Materials Data on Na2FePO4F by Materials Project
Na2FePO4F crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 6-coordinate geometry to four O2- and two F1- atoms. There are a spread of Na–O bond distances ranging from 2.39–2.49 Å. There are one shorter (2.38 Å) and one longer (2.55 Å) Na–F bond lengths. In the second Na1+ site, Na1+ is bonded in a 7-coordinate geometry to five O2- and two F1- atoms. There are a spread of Na–O bond distances ranging from 2.32–2.84 Å. There are one shorter (2.36 Å) and one longer (2.44 Å) Na–F bond lengths. Fe2+ is bonded to four O2- and two F1- atoms to form distorted FeO4F2 octahedra that share a cornercorner with one FeO4F2 octahedra, corners with four equivalent PO4 tetrahedra, and a faceface with one FeO4F2 octahedra. The corner-sharing octahedral tilt angles are 74°. There are a spread of Fe–O bond distances ranging from 2.07–2.21 Å. There are one shorter (2.13 Å) and one longer (2.20 Å) Fe–F bond lengths. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four equivalent FeO4F2 octahedra. The corner-sharing octahedra tilt angles range from 40–53°. There are a spread of P–O bond distances ranging from 1.54–1.58 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+, one Fe2+, and one P5+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+ and one P5+ atom. In the third O2- site, O2- is bonded to two Na1+, one Fe2+, and one P5+ atom to form distorted ONa2FeP tetrahedra that share corners with six FNa4Fe2 octahedra. The corner-sharing octahedra tilt angles range from 6–70°. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Na1+, two equivalent Fe2+, and one P5+ atom. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded to four Na1+ and two equivalent Fe2+ atoms to form FNa4Fe2 octahedra that share corners with six equivalent ONa2FeP tetrahedra and faces with two equivalent FNa4Fe2 octahedra. In the second F1- site, F1- is bonded to four Na1+ and two equivalent Fe2+ atoms to form distorted FNa4Fe2 octahedra that share corners with six equivalent ONa2FeP tetrahedra and faces with two equivalent FNa4Fe2 octahedra.