QUANTITATIVE-ANALYSIS OF EFTEM ELEMENTAL DISTRIBUTION IMAGES

Energy-filtering TEM (EFTEM) can be used to record elemental distribut ion images at nanometer resolution and with short acquisition times, I n this paper we show how elemental maps can be converted into concentr ation maps. In order to demonstrate the application of the quantificat ion procedures, we have chosen a sample consisting of CVD grown titani um carbonitride layers on a hard metal. Two approaches have been teste d: Absolute quantification which is successfully applied to biological (amorphous) specimens yields a concentration map in terms of atoms pe r unit area. However, it turned out that this method is not suitable f or crystalline materials due to diffraction and/or thickness variation effects. In the second method, atomic ratio maps are calculated from two elemental maps by ratioing the elemental maps and dividing them by the partial ionization cross-sections (or Ii-factors), This method yi elds concentration maps in terms of atomic ratios offering the advanta ge that diffraction and/or thickness variation effects are eliminated. Therefore, this method is well suited for the quantification of cryst alline materials science specimens. In the second part of the paper we describe how related sets of elemental maps can be examined and combi ned in one chemical phase map. This can be provided by scatter diagram analysis (2-dimensional) and automatic classification procedures in-d imensional) that show how intensities of corresponding pixels are corr elated. These techniques have been applied to a typical material scien ce specimen (Si-nitride ceramics with SiC and carbon inclusions) so th at the reader may get a feeling for the advantages and limitations of these techniques in EFTEM-investigations. Finally, it is shown that th e scatter diagram technique can be also applied to atomic ratio maps t hus providing fully quantitative chemical phase maps.