Three-dimensional atomic interface between metal and oxide in Zr-ZrO2 nanoparticles

Metal-oxide interfaces with poor coherency have unique properties comparing to the bulk materials and offer broad applications in the fields of heterogeneous catalysis, battery, and electronics. However, current understanding of the three-dimensional (3D) atomic metal-oxide interfaces remains limited because of their inherent structural complexity and limitations of conventional two-dimensional imaging techniques. Here, we determine the 3D atomic structure of metal-oxide interfaces in zirconium-zirconia nanoparticles using atomic-resolution electron tomography. We quantitatively analyze the atomic concentration and the degree of oxidation, and find the coherency and translational symmetry of the interfaces are broken. Atoms at the interface have low structural ordering, low coordination and elongated bond length. Moreover, we observe porous structures such as Zr vacancies and nano-pores and investigate their distribution. Our findings provide a clear 3D atomic picture of metal-oxide interface with direct experimental evidence. We anticipate this work could encourage future studies on fundamental problems of oxides such as interfacial structures in semiconductor and atomic motion during oxidation process.与块体材料相比，低相干性金属-氧化物界面具备独特的物性，并在多相催化、电池及电子学领域拥有广泛应用前景。然而，由于其固有结构复杂性以及传统二维成像技术的局限性，当前学界对三维（3D）原子级金属-氧化物界面的认知仍较为有限。本研究借助原子分辨电子断层成像技术，解析了锆-氧化锆纳米颗粒中金属-氧化物界面的三维原子级结构。我们对原子浓度与氧化程度进行了定量分析，发现该界面的相干性与平移对称性均已破缺。界面处的原子呈现出较低的结构有序度、配位数以及更长的键长。此外，我们还观测到了锆空位与纳米孔等多孔结构，并对其分布特征展开了研究。本研究的发现为金属-氧化物界面提供了清晰的三维原子级可视化图像，并辅以直接的实验证据。我们期望本工作能够推动后续针对氧化物基础科学问题的探索，例如半导体界面结构以及氧化过程中的原子运动等方向。