Fig. 4: Atomic structure and atomistic oxidation model.
From: Absence of a pressure gap and atomistic mechanism of the oxidation of pure Co nanoparticles
a High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of a pure metallic nanoparticle (state A); insets (i) and (ii) show fast Fourier transforms (FFTs) and the deduced zone axes of the areas with the same labels marked by white squares (scale bar is 5 nm). b Enlarged image with atomic-level resolution of a nanoparticle in state B; the insets (i–iii) show FFTs of the areas with the same labels marked by white squares revealing one Co3O4, (i), and two CoO crystallites, (ii) and (iii), with different orientations (scale bar is 2 nm). Notice the preferred orientation between CoO and Co3O4 crystallites in region “i” and “ii'', where the {110}-planes of CoO and {110}-planes of Co3O4 are parallel, but without a specific in-plane orientation of the crystal axes. c–e Model of the oxidation process showing the onset of the different oxidation states, A, B, and C.
