Materials Data on Ba9Sc2(SiO4)6 by Materials Project

Abstract

Ba9Sc2Si6O24 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are three inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.60–3.20 Å. In the second Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.80–3.14 Å. In the third Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share edges with six equivalent SiO4 tetrahedra and faces with two equivalent ScO6 octahedra. There are six shorter (2.92 Å) and six longer (3.26 Å) Ba–O bond lengths. Sc3+ is bonded to six O2- atoms to form ScO6 octahedra that share corners with six equivalent SiO4 tetrahedra and a faceface with one BaO12 cuboctahedra. There are three shorter (2.10 Å) and three longer (2.16 Å) Sc–O bond lengths. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent ScO6 octahedra and an edgeedge with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–14°. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+, one Sc3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to four Ba2+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four Ba2+, one Sc3+, and one Si4+ atom.