Materials Data on Cr3(PO4)4 by Materials Project

Abstract

Cr3(PO4)4 crystallizes in the monoclinic C2/c space group. The structure is two-dimensional and consists of two Cr3(PO4)4 sheets oriented in the (1, 0, 0) direction. there are two inequivalent Cr4+ sites. In the first Cr4+ site, Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent CrO6 octahedra, corners with four PO4 tetrahedra, and an edgeedge with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Cr–O bond distances ranging from 1.91–2.07 Å. In the second Cr4+ site, Cr4+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with four equivalent CrO6 octahedra and corners with six PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–58°. There are a spread of Cr–O bond distances ranging from 1.94–2.08 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 three CrO6 octahedra. The corner-sharing octahedra tilt angles range from 46–49°. There are a spread of P–O bond distances ranging from 1.53–1.56 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four CrO6 octahedra and an edgeedge with one CrO6 octahedra. The corner-sharing octahedra tilt angles range from 38–55°. There is two shorter (1.51 Å) and two longer (1.61 Å) P–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr4+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Cr4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cr4+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Cr4+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom.