화학공학소재연구정보센터
Journal of Materials Science, Vol.56, No.12, 7286-7297, 2021
Exploring (1(1)over-bar2)-related ordered structure in oxidationsynthesized alpha-Fe2O3 nanowhiskers
Hematite (alpha-Fe2O3) nanowhiskers (NWs) synthesized via oxidation of ironbased substrates are a promising photoanode material for photoelectrochemical water splitting. Such synthesized alpha-Fe2O3 NWs have been found to contain ordered axial structures. Herein, we reveal that the known (1 (1) over bar2)-related ordered structure actually exists in bicrystalline alpha-Fe2O3 NWs instead of single-crystalline alpha-Fe2O3 NWs and that it is associated with another known (330)-related ordered structure. Through a spherical aberration (C-S)-corrected high-resolution transmission electron microscopy (HR-TEM) investigation, the microstructural characteristic of the (1 (1) over bar2)-related ordered structure is verified to be periodic atomic column displacements serving as tensile strain accommodation. The HRTEM observation are also supported by a monochromated O K-edge EELS analysis, which indicates that alpha-Fe2O3 NWs hosting the (1 (1) over bar2)-related ordered structure are indeed associated with lattice expansion. In sum, our microstructural study elucidates the root cause of the long-asserted relationship between the (1 (1) over bar2)-related ordered structure and oxygen vacancy ordering.