DOI: 10.17188/1738307
title: Materials Data on Ba2Ti3Nb4O18 by Materials Project

description: Ba2Ti3Nb4O18 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with three NbO6 octahedra, corners with four TiO6 octahedra, edges with two equivalent BaO12 cuboctahedra, edges with two NbO6 octahedra, edges with three TiO6 octahedra, a faceface with one BaO12 cuboctahedra, and faces with three NbO6 octahedra. The corner-sharing octahedra tilt angles range from 33–54°. There are a spread of Ba–O bond distances ranging from 2.85–3.11 Å. 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 four equivalent BaO12 cuboctahedra, corners with two equivalent TiO6 octahedra, corners with two equivalent NbO6 octahedra, edges with two equivalent BaO12 cuboctahedra, and edges with two equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 46–50°. There are a spread of Ti–O bond distances ranging from 1.93–2.01 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with two equivalent BaO12 cuboctahedra, a cornercorner with one TiO6 octahedra, corners with three NbO6 octahedra, edges with two equivalent BaO12 cuboctahedra, an edgeedge with one TiO6 octahedra, and edges with two equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 38–54°. There are a spread of Ti–O bond distances ranging from 1.83–2.21 Å. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share a cornercorner with one BaO12 cuboctahedra, corners with two TiO6 octahedra, corners with three NbO6 octahedra, an edgeedge with one BaO12 cuboctahedra, an edgeedge with one TiO6 octahedra, and faces with two equivalent BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 43–50°. There are a spread of Nb–O bond distances ranging from 1.86–2.27 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with two equivalent BaO12 cuboctahedra, corners with two equivalent TiO6 octahedra, corners with three NbO6 octahedra, an edgeedge with one BaO12 cuboctahedra, edges with two equivalent TiO6 octahedra, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 38–54°. There are a spread of Nb–O bond distances ranging from 1.91–2.26 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ba2+, two equivalent Ti4+, and one Nb5+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ba2+, one Ti4+, and one Nb5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+, one Ti4+, and two equivalent Nb5+ atoms. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ba2+ and two equivalent Nb5+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+ and two Nb5+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ba2+, one Ti4+, and one Nb5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two Ti4+ and one Nb5+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Ti4+, and one Nb5+ atom. In the ninth O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Ba2+, one Ti4+, and one Nb5+ atom.