Quantitative Microanalysis Using Electron Energy-Loss Spectrometry: II. Compounds with Heavier Elements

Abstract

Electron energy-loss spectrometry (EELS) in the TEM can be used for the quantitative analysis of compounds including both light and heavy elements at a submicrometre scale. However, EELS-quantification can become complicated due to low edge-to-background ratios, problems with multiple scattering in case of thicker samples, inaccuracies due to background extrapolation or edge-overlapping. All these problems can be overcome by careful use of well known procedures. A further problem of quantitative EELS is the need for precise partial ionization cross-sections that are sometimes not well known. In this work, we have quantified EELS-spectra of compounds with known composition: LaCoO 3 , YBa 2 Cu 3 O 7 and LaB 6 . To demonstrate the achievable accuracy with different models, the quantifications have been calculated with theoretical cross-sections (hydrogenic model and Hartree-Slater model) and experimentally determined k-factors. In every single case more accurate quantification results could be obtained when experimentally derived cross-sections (or k-factors) were used, giving concentration values that lie within 5 rel% of the nominal composition.