Materials Data on Ca2IrO4 by Materials Project

Abstract

Ca2IrO4 crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are three inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six equivalent O2- atoms to form distorted CaO6 pentagonal pyramids that share corners with six equivalent IrO6 octahedra, edges with three equivalent IrO6 octahedra, edges with six equivalent CaO7 pentagonal bipyramids, and faces with two equivalent CaO6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 7°. All Ca–O bond lengths are 2.38 Å. In the second Ca2+ site, Ca2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are six shorter (2.47 Å) and three longer (2.82 Å) Ca–O bond lengths. In the third Ca2+ site, Ca2+ is bonded to seven O2- atoms to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent IrO6 octahedra, corners with two equivalent CaO7 pentagonal bipyramids, edges with four equivalent IrO6 octahedra, edges with two equivalent CaO7 pentagonal bipyramids, and edges with two equivalent CaO6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 54°. There are a spread of Ca–O bond distances ranging from 2.29–2.65 Å. Ir4+ is bonded to six O2- atoms to form IrO6 octahedra that share corners with two equivalent CaO7 pentagonal bipyramids, corners with two equivalent CaO6 pentagonal pyramids, edges with two equivalent IrO6 octahedra, edges with four equivalent CaO7 pentagonal bipyramids, and an edgeedge with one CaO6 pentagonal pyramid. There are a spread of Ir–O bond distances ranging from 2.02–2.10 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four Ca2+ and two equivalent Ir4+ atoms to form distorted OCa4Ir2 octahedra that share corners with four equivalent OCa4Ir2 octahedra, corners with four equivalent OCa4Ir trigonal bipyramids, edges with two equivalent OCa4Ir2 octahedra, edges with four equivalent OCa4Ir trigonal bipyramids, and faces with two equivalent OCa4Ir2 octahedra. The corner-sharing octahedral tilt angles are 43°. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three Ca2+ and two equivalent Ir4+ atoms. In the third O2- site, O2- is bonded to four Ca2+ and one Ir4+ atom to form distorted OCa4Ir trigonal bipyramids that share corners with two equivalent OCa4Ir2 octahedra, corners with seven equivalent OCa4Ir trigonal bipyramids, edges with two equivalent OCa4Ir2 octahedra, and edges with five equivalent OCa4Ir trigonal bipyramids. The corner-sharing octahedral tilt angles are 61°.