Materials Data on KFeNi(PO4)2 by Materials Project
KFeNi(PO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.77–3.32 Å. Fe3+ is bonded to five O2- atoms to form FeO5 trigonal bipyramids that share a cornercorner with one NiO6 octahedra and corners with five PO4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. There are a spread of Fe–O bond distances ranging from 1.93–2.04 Å. Ni2+ is bonded to six O2- atoms to form NiO6 octahedra that share corners with four PO4 tetrahedra, a cornercorner with one FeO5 trigonal bipyramid, edges with two equivalent NiO6 octahedra, and an edgeedge with one PO4 tetrahedra. There are a spread of Ni–O bond distances ranging from 2.04–2.23 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 three equivalent NiO6 octahedra and corners with two equivalent FeO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 56–58°. There are a spread of P–O bond distances ranging from 1.54–1.57 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one NiO6 octahedra, corners with three equivalent FeO5 trigonal bipyramids, and an edgeedge with one NiO6 octahedra. The corner-sharing octahedral tilt angles are 4°. There are a spread of P–O bond distances ranging from 1.54–1.58 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ni2+, and one P5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, two equivalent Ni2+, and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Fe3+, one Ni2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Fe3+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Fe3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Fe3+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Fe3+, and one P5+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, two equivalent Ni2+, and one P5+ atom.