Materials Data on Ca2Os2O7 by Materials Project

Abstract

Ca2Os2O7 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to eight O2- atoms to form distorted CaO8 hexagonal bipyramids that share corners with two equivalent CaO8 hexagonal bipyramids, corners with two equivalent OsO6 octahedra, and edges with six OsO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Ca–O bond distances ranging from 2.24–2.84 Å. In the second Ca2+ site, Ca2+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.40 Å) and four longer (2.76 Å) Ca–O bond lengths. There are two inequivalent Os5+ sites. In the first Os5+ site, Os5+ is bonded to six O2- atoms to form OsO6 octahedra that share corners with six OsO6 octahedra and edges with four equivalent CaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 39–42°. There is two shorter (1.92 Å) and four longer (1.96 Å) Os–O bond length. In the second Os5+ site, Os5+ is bonded to six O2- atoms to form OsO6 octahedra that share corners with two equivalent CaO8 hexagonal bipyramids, corners with four equivalent OsO6 octahedra, and edges with two equivalent CaO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. There is four shorter (1.96 Å) and two longer (1.99 Å) Os–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Os5+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ca2+ and two equivalent Os5+ atoms. In the third O2- site, O2- is bonded to three Ca2+ and one Os5+ atom to form a mixture of distorted edge and corner-sharing OCa3Os tetrahedra.