Materials Data on K2FePCO7 by Materials Project
K2FeCPO7 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.58–3.03 Å. Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent PO4 tetrahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.15 Å. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.25–1.33 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 29–38°. There are a spread of P–O bond distances ranging from 1.55–1.58 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent K1+ and one C4+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent K1+, one Fe3+, and one C4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent K1+, one Fe3+, and one C4+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent 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 distorted bent 150 degrees geometry to two equivalent K1+, one Fe3+, and one P5+ atom.