Materials Data on NaFe2(Si2O5)3 by Materials Project
NaFe2(Si2O5)3 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.36–2.76 Å. There are two inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. All Fe–O bond lengths are 2.02 Å. In the second Fe+2.50+ site, Fe+2.50+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six SiO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.13 Å. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 36°. There are a spread of Si–O bond distances ranging from 1.62–1.65 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 36°. There are a spread of Si–O bond distances ranging from 1.60–1.65 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two Fe+2.50+ and one Si4+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two Si4+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Fe+2.50+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Fe+2.50+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+ and two Si4+ atoms. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms.