Fast Atomic-Scale Elemental Mapping of Crystalline Materials by STEM Energy-Dispersive X-Ray Spectroscopy Achieved with Thin Specimens [Fast Atomic-Scale Chemical Imaging of Crystalline Materials by STEM Energy-Dispersive X-ray Spectroscopy Achieved with Thin Specimens].

Journal Article · 23 February 2017 · Microscopy and Microanalysis

DOI: https://doi.org/10.1017/S1431927617000113 · OSTI ID:1356226

Lu, Ping ^[1]; Yuan, Renliang ^[2]; Zuo, Jian Min ^[2]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2. Univ. of Illinois, Urbana-Champaign, IL (United States)

Abstract Elemental mapping at the atomic-scale by scanning transmission electron microscopy (STEM) using energy-dispersive X-ray spectroscopy (EDS) provides a powerful real-space approach to chemical characterization of crystal structures. However, applications of this powerful technique have been limited by inefficient X-ray emission and collection, which require long acquisition times. Recently, using a lattice-vector translation method, we have shown that rapid atomic-scale elemental mapping using STEM-EDS can be achieved. This method provides atomic-scale elemental maps averaged over crystal areas of ~few 10 nm²with the acquisition time of ~2 s or less. Here we report the details of this method, and, in particular, investigate the experimental conditions necessary for achieving it. It shows, that in addition to usual conditions required for atomic-scale imaging, a thin specimen is essential for the technique to be successful. Phenomenological modeling shows that the localization of X-ray signals to atomic columns is a key reason. The effect of specimen thickness on the signal delocalization is studied by multislice image simulations. The results show that the X-ray localization can be achieved by choosing a thin specimen, and the thickness of less than about 22 nm is preferred for SrTiO₃in [001] projection for 200 keV electrons.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1356226
• Report Number(s): SAND-2016-10599J; applab; PII: S1431927617000113
• Journal Information: Microscopy and Microanalysis, Vol. 23, Issue 01; ISSN 1431-9276
• Publisher: Microscopy Society of America (MSA)Copyright Statement
• Country of Publication: United States
• Language: English