Materials Data on Mg3Cr6(FeO6)4 by Materials Project
Mg3Cr6(FeO6)4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with six CrO4 tetrahedra, and corners with two equivalent MgO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 57°. There are a spread of Mg–O bond distances ranging from 2.03–2.50 Å. In the second Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share a cornercorner with one MgO6 octahedra, corners with five CrO4 tetrahedra, and edges with two FeO6 octahedra. The corner-sharing octahedral tilt angles are 60°. There are a spread of Mg–O bond distances ranging from 2.03–2.08 Å. There are three inequivalent Cr5+ sites. In the first Cr5+ site, Cr5+ is bonded to four O2- atoms to form CrO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with four FeO6 octahedra, and corners with two equivalent MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 24–62°. There are a spread of Cr–O bond distances ranging from 1.66–1.75 Å. In the second Cr5+ site, Cr5+ is bonded to four O2- atoms to form CrO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with five FeO6 octahedra, and a cornercorner with one MgO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 28–56°. There are a spread of Cr–O bond distances ranging from 1.65–1.78 Å. In the third Cr5+ site, Cr5+ is bonded to four O2- atoms to form CrO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with three FeO6 octahedra, and corners with two equivalent MgO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 24–65°. There are a spread of Cr–O bond distances ranging from 1.69–1.76 Å. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one MgO6 octahedra, corners with six CrO4 tetrahedra, an edgeedge with one FeO6 octahedra, and an edgeedge with one MgO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 57°. There are a spread of Fe–O bond distances ranging from 1.93–2.11 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six CrO4 tetrahedra, an edgeedge with one FeO6 octahedra, and an edgeedge with one MgO5 trigonal bipyramid. There are a spread of Fe–O bond distances ranging from 1.95–2.13 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Cr5+, and one Fe3+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr5+ and one Fe3+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Mg2+ and one Cr5+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one Cr5+ atom. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to one Mg2+, one Cr5+, and one Fe3+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cr5+ and two equivalent Fe3+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Cr5+, and one Fe3+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Cr5+, and one Fe3+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Mg2+, one Cr5+, and one Fe3+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Cr5+ and two equivalent Fe3+ atoms. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr5+ and one Fe3+ atom. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr5+ and one Fe3+ atom.