Materials Data on Ba2Sm3Si3SeO12 by Materials Project

Ba2Sm3Si3SeO12 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.72–2.95 Å. Sm3+ is bonded in a 6-coordinate geometry to two equivalent Se1- and six O2- atoms. Both Sm–Se bond lengths are 3.22 Å. There are a spread of Sm–O bond distances ranging from 2.24–2.59 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent SeSm6O6 cuboctahedra. There is one shorter (1.63 Å) and three longer (1.66 Å) Si–O bond length. Se1- is bonded to six equivalent Sm3+ and six equivalent O2- atoms to form SeSm6O6 cuboctahedra that share corners with six equivalent SiO4 tetrahedra and faces with two equivalent SeSm6O6 cuboctahedra. All Se–O bond lengths are 3.15 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, one Sm3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Ba2+, two equivalent Sm3+, one Si4+, and one Se1- atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Sm3+, and one Si4+ atom.