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Performing elemental microanalysis with high accuracy and high precision by scanning electron microscopy/silicon drift detector energy-dispersive X-ray spectrometry (SEM/SDD-EDS).

Newbury DE, Ritchie NW - J Mater Sci (2014)

Bottom Line: SDD-EDS throughput, resolution, and stability provide practical operating conditions for measurement of high-count spectra that form the basis for peak fitting procedures that recover the characteristic peak intensities even for elemental combination where severe peak overlaps occur, such PbS, MoS2, BaTiO3, SrWO4, and WSi2.Accurate analyses are also demonstrated for interferences involving large concentration ratios: a major constituent on a minor constituent (Ba at 0.4299 mass fraction on Ti at 0.0180) and a major constituent on a trace constituent (Ba at 0.2194 on Ce at 0.00407; Si at 0.1145 on Ta at 0.0041).Measurement of trace constituents with limits of detection below 0.001 mass fraction (1000 ppm) is possible within a practical measurement time of 500 s.

View Article: PubMed Central - PubMed

Affiliation: Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA.

ABSTRACT

Electron-excited X-ray microanalysis performed in the scanning electron microscope with energy-dispersive X-ray spectrometry (EDS) is a core technique for characterization of the microstructure of materials. The recent advances in EDS performance with the silicon drift detector (SDD) enable accuracy and precision equivalent to that of the high spectral resolution wavelength-dispersive spectrometer employed on the electron probe microanalyzer platform. SDD-EDS throughput, resolution, and stability provide practical operating conditions for measurement of high-count spectra that form the basis for peak fitting procedures that recover the characteristic peak intensities even for elemental combination where severe peak overlaps occur, such PbS, MoS2, BaTiO3, SrWO4, and WSi2. Accurate analyses are also demonstrated for interferences involving large concentration ratios: a major constituent on a minor constituent (Ba at 0.4299 mass fraction on Ti at 0.0180) and a major constituent on a trace constituent (Ba at 0.2194 on Ce at 0.00407; Si at 0.1145 on Ta at 0.0041). Accurate analyses of low atomic number elements, C, N, O, and F, are demonstrated. Measurement of trace constituents with limits of detection below 0.001 mass fraction (1000 ppm) is possible within a practical measurement time of 500 s.

No MeSH data available.


Related in: MedlinePlus

Automatic peak identification of potassium bromide, showing misidentification of BrLα,β as AlK; note also misidentification of minor BrLl peak as AsLα,β [16–18]
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Fig6: Automatic peak identification of potassium bromide, showing misidentification of BrLα,β as AlK; note also misidentification of minor BrLl peak as AsLα,β [16–18]

Mentions: A separate but extremely significant issue is the reliability of elemental identification in the EDS spectrum. The critical first step of qualitative analysis obviously must be correct if the subsequent quantitative analysis is to have any value at all. Automatic identification of the characteristic peaks in the EDS spectrum is a valuable software tool that has been progressively developed with the rise of computing power and speed. Despite its modern sophistication, however, commercial automatic peak identification procedures have been shown to be vulnerable to occasional failures in the labeling of even the highest intensity peaks that correspond to major constituents, despite the EDS being properly calibrated, operated at a reasonable input count rate, and in the absence of significant peak interferences [16–18]. Examples of failures in identification of major constituent peaks as well as false positive identification of minor/trace constituents are shown in Figs. 6, 7, and 8, which illustrate some of the classic blunders encountered. Commercial implementations of automatic peak identification have been found to vary in their particular vulnerabilities. The specific nature and frequency of mistakes encountered depends on the particular system and the choice of the beam energy, which can provide important redundancy when two families of X-rays can be excited for certain elements, e.g., K- and L-families (Z ≥ 21, Sc) or L- and M-families (Z ≥ 56, Ba). Elemental misidentification typically occurs in a few percent of attempted peak identifications for major constituents, with the frequency of mistakes increasing significantly for minor and trace constituents and especially in cases where peak interference occurs [16–18]. Table 4 lists examples of groups of elements whose characteristic peaks occur sufficiently close in energy that peak identification mistakes have been observed in at least one of the peak identification systems tested.Fig. 6


Performing elemental microanalysis with high accuracy and high precision by scanning electron microscopy/silicon drift detector energy-dispersive X-ray spectrometry (SEM/SDD-EDS).

Newbury DE, Ritchie NW - J Mater Sci (2014)

Automatic peak identification of potassium bromide, showing misidentification of BrLα,β as AlK; note also misidentification of minor BrLl peak as AsLα,β [16–18]
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4555346&req=5

Fig6: Automatic peak identification of potassium bromide, showing misidentification of BrLα,β as AlK; note also misidentification of minor BrLl peak as AsLα,β [16–18]
Mentions: A separate but extremely significant issue is the reliability of elemental identification in the EDS spectrum. The critical first step of qualitative analysis obviously must be correct if the subsequent quantitative analysis is to have any value at all. Automatic identification of the characteristic peaks in the EDS spectrum is a valuable software tool that has been progressively developed with the rise of computing power and speed. Despite its modern sophistication, however, commercial automatic peak identification procedures have been shown to be vulnerable to occasional failures in the labeling of even the highest intensity peaks that correspond to major constituents, despite the EDS being properly calibrated, operated at a reasonable input count rate, and in the absence of significant peak interferences [16–18]. Examples of failures in identification of major constituent peaks as well as false positive identification of minor/trace constituents are shown in Figs. 6, 7, and 8, which illustrate some of the classic blunders encountered. Commercial implementations of automatic peak identification have been found to vary in their particular vulnerabilities. The specific nature and frequency of mistakes encountered depends on the particular system and the choice of the beam energy, which can provide important redundancy when two families of X-rays can be excited for certain elements, e.g., K- and L-families (Z ≥ 21, Sc) or L- and M-families (Z ≥ 56, Ba). Elemental misidentification typically occurs in a few percent of attempted peak identifications for major constituents, with the frequency of mistakes increasing significantly for minor and trace constituents and especially in cases where peak interference occurs [16–18]. Table 4 lists examples of groups of elements whose characteristic peaks occur sufficiently close in energy that peak identification mistakes have been observed in at least one of the peak identification systems tested.Fig. 6

Bottom Line: SDD-EDS throughput, resolution, and stability provide practical operating conditions for measurement of high-count spectra that form the basis for peak fitting procedures that recover the characteristic peak intensities even for elemental combination where severe peak overlaps occur, such PbS, MoS2, BaTiO3, SrWO4, and WSi2.Accurate analyses are also demonstrated for interferences involving large concentration ratios: a major constituent on a minor constituent (Ba at 0.4299 mass fraction on Ti at 0.0180) and a major constituent on a trace constituent (Ba at 0.2194 on Ce at 0.00407; Si at 0.1145 on Ta at 0.0041).Measurement of trace constituents with limits of detection below 0.001 mass fraction (1000 ppm) is possible within a practical measurement time of 500 s.

View Article: PubMed Central - PubMed

Affiliation: Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA.

ABSTRACT

Electron-excited X-ray microanalysis performed in the scanning electron microscope with energy-dispersive X-ray spectrometry (EDS) is a core technique for characterization of the microstructure of materials. The recent advances in EDS performance with the silicon drift detector (SDD) enable accuracy and precision equivalent to that of the high spectral resolution wavelength-dispersive spectrometer employed on the electron probe microanalyzer platform. SDD-EDS throughput, resolution, and stability provide practical operating conditions for measurement of high-count spectra that form the basis for peak fitting procedures that recover the characteristic peak intensities even for elemental combination where severe peak overlaps occur, such PbS, MoS2, BaTiO3, SrWO4, and WSi2. Accurate analyses are also demonstrated for interferences involving large concentration ratios: a major constituent on a minor constituent (Ba at 0.4299 mass fraction on Ti at 0.0180) and a major constituent on a trace constituent (Ba at 0.2194 on Ce at 0.00407; Si at 0.1145 on Ta at 0.0041). Accurate analyses of low atomic number elements, C, N, O, and F, are demonstrated. Measurement of trace constituents with limits of detection below 0.001 mass fraction (1000 ppm) is possible within a practical measurement time of 500 s.

No MeSH data available.


Related in: MedlinePlus