DOI: 10.17188/1300922
title: Materials Data on Ni4P2O9 by Materials Project

description: Ni4P2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Ni2+ sites. In the first Ni2+ site, Ni2+ is bonded to five O2- atoms to form distorted NiO5 trigonal bipyramids that share corners with four NiO6 octahedra, corners with two equivalent NiO6 pentagonal pyramids, corners with two PO4 tetrahedra, an edgeedge with one NiO6 pentagonal pyramid, an edgeedge with one PO4 tetrahedra, and an edgeedge with one NiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 51–79°. There are a spread of Ni–O bond distances ranging from 1.92–2.34 Å. In the second Ni2+ site, Ni2+ is bonded to six O2- atoms to form distorted NiO6 octahedra that share corners with two equivalent NiO6 pentagonal pyramids, corners with three PO4 tetrahedra, corners with two equivalent NiO5 trigonal bipyramids, edges with two equivalent NiO6 octahedra, an edgeedge with one NiO6 pentagonal pyramid, and an edgeedge with one PO4 tetrahedra. There are a spread of Ni–O bond distances ranging from 2.01–2.17 Å. In the third Ni2+ site, Ni2+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with five PO4 tetrahedra, corners with two equivalent NiO5 trigonal bipyramids, edges with three NiO6 octahedra, and an edgeedge with one NiO6 pentagonal pyramid. There are a spread of Ni–O bond distances ranging from 2.03–2.18 Å. In the fourth Ni2+ site, Ni2+ is bonded to six O2- atoms to form distorted NiO6 pentagonal pyramids that share corners with two equivalent NiO6 octahedra, corners with three PO4 tetrahedra, corners with two equivalent NiO5 trigonal bipyramids, edges with two NiO6 octahedra, an edgeedge with one PO4 tetrahedra, and an edgeedge with one NiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 44–62°. There are a spread of Ni–O bond distances ranging from 1.99–2.25 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 four NiO6 octahedra, a cornercorner with one NiO6 pentagonal pyramid, a cornercorner with one NiO5 trigonal bipyramid, an edgeedge with one NiO6 octahedra, and an edgeedge with one NiO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 32–62°. There are a spread of P–O bond distances ranging from 1.53–1.58 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four NiO6 octahedra, corners with two equivalent NiO6 pentagonal pyramids, a cornercorner with one NiO5 trigonal bipyramid, and an edgeedge with one NiO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 46–53°. There are a spread of P–O bond distances ranging from 1.53–1.57 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted T-shaped geometry to two Ni2+ and one P5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Ni2+ and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Ni2+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Ni2+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ni2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted tetrahedral geometry to four Ni2+ atoms. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Ni2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Ni2+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Ni2+ and one P5+ atom.