Materials Data on Na9Cu2O7 by Materials Project

Abstract

Na9Cu2O7 crystallizes in the cubic P2_13 space group. The structure is three-dimensional. there are five inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share a cornercorner with one NaO6 octahedra, a cornercorner with one CuO4 tetrahedra, corners with six equivalent NaO5 trigonal bipyramids, an edgeedge with one CuO4 tetrahedra, and a faceface with one NaO6 octahedra. The corner-sharing octahedral tilt angles are 38°. There are a spread of Na–O bond distances ranging from 2.27–2.65 Å. In the second Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.36–2.77 Å. In the third Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.41 Å) and three longer (2.79 Å) Na–O bond lengths. In the fourth Na1+ site, Na1+ is bonded in a 3-coordinate geometry to three equivalent O2- atoms. All Na–O bond lengths are 2.33 Å. In the fifth Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with three equivalent CuO4 tetrahedra, corners with three equivalent NaO5 trigonal bipyramids, and faces with three equivalent NaO5 trigonal bipyramids. There are three shorter (2.36 Å) and three longer (2.59 Å) Na–O bond lengths. There are two inequivalent Cu+2.50+ sites. In the first Cu+2.50+ site, Cu+2.50+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All Cu–O bond lengths are 1.85 Å. In the second Cu+2.50+ site, Cu+2.50+ is bonded to four O2- atoms to form CuO4 tetrahedra that share corners with three equivalent NaO6 octahedra, corners with three equivalent NaO5 trigonal bipyramids, and edges with three equivalent NaO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 44°. There are three shorter (1.92 Å) and one longer (2.11 Å) Cu–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 7-coordinate geometry to six Na1+ and one Cu+2.50+ atom. In the second O2- site, O2- is bonded in a 8-coordinate geometry to seven Na1+ and one Cu+2.50+ atom. In the third O2- site, O2- is bonded in a distorted pentagonal bipyramidal geometry to six Na1+ and one Cu+2.50+ atom.