DOI: 10.17188/1285543
title: Materials Data on Na2AlFeF7 by Materials Project

description: Na2FeAlF7 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 a cornercorner with one NaF8 hexagonal bipyramid, corners with two AlF6 octahedra, edges with two equivalent AlF6 octahedra, and edges with four FeF6 octahedra. The corner-sharing octahedra tilt angles range from 43–54°. There are a spread of Na–F bond distances ranging from 2.19–2.75 Å. In the second Na1+ site, Na1+ is bonded to eight F1- atoms to form NaF8 hexagonal bipyramids that share corners with two equivalent NaF8 hexagonal bipyramids, corners with two equivalent AlF6 octahedra, edges with two equivalent AlF6 octahedra, and edges with four FeF6 octahedra. The corner-sharing octahedral tilt angles are 45°. There are a spread of Na–F bond distances ranging from 2.23–2.69 Å. In the third 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 2.31–2.88 Å. In the fourth 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 2.42–2.92 Å. In the fifth 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 2.44–2.88 Å. In the sixth 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 2.47–2.91 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 AlF6 octahedra, and edges with three NaF8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 37–59°. There are a spread of Fe–F bond distances ranging from 2.06–2.09 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 AlF6 octahedra, and edges with three NaF8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 34–59°. There are a spread of Fe–F bond distances ranging from 2.06–2.10 Å. There are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share corners with two equivalent NaF8 hexagonal bipyramids and corners with four FeF6 octahedra. The corner-sharing octahedra tilt angles range from 38–41°. There are a spread of Al–F bond distances ranging from 1.81–1.84 Å. In the second Al3+ site, Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share a cornercorner with one NaF8 hexagonal bipyramid, 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 Al–F bond distances ranging from 1.82–1.84 Å. In the third Al3+ site, Al3+ is bonded to six F1- atoms to form AlF6 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 34–37°. There are a spread of Al–F bond distances ranging from 1.81–1.86 Å. There are fourteen inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to three Na1+ and one Al3+ atom. In the second F1- site, F1- is bonded in a 2-coordinate geometry to two Na1+, one Fe2+, and one Al3+ atom. In the third F1- site, F1- is bonded in a 2-coordinate geometry to two Na1+, one Fe2+, and one Al3+ atom. In the fourth F1- site, F1- is bonded in a 2-coordinate geometry to two equivalent Na1+, one Fe2+, and one Al3+ atom. In the fifth F1- site, F1- is bonded in a 2-coordinate geometry to two Na1+, one Fe2+, and one Al3+ atom. In the sixth F1- site, F1- is bonded in a 4-coordinate geometry to three Na1+ and one Al3+ atom. In the seventh F1- site, F1- is bonded in a 2-coordinate geometry to two Na1+, one Fe2+, and one Al3+ atom. In the eighth F1- site, F1- is bonded in a 2-coordinate geometry to two Na1+, one Fe2+, and one Al3+ atom. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two Na1+, one Fe2+, and one Al3+ atom. 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+ and two Fe2+ atoms. In the twelfth F1- site, F1- is bonded in a 4-coordinate geometry to three Na1+ and one Al3+ atom. In the thirteenth F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one Fe2+, and one Al3+ atom. In the fourteenth F1- site, F1- is bonded in a 4-coordinate geometry to three Na1+ and one Al3+ atom.