DOI: 10.17188/1705780
title: Materials Data on KFe4(PO4)3 by Materials Project

description: KFe4(PO4)3 crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. K1+ is bonded in a 6-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.81–3.25 Å. There are three inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to five O2- atoms to form FeO5 trigonal bipyramids that share corners with two equivalent FeO6 octahedra, corners with five PO4 tetrahedra, and an edgeedge with one FeO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 62°. There are a spread of Fe–O bond distances ranging from 2.03–2.22 Å. In the second Fe2+ site, Fe2+ is bonded to six O2- atoms to form distorted FeO6 pentagonal pyramids that share corners with two equivalent FeO6 octahedra, corners with four PO4 tetrahedra, edges with two equivalent FeO6 octahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 70°. There are a spread of Fe–O bond distances ranging from 2.01–2.37 Å. In the third Fe2+ site, Fe2+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share a cornercorner with one FeO6 pentagonal pyramid, corners with four PO4 tetrahedra, a cornercorner with one FeO5 trigonal bipyramid, edges with two equivalent FeO6 octahedra, an edgeedge with one FeO6 pentagonal pyramid, and an edgeedge with one PO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 2.10–2.55 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 four equivalent FeO6 octahedra, a cornercorner with one FeO6 pentagonal pyramid, and corners with two equivalent FeO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 49–56°. There are a spread of P–O bond distances ranging from 1.53–1.61 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent FeO6 octahedra, corners with two equivalent FeO6 pentagonal pyramids, a cornercorner with one FeO5 trigonal bipyramid, and edges with two equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are a spread of P–O bond distances ranging from 1.54–1.59 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent FeO6 octahedra, a cornercorner with one FeO6 pentagonal pyramid, corners with two equivalent FeO5 trigonal bipyramids, and an edgeedge with one FeO6 pentagonal pyramid. The corner-sharing octahedral tilt angles are 59°. There are a spread of P–O bond distances ranging from 1.52–1.57 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Fe2+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Fe2+ and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two Fe2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Fe2+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Fe2+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one K1+, two Fe2+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted tetrahedral geometry to three Fe2+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Fe2+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted linear geometry to two equivalent K1+, one Fe2+, and one P5+ atom.