Materials Data on K4Fe4(PO4)5 by Materials Project
K4Fe4P5O20 crystallizes in the tetragonal P-42_1c 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 2.79–3.25 Å. Fe+2.75+ is bonded to five O2- atoms to form FeO5 trigonal bipyramids that share corners with five PO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.05 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 equivalent FeO5 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.54–1.56 Å. In the second P5+ site, P5+ is bonded to four equivalent O2- atoms to form PO4 tetrahedra that share corners with four equivalent FeO5 trigonal bipyramids. All P–O bond lengths are 1.55 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Fe+2.75+, and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Fe+2.75+, and one P5+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Fe+2.75+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Fe+2.75+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Fe+2.75+, and one P5+ atom.