Materials Data on Er4Si2S3O7 by Materials Project
Er4Si2S3O7 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. there are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded in a 9-coordinate geometry to three S2- and six O2- atoms. There are one shorter (2.84 Å) and two longer (2.86 Å) Er–S bond lengths. There are a spread of Er–O bond distances ranging from 2.35–2.51 Å. In the second Er3+ site, Er3+ is bonded in a 6-coordinate geometry to three S2- and three O2- atoms. There are two shorter (2.75 Å) and one longer (2.78 Å) Er–S bond lengths. There are one shorter (2.27 Å) and two longer (2.42 Å) Er–O bond lengths. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SEr4O2 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 63°. There is three shorter (1.64 Å) and one longer (1.65 Å) Si–O bond length. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted square co-planar geometry to four equivalent Er3+ and twelve O2- atoms. There are eight shorter (3.15 Å) and four longer (3.18 Å) S–O bond lengths. In the second S2- site, S2- is bonded to four equivalent Er3+ and two equivalent O2- atoms to form distorted SEr4O2 octahedra that share corners with four equivalent SiO4 tetrahedra. Both S–O bond lengths are 3.05 Å. In the third S2- site, S2- is bonded in a 2-coordinate geometry to four Er3+ atoms. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent Si4+ and one S2- atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Er3+, one Si4+, and one S2- atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three Er3+, one Si4+, and one S2- atom.