DOI: 10.17188/1306057
title: Materials Data on Na8Cu2O7 by Materials Project

description: Na8Cu2O7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are eight inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.26–2.43 Å. In the second Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share a cornercorner with one NaO6 octahedra, corners with two equivalent NaO5 square pyramids, corners with two NaO4 tetrahedra, corners with four CuO4 tetrahedra, corners with two equivalent NaO4 trigonal pyramids, edges with two equivalent NaO6 octahedra, an edgeedge with one NaO5 square pyramid, an edgeedge with one CuO4 tetrahedra, edges with two NaO4 tetrahedra, and an edgeedge with one NaO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 53°. There are a spread of Na–O bond distances ranging from 2.32–2.56 Å. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with seven NaO4 tetrahedra, a cornercorner with one NaO5 trigonal bipyramid, an edgeedge with one NaO5 square pyramid, an edgeedge with one NaO4 tetrahedra, edges with four CuO4 tetrahedra, edges with two equivalent NaO5 trigonal bipyramids, and an edgeedge with one NaO4 trigonal pyramid. The corner-sharing octahedral tilt angles are 28°. There are a spread of Na–O bond distances ranging from 2.46–2.68 Å. In the fourth Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share corners with two equivalent NaO6 octahedra, corners with two equivalent NaO5 square pyramids, corners with three CuO4 tetrahedra, corners with four NaO4 tetrahedra, a cornercorner with one NaO5 trigonal bipyramid, corners with two equivalent NaO4 trigonal pyramids, an edgeedge with one NaO6 octahedra, and an edgeedge with one CuO4 tetrahedra. The corner-sharing octahedra tilt angles range from 13–53°. There are a spread of Na–O bond distances ranging from 2.30–2.44 Å. In the fifth Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 square pyramids that share corners with two equivalent NaO5 square pyramids, a cornercorner with one CuO4 tetrahedra, corners with five NaO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, a cornercorner with one NaO4 trigonal pyramid, an edgeedge with one NaO6 octahedra, an edgeedge with one NaO4 tetrahedra, edges with two equivalent CuO4 tetrahedra, an edgeedge with one NaO5 trigonal bipyramid, and an edgeedge with one NaO4 trigonal pyramid. There are a spread of Na–O bond distances ranging from 2.34–2.73 Å. In the sixth Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share corners with three equivalent NaO6 octahedra, corners with two equivalent NaO5 square pyramids, corners with two CuO4 tetrahedra, corners with three NaO4 tetrahedra, corners with two equivalent NaO4 trigonal pyramids, an edgeedge with one NaO4 tetrahedra, an edgeedge with one CuO4 tetrahedra, an edgeedge with one NaO5 trigonal bipyramid, and an edgeedge with one NaO4 trigonal pyramid. The corner-sharing octahedra tilt angles range from 16–41°. There are a spread of Na–O bond distances ranging from 2.23–2.42 Å. In the seventh Na1+ site, Na1+ is bonded to four O2- atoms to form NaO4 tetrahedra that share corners with two equivalent NaO6 octahedra, a cornercorner with one NaO5 square pyramid, corners with three NaO4 tetrahedra, corners with four CuO4 tetrahedra, a cornercorner with one NaO5 trigonal bipyramid, a cornercorner with one NaO4 trigonal pyramid, an edgeedge with one NaO5 square pyramid, an edgeedge with one NaO4 tetrahedra, an edgeedge with one NaO5 trigonal bipyramid, and an edgeedge with one NaO4 trigonal pyramid. The corner-sharing octahedra tilt angles range from 26–91°. There are a spread of Na–O bond distances ranging from 2.26–2.39 Å. In the eighth Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 trigonal pyramids that share a cornercorner with one NaO5 square pyramid, corners with two CuO4 tetrahedra, corners with five NaO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, an edgeedge with one NaO6 octahedra, an edgeedge with one NaO5 square pyramid, an edgeedge with one CuO4 tetrahedra, and edges with two NaO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.32–2.44 Å. There are two inequivalent Cu3+ sites. In the first Cu3+ site, Cu3+ is bonded to four O2- atoms to form CuO4 tetrahedra that share a cornercorner with one CuO4 tetrahedra, corners with four NaO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, a cornercorner with one NaO4 trigonal pyramid, edges with two equivalent NaO6 octahedra, edges with two equivalent NaO5 square pyramids, and an edgeedge with one NaO5 trigonal bipyramid. There are a spread of Cu–O bond distances ranging from 1.87–2.01 Å. In the second Cu3+ site, Cu3+ is bonded to four O2- atoms to form CuO4 tetrahedra that share a cornercorner with one NaO5 square pyramid, a cornercorner with one CuO4 tetrahedra, corners with five NaO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, a cornercorner with one NaO4 trigonal pyramid, edges with two equivalent NaO6 octahedra, edges with two NaO4 tetrahedra, and an edgeedge with one NaO4 trigonal pyramid. There are a spread of Cu–O bond distances ranging from 1.90–1.97 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded to five Na1+ and one Cu3+ atom to form a mixture of distorted corner and edge-sharing ONa5Cu octahedra. The corner-sharing octahedral tilt angles are 65°. In the second O2- site, O2- is bonded in a 6-coordinate geometry to four Na1+ and two Cu3+ atoms. In the third O2- site, O2- is bonded to five Na1+ and one Cu3+ atom to form a mixture of distorted corner and edge-sharing ONa5Cu octahedra. The corner-sharing octahedra tilt angles range from 5–65°. In the fourth O2- site, O2- is bonded in a 7-coordinate geometry to six Na1+ and one Cu3+ atom. In the fifth O2- site, O2- is bonded to five Na1+ and one Cu3+ atom to form a mixture of distorted corner and edge-sharing ONa5Cu octahedra. The corner-sharing octahedral tilt angles are 5°. In the sixth O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one Cu3+ atom. In the seventh O2- site, O2- is bonded in a 7-coordinate geometry to six Na1+ and one Cu3+ atom.