Materials Data on K2FeP2O7 by Materials Project
K2FeP2O7 crystallizes in the tetragonal P-42_1m space group. The structure is three-dimensional. K1+ is bonded in a 5-coordinate geometry to three equivalent O2- atoms. There are two shorter (2.63 Å) and one longer (2.64 Å) K–O bond lengths. Fe2+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Fe–O bond lengths are 2.00 Å. P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There is three shorter (1.53 Å) and one longer (1.64 Å) P–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent P5+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to one Fe2+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one P5+ atom.