Materials Data on Na2Fe2Ni(PO4)3 by Materials Project

Na2Fe2Ni(PO4)3 crystallizes in the monoclinic C2/c 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 2.44–2.87 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 2.35–2.92 Å. Fe+2.50+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six PO4 tetrahedra, an edgeedge with one FeO6 octahedra, and an edgeedge with one NiO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.15 Å. Ni2+ is bonded to six O2- atoms to form distorted NiO6 octahedra that share corners with six PO4 tetrahedra and edges with two equivalent FeO6 octahedra. There are a spread of Ni–O bond distances ranging from 2.13–2.20 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent NiO6 octahedra and corners with four equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 52–59°. There is two shorter (1.54 Å) and two longer (1.57 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 two equivalent NiO6 octahedra and corners with four equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 38–58°. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Na1+, one Fe+2.50+, and one P5+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Ni2+, and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Fe+2.50+, one Ni2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Fe+2.50+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Fe+2.50+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Fe+2.50+, one Ni2+, and one P5+ atom.