Materials Data on Na2Fe7(PO4)6 by Materials Project
Na2Fe7(PO4)6 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Na1+ is bonded in a 4-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.38–2.92 Å. There are four inequivalent Fe+2.29+ sites. In the first Fe+2.29+ site, Fe+2.29+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and edges with two FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.15 Å. In the second Fe+2.29+ site, Fe+2.29+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra and edges with two FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.16 Å. In the third Fe+2.29+ site, Fe+2.29+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share corners with six PO4 tetrahedra and edges with two FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.12–2.31 Å. In the fourth Fe+2.29+ site, Fe+2.29+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Fe–O bond distances ranging from 2.19–2.42 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 37–61°. There are a spread of P–O bond distances ranging from 1.54–1.58 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 40–59°. There is one shorter (1.55 Å) and three 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 six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 53–63°. There are a spread of P–O bond distances ranging from 1.52–1.57 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one Fe+2.29+ and one P5+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, two Fe+2.29+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, two Fe+2.29+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Fe+2.29+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Fe+2.29+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Fe+2.29+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Fe+2.29+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, two Fe+2.29+, and one P5+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, two Fe+2.29+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Fe+2.29+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to two Fe+2.29+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Fe+2.29+ and one P5+ atom.