Figure 7
Structural changes in the oxygen sublattice. (a) [010] HAADF-STEM image of the charged Li0.5IrO3 sample showing the ordered sequence of the Ir layers that corresponds to the O1-type structure. N migration of the Ir cations to the Li layers is observed, and a few antisite point defects are marked with the arrowheads. (b) [001] HAADF-STEM and ABF-STEM images of the same sample. (c) Enlarged ABF-STEM image; the O–O pairs with short projected distances are marked with dumbbells, whereas the different O–O pairs arise from twisting the opposite triangular faces of the IrO6 octahedra (shown in yellow). (d) ABF intensity profiles along the O–O pairs with long (blue) and short (red) projected distances. (e) [001] projection of the Li0.5IrO3 in the O1 stacking configuration obtained from DFT calculations (Li atoms are omitted for clarity, Ir atoms are shown in blue, O atoms are in red and the yellow surfaces represent the Fukui orbitals). (f) Structure of the charged Li–Ir–O material obtained from neutron powder diffraction overlaid on the pristine structure, shown in black, that clearly illustrates the formation of O–O dimers. Reproduced with permission.58
