Materials Data on MgCr3(SO4)6 by Materials Project
MgCr3(SO4)6 crystallizes in the trigonal R3 space group. The structure is three-dimensional. Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six SO4 tetrahedra. There are three shorter (2.06 Å) and three longer (2.08 Å) Mg–O bond lengths. There are three inequivalent Cr6+ sites. In the first Cr6+ site, Cr6+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six SO4 tetrahedra. All Cr–O bond lengths are 2.01 Å. In the second Cr6+ site, Cr6+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six SO4 tetrahedra. There is three shorter (1.98 Å) and three longer (2.00 Å) Cr–O bond length. In the third Cr6+ site, Cr6+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six SO4 tetrahedra. There are three shorter (2.00 Å) and three longer (2.02 Å) Cr–O bond lengths. There are two inequivalent S+4.67+ sites. In the first S+4.67+ site, S+4.67+ is bonded to four O2- atoms to form SO4 tetrahedra that share a cornercorner with one MgO6 octahedra and corners with three CrO6 octahedra. The corner-sharing octahedra tilt angles range from 28–42°. There are a spread of S–O bond distances ranging from 1.46–1.50 Å. In the second S+4.67+ site, S+4.67+ is bonded to four O2- atoms to form SO4 tetrahedra that share a cornercorner with one MgO6 octahedra and corners with three CrO6 octahedra. The corner-sharing octahedra tilt angles range from 30–43°. There is one shorter (1.46 Å) and three longer (1.49 Å) S–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 Mg2+ and one S+4.67+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr6+ and one S+4.67+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Mg2+ and one S+4.67+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr6+ and one S+4.67+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr6+ and one S+4.67+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Cr6+ and one S+4.67+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr6+ and one S+4.67+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Cr6+ and one S+4.67+ atom.