DOI: 10.17188/1714631
title: Materials Data on Na4CaFe4(PO4)6 by Materials Project

description: Na4CaFe4(PO4)6 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are three 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 2.27–2.58 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 2.54–2.92 Å. In the third 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 2.33–2.43 Å. Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are four shorter (2.34 Å) and two longer (2.39 Å) Ca–O bond lengths. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.20 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.22 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four FeO6 octahedra. The corner-sharing octahedra tilt angles range from 47–51°. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four FeO6 octahedra. The corner-sharing octahedra tilt angles range from 47–50°. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four FeO6 octahedra. The corner-sharing octahedra tilt angles range from 40–57°. There are a spread of P–O bond distances ranging from 1.53–1.58 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four FeO6 octahedra. The corner-sharing octahedra tilt angles range from 41–57°. There are a spread of P–O bond distances ranging from 1.51–1.59 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Ca2+, one Fe3+, and one P5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+, one Fe3+, and one P5+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Ca2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Fe3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Fe3+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Fe3+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Fe3+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+, one Fe3+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Fe3+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Fe3+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to two Fe3+ and one P5+ atom.