Direct Visualization of the Grain Boundary Solute Segregation in Oxide Material at Atomic Resolution Using STEM-EDS

Grain boundaries usually govern the macroscopic properties of polycrystalline materials in practical use. Grain boundary segregation is a fundamental yet critical issue in this field since it affects the local structure and chemistry. Although the advanced aberration-corrected scanning transmission electron microscopy (STEM) has provided deep insights into such complex phenomenon even down to the atomic dimensions [1], most of these studies have been focused on the non-solute segregation. For this sort of segregation, the dopant atoms can only reside at grain boundaries and thus the experimental identification is straightforward [2]. On the other hand, for solute segregation, in which the dopant atoms can reside both at the grain interiors and grain boundaries, it is still challenging to clarify such phenomenon from experiment especially at atomic resolution.