Quantitative X-ray microanalysis in analytical electron microscopy

Abstract

This paper presents an overview of the principles and procedures for the quantitative X-ray microanalysis of thin specimens using an analytical electron microscope (AEM) equipped with an energy dispersive X-ray spectrometer (EDS). The factors affecting the reliability of the quantification are also summarized. The quantitative X-ray microanalysis with the AEM-EDS system is effective for the composition determination, the thickness determination and the site-occupancy determination. For the compositional determination, the Cliff-Lorimer ratio method is introduced. A special emphasis is placed on the k-factor determination and the absorption correction to enhance reliability of the quantification. For the thickness determination, it is illustrated that there are two primary procedures with the AEM-EDS system: one is to make use of the proportionality between the X-ray intensity and the thickness and the other is to take advantage of the difference between the magnitudes of X-ray absorption in the specimen. For the site-occupancy determination, the AL-CHEMI (atom location by channeling enhanced microanalysis) technique is described. A general form of an equation is presented, which can encompass various premises on the antisite occupation of host elements. It is shown that an error may be introduced from the delocalization effect in the quantification, and some correction procedures for this effect are suggested.