Gorobtsov Oleg, Singer Andrej
Department of Materials Science and Engineering, Cornell University, 418 Thurston Hall, Ithaca, NY 14853, USA.
J Synchrotron Radiat. 2022 May 1;29(Pt 3):866-870. doi: 10.1107/S1600577522002363. Epub 2022 Apr 5.
Bragg coherent X-ray diffractive imaging is a cutting-edge method for recovering three-dimensional crystal structure with nanoscale resolution. Phase retrieval provides an atomic displacement parallel to the Bragg peak reciprocal lattice vector. The derivative of the displacement along the same vector provides the normal strain field, which typically serves as a proxy for any structural changes. In this communication it is found that the other component of the displacement gradient, perpendicular to the reciprocal lattice vector, provides additional information from the experimental data collected from nanocrystals with mobile dislocations. Demonstration on published experimental data show how the perpendicular component of the displacement gradient adds to existing analysis, enabling an estimate for the external stresses, pinpointing the location of surface dislocations, and predicting the dislocation motion in in situ experiments.
布拉格相干X射线衍射成像技术是一种前沿方法，用于以纳米级分辨率恢复三维晶体结构。相位恢复可提供与布拉格峰倒易晶格矢量平行的原子位移。沿同一矢量的位移导数提供法向应变场，该应变场通常可作为任何结构变化的替代指标。在本通讯中发现，位移梯度的另一个分量，即垂直于倒易晶格矢量的分量，可从具有可移动位错的纳米晶体收集的实验数据中提供额外信息。对已发表实验数据的论证表明，位移梯度的垂直分量如何补充现有分析，从而能够估算外部应力、确定表面位错的位置，并预测原位实验中的位错运动。
