Materials Data on Ba7Sc6Al2O19 by Materials Project

Abstract

Ba7Sc6Al2O19 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are four inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are three shorter (2.69 Å) and six longer (2.98 Å) Ba–O bond lengths. 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 ScO6 octahedra, and a faceface with one AlO4 tetrahedra. There are a spread of Ba–O bond distances ranging from 2.93–3.23 Å. In the third Ba2+ site, Ba2+ is bonded in a distorted q6 geometry to nine O2- atoms. There are three shorter (2.73 Å) and six longer (2.96 Å) Ba–O bond lengths. In the fourth Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to six equivalent O2- atoms. All Ba–O bond lengths are 2.88 Å. There are three inequivalent Sc3+ sites. In the first Sc3+ site, Sc3+ is bonded to six O2- atoms to form ScO6 octahedra that share corners with three equivalent ScO6 octahedra, corners with three equivalent AlO4 tetrahedra, and faces with three equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 2°. There are three shorter (2.12 Å) and three longer (2.15 Å) Sc–O bond lengths. In the second Sc3+ site, Sc3+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. There are three shorter (2.09 Å) and three longer (2.26 Å) Sc–O bond lengths. In the third Sc3+ site, Sc3+ is bonded to six O2- atoms to form ScO6 octahedra that share corners with three equivalent ScO6 octahedra and faces with three equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 2°. There are three shorter (2.08 Å) and three longer (2.19 Å) Sc–O bond lengths. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three equivalent ScO6 octahedra, a cornercorner with one AlO4 tetrahedra, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 18°. There is one shorter (1.74 Å) and three longer (1.77 Å) Al–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent Al3+ atoms. In the second O2- site, O2- is bonded in a 6-coordinate geometry to three Ba2+ and three Sc3+ atoms. In the third O2- site, O2- is bonded to four Ba2+ and two Sc3+ atoms to form a mixture of distorted corner and face-sharing OBa4Sc2 octahedra. The corner-sharing octahedra tilt angles range from 7–60°. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+, one Sc3+, and one Al3+ atom.