Materials Data on K2Cr2(PO4)3 by Materials Project

Abstract

K2Cr2(PO4)3 crystallizes in the cubic P2_13 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.88–2.99 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.83–3.13 Å. There are two inequivalent Cr+3.50+ sites. In the first Cr+3.50+ site, Cr+3.50+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six equivalent PO4 tetrahedra. There is three shorter (1.97 Å) and three longer (2.00 Å) Cr–O bond length. In the second Cr+3.50+ site, Cr+3.50+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six equivalent PO4 tetrahedra. There are three shorter (1.99 Å) and three longer (2.01 Å) Cr–O bond lengths. P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four CrO6 octahedra. The corner-sharing octahedra tilt angles range from 15–50°. There is two shorter (1.54 Å) and two longer (1.55 Å) P–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+, one Cr+3.50+, and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Cr+3.50+, and one P5+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two K1+, one Cr+3.50+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Cr+3.50+, and one P5+ atom.