DOE OSTI2020
Ti3Sn7O20 is Hydrophilite-derived structured and crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. there are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with eight SnO6 octahedra and edges with two SnO6 octahedra. The corner-sharing octahedra tilt angles range from 48–49°. There are a spread of Ti–O bond distances ranging from 1.98–2.00 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with eight equivalent SnO6 octahedra and edges with two equivalent SnO6 octahedra. The corner-sharing octahedra tilt angles range from 48–49°. There are four shorter (1.99 Å) and two longer (2.01 Å) Ti–O bond lengths. There are four inequivalent Sn4+ sites. In the first Sn4+ site, Sn4+ is bonded to six O2- atoms to form SnO6 octahedra that share corners with four equivalent TiO6 octahedra, corners with four equivalent SnO6 octahedra, an edgeedge with one TiO6 octahedra, and an edgeedge with one SnO6 octahedra. The corner-sharing octahedra tilt angles range from 48–54°. There are four shorter (2.09 Å) and two longer (2.10 Å) Sn–O bond lengths. In the second Sn4+ site, Sn4+ is bonded to six O2- atoms to form SnO6 octahedra that share corners with eight equivalent SnO6 octahedra and edges with two equivalent TiO6 octahedra. The corner-sharing octahedra tilt angles range from 51–53°. There are two shorter (2.07 Å) and four longer (2.10 Å) Sn–O bond lengths. In the third Sn4+ site, Sn4+ is bonded to six O2- atoms to form SnO6 octahedra that share corners with four equivalent TiO6 octahedra, corners with four equivalent SnO6 octahedra, and edges with two SnO6 octahedra. The corner-sharing octahedra tilt angles range from 49–53°. There are four shorter (2.08 Å) and two longer (2.10 Å) Sn–O bond lengths. In the fourth Sn4+ site, Sn4+ is bonded to six O2- atoms to form SnO6 octahedra that share corners with four equivalent TiO6 octahedra, corners with four equivalent SnO6 octahedra, an edgeedge with one TiO6 octahedra, and an edgeedge with one SnO6 octahedra. The corner-sharing octahedra tilt angles range from 48–54°. All Sn–O bond lengths are 2.09 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ti4+ and two Sn4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ti4+ and two equivalent Sn4+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ti4+ and two Sn4+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ti4+ and two Sn4+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ti4+ and two Sn4+ atoms. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to three Sn4+ atoms.