Atomic-Scale Characterization of Nanostructured Metallic Materials by HAADF/Z-contrast STEM

Abstract

We demonstrate that high-angle annular-dark-field scanning transmission electron microscopy (HAADF-STEM) with a finely-focused electron probe (∼0. 15 nm) is very powerful technique to provide direct information on a local chemistry of nano-materials at atomic scale. This is due to an atomic-number (Z) sensitive nature of the HAADF contrast (Z-contrast). We describe the microstructures of some crystalline, quasicrystalline and amorphous metallic materials with focusing on their local chemical environments. Not only the chemical Z-contrast, HAADF-STEM possesses more substantial advantages compared to the conventional phase-contrast high-resolution imaging, so that it would be one of the most powerful methods for total characterization of nano-structured materials.