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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

Analysis of NIST SRM 470 (K411 glass) in various geometric forms (flat, polished bulk; scratched surface after 600-grit grinding; shallow surface holes, chips, and shards) using the k-ratio protocol with SDD-EDS measurements and NIST DTSA-II: a Mg (normalized weight percent) vs. the raw analytical total (weight percent), including oxygen calculated by assumed stoichiometry [19], b Fe (normalized weight percent) vs. the raw analytical total (weight percent), including oxygen calculated by assumed stoichiometry [19]
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Fig5: Analysis of NIST SRM 470 (K411 glass) in various geometric forms (flat, polished bulk; scratched surface after 600-grit grinding; shallow surface holes, chips, and shards) using the k-ratio protocol with SDD-EDS measurements and NIST DTSA-II: a Mg (normalized weight percent) vs. the raw analytical total (weight percent), including oxygen calculated by assumed stoichiometry [19], b Fe (normalized weight percent) vs. the raw analytical total (weight percent), including oxygen calculated by assumed stoichiometry [19]

Mentions: Analysis with the standards-based k-ratio/matrix corrections protocol reveals the impact of geometric effects on X-ray microanalysis through the behavior of the raw analytical total [19]. Figure 5a and b individually plot the normalized magnesium and iron concentrations against the raw analytical total from the k-ratio/standards analysis procedure, showing how well the raw analytical total is correlated with the magnitude of the relative error. This example illustrates well the pitfalls of blindly attempting to quantitatively analyze the EDS spectrum obtained from randomly shaped objects. Because of the inevitable normalization that must occur in the standardless analysis procedure, the important clue that the raw analytical total provides that will identify such dubious analyses is lost. By losing this critical information, standardless analysis enables risky analytical behavior with SEM/EDS which contributes enormously to the dismissal of SEM/EDS as being only “semi-quantitative.” Unless the specimen geometry is carefully controlled, SEM/EDS analysis is subject to errors so broad as to render the compositional results of questionable value for many applications.Fig. 5


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)

Analysis of NIST SRM 470 (K411 glass) in various geometric forms (flat, polished bulk; scratched surface after 600-grit grinding; shallow surface holes, chips, and shards) using the k-ratio protocol with SDD-EDS measurements and NIST DTSA-II: a Mg (normalized weight percent) vs. the raw analytical total (weight percent), including oxygen calculated by assumed stoichiometry [19], b Fe (normalized weight percent) vs. the raw analytical total (weight percent), including oxygen calculated by assumed stoichiometry [19]
© Copyright Policy
Related In: Results  -  Collection

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

Fig5: Analysis of NIST SRM 470 (K411 glass) in various geometric forms (flat, polished bulk; scratched surface after 600-grit grinding; shallow surface holes, chips, and shards) using the k-ratio protocol with SDD-EDS measurements and NIST DTSA-II: a Mg (normalized weight percent) vs. the raw analytical total (weight percent), including oxygen calculated by assumed stoichiometry [19], b Fe (normalized weight percent) vs. the raw analytical total (weight percent), including oxygen calculated by assumed stoichiometry [19]
Mentions: Analysis with the standards-based k-ratio/matrix corrections protocol reveals the impact of geometric effects on X-ray microanalysis through the behavior of the raw analytical total [19]. Figure 5a and b individually plot the normalized magnesium and iron concentrations against the raw analytical total from the k-ratio/standards analysis procedure, showing how well the raw analytical total is correlated with the magnitude of the relative error. This example illustrates well the pitfalls of blindly attempting to quantitatively analyze the EDS spectrum obtained from randomly shaped objects. Because of the inevitable normalization that must occur in the standardless analysis procedure, the important clue that the raw analytical total provides that will identify such dubious analyses is lost. By losing this critical information, standardless analysis enables risky analytical behavior with SEM/EDS which contributes enormously to the dismissal of SEM/EDS as being only “semi-quantitative.” Unless the specimen geometry is carefully controlled, SEM/EDS analysis is subject to errors so broad as to render the compositional results of questionable value for many applications.Fig. 5

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