complexity through nanocomposite design of functional thin films with derived from CCOs. Because this emerging material class includes HEOs and ESOs, this study also lays the groundwork for additional synthetic control and material functionalities arising from tunable configurational entropy [5].