DOI: 10.17188/1305577
title: Materials Data on Na6Sn2O7 by Materials Project

description: Na6Sn2O7 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent NaO6 octahedra, corners with two equivalent SnO4 tetrahedra, a cornercorner with one NaO5 trigonal bipyramid, corners with two equivalent NaO4 trigonal pyramids, an edgeedge with one NaO6 octahedra, edges with two equivalent SnO4 tetrahedra, and an edgeedge with one NaO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 21–62°. There are a spread of Na–O bond distances ranging from 2.32–2.68 Å. In the second Na1+ site, Na1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.53 Å. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent SnO4 tetrahedra, corners with four equivalent NaO5 trigonal bipyramids, edges with two equivalent SnO4 tetrahedra, edges with two equivalent NaO5 trigonal bipyramids, and edges with two equivalent NaO4 trigonal pyramids. There are two shorter (2.46 Å) and four longer (2.57 Å) Na–O bond lengths. In the fourth Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 trigonal pyramids that share corners with four equivalent SnO4 tetrahedra, corners with four equivalent NaO5 trigonal bipyramids, and edges with two equivalent NaO6 octahedra. There are two shorter (2.38 Å) and two longer (2.42 Å) Na–O bond lengths. Sn4+ is bonded to four O2- atoms to form SnO4 tetrahedra that share a cornercorner with one NaO6 octahedra, a cornercorner with one SnO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, corners with two equivalent NaO4 trigonal pyramids, an edgeedge with one NaO6 octahedra, and edges with two equivalent NaO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 26°. There are a spread of Sn–O bond distances ranging from 1.97–2.05 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to four Na1+ and one Sn4+ atom to form distorted ONa4Sn trigonal bipyramids that share a cornercorner with one ONa5Sn octahedra, corners with five ONa4Sn trigonal bipyramids, edges with three equivalent ONa5Sn octahedra, and edges with two equivalent ONa4Sn trigonal bipyramids. The corner-sharing octahedral tilt angles are 95°. In the second O2- site, O2- is bonded to four Na1+ and one Sn4+ atom to form distorted ONa4Sn trigonal bipyramids that share corners with five equivalent ONa5Sn octahedra, corners with five ONa4Sn trigonal bipyramids, an edgeedge with one ONa5Sn octahedra, and edges with two equivalent ONa4Sn trigonal bipyramids. The corner-sharing octahedra tilt angles range from 41–78°. In the third O2- site, O2- is bonded to five Na1+ and one Sn4+ atom to form distorted ONa5Sn octahedra that share a cornercorner with one ONa5Sn octahedra, corners with six ONa4Sn trigonal bipyramids, edges with two equivalent ONa5Sn octahedra, and edges with four ONa4Sn trigonal bipyramids. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two equivalent Sn4+ atoms.