Atomic-resolution chemical mapping using energy-dispersive x-ray spectroscopy

D’Alfonso, Adrian J.; Freitag, Bert; Klenov, Dmitri O.; Allen, L. J.

doi:10.1103/physrevb.81.100101

Cited by 195 publications

(152 citation statements)

References 25 publications

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“…Conversely, X-ray energy-dispersive spectroscopy (EDS) only measures the elemental composition, and requires exposing a specimen to a vast amount of electrons in order to produce enough signal to extract atomic-resolution information. Nevertheless, some excellent highresolution EDS maps of small areas have been created, of materials such as oxides (Feng et al, 2016;Dycus et al, 2016;D'Alfonso et al 2010), semiconductors (Chu et al, 2010;Klenov and Zide, 2011) and magnetic alloys (Lu et al, 2014a). STEM-EELS is the ideal technique only for an ideal specimen; that is a thin, non-contaminating specimen with no carbon or SiN supports (as these elements would give huge background signals that complicate spectrum analysis).…”

Section: Introductionmentioning

confidence: 99%

Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy

Wenner

Jones

Marioara

et al. 2017

Micron

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Scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDS) is a common technique for chemical mapping in thin samples. Obtaining high-resolution elemental maps in the STEM is jointly dependent on stepping the sharply focused electron probe in a precise raster, on collecting a significant number of characteristic X-rays over time, and on avoiding damage to the sample. In this work, 80 kV aberration-corrected STEM-EDS mapping was performed on ordered precipitates in aluminium alloys. Probe and sample instability problems are handled by acquiring series of annular dark-field (ADF) images and simultaneous EDS volumes, which are aligned and non-rigidly registered after acquisition. The summed EDS volumes yield elemental maps of Al, Mg, Si, and Cu, with sufficient resolution and signal-to-noise ratio to determine the elemental species of each atomic column in a periodic structure, and in some cases the species of single atomic columns. Within the uncertainty of the technique, S and β'' phases were found to have pure elemental atomic columns with compositions Al 2 CuMg and Al 2 Mg 5 Si 4 , respectively. The Q' phase showed some variation in chemistry across a single precipitate, although the majority of unit cells had a composition Al 6 Mg 6 Si 7.2 Cu 2 .

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Section: Introductionmentioning

confidence: 99%

Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy

Wenner

Jones

Marioara

et al. 2017

Micron

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“…Consequently, using EELS spectrometer and EDS detector, the energy loss electrons and X-rays yielded by the interaction between electron beam and the probed species enable qualitative and quantitative element analysis [55].…”

Section: Eds and Eelsmentioning

confidence: 99%

Transmission electron microscopy analysis of some transition metal compounds for energy storage and conversion

Liang

Fu-xin

Fan

et al. 2017

TrAC Trends in Analytical Chemistry

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“…So far, most of these efforts have been applied to materials such as perovskite oxides [1][2][3], e.g. SrTiO 3 , and compound semiconductors [4,5], which have well-known crystal structures with relatively large lattice spacings, that are also comparatively resistant to electronbeam irradiation.…”

mentioning

confidence: 99%

“…Significant improvement in the S/N ratio of EDS mapping can be achieved by lattice-averaging ( Fig.1), which compensates for reduction in X-ray count due to the selection of small electron probe and thin specimen, and also leads to an overall reduction of electron dose necessary for EDS mapping [6]. By choosing a thin TEM specimen, the EDS signal is localized to atomic columns [1,3,6, 7] and X-ray counts from individual atomic columns can be approximated by a Gaussian distribution. The width of the Gaussian peak is then effectively determined by convoluting the electron probe with the effective EDS local ionization potential, leading to a spatial resolution of better than 2.0 Å [6].…”

mentioning

confidence: 99%

Improving the Spatial Resolution of Atomic-Scale EDS Mapping for Chemical Imaging and Quantification of Metallic Alloy Structures

Lu¹,

Romero²,

Zhou³

et al. 2014

Microsc Microanal

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Recent technical advances in scanning transmission electron microscopy (STEM) and x-ray detector technology have made it possible to do atomic-resolution chemical mapping using energydispersive x-ray spectroscopy (EDS). So far, most of these efforts have been applied to materials such as perovskite oxides [1][2][3], e.g. SrTiO 3 , and compound semiconductors [4,5], which have well-known crystal structures with relatively large lattice spacings, that are also comparatively resistant to electronbeam irradiation. This radiation-resistant property allows longer dwell times at each recording point (i.e., pixel) for achieving the signal-to-noise (S/N) ratio that is necessary for elemental mapping. For the study of intermetallics such as body-centered-cubic (bcc) alloys that have small interatomic distances and are relatively sensitive to the electron radiation, improvement in the spatial resolution as well as reduction in the overall electron dose are required. In this work, we report our strategy to overcome these difficulties as well as applications of the techniques for quantification of chemical composition at the lattice sites in intermetallic bcc alloys [6].In chemical mapping, the shortest lateral distance between columns of identical atoms in a crystal projection determines the required spatial resolution necessary for resolving the atomic columns [6, 7]. The required spatial resolution is 3.9 Å for SrTiO 3 in the [001] direction and about 3.5 Å for GaAs in the [110] direction. The smaller dimensions of the unit cell (~2.9 Å) for bcc intermetallic alloys require higher spatial resolution. This improvement can be achieved by a combination of small electron probe (<1.5 Å), using a thin TEM specimen (< 20 nm) and improving the S/N ratio through averaging of EDS maps that are related to each other via lattice-vector translations in the image plane (for convenience, we have termed this process "lattice-averaging"). Significant improvement in the S/N ratio of EDS mapping can be achieved by lattice-averaging (Fig.1), which compensates for reduction in X-ray count due to the selection of small electron probe and thin specimen, and also leads to an overall reduction of electron dose necessary for EDS mapping [6]. By choosing a thin TEM specimen, the EDS signal is localized to atomic columns [1,3, 6, 7] and X-ray counts from individual atomic columns can be approximated by a Gaussian distribution. The width of the Gaussian peak is then effectively determined by convoluting the electron probe with the effective EDS local ionization potential, leading to a spatial resolution of better than 2.0 Å [6]. Fig.2 shows EDS maps of Fe Κα and Co Κα, obtained from a Fe-Co alloy, showing an ordered bcc structure with the Fe and Co atoms preferentially occupying the A-sites and B-sites in the bcc lattice [6]. Furthermore, the chemical composition at the atomic column positions can be quantified column-by-column using the Cliff-Lorimer method [6][7][8][9].

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Atomic-resolution chemical mapping using energy-dispersive x-ray spectroscopy

Cited by 195 publications

References 25 publications

Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy

Atomic-resolution chemical mapping of ordered precipitates in Al alloys using energy-dispersive X-ray spectroscopy

Transmission electron microscopy analysis of some transition metal compounds for energy storage and conversion

Improving the Spatial Resolution of Atomic-Scale EDS Mapping for Chemical Imaging and Quantification of Metallic Alloy Structures

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