Materials Data on Mg3Cr8FeO16 by Materials Project
Mg3Cr8FeO16 is Spinel-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with twelve CrO6 octahedra. The corner-sharing octahedra tilt angles range from 58–59°. There are one shorter (2.00 Å) and three longer (2.01 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with twelve CrO6 octahedra. The corner-sharing octahedra tilt angles range from 58–59°. All Mg–O bond lengths are 2.00 Å. In the third Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with twelve CrO6 octahedra. The corner-sharing octahedra tilt angles range from 58–59°. There are one shorter (2.00 Å) and three longer (2.01 Å) Mg–O bond lengths. There are four inequivalent Cr3+ sites. In the first Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with three equivalent MgO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, and edges with six CrO6 octahedra. There are three shorter (2.02 Å) and three longer (2.04 Å) Cr–O bond lengths. In the second Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with six MgO4 tetrahedra and edges with six CrO6 octahedra. There are three shorter (2.03 Å) and three longer (2.04 Å) Cr–O bond lengths. In the third Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four MgO4 tetrahedra, and edges with six CrO6 octahedra. There are five shorter (2.03 Å) and one longer (2.04 Å) Cr–O bond lengths. In the fourth Cr3+ site, Cr3+ is bonded to six O2- atoms to form CrO6 octahedra that share a cornercorner with one FeO4 tetrahedra, corners with five MgO4 tetrahedra, and edges with six CrO6 octahedra. There are two shorter (2.03 Å) and four longer (2.04 Å) Cr–O bond lengths. Fe2+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with twelve CrO6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are one shorter (1.98 Å) and three longer (2.03 Å) Fe–O bond lengths. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to one Mg2+ and three equivalent Cr3+ atoms to form distorted OMgCr3 trigonal pyramids that share corners with twelve OMgCr3 trigonal pyramids and edges with three equivalent OCr3Fe trigonal pyramids. In the second O2- site, O2- is bonded to three equivalent Cr3+ and one Fe2+ atom to form a mixture of distorted edge and corner-sharing OCr3Fe trigonal pyramids. In the third O2- site, O2- is bonded to three Cr3+ and one Fe2+ atom to form distorted OCr3Fe trigonal pyramids that share corners with twelve OCr3Fe trigonal pyramids and edges with three OMgCr3 trigonal pyramids. In the fourth O2- site, O2- is bonded to one Mg2+ and three Cr3+ atoms to form distorted OMgCr3 trigonal pyramids that share corners with twelve OMgCr3 trigonal pyramids and edges with three OCr3Fe trigonal pyramids. In the fifth O2- site, O2- is bonded to one Mg2+ and three equivalent Cr3+ atoms to form a mixture of distorted edge and corner-sharing OMgCr3 trigonal pyramids. In the sixth O2- site, O2- is bonded to one Mg2+ and three equivalent Cr3+ atoms to form distorted OMgCr3 trigonal pyramids that share corners with twelve OCr3Fe trigonal pyramids and edges with three equivalent OMgCr3 trigonal pyramids. In the seventh O2- site, O2- is bonded to one Mg2+ and three Cr3+ atoms to form a mixture of distorted edge and corner-sharing OMgCr3 trigonal pyramids. In the eighth O2- site, O2- is bonded to one Mg2+ and three Cr3+ atoms to form distorted OMgCr3 trigonal pyramids that share corners with twelve OCr3Fe trigonal pyramids and edges with three OMgCr3 trigonal pyramids.