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Fast Atomic-Scale Elemental Mapping of Crystalline Materials by STEM Energy-Dispersive X-Ray Spectroscopy Achieved with Thin Specimens

Published online by Cambridge University Press:  23 February 2017

Ping Lu ,
Renliang Yuan  and
Jian Min Zuo
Ping Lu*
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185, USA
Renliang Yuan
Affiliation:
Department of Materials Science and Engineering, University of Illinois at Urbana–Champaign, 1304 W Green St, Urbana, IL 61801, USA
Jian Min Zuo
Affiliation:
Department of Materials Science and Engineering, University of Illinois at Urbana–Champaign, 1304 W Green St, Urbana, IL 61801, USA
*
*Corresponding author: plu@sandia.gov
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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 nm2 with 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 SrTiO3 in [001] projection for 200 keV electrons.

Keywords

STEM-EDSfast chemical imagingatomic-scalethin specimenelemental mapping
Type
Materials Applications
Information
Microscopy and Microanalysis , Volume 23 , Issue 1 , February 2017 , pp. 145 - 154
Copyright
© Microscopy Society of America 2017 

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