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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.


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SDD-EDS spectrum of Cr2N (red) and residual spectrum (blue) after MLLS fitting: a full spectrum, b expanded to show the low photon energy region (Color figure online)
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Fig19: SDD-EDS spectrum of Cr2N (red) and residual spectrum (blue) after MLLS fitting: a full spectrum, b expanded to show the low photon energy region (Color figure online)

Mentions: SDD-EDS provides improved measurement sensitivity for photon energies below 1 keV compared to Si(Li)-EDS, and the stable, high-count SDD-EDS spectra can be used to directly measure and quantify the low atomic number elements. The analytical strategy that was employed included selection of a beam energy of 10 keV to provide access to the K-shell X-rays of the transition elements and the L-shell X-rays of higher atomic elements; a beam current to restrict the deadtime to approximately 10 % to minimize coincidence peaks; and a dose to provide spectra with approximately 107 integrated counts. An example of the peak fitting in the low photon energy region (N K and Cr L) for Cr2N is shown in Fig. 19. Quantitative results for several materials containing low atomic number elements are presented in Tables 13 (carbides), 14 (nitrides), 15 (oxides), and 16 (fluorides). The accuracy is adequate to place the results within the ±5 % relative error envelope. The results demonstrate sufficient accuracy to confidently distinguish among compounds with similar amounts of the low atomic number species, e.g., Cr3C2, Cr23C6, and Cr7C3; SiO2 and SiO; and CuO and Cu2O.Fig. 19


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)

SDD-EDS spectrum of Cr2N (red) and residual spectrum (blue) after MLLS fitting: a full spectrum, b expanded to show the low photon energy region (Color figure online)
© Copyright Policy
Related In: Results  -  Collection

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

Fig19: SDD-EDS spectrum of Cr2N (red) and residual spectrum (blue) after MLLS fitting: a full spectrum, b expanded to show the low photon energy region (Color figure online)
Mentions: SDD-EDS provides improved measurement sensitivity for photon energies below 1 keV compared to Si(Li)-EDS, and the stable, high-count SDD-EDS spectra can be used to directly measure and quantify the low atomic number elements. The analytical strategy that was employed included selection of a beam energy of 10 keV to provide access to the K-shell X-rays of the transition elements and the L-shell X-rays of higher atomic elements; a beam current to restrict the deadtime to approximately 10 % to minimize coincidence peaks; and a dose to provide spectra with approximately 107 integrated counts. An example of the peak fitting in the low photon energy region (N K and Cr L) for Cr2N is shown in Fig. 19. Quantitative results for several materials containing low atomic number elements are presented in Tables 13 (carbides), 14 (nitrides), 15 (oxides), and 16 (fluorides). The accuracy is adequate to place the results within the ±5 % relative error envelope. The results demonstrate sufficient accuracy to confidently distinguish among compounds with similar amounts of the low atomic number species, e.g., Cr3C2, Cr23C6, and Cr7C3; SiO2 and SiO; and CuO and Cu2O.Fig. 19

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