DOI: 10.17188/1721123
title: Materials Data on Na3CaFe4(SiO3)8 by Materials Project

description: Na3CaFe4(SiO3)8 is Esseneite-derived structured and 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 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.40–2.91 Å. In the second Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.41–2.90 Å. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.37–2.81 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 FeO6 octahedra that share corners with six SiO4 tetrahedra and edges with two FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.12 Å. In the second Fe+2.75+ site, Fe+2.75+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six SiO4 tetrahedra and edges with two equivalent FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.06–2.25 Å. In the third Fe+2.75+ site, Fe+2.75+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six SiO4 tetrahedra and edges with two equivalent FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.14 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 FeO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 34–62°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three FeO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 33–58°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three FeO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–58°. There are a spread of Si–O bond distances ranging from 1.58–1.68 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three FeO6 octahedra and corners with two SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 33–63°. There are a spread of Si–O bond distances ranging from 1.62–1.69 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 2-coordinate geometry to two Na1+ and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+, one Fe+2.75+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two Fe+2.75+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ca2+, one Fe+2.75+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Ca2+, and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Ca2+, and two Si4+ atoms. In the ninth O2- site, O2- is bonded in a distorted T-shaped 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 2-coordinate geometry to two Na1+ and two Si4+ atoms. In the twelfth O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+, one Fe+2.75+, and one Si4+ atom.