Materials Data on Na2IrO3 by Materials Project
Na2IrO3 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with six NaO6 octahedra, edges with six NaO6 octahedra, and edges with six equivalent IrO6 octahedra. The corner-sharing octahedral tilt angles are 15°. All Na–O bond lengths are 2.32 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with four equivalent IrO6 octahedra, edges with four equivalent IrO6 octahedra, and edges with eight NaO6 octahedra. The corner-sharing octahedra tilt angles range from 12–15°. There are two shorter (2.28 Å) and four longer (2.51 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with four equivalent IrO6 octahedra, edges with four equivalent IrO6 octahedra, and edges with eight NaO6 octahedra. The corner-sharing octahedra tilt angles range from 12–15°. There are a spread of Na–O bond distances ranging from 2.30–2.53 Å. Ir4+ is bonded to six O2- atoms to form IrO6 octahedra that share corners with six NaO6 octahedra, edges with three equivalent IrO6 octahedra, and edges with nine NaO6 octahedra. The corner-sharing octahedral tilt angles are 12°. There are four shorter (2.06 Å) and two longer (2.07 Å) Ir–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four Na1+ and two equivalent Ir4+ atoms to form a mixture of distorted edge and corner-sharing ONa4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–11°. In the second O2- site, O2- is bonded to four Na1+ and two equivalent Ir4+ atoms to form a mixture of edge and corner-sharing ONa4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–10°.