Understanding of scanning-system distortions of atomic-scale scanning transmission electron microscopy images for accura
- PDF / 1,930,575 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 49 Downloads / 256 Views
Understanding of scanning-system distortions of atomic-scale scanning transmission electron microscopy images for accurate lattice parameter measurements Syota Fujinaka1, Yukio Sato1,* 1
, Ryo Teranishi1, and Kenji Kaneko1
Department of Materials Science and Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
Received: 6 December 2019
ABSTRACT
Accepted: 23 March 2020
Atomic-scale scanning transmission electron microscopy (STEM) imaging has opened up the possibility of studying the local lattice parameters of crystalline materials. To ensure more accurate measurements, low-frequency distortions of the images should be properly calibrated, which requires a better understanding of their causes. Although the major possible causes are sample drift and the scanning systems of microscopes, their effects are intricate because the rates of sample drifts differ in respective measurements. In the present study, low-frequency distortions of STEM images and their dependence on scan rotations were evaluated by measuring the lattice parameters of a reference specimen, strontium titanate. The distortions due to sample drifts and the scanning system of a microscope were separately calculated and corrected using affine transformations. In the as-observed images, the length scales in the x and y directions were underestimated by 0.4–1.2% and 2.7–3.6%, respectively, with shear distortions of 0.6°–1.2°, and the magnitudes of the underestimation and shear distortions were dependent on the scan rotations. On the basis of these findings, a methodology was proposed for the correction of distortions for accurate measurement of the lattice parameters of materials.
Published online: 1 April 2020
Ó
Springer Science+Business
Media, LLC, part of Springer Nature 2020
Introduction Scanning transmission electron microscopy (STEM) is a powerful tool that has been used to characterize material structures on the atomic scale, particularly after the invention of spherical-aberration correctors for the electron probe [1, 2]. Annular dark-field (ADF)
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10853-020-04602-w
imaging is the most popular mode because the image contrast provides a straightforward interpretation of atomic positions and atomic-number-related information [3]. It has been thus far demonstrated that atomic positions can be measured with precisions of * 0.8–10 pm [4–6], which is useful for the study of local strain near precipitates [7] and twin boundaries
8124 [6], surface atomic reconstruction [5], and crystal structure [4, 8]. Thus, ADF STEM imaging is useful for the measurement of the lattice parameters of local regions of materials and/or nanoscale objects. However, the accuracy of measured lattice parameters is often a concern. Low-frequency image distortion is considered the major cause of inaccuracy in measured lattice parameters [7]. Despite several efforts [7–12], the correction of low-frequency distortions remains an unresolved issue, mostly because th
Data Loading...
