DOI: 10.17188/1285424
title: Materials Data on Na3CaFe4(SiO3)8 by Materials Project

description: Na3CaFe4(SiO3)8 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.33–2.72 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.32–2.74 Å. Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.85 Å. There are three inequivalent Fe+2.75+ sites. In the first Fe+2.75+ site, Fe+2.75+ is bonded to six O2- atoms to form distorted FeO6 pentagonal pyramids that share corners with two SiO4 tetrahedra, edges with two FeO6 pentagonal pyramids, and edges with two SiO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 2.00–2.39 Å. In the second Fe+2.75+ site, Fe+2.75+ is bonded to six O2- atoms to form distorted FeO6 pentagonal pyramids that share corners with two equivalent SiO4 tetrahedra, edges with two equivalent FeO6 pentagonal pyramids, and edges with two equivalent SiO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.32 Å. In the third Fe+2.75+ site, Fe+2.75+ is bonded to six O2- atoms to form distorted FeO6 pentagonal pyramids that share corners with two equivalent SiO4 tetrahedra, edges with two equivalent FeO6 pentagonal pyramids, and edges with two equivalent SiO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.99–2.28 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 a cornercorner with one FeO6 pentagonal pyramid, corners with two SiO4 tetrahedra, and an edgeedge with one FeO6 pentagonal pyramid. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 pentagonal pyramid, corners with two SiO4 tetrahedra, and an edgeedge with one FeO6 pentagonal pyramid. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 pentagonal pyramid, corners with two SiO4 tetrahedra, and an edgeedge with one FeO6 pentagonal pyramid. There are a spread of Si–O bond distances ranging from 1.64–1.69 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one FeO6 pentagonal pyramid, corners with two SiO4 tetrahedra, and an edgeedge with one FeO6 pentagonal pyramid. There are a spread of Si–O bond distances ranging from 1.64–1.70 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two Fe+2.75+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, two Fe+2.75+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Fe+2.75+, and one Si4+ atom. In the fifth O2- site, O2- is bonded to one Na1+, two Fe+2.75+, and one Si4+ atom to form distorted corner-sharing ONaFe2Si trigonal pyramids. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Fe+2.75+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Na1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ca2+ and two Si4+ atoms. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Fe+2.75+, and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two Fe+2.75+, and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Si4+ atoms. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Fe+2.75+, and one Si4+ atom.