A high-resolution transmission electron microscopy study of defects in γ-Al2O3 nanorods

Surface and planar defect structures of gamma-Al2O3, nanorods synthesized by the arc-discharge method were studied by means of high-resolution transmission electron microscopy and image simulation. Our investigation showed that there was a high number density of twins in the nanorods. We suggested a possible configuration of [ I I I I twins in gamma-Al2O3, and this model fit our experimental result well. In some nanorods, the ordering of nanotwins gave rise to a local hexagonal-like structure. The twinned nanorods were usually enclosed by {100} and I I I I I facets, and their growth direction was changed from (I 10) into I 11). The surface structures of the nanorods confirmed that the {111}-type surface should be more stable.