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EELS of Niobium and Stoichiometric Niobium-Oxide Phases—Part II: Quantification

Published online by Cambridge University Press:  26 October 2009

David Bach ,
Reinhard Schneider  and
Dagmar Gerthsen
David Bach*
Affiliation:
Laboratorium für Elektronenmikroskopie, Universität Karlsruhe (TH), D-76128 Karlsruhe, Germany
Reinhard Schneider
Affiliation:
Laboratorium für Elektronenmikroskopie, Universität Karlsruhe (TH), D-76128 Karlsruhe, Germany
Dagmar Gerthsen
Affiliation:
Laboratorium für Elektronenmikroskopie, Universität Karlsruhe (TH), D-76128 Karlsruhe, Germany
*
Corresponding author. E-mail: [email protected]
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Abstract

A comprehensive electron energy-loss spectroscopy (EELS) study of niobium (Nb) and stable Nb-oxide phases (NbO, NbO2, Nb2O5) was carried out. Part II of this work is devoted to quantitative EELS by means of experimental k-factors derived from the intensity ratio of the O-K edge and the Nb-M4,5 or Nb-M2,3 edges for all three stable Nb-oxides. The precision and accuracy of the quantification are investigated with respect to the influence of intensity-measurement energy windows, background subtraction, and sample thickness. Integration-window widths allowing optimum accuracy are determined. Owing to background-subtraction errors, the Nb-M4,5 edges rather than Nb-M2,3 are preferred for quantification. Different approaches are applied to improve the precision with regard to thickness-related errors. Thus, a precision up to ±1.5% is achieved by averaging spectra from all three reference oxides to determine a k-factor using Nb-M4,5. Using the experimental k-factor, the determination of atomic concentration ratios CNb/CO in the range of 0.4 (Nb2O5) to 1 (NbO) was found to be possible with an accuracy of 0.6% (relative deviation between measured and nominal composition), whereas ratios of calculated partial ionization cross sections lead to less accurate results.

Keywords

niobium oxideNbONbO2Nb2O5EELSquantificationk-factorprecisionaccuracy
Type
Materials Science Applications
Information
Microscopy and Microanalysis , Volume 15 , Issue 6 , December 2009 , pp. 524 - 538
Copyright
Copyright © Microscopy Society of America 2009

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