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DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

MgFe2O4 crystallizes in the orthorhombic Pbcm space group. The structure is three-dimensional. Mg2+ is bonded in a 6-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.04–2.70 Å. Fe3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 0–56°. There are a spread of Fe–O bond distances ranging from 1.98–2.09 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Mg2+ and three equivalent Fe3+ atoms to form distorted OMg2Fe3 trigonal bipyramids that share corners with five equivalent OMg2Fe2 tetrahedra, corners with two equivalent OMg2Fe3 trigonal bipyramids, an edgeedge with one OMg2Fe2 tetrahedra, and edges with five equivalent OMg2Fe3 trigonal bipyramids. In the second O2- site, O2- is bonded in a distorted square co-planar geometry to two equivalent Mg2+ and four equivalent Fe3+ atoms. In the third O2- site, O2- is bonded to two equivalent Mg2+ and two equivalent Fe3+ atoms to form OMg2Fe2 tetrahedra that share corners with two equivalent OMg2Fe2 tetrahedra, corners with ten equivalent OMg2Fe3 trigonal bipyramids, and edges with two equivalent OMg2Fe3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

MgFe2O4 crystallizes in the orthorhombic Pmc2_1 space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.23–2.60 Å. In the second Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.22–2.53 Å. There are four inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–63°. There are a spread of Fe–O bond distances ranging from 1.92–2.02 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–65°. There are a spread of Fe–O bond distances ranging from 1.96–2.09 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–63°. There are a spread of Fe–O bond distances ranging from 1.98–2.10 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–65°. There are a spread of Fe–O bond distances ranging from 1.98–2.09 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Fe3 trigonal bipyramids. In the second O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Fe3 trigonal bipyramids. In the third O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Fe3+ atoms. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Fe3+ atoms. In the fifth O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Fe3 trigonal bipyramids. In the sixth O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Fe3 square pyramids. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Mg2+ and three Fe3+ atoms. In the eighth O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OMg2Fe3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

MgFe2O4 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.19–2.53 Å. In the second Mg2+ site, Mg2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Mg–O bond distances ranging from 2.20–2.53 Å. There are four inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Fe–O bond distances ranging from 1.90–2.00 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Fe–O bond distances ranging from 1.90–2.00 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Fe–O bond distances ranging from 1.90–2.01 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Fe–O bond distances ranging from 1.91–2.01 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OMg2Fe3 trigonal bipyramids. In the second O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OMg2Fe3 trigonal bipyramids. In the third O2- site, O2- is bonded to two equivalent Mg2+ and three equivalent Fe3+ atoms to form a mixture of distorted corner and edge-sharing OMg2Fe3 trigonal bipyramids. In the fourth O2- site, O2- is bonded to two equivalent Mg2+ and three equivalent Fe3+ atoms to form a mixture of distorted corner and edge-sharing OMg2Fe3 trigonal bipyramids. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Fe3+ atoms. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to two Mg2+ and three Fe3+ atoms. In the seventh O2- site, O2- is bonded to two equivalent Mg2+ and three equivalent Fe3+ atoms to form a mixture of distorted corner and edge-sharing OMg2Fe3 trigonal bipyramids. In the eighth O2- site, O2- is bonded to two equivalent Mg2+ and three equivalent Fe3+ atoms to form a mixture of distorted corner and edge-sharing OMg2Fe3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

MgFe2O4 is Spinel-like structured and crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent MgO6 octahedra, and edges with four equivalent FeO6 octahedra. There are four shorter (2.09 Å) and two longer (2.10 Å) Mg–O bond lengths. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six equivalent MgO6 octahedra and corners with six equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–57°. There is two shorter (1.91 Å) and two longer (1.97 Å) Fe–O bond length. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent FeO6 octahedra, and edges with four equivalent MgO6 octahedra. There are two shorter (2.04 Å) and four longer (2.07 Å) Fe–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg2+ and two Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

MgFe2O4 is Spinel-like structured and crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are six inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with three MgO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–59°. There are a spread of Mg–O bond distances ranging from 1.99–2.02 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six FeO4 tetrahedra, edges with two MgO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.09–2.11 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent MgO4 tetrahedra, corners with four FeO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.08–2.11 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six FeO4 tetrahedra, edges with two MgO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.09–2.11 Å. In the fifth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six FeO4 tetrahedra, edges with two MgO6 octahedra, and edges with four equivalent FeO6 octahedra. There are five shorter (2.09 Å) and one longer (2.10 Å) Mg–O bond lengths. In the sixth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share a cornercorner with one MgO4 tetrahedra, corners with five FeO4 tetrahedra, an edgeedge with one MgO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.07–2.10 Å. There are nine inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent MgO4 tetrahedra, corners with four FeO4 tetrahedra, edges with three MgO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.09 Å. In the second Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six MgO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–57°. There are a spread of Fe–O bond distances ranging from 1.91–1.97 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent MgO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, edges with two MgO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.99–2.10 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra, edges with two equivalent FeO6 octahedra, and edges with four MgO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.03–2.07 Å. In the fifth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six MgO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–57°. There are a spread of Fe–O bond distances ranging from 1.91–1.96 Å. In the sixth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one MgO4 tetrahedra, corners with five FeO4 tetrahedra, edges with three MgO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.00–2.10 Å. In the seventh Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six MgO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedral tilt angles are 57°. There is two shorter (1.91 Å) and two longer (1.97 Å) Fe–O bond length. In the eighth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six MgO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–58°. There is two shorter (1.91 Å) and two longer (1.97 Å) Fe–O bond length. In the ninth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three MgO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–58°. There is three shorter (1.93 Å) and one longer (1.98 Å) Fe–O bond length. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the ninth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the eleventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the twelfth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the thirteenth O2- site, O2- is bonded to two Mg2+ and two equivalent Fe3+ atoms to form distorted corner-sharing OMg2Fe2 trigonal pyramids. In the fourteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the sixteenth O2- site, O2- is bonded to four Fe3+ atoms to form distorted OFe4 trigonal pyramids that share corners with four OMg2Fe2 trigonal pyramids and edges with three OMgFe3 trigonal pyramids. In the seventeenth O2- site, O2- is bonded to one Mg2+ and three Fe3+ atoms to form distorted OMgFe3 trigonal pyramids that share corners with four OMg2Fe2 trigonal pyramids and edges with three OFe4 trigonal pyramids. In the eighteenth O2- site, O2- is bonded to one Mg2+ and three Fe3+ atoms to form distorted OMgFe3 trigonal pyramids that share corners with three equivalent OMg2Fe2 trigonal pyramids and edges with three OFe4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

MgFe2O4 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 distorted MgO6 pentagonal pyramids that share corners with six FeO6 octahedra, edges with six FeO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 3–17°. There are a spread of Mg–O bond distances ranging from 2.09–2.26 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 pentagonal pyramids that share corners with twelve FeO6 octahedra, edges with two equivalent MgO6 pentagonal pyramids, and faces with two FeO6 octahedra. The corner-sharing octahedra tilt angles range from 44–53°. There are a spread of Mg–O bond distances ranging from 2.14–2.23 Å. There are six inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with five MgO6 pentagonal pyramids, edges with six FeO6 octahedra, an edgeedge with one MgO6 pentagonal pyramid, and a faceface with one MgO6 pentagonal pyramid. There are a spread of Fe–O bond distances ranging from 2.00–2.17 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with five MgO6 pentagonal pyramids, edges with six FeO6 octahedra, an edgeedge with one MgO6 pentagonal pyramid, and a faceface with one MgO6 pentagonal pyramid. There are a spread of Fe–O bond distances ranging from 2.00–2.18 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent MgO6 pentagonal pyramids, edges with six FeO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 1.99–2.08 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent MgO6 pentagonal pyramids, edges with six FeO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 1.99–2.08 Å. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent MgO6 pentagonal pyramids, edges with six FeO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 2.00–2.08 Å. In the sixth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent MgO6 pentagonal pyramids, edges with six FeO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 2.00–2.08 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the fifth O2- site, O2- is bonded to two Mg2+ and three Fe3+ atoms to form a mixture of edge and corner-sharing OMg2Fe3 trigonal bipyramids. In the sixth O2- site, O2- is bonded to two Mg2+ and three Fe3+ atoms to form a mixture of edge and corner-sharing OMg2Fe3 trigonal bipyramids. In the seventh O2- site, O2- is bonded to two Mg2+ and three Fe3+ atoms to form a mixture of edge and corner-sharing OMg2Fe3 trigonal bipyramids. In the eighth O2- site, O2- is bonded to two Mg2+ and three Fe3+ atoms to form a mixture of edge and corner-sharing OMg2Fe3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

MgFe2O4 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with four FeO6 octahedra, corners with four FeO5 trigonal bipyramids, an edgeedge with one FeO5 trigonal bipyramid, edges with two equivalent MgO5 trigonal bipyramids, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 40–61°. There are two shorter (2.04 Å) and three longer (2.08 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with four FeO6 octahedra, corners with four FeO5 trigonal bipyramids, an edgeedge with one FeO5 trigonal bipyramid, edges with two equivalent MgO5 trigonal bipyramids, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 40–60°. There are two shorter (2.04 Å) and three longer (2.08 Å) Mg–O bond lengths. There are four inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to five O2- atoms to form distorted FeO5 trigonal bipyramids that share corners with four FeO6 octahedra, corners with four MgO5 trigonal bipyramids, an edgeedge with one MgO5 trigonal bipyramid, and edges with two equivalent FeO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 51°. There are a spread of Fe–O bond distances ranging from 1.93–2.06 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four MgO5 trigonal bipyramids, corners with four FeO5 trigonal bipyramids, edges with four FeO6 octahedra, and a faceface with one MgO5 trigonal bipyramid. There are a spread of Fe–O bond distances ranging from 1.95–2.18 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four MgO5 trigonal bipyramids, corners with four FeO5 trigonal bipyramids, edges with four FeO6 octahedra, and a faceface with one MgO5 trigonal bipyramid. There are a spread of Fe–O bond distances ranging from 1.95–2.18 Å. In the fourth Fe3+ site, Fe3+ is bonded to five O2- atoms to form distorted FeO5 trigonal bipyramids that share corners with four FeO6 octahedra, corners with four MgO5 trigonal bipyramids, an edgeedge with one MgO5 trigonal bipyramid, and edges with two equivalent FeO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 51°. There are a spread of Fe–O bond distances ranging from 1.92–2.07 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to one Mg2+ and three Fe3+ atoms to form distorted OMgFe3 tetrahedra that share corners with two equivalent OMgFe3 tetrahedra, a cornercorner with one OMg2Fe3 trigonal bipyramid, and edges with two equivalent OMg2Fe3 trigonal bipyramids. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe3+ atoms. In the fourth O2- site, O2- is bonded to one Mg2+ and three Fe3+ atoms to form distorted OMgFe3 tetrahedra that share corners with two equivalent OMgFe3 tetrahedra, a cornercorner with one OMg2Fe3 trigonal bipyramid, and edges with two equivalent OMg2Fe3 trigonal bipyramids. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Mg2+ and two equivalent Fe3+ atoms. In the sixth O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form distorted OMg2Fe3 trigonal bipyramids that share a cornercorner with one OMgFe3 tetrahedra, edges with two equivalent OMgFe3 tetrahedra, and edges with four OMg2Fe3 trigonal bipyramids. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Mg2+ and two equivalent Fe3+ atoms. In the eighth O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form distorted OMg2Fe3 trigonal bipyramids that share a cornercorner with one OMgFe3 tetrahedra, edges with two equivalent OMgFe3 tetrahedra, and edges with four OMg2Fe3 trigonal bipyramids.

36 MATERIALS SCIENCE↗