QUANTITATIVE MICROANALYSIS USING ELECTRON-ENERGY-LOSS SPECTROMETRY .2. COMPOUNDS WITH HEAVIER ELEMENTS

Electron energy-loss spectrometry (EELS) in the TEM can be used for th e quantitative analysis of compounds including both light and heavy el ements at a submicrometre scale. However, EELS-quantification can beco me complicated due to low edge-to-background ratios, problems with mul tiple scattering in case of thicker samples, inaccuracies due to backg round extrapolation or edge-overlapping. All these problems can be ove rcome by careful use of well known procedures. A further problem of qu antitative EELS is the need for precise partial ionization cross-secti ons that are sometimes not well known. In this work, we have quantifie d EELS-spectra of compounds with known composition: LaCoO3, YBa2Cu3O7 and LaB6. To demonstrate the achievable accuracy with different models , the quantifications have been calculated with theoretical cross-sect ions (hydrogenic model and Hartree-Slater model) and experimentally de termined 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.