DOI: 10.17188/1285554
title: Materials Data on Na2CrFeF7 by Materials Project

description: Na2CrFeF7 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are six inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to eight F1- atoms to form distorted NaF8 hexagonal bipyramids that share corners with two NaF8 hexagonal bipyramids, corners with two CrF6 octahedra, an edgeedge with one NaF8 hexagonal bipyramid, edges with two equivalent CrF6 octahedra, and edges with four FeF6 octahedra. The corner-sharing octahedra tilt angles range from 48–56°. There are a spread of Na–F bond distances ranging from 2.20–2.88 Å. In the second Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Na–F bond distances ranging from 2.42–2.89 Å. In the third Na1+ site, Na1+ is bonded to eight F1- atoms to form distorted NaF8 hexagonal bipyramids that share a cornercorner with one NaF8 hexagonal bipyramid, a cornercorner with one CrF6 octahedra, edges with three NaF8 hexagonal bipyramids, edges with three CrF6 octahedra, and edges with three FeF6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are a spread of Na–F bond distances ranging from 2.32–2.88 Å. In the fourth Na1+ site, Na1+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are a spread of Na–F bond distances ranging from 2.46–2.87 Å. In the fifth Na1+ site, Na1+ is bonded to eight F1- atoms to form distorted NaF8 hexagonal bipyramids that share corners with two equivalent NaF8 hexagonal bipyramids, corners with two equivalent CrF6 octahedra, edges with two equivalent CrF6 octahedra, and edges with four FeF6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of Na–F bond distances ranging from 2.24–2.83 Å. In the sixth Na1+ site, Na1+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are a spread of Na–F bond distances ranging from 2.48–2.87 Å. There are three inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded to six F1- atoms to form CrF6 octahedra that share corners with two NaF8 hexagonal bipyramids, corners with four FeF6 octahedra, and edges with three NaF8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 43–45°. There are a spread of Cr–F bond distances ranging from 1.93–1.98 Å. In the second Cr3+ site, Cr3+ is bonded to six F1- atoms to form CrF6 octahedra that share corners with two equivalent NaF8 hexagonal bipyramids, corners with four FeF6 octahedra, and edges with four equivalent NaF8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 43–45°. There is two shorter (1.94 Å) and four longer (1.95 Å) Cr–F bond length. In the third Cr3+ site, Cr3+ is bonded to six F1- atoms to form CrF6 octahedra that share corners with two equivalent NaF8 hexagonal bipyramids, corners with four FeF6 octahedra, and edges with two equivalent NaF8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 39–41°. There are a spread of Cr–F bond distances ranging from 1.93–1.98 Å. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to six F1- atoms to form FeF6 octahedra that share corners with two equivalent FeF6 octahedra, corners with four CrF6 octahedra, and edges with four NaF8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 39–50°. There are a spread of Fe–F bond distances ranging from 2.02–2.10 Å. In the second Fe2+ site, Fe2+ is bonded to six F1- atoms to form FeF6 octahedra that share corners with two equivalent FeF6 octahedra, corners with four CrF6 octahedra, and edges with five NaF8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 41–50°. There are a spread of Fe–F bond distances ranging from 2.07–2.09 Å. There are fourteen inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one Cr3+, and one Fe2+ atom. In the second F1- site, F1- is bonded in a 2-coordinate geometry to two Na1+, one Cr3+, and one Fe2+ atom. In the third F1- site, F1- is bonded in a 2-coordinate geometry to two Na1+ and two Fe2+ atoms. In the fourth F1- site, F1- is bonded to three Na1+ and one Cr3+ atom to form a mixture of distorted edge and corner-sharing FNa3Cr tetrahedra. In the fifth F1- site, F1- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Cr3+, and one Fe2+ atom. In the sixth F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one Cr3+, and one Fe2+ atom. In the seventh F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one Cr3+, and one Fe2+ atom. In the eighth F1- site, F1- is bonded in a 4-coordinate geometry to three Na1+ and one Cr3+ atom. In the ninth F1- site, F1- is bonded to three Na1+ and one Cr3+ atom to form a mixture of distorted edge and corner-sharing FNa3Cr tetrahedra. In the tenth F1- site, F1- is bonded in a 2-coordinate geometry to two Na1+ and two Fe2+ atoms. In the eleventh F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one Cr3+, and one Fe2+ atom. In the twelfth F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one Cr3+, and one Fe2+ atom. In the thirteenth F1- site, F1- is bonded to three Na1+ and one Cr3+ atom to form a mixture of distorted edge and corner-sharing FNa3Cr tetrahedra. In the fourteenth F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one Cr3+, and one Fe2+ atom.