DOI: 10.17188/1716062
title: Materials Data on Ba2Sr3CaMg2(SiO4)4 by Materials Project

description: Ba2Sr3CaMg2(SiO4)4 crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share edges with six equivalent BaO12 cuboctahedra, edges with six SiO4 tetrahedra, and faces with two MgO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.81–3.20 Å. In the second Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share edges with six equivalent BaO12 cuboctahedra, edges with six SiO4 tetrahedra, and faces with two MgO6 octahedra. There are six shorter (2.84 Å) and six longer (3.20 Å) Ba–O bond lengths. There are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 1-coordinate geometry to ten O2- atoms. There are a spread of Sr–O bond distances ranging from 2.40–2.85 Å. In the second Sr2+ site, Sr2+ is bonded in a 1-coordinate geometry to ten O2- atoms. There are a spread of Sr–O bond distances ranging from 2.37–2.83 Å. In the third Sr2+ site, Sr2+ is bonded in a 1-coordinate geometry to ten O2- atoms. There are a spread of Sr–O bond distances ranging from 2.39–2.82 Å. Ca2+ is bonded in a 1-coordinate geometry to ten O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.85 Å. There are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six SiO4 tetrahedra and faces with two BaO12 cuboctahedra. There are three shorter (2.09 Å) and three longer (2.10 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six SiO4 tetrahedra and faces with two BaO12 cuboctahedra. All Mg–O bond lengths are 2.09 Å. There are four inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent MgO6 octahedra and edges with three equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. There is one shorter (1.63 Å) and three longer (1.66 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent MgO6 octahedra and edges with three equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. There is one shorter (1.62 Å) and three longer (1.66 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent MgO6 octahedra and edges with three equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. There is one shorter (1.61 Å) and three longer (1.66 Å) Si–O bond length. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent MgO6 octahedra and edges with three equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. There is one shorter (1.62 Å) and three longer (1.66 Å) Si–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to three equivalent Ba2+, one Ca2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to three equivalent Ba2+, one Sr2+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to three equivalent Ba2+, one Sr2+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted linear geometry to three equivalent Ba2+, one Sr2+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, three Sr2+, one Mg2+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, two equivalent Sr2+, one Ca2+, one Mg2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, one Sr2+, two equivalent Ca2+, one Mg2+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, three Sr2+, one Mg2+, and one Si4+ atom.