Materials Data on Ba5Ta4O15 by Materials Project

Abstract

Ba5Ta4O15 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are three inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with nine equivalent BaO12 cuboctahedra, faces with three equivalent BaO12 cuboctahedra, and faces with seven TaO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.71–3.05 Å. In the second Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with six equivalent BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, and faces with eight TaO6 octahedra. There are six shorter (2.86 Å) and six longer (2.93 Å) Ba–O bond lengths. 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 2.79–3.33 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and faces with seven BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–8°. There are three shorter (1.97 Å) and three longer (2.10 Å) Ta–O bond lengths. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with three equivalent TaO6 octahedra and faces with four BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 8°. There are three shorter (1.87 Å) and three longer (2.26 Å) Ta–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to four Ba2+ and one Ta5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+ and two Ta5+ atoms. In the third O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two equivalent Ta5+ atoms.