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Chemical Quantification of Atomic-Scale EDS Maps under Thin Specimen Conditions

Published online by Cambridge University Press:  13 October 2014

Ping Lu*
Affiliation:
Sandia National Laboratories, PO Box 5800, MS 1411, Albuquerque, NM 87185-1411, USA
Eric Romero
Affiliation:
Sandia National Laboratories, PO Box 5800, MS 1411, Albuquerque, NM 87185-1411, USA
Shinbuhm Lee
Affiliation:
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK
Judith L. MacManus-Driscoll
Affiliation:
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK
Quanxi Jia
Affiliation:
Los Alamos National Laboratory, Center for Integrated Nanotechnologies, Los Alamos, NM 87545, USA
*
*Corresponding author. plu@sandia.gov
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Abstract

We report our effort to quantify atomic-scale chemical maps obtained by collecting energy-dispersive X-ray spectra (EDS) using scanning transmission electron microscopy (STEM) (STEM-EDS). With thin specimen conditions and localized EDS scattering potential, the X-ray counts from atomic columns can be properly counted by fitting Gaussian peaks at the atomic columns, and can then be used for site-by-site chemical quantification. The effects of specimen thickness and X-ray energy on the Gaussian peak width are investigated using SrTiO3 (STO) as a model specimen. The relationship between the peak width and spatial resolution of an EDS map is also studied. Furthermore, the method developed by this work is applied to study cation occupancy in a Sm-doped STO thin film and antiphase boundaries (APBs) present within the STO film. We find that Sm atoms occupy both Sr and Ti sites but preferably the Sr sites, and Sm atoms are relatively depleted at the APBs likely owing to the effect of strain.

Type
Materials Applications
Copyright
© Microscopy Society of America 2014 

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