Direct visualization of dynamic atomistic processes of Cu2O crystal growth through gas-solid reaction

Abstract

Crystal growth involves “mysterious” long-range ordering of atoms or molecules through local-only interaction, which requires repeated addition of atoms or molecules to the growing surface from the liquid or vapour phase. Although the canonical theory has successfully explained crystal growth behaviors, detailed atomistic mechanisms, especially for the growth of crystals involving chemical reactions (covalent bond formation), remain mostly elusive. Herein, we reveal such atomistic mechanisms of Cu2O growth during the oxidation process by real-time atomic imaging in an aberration-corrected environmental transmission electron microscope (AC-ETEM). We directly visualize the atomistic process of sequential bonding between Cu and O atoms onto the growing oxide surface. Besides, we also reveal the unique role of surface defects during the crystal growth process and the effect of growing kinetics on the ending morphology of the oxide crystals. The obtained results provide the fundamental understanding of the crystal growth process and further enrich the metal oxidation theory.