Scanning transmission electron microscopy (STEM) allows detailed atomic displacements in ferroelectrics to be studied. Although the interpretation of the displacements is straightforward for single-domain structures, it is complicated when multiple domains are present in the direction of the electron beam. In the present study, we simulated STEM images to obtain insight into the observed ionic displacements for multi-domain structures in a prototypic ferroelectric, barium titanate. We found that the observed displacements can vary depending on the domain configuration, domain thicknesses, and the defocus of the electron probes. Observed displacement behaviors were dominantly contributed by the upper domain when focusing the electron beam on the upper surface of samples, whereas interpretation of the behaviors became complex when the electron probe was focused on their inside. These results suggest that comparison of experimental observations with simulations is necessary to better understand the displacement behavior.

中文翻译：

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多域钛酸钡的扫描透射电子显微镜模拟

扫描透射电子显微镜（STEM）可以研究铁电体中详细的原子位移。尽管对于单畴结构，位移的解释是直接的，但是当在电子束方向上存在多个畴时，则很复杂。在本研究中，我们模拟了STEM图像，以深入了解原型铁电体钛酸钡中多畴结构的离子位移。我们发现观察到的位移可以根据畴结构，畴厚度和电子探针的散焦而变化。当电子束聚焦在样品的上表面时，观察到的位移行为主要由上部域贡献，当电子探针聚焦在其内部时，行为的解释变得复杂。这些结果表明，将实验观察结果与模拟结果进行比较对于更好地了解位移行为是必要的。