Materials Data on Na4NiP2O7F2 by Materials Project
Na4NiP2O7F2 crystallizes in the orthorhombic Imma 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 equivalent F1- atoms. There are two shorter (2.44 Å) and two longer (2.48 Å) Na–O bond lengths. Both Na–F bond lengths are 2.67 Å. In the second Na1+ site, Na1+ is bonded in a 5-coordinate geometry to three O2- and two F1- atoms. There are one shorter (2.33 Å) and two longer (2.52 Å) Na–O bond lengths. There are one shorter (2.13 Å) and one longer (2.21 Å) Na–F bond lengths. Ni2+ is bonded to four equivalent O2- and two equivalent F1- atoms to form NiO4F2 octahedra that share corners with two equivalent NiO4F2 octahedra and corners with four equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 54°. All Ni–O bond lengths are 2.09 Å. Both Ni–F bond lengths are 2.01 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent NiO4F2 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 57°. There are a spread of P–O bond distances ranging from 1.52–1.66 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent P5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Ni2+, and one P5+ atom. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded to two equivalent Na1+ and two equivalent Ni2+ atoms to form FNa2Ni2 tetrahedra that share corners with two equivalent FNa6 octahedra and corners with two equivalent FNa2Ni2 tetrahedra. The corner-sharing octahedral tilt angles are 51°. In the second F1- site, F1- is bonded to six Na1+ atoms to form distorted FNa6 octahedra that share corners with four equivalent FNa6 octahedra and corners with two equivalent FNa2Ni2 tetrahedra. The corner-sharing octahedral tilt angles are 11°.