Materials Data on K4P2O7 by Materials Project
K4P2O7 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to nine equivalent O2- atoms. There are six shorter (3.05 Å) and three longer (3.35 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All K–O bond lengths are 2.85 Å. In the third K1+ site, K1+ is bonded to six equivalent O2- atoms to form KO6 octahedra that share corners with six equivalent PO4 tetrahedra. All K–O bond lengths are 2.64 Å. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent KO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 25°. There is three shorter (1.53 Å) and one longer (1.62 Å) P–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to five K1+ and one P5+ atom. In the second O2- site, O2- is bonded in a linear geometry to two equivalent P5+ atoms.