DOI: 10.17188/1744685
title: Materials Data on Mg2Cr5(PO4)6 by Materials Project

description: Mg2Cr5(PO4)6 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share a cornercorner with one CrO6 octahedra, corners with five PO4 tetrahedra, and edges with two CrO6 octahedra. The corner-sharing octahedral tilt angles are 64°. There are a spread of Mg–O bond distances ranging from 2.01–2.09 Å. There are three inequivalent Cr+2.80+ sites. In the first Cr+2.80+ site, Cr+2.80+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six PO4 tetrahedra, an edgeedge with one CrO6 octahedra, and an edgeedge with one MgO5 trigonal bipyramid. There are a spread of Cr–O bond distances ranging from 1.94–2.15 Å. In the second Cr+2.80+ site, Cr+2.80+ is bonded to six O2- atoms to form CrO6 octahedra that share a cornercorner with one CrO6 octahedra, corners with six PO4 tetrahedra, an edgeedge with one CrO6 octahedra, and an edgeedge with one MgO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 65°. There are a spread of Cr–O bond distances ranging from 1.94–2.08 Å. In the third Cr+2.80+ site, Cr+2.80+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent CrO6 octahedra, corners with six PO4 tetrahedra, and corners with two equivalent MgO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 65°. There are a spread of Cr–O bond distances ranging from 2.05–2.29 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four CrO6 octahedra and corners with two equivalent MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 27–61°. There are a spread of P–O bond distances ranging from 1.53–1.59 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with six CrO6 octahedra and a cornercorner with one MgO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 25–55°. There are a spread of P–O bond distances ranging from 1.50–1.58 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with five CrO6 octahedra and corners with two equivalent MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 34–61°. There is one shorter (1.51 Å) and three longer (1.57 Å) P–O bond length. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Cr+2.80+, and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr+2.80+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr+2.80+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Cr+2.80+, and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Cr+2.80+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Cr+2.80+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Cr+2.80+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr+2.80+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr+2.80+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Cr+2.80+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Cr+2.80+, and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Cr+2.80+, and one P5+ atom.