DOI: 10.17188/1307108
title: Materials Data on Ba8Nb7O24 by Materials Project

description: Ba8Nb7O24 crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are eight inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with six equivalent BaO12 cuboctahedra, corners with three equivalent NbO6 octahedra, faces with four BaO12 cuboctahedra, and faces with seven NbO6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are a spread of Ba–O bond distances ranging from 2.88–2.97 Å. In the second Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with nine BaO12 cuboctahedra, faces with three equivalent BaO12 cuboctahedra, and faces with five NbO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.94–3.09 Å. In the third Ba2+ site, Ba2+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Ba–O bond distances ranging from 2.68–3.23 Å. In the fourth Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with nine BaO12 cuboctahedra, corners with three equivalent NbO6 octahedra, faces with seven BaO12 cuboctahedra, and faces with seven NbO6 octahedra. The corner-sharing octahedral tilt angles are 13°. There are a spread of Ba–O bond distances ranging from 2.84–3.07 Å. In the fifth Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with twelve BaO12 cuboctahedra, faces with six BaO12 cuboctahedra, and faces with eight NbO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.84–3.01 Å. In the sixth Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with nine BaO12 cuboctahedra, faces with six BaO12 cuboctahedra, and faces with eight NbO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.89–2.98 Å. In the seventh Ba2+ site, Ba2+ is bonded in a 12-coordinate geometry to nine O2- atoms. There are three shorter (2.79 Å) and six longer (3.02 Å) Ba–O bond lengths. In the eighth Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with nine BaO12 cuboctahedra, faces with six BaO12 cuboctahedra, and faces with seven NbO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.72–3.09 Å. There are seven inequivalent Nb+4.57+ sites. In the first Nb+4.57+ site, Nb+4.57+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with eight BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 2–7°. There are three shorter (2.01 Å) and three longer (2.11 Å) Nb–O bond lengths. In the second Nb+4.57+ site, Nb+4.57+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, corners with three equivalent NbO6 octahedra, faces with six BaO12 cuboctahedra, and a faceface with one NbO6 octahedra. The corner-sharing octahedral tilt angles are 6°. There are three shorter (2.05 Å) and three longer (2.11 Å) Nb–O bond lengths. In the third Nb+4.57+ site, Nb+4.57+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, corners with three equivalent NbO6 octahedra, faces with seven BaO12 cuboctahedra, and a faceface with one NbO6 octahedra. The corner-sharing octahedral tilt angles are 2°. There are three shorter (2.07 Å) and three longer (2.11 Å) Nb–O bond lengths. In the fourth Nb+4.57+ site, Nb+4.57+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with three equivalent NbO6 octahedra and faces with seven BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 7°. There are three shorter (1.88 Å) and three longer (2.29 Å) Nb–O bond lengths. In the fifth Nb+4.57+ site, Nb+4.57+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three equivalent NbO6 octahedra and faces with two BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 9°. There are three shorter (1.88 Å) and three longer (2.25 Å) Nb–O bond lengths. In the sixth Nb+4.57+ site, Nb+4.57+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with four BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 6–9°. There are three shorter (1.96 Å) and three longer (2.12 Å) Nb–O bond lengths. In the seventh Nb+4.57+ site, Nb+4.57+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with eight BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 2°. All Nb–O bond lengths are 2.07 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+ and two Nb+4.57+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to three Ba2+ and two Nb+4.57+ atoms. In the third O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two Nb+4.57+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+ and two Nb+4.57+ atoms. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to four Ba2+ and one Nb+4.57+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to four Ba2+ and one Nb+4.57+ atom. In the seventh O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two Nb+4.57+ atoms. In the eighth O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two Nb+4.57+ atoms.