Materials Data on NaCo2Se2O7 by Materials Project
NaCo2Se2O7 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share corners with five CoO6 octahedra. The corner-sharing octahedra tilt angles range from 61–79°. There are a spread of Na–O bond distances ranging from 2.27–2.34 Å. There are two inequivalent Co+2.50+ sites. In the first Co+2.50+ site, Co+2.50+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent NaO4 tetrahedra and edges with four CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.90–2.17 Å. In the second Co+2.50+ site, Co+2.50+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with three equivalent NaO4 tetrahedra and edges with two equivalent CoO6 octahedra. There are a spread of Co–O bond distances ranging from 2.10–2.17 Å. There are two inequivalent Se4+ sites. In the first Se4+ site, Se4+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.73 Å) and one longer (1.78 Å) Se–O bond length. In the second Se4+ site, Se4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.71 Å) and two longer (1.75 Å) Se–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to one Na1+, two equivalent Co+2.50+, and one Se4+ atom to form distorted corner-sharing ONaCo2Se tetrahedra. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Co+2.50+, and one Se4+ atom. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Co+2.50+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Co+2.50+ and one Se4+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+, one Co+2.50+, and one Se4+ atom.