Fig. 5: Suppression of lattice oxygen participation and electronic structures.
a A representative morphology of Ba4NbIr3O12 particles is shown in this STEM image. The Ir-termination at the (001) surface and the Ir-Nb mixed termination at the (101) surface are observed in the magnified images. b, c DOS plots are presented for the [IrO6] octahedron in the trimer and the [NbO6] octahedron at the bridging site, as denoted in the illustration in (c). Arrows in the plots indicate the variation of O 2p states near EF. d An isosurface map is presented for the electron density difference field around each atom. No density distribution around Nb is noted. e Schematic energy band diagrams for [IrO6] and [NbO6] are illustrated. The O 2p states at a lower level and the empty Nb 4d states at an upper level are dominant in the [NbO6] case, indicating ionic Nb–O bonding. f, g DOS plots are provided for the [IrO6] [NbO6] units in the oxyhydroxide paracrystalline supercell without Ba, as illustrated in (g).
