Elemental mapping at the atomic scale using low accelerating voltages

Atomic resolved elemental mapping is demonstrated at 80 keV with an aberration-corrected scanning transmission electron microscope on specimens of SrTiO3 and BaTiO3/SrTiO3. The maps were acquired with acquisition times as short as 30 ms per pixel (limited by the spectrometer speed), and show very high signal-to-noise ratio and very good detection limits. The features in the elemental maps are interpreted with the help of elastic–inelastic multislice calculations, which show good agreement with experimental images. The elemental maps of Ti, Sr and Ba and their contrast at the interface between BaTiO3 and SrTiO3 are discussed, following a comparison with calculations, assuming an atomically sharp interface. The features in the energy-filtered maps and the background intensities, and the influence of the energy position of the integration windows are discussed in terms of the origins of the signals and the features with respect to the details shown in the high-angle annular dark-field images. The benefits of elemental mapping at 80 keV as compared to 200 keV are also discussed in terms of electron beam damage. Finally, applications of elemental mapping to the detection of La atoms in solid solution in Ba3.25La0.75Ti3O12 films are also shown.