On the quantitativeness of grain boundary chemistry using STEM EDS: A ZrO Σ9 model grain boundary case study.

Atomic-resolution energy dispersive X-ray spectroscopy (EDS) in scanning transmission electron microscopy (STEM) has recently been shown to be a powerful approach to investigate local chemistry of nanoscale structures quantitatively. While most of the studies have been focused on the quantification of the chemical composition in bulk crystals, few were discussed on interfaces. In this study, we theoretically explored the applicability of STEM EDS for the quantification of local chemistry in grain boundaries (GBs), where the electron channeling can be dramatically changed compared with the bulk due to non-periodic atomic arrangement. We find that: (1) line scan analysis across the GBs or mapping analysis, which have been widely used for interface analysis, sometimes leads to misinterpretation of true interface chemistry. (2) Tilting the specimen, which is effective to reduce the effects of scattering, is not always useful for the quantification of GBs. (3) EDS analysis covering the whole GB structure unit, such as using a box scan, can provide true chemical information. Our study provides useful insights into characterization of interface chemistry using STEM EDS.