Wang Sihan, Eldred Tim B, Smith Jacob G, Gao Wenpei
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, United States.
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, United States; Analytical Instrumentation Facility, North Carolina State University, Raleigh, NC 27695, United States.
Ultramicroscopy. 2022 Jun;236:113513. doi: 10.1016/j.ultramic.2022.113513. Epub 2022 Mar 10.
Development in lattice strain mapping using four-dimensional scanning transmission electron microscopy (4D-STEM) method now offers improved precision and feasibility. However, automatic and accurate diffraction analysis is still challenging due to noise and the complexity of intensity in diffraction patterns. In this work, we demonstrate an approach, employing the blob detection on cross-correlated diffraction patterns followed by a lattice fitting algorithm, to automate the processing of four-dimensional data, including identifying and locating disks, and extracting local lattice parameters without prior knowledge about the material. The approach is both tested using simulated diffraction patterns and applied on experimental data acquired from a Pd@Pt core-shell nanoparticle. Our method shows robustness against various sample thicknesses and high noise, capability to handle complex patterns, and picometer-scale accuracy in strain measurement, making it a promising tool for high-throughput 4D-STEM data processing.
利用四维扫描透射电子显微镜（4D-STEM）方法进行晶格应变映射的发展，现在提供了更高的精度和可行性。然而，由于噪声和衍射图案中强度的复杂性，自动且准确的衍射分析仍然具有挑战性。在这项工作中，我们展示了一种方法，该方法在互相关衍射图案上采用斑点检测，然后是晶格拟合算法，以自动处理四维数据，包括识别和定位圆盘，以及在无需关于材料的先验知识的情况下提取局部晶格参数。该方法既使用模拟衍射图案进行了测试，也应用于从Pd@Pt核壳纳米颗粒获取的实验数据。我们的方法显示出对各种样品厚度和高噪声的鲁棒性、处理复杂图案的能力以及在应变测量中皮米级的精度，使其成为高通量4D-STEM数据处理的一个有前途的工具。
