DOI: 10.17188/1268969
title: Materials Data on BaNb10SiO19 by Materials Project

description: BaNb10SiO19 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with three equivalent NbO6 octahedra, corners with six NbO5 square pyramids, edges with three equivalent NbO5 square pyramids, faces with four NbO6 octahedra, and faces with three equivalent NbO5 square pyramids. The corner-sharing octahedral tilt angles are 37°. There are a spread of Ba–O bond distances ranging from 2.85–3.02 Å. There are four inequivalent Nb+3.20+ sites. In the first Nb+3.20+ site, Nb+3.20+ is bonded to five O2- atoms to form NbO5 square pyramids that share a cornercorner with one BaO12 cuboctahedra, corners with three NbO6 octahedra, corners with four NbO5 square pyramids, a cornercorner with one SiO4 tetrahedra, an edgeedge with one NbO6 octahedra, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–10°. There are a spread of Nb–O bond distances ranging from 2.08–2.26 Å. In the second Nb+3.20+ site, Nb+3.20+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three equivalent NbO6 octahedra, corners with three equivalent NbO5 square pyramids, edges with three equivalent NbO5 square pyramids, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 41°. There are three shorter (2.00 Å) and three longer (2.08 Å) Nb–O bond lengths. In the third Nb+3.20+ site, Nb+3.20+ is bonded to five O2- atoms to form NbO5 square pyramids that share a cornercorner with one BaO12 cuboctahedra, corners with three equivalent NbO6 octahedra, corners with four NbO5 square pyramids, a cornercorner with one SiO4 tetrahedra, an edgeedge with one BaO12 cuboctahedra, and an edgeedge with one NbO6 octahedra. The corner-sharing octahedra tilt angles range from 39–55°. There are a spread of Nb–O bond distances ranging from 2.09–2.25 Å. In the fourth Nb+3.20+ site, Nb+3.20+ is bonded to six O2- atoms to form NbO6 octahedra that share a cornercorner with one BaO12 cuboctahedra, a cornercorner with one NbO6 octahedra, corners with five NbO5 square pyramids, a cornercorner with one SiO4 tetrahedra, edges with two equivalent NbO6 octahedra, an edgeedge with one NbO5 square pyramid, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of Nb–O bond distances ranging from 2.06–2.23 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent NbO6 octahedra and corners with six NbO5 square pyramids. The corner-sharing octahedral tilt angles are 47°. There is three shorter (1.63 Å) and one longer (1.67 Å) Si–O bond length. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ba2+ and three Nb+3.20+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three Nb+3.20+ atoms. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three equivalent Nb+3.20+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Nb+3.20+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.20+ atoms. In the sixth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ba2+ and three Nb+3.20+ atoms. In the seventh O2- site, O2- is bonded in a distorted T-shaped geometry to one Ba2+ and three Nb+3.20+ atoms.