Materials Data on Ba4Ta2O9 by Materials Project
Ba4Ta2O9 is Orthorhombic Perovskite-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are five inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to six O2- atoms to form BaO6 octahedra that share corners with six TaO6 octahedra. The corner-sharing octahedra tilt angles range from 19–28°. There are a spread of Ba–O bond distances ranging from 2.57–2.60 Å. In the second Ba2+ site, Ba2+ is bonded to six O2- atoms to form BaO6 octahedra that share corners with six TaO6 octahedra. The corner-sharing octahedra tilt angles range from 23–28°. There are two shorter (2.58 Å) and four longer (2.59 Å) Ba–O bond lengths. In the third Ba2+ site, Ba2+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.69–3.34 Å. In the fourth Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.70–3.08 Å. In the fifth Ba2+ site, Ba2+ is bonded in a 3-coordinate geometry to five O2- atoms. There are a spread of Ba–O bond distances ranging from 2.65–2.97 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 three BaO6 octahedra and corners with three TaO6 octahedra. The corner-sharing octahedra tilt angles range from 13–28°. There are a spread of Ta–O bond distances ranging from 1.92–2.22 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with three BaO6 octahedra and corners with three TaO6 octahedra. The corner-sharing octahedra tilt angles range from 16–28°. There are a spread of Ta–O bond distances ranging from 1.93–2.23 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to three Ba2+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Ba2+ and two Ta5+ atoms. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+ and one Ta5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+ and one Ta5+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+ and one Ta5+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+ and one Ta5+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+ and one Ta5+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+ and one Ta5+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+ and two equivalent Ta5+ atoms.