Local atomic-scale structure of ionic conducting oxides from atom probe tomography

固体材料的原子排列、势能图和离子电导率是紧密联系在一起的。固体中原子的化学同一性、电子结构和局部排列决定了势能格局，这反过来又控制了可移动物种的能量学和动力学。它们的运动改变了原子结构，改变了能量格局，导致了一种耦合的动态状态。通过对溶解度、分离系数以及离子导电性和扩散的实验研究，可以获得对能量图景的洞察。结合理论，这些研究为发展原子尺度结构和迁移率之间的动态耦合的完整图景提供了基础。ELSICS研究单位的目标是应用这一方法来从机理上了解几种与技术相关的离子导体模型中的离子迁移率。原子探针层析成像(APT)在过去几十年中已经成为一种获得材料中三维元素分布的局部、原子尺度信息的强大方法。即使是具有挑战性的材料，如电绝缘、离子导电和脆性氧化物，也可以使用激光激发并通过仔细优化测量参数和重建算法来成功地进行分析。在拟议的研究单位范围内，APT将与SIMS(P1 Weitzel)、核磁共振(P2 Vogel)和透射电子显微镜(P4 Jooss)相结合，以确定几个离子导体的浓度梯度和原子尺度结构，根据这些结构，将通过理论(P5 Maass和P6 Jacob)预测位置能量分布和离子电导率，并与CAIT(P1 Weitzel)和核磁共振(P2 Vogel)测量的离子运动进行比较。最近，原子探测方法也被用来通过选择场蒸发和随后的APT来获得关于单个离子动力学的信息。还将探索这种方法检测离子导体中局部迁移路径的可能性和潜力。

Atomic arrangements, potential energy landscapes and ion conductivities of solid state materials are intimately interconnected. The chemical identity, electronic structure and local arrangement of atoms in a solid prescribes the potential energy landscape, and this in turn controls the energetics and kinetics of the mobile species. Their motion changes the atomic structure and shifts the energy landscape, leading to a coupled and dynamic state. Insights into the energy landscape can be gained from experimental studies of solubilities, segregation coefficients and ion conductivity and diffusion. Combined with theory, these studies provide the basis for developing a complete picture of the dynamic coupling between atomic scale structure and mobility. The goal of the ELSICS Research Unit is to apply this methodology to gain a mechanistic understanding of ion mobility in several model technologically relevant ion conductors.Atom probe tomography (APT) has emerged over the last several decades as a powerful method to obtain local, atomic-scale information of three-dimensional element distributions in materials. Even challenging materials such as electrically insulating, ionic conducting, and brittle oxides have been successfully analysed using laser excitation and by careful optimization of measurement parameters and reconstruction algorithms. In the context of the proposed Research Unit, APT will be combined with SIMS (P1 Weitzel), NMR (P2 Vogel), and TEM (P4 Jooss) to determine concentration gradients and atomic scale structure of several ion conductors, from which site energy distributions and ion conductivity will be predicted by theory (P5 Maass and P6 Jacob) and compared with measurements of ion motion with CAIT (P1 Weitzel) and NMR (P2 Vogel). Very recently, atom probe methods have also been used to gain information about individual ion dynamics using selective field evaporation and subsequent APT. The possibilities and potential of this method to detect local migration paths in ion conductors will also be explored.