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DOE OSTI2020

Materials Data on Ti(FeO2)2 by Materials Project

Fe2TiO4 is Spinel-like structured and crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent TiO6 octahedra, and edges with four equivalent FeO6 octahedra. There is two shorter (1.97 Å) and four longer (2.02 Å) Ti–O bond length. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six equivalent TiO6 octahedra and corners with six equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 52–62°. There are two shorter (2.03 Å) and two longer (2.07 Å) Fe–O bond lengths. In the second Fe2+ site, Fe2+ 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 TiO6 octahedra. There are four shorter (2.13 Å) and two longer (2.21 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 two equivalent Ti4+ and two Fe2+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ti4+ and three Fe2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(FeO2)2 by Materials Project

ZnFe2O4 is Spinel-like structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are six 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 FeO4 tetrahedra, corners with five ZnO4 tetrahedra, an edgeedge with one ZnO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.02–2.11 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six ZnO4 tetrahedra and edges with six FeO6 octahedra. There are three shorter (2.05 Å) and three longer (2.06 Å) Fe–O bond lengths. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six ZnO4 tetrahedra and edges with six FeO6 octahedra. There are three shorter (2.03 Å) and three longer (2.06 Å) Fe–O bond lengths. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four ZnO4 tetrahedra, an edgeedge with one ZnO6 octahedra, and edges with five FeO6 octahedra. There are four shorter (2.05 Å) and two longer (2.07 Å) Fe–O bond lengths. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six ZnO4 tetrahedra and edges with six FeO6 octahedra. There are three shorter (2.04 Å) and three longer (2.06 Å) Fe–O bond lengths. In the sixth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three equivalent ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–59°. There is three shorter (1.94 Å) and one longer (1.95 Å) Fe–O bond length. There are six inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with three equivalent ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–59°. There are three shorter (1.98 Å) and one longer (2.05 Å) Zn–O bond lengths. In the second Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedral tilt angles are 58°. There are one shorter (2.00 Å) and three longer (2.01 Å) Zn–O bond lengths. In the third Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with three equivalent FeO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, and edges with six FeO6 octahedra. There are three shorter (2.10 Å) and three longer (2.16 Å) Zn–O bond lengths. In the fourth Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 58–59°. There are one shorter (1.99 Å) and three longer (2.01 Å) Zn–O bond lengths. In the fifth Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–59°. There are three shorter (2.01 Å) and one longer (2.02 Å) Zn–O bond lengths. In the sixth Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–59°. There are three shorter (2.00 Å) and one longer (2.03 Å) Zn–O bond lengths. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Fe3+ and two Zn2+ atoms. In the second O2- site, O2- is bonded to three equivalent Fe3+ and one Zn2+ atom to form distorted corner-sharing OZnFe3 trigonal pyramids. In the third O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form a mixture of distorted corner and edge-sharing OZnFe3 trigonal pyramids. In the fourth O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form a mixture of distorted corner and edge-sharing OZnFe3 trigonal pyramids. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe3+ atoms. In the sixth O2- site, O2- is bonded to three equivalent Fe3+ and one Zn2+ atom to form a mixture of distorted corner and edge-sharing OZnFe3 trigonal pyramids. In the seventh O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form a mixture of distorted corner and edge-sharing OZnFe3 trigonal pyramids. In the eighth O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form a mixture of distorted corner and edge-sharing OZnFe3 trigonal pyramids. In the ninth O2- site, O2- is bonded to three equivalent Fe3+ and one Zn2+ atom to form a mixture of distorted corner and edge-sharing OZnFe3 trigonal pyramids. In the tenth O2- site, O2- is bonded to three equivalent Fe3+ and one Zn2+ atom to form a mixture of distorted corner and edge-sharing OZnFe3 trigonal pyramids. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the twelfth O2- site, O2- is bonded to three equivalent Fe3+ and one Zn2+ atom to form distorted corner-sharing OZnFe3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(FeO2)2 by Materials Project

ZnFe2O4 is Spinel-like structured and crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. 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 FeO6 octahedra and corners with six equivalent ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 54–58°. There is two shorter (1.92 Å) and two longer (1.94 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 ZnO6 octahedra. There are two shorter (2.03 Å) and four longer (2.06 Å) Fe–O bond lengths. Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent ZnO6 octahedra, and edges with four equivalent FeO6 octahedra. There are four shorter (2.10 Å) and two longer (2.16 Å) Zn–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two equivalent Zn2+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(FeO2)2 by Materials Project

ZnFe2O4 is Spinel-like structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. 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 three FeO4 tetrahedra, corners with three ZnO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four equivalent FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.10 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one FeO4 tetrahedra, corners with five ZnO4 tetrahedra, an edgeedge with one ZnO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.11 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six ZnO4 tetrahedra and edges with six FeO6 octahedra. There are three shorter (2.02 Å) and three longer (2.07 Å) Fe–O bond lengths. In the fourth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three equivalent ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–58°. There is three shorter (1.94 Å) and one longer (1.97 Å) Fe–O bond length. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four ZnO4 tetrahedra, an edgeedge with one ZnO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.04–2.08 Å. In the sixth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three equivalent ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–59°. There is three shorter (1.93 Å) and one longer (1.97 Å) Fe–O bond length. There are six inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with three equivalent ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–59°. There are three shorter (1.99 Å) and one longer (2.03 Å) Zn–O bond lengths. In the second Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with three equivalent ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–59°. There are three shorter (1.98 Å) and one longer (2.03 Å) Zn–O bond lengths. In the third Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with three equivalent FeO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, and edges with six FeO6 octahedra. There are three shorter (2.11 Å) and three longer (2.14 Å) Zn–O bond lengths. In the fourth Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–59°. There is one shorter (1.98 Å) and three longer (2.01 Å) Zn–O bond length. In the fifth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with three equivalent FeO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, and edges with six FeO6 octahedra. There are three shorter (2.10 Å) and three longer (2.15 Å) Zn–O bond lengths. In the sixth Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–60°. There are three shorter (2.01 Å) and one longer (2.06 Å) Zn–O bond lengths. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Fe3+ and two Zn2+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Fe3+ and one Zn2+ atom. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Fe3+ and two Zn2+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Fe3+ and one Zn2+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to four Fe3+ atoms. In the seventh O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form a mixture of distorted edge and corner-sharing OZnFe3 trigonal pyramids. In the eighth O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form a mixture of distorted edge and corner-sharing OZnFe3 trigonal pyramids. In the ninth O2- site, O2- is bonded to three equivalent Fe3+ and one Zn2+ atom to form a mixture of distorted edge and corner-sharing OZnFe3 trigonal pyramids. In the tenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe3+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the twelfth O2- site, O2- is bonded to three equivalent Fe3+ and one Zn2+ atom to form distorted corner-sharing OZnFe3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

MgFe2O4 is Spinel-like structured and crystallizes in the triclinic P1 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 55–60°. There are a spread of Mg–O bond distances ranging from 1.99–2.03 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 2.08–2.12 Å. In the third 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 2.06–2.11 Å. In the fourth 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 2.07–2.10 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 FeO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.08–2.12 Å. In the sixth 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 2.07–2.11 Å. There are twelve inequivalent Fe3+ sites. In the first 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 55–59°. There are a spread of Fe–O bond distances ranging from 1.90–1.96 Å. In the second 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 2.00–2.07 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 1.94–2.04 Å. In the fourth 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 2.00–2.08 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 55–59°. There are a spread of Fe–O bond distances ranging from 1.90–1.94 Å. In the sixth 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 2.03–2.09 Å. In the seventh 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 1.97–2.13 Å. In the eighth 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 1.99–2.08 Å. In the ninth 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 54–58°. There are a spread of Fe–O bond distances ranging from 1.91–1.94 Å. In the tenth 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 1.98–2.09 Å. In the eleventh 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 55–59°. There are a spread of Fe–O bond distances ranging from 1.90–1.97 Å. In the twelfth 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 55–60°. There are a spread of Fe–O bond distances ranging from 1.91–1.98 Å. There are twenty-four 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 rectangular see-saw-like geometry to two Mg2+ and two 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 in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to two Mg2+ and two Fe3+ atoms. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the ninth O2- site, O2- is bonded in a distorted trigonal pyramidal 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 rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to two Mg2+ and two Fe3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the nineteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the twentieth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Mg2+ and two Fe3+ atoms. In the twenty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the twenty-fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three 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 Zn(FeO2)2 by Materials Project

ZnFe2O4 is Spinel-like structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. 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 three equivalent ZnO6 octahedra and corners with nine equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–58°. There is three shorter (1.94 Å) and one longer (1.99 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 three equivalent FeO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, edges with two equivalent ZnO6 octahedra, and edges with four equivalent FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.11 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with three equivalent ZnO6 octahedra and corners with nine equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–59°. There are three shorter (1.99 Å) and one longer (2.02 Å) Zn–O bond lengths. In the second Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with three equivalent FeO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, and edges with six equivalent FeO6 octahedra. There are three shorter (2.11 Å) and three longer (2.13 Å) Zn–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the second O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to four Fe3+ atoms. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Fe3+ and one Zn2+ atom. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Fe3+ and two Zn2+ atoms.

36 MATERIALS SCIENCE↗
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 Mn(FeO2)2 by Materials Project

MnFe2O4 is Spinel-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are ten inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded to four O2- atoms to form MnO4 tetrahedra that share corners with two equivalent MnO6 octahedra and corners with ten FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–63°. There are a spread of Mn–O bond distances ranging from 2.06–2.09 Å. In the second Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four MnO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Mn–O bond distances ranging from 2.00–2.19 Å. In the third Mn2+ site, Mn2+ is bonded to four O2- atoms to form MnO4 tetrahedra that share corners with three MnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–63°. There are a spread of Mn–O bond distances ranging from 2.05–2.08 Å. In the fourth Mn2+ site, Mn2+ is bonded to four O2- atoms to form MnO4 tetrahedra that share corners with three MnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–60°. There are a spread of Mn–O bond distances ranging from 2.05–2.09 Å. In the fifth Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with three MnO4 tetrahedra, corners with three FeO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Mn–O bond distances ranging from 2.01–2.24 Å. In the sixth Mn2+ site, Mn2+ is bonded to four O2- atoms to form MnO4 tetrahedra that share corners with three MnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 55–64°. There are a spread of Mn–O bond distances ranging from 2.03–2.07 Å. In the seventh Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with three MnO4 tetrahedra, corners with three FeO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Mn–O bond distances ranging from 2.08–2.25 Å. In the eighth Mn2+ site, Mn2+ is bonded to four O2- atoms to form MnO4 tetrahedra that share a cornercorner with one MnO6 octahedra and corners with eleven FeO6 octahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of Mn–O bond distances ranging from 2.06–2.10 Å. In the ninth Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with three MnO4 tetrahedra, corners with three FeO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Mn–O bond distances ranging from 2.01–2.18 Å. In the tenth Mn2+ site, Mn2+ is bonded to four O2- atoms to form MnO4 tetrahedra that share a cornercorner with one MnO6 octahedra and corners with eleven FeO6 octahedra. The corner-sharing octahedra tilt angles range from 58–62°. There are a spread of Mn–O bond distances ranging from 2.07–2.10 Å. There are twenty 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 FeO4 tetrahedra, corners with four MnO4 tetrahedra, edges with two equivalent MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.05–2.09 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six MnO4 tetrahedra, an edgeedge with one MnO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.04 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra, corners with four MnO4 tetrahedra, edges with two equivalent MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.03–2.08 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three MnO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.00–2.14 Å. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent MnO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, edges with two MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.02–2.08 Å. In the sixth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three MnO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.99–2.15 Å. In the seventh Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three MnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 55–63°. There are a spread of Fe–O bond distances ranging from 2.01–2.09 Å. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three MnO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.11 Å. In the ninth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent MnO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, edges with two MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.03–2.11 Å. In the tenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three MnO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.12 Å. In the eleventh Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three MnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 53–61°. There are a spread of Fe–O bond distances ranging from 1.92–1.99 Å. In the twelfth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent MnO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, edges with two MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.00–2.09 Å. In the thirteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three MnO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.02–2.09 Å. In the fourteenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three MnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of Fe–O bond distances ranging from 2.02–2.08 Å. In the fifteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent MnO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, an edgeedge with one MnO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.04–2.08 Å. In the sixteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three MnO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent MnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.04–2.09 Å. In the seventeenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one FeO4 tetrahedra, corners with five MnO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.03 Å. In the eighteenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with two equivalent MnO6 octahedra and corners with ten FeO6 octahedra. The corner-sharing octahedra tilt angles range from 55–62°. There are a spread of Fe–O bond distances ranging from 2.00–2.09 Å. In the nineteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one FeO4 tetrahedra, corners with five MnO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.05–2.10 Å. In the twentieth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one FeO4 tetrahedra, corners with five MnO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.04–2.08 Å. There are forty inequivalent O2- sites. In the first O2- site, O2- is bonded to two Mn2+ and two Fe3+ atoms to form distorted OMn2Fe2 tetrahedra that share corners with four OMnFe3 tetrahedra, corners with five OMnFe3 trigonal pyramids, and an edgeedge with one OMn2Fe2 trigonal pyramid. In the second O2- site, O2- is bonded to two Mn2+ and two Fe3+ atoms to form a mixture of distorted edge and corner-sharing OMn2Fe2 trigonal pyramids. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Mn2+ and two Fe3+ atoms. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Mn2+ and three Fe3+ atoms. In the fifth O2- site, O2- is bonded to two Mn2+ and two Fe3+ atoms to form distorted OMn2Fe2 trigonal pyramids that share corners with two equivalent OMnFe3 tetrahedra and corners with three OFe4 trigonal pyramids. In the sixth O2- site, O2- is bonded to four Fe3+ atoms to form distorted OFe4 trigonal pyramids that share corners with two OMnFe3 tetrahedra, corners with four OMn2Fe2 trigonal pyramids, an edgeedge with one OMn2Fe2 tetrahedra, and an edgeedge with one OMnFe3 trigonal pyramid. In the seventh O2- site, O2- is bonded to two Mn2+ and two Fe3+ atoms to form a mixture of distorted edge and corner-sharing OMn2Fe2 tetrahedra. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mn2+ and two Fe3+ atoms. In the ninth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Mn2+ and two Fe3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mn2+ and three Fe3+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mn2+ and three Fe3+ atoms. In the twelfth O2- site, O2- is bonded to one Mn2+ and three Fe3+ atoms to form distorted OMnFe3 trigonal pyramids that share corners with three OMnFe3 tetrahedra, corners with four OMn2Fe2 trigonal pyramids, an edgeedge with one OMn2Fe2 tetrahedra, and an edgeedge with one OFe4 trigonal pyramid. In the thirteenth O2- site, O2- is bonded to two Mn2+ and two Fe3+ atoms to form a mixture of distorted edge and corner-sharing OMn2Fe2 trigonal pyramids. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the fifteenth O2- site, O2- is bonded to one Mn2+ and three Fe3+ atoms to form distorted corner-sharing OMnFe3 tetrahedra. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mn2+ and three Fe3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Mn2+ and two Fe3+ atoms. In the eighteenth O2- site, O2- is bonded to two Mn2+ and two Fe3+ atoms to form a mixture of distorted edge and corner-sharing OMn2Fe2 trigonal pyramids. In the nineteenth O2- site, O2- is bonded in a rec

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(FeO2)2 by Materials Project

ZnFe2O4 is Spinel-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twenty inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, edges with three FeO6 octahedra, and edges with three ZnO6 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 six O2- atoms to form FeO6 octahedra that share corners with three FeO4 tetrahedra, corners with three ZnO4 tetrahedra, edges with two equivalent ZnO6 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 third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three FeO4 tetrahedra, corners with three ZnO4 tetrahedra, edges with two equivalent ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.99–2.11 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.00–2.09 Å. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three FeO4 tetrahedra, corners with three ZnO4 tetrahedra, edges with two equivalent ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.10 Å. In the sixth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 55–60°. There are a spread of Fe–O bond distances ranging from 1.92–1.97 Å. In the seventh Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three FeO4 tetrahedra, corners with three ZnO4 tetrahedra, edges with two equivalent ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.14 Å. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO4 tetrahedra, corners with three equivalent ZnO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.02–2.08 Å. In the ninth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with five ZnO6 octahedra and corners with seven FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–61°. There are a spread of Fe–O bond distances ranging from 1.91–1.96 Å. In the tenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent ZnO4 tetrahedra, corners with four FeO4 tetrahedra, edges with two equivalent ZnO6 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 eleventh Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There is two shorter (1.92 Å) and two longer (1.95 Å) Fe–O bond length. In the twelfth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent ZnO4 tetrahedra, corners with four FeO4 tetrahedra, edges with two equivalent ZnO6 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 thirteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra, edges with three FeO6 octahedra, and edges with three ZnO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.04 Å. In the fourteenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six FeO6 octahedra and corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 53–60°. There are a spread of Fe–O bond distances ranging from 1.90–1.96 Å. In the fifteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra, edges with two FeO6 octahedra, and edges with four ZnO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.02 Å. In the sixteenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with four ZnO6 octahedra and corners with eight FeO6 octahedra. The corner-sharing octahedra tilt angles range from 53–60°. There are a spread of Fe–O bond distances ranging from 1.89–2.01 Å. In the seventeenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra, edges with two FeO6 octahedra, and edges with four ZnO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.02 Å. In the eighteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one ZnO4 tetrahedra, corners with five FeO4 tetrahedra, edges with two FeO6 octahedra, and edges with four ZnO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.00–2.10 Å. In the nineteenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six FeO6 octahedra and corners with six ZnO6 octahedra. The corner-sharing octahedra tilt angles range from 55–59°. There are a spread of Fe–O bond distances ranging from 1.88–1.99 Å. In the twentieth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with five ZnO6 octahedra and corners with seven FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Fe–O bond distances ranging from 1.89–1.95 Å. There are ten inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with four ZnO6 octahedra and corners with eight FeO6 octahedra. The corner-sharing octahedra tilt angles range from 55–60°. There are a spread of Zn–O bond distances ranging from 1.96–2.02 Å. In the second Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with three ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–59°. There are a spread of Zn–O bond distances ranging from 1.97–1.99 Å. In the third Zn2+ site, Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with three ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–61°. There are a spread of Zn–O bond distances ranging from 1.97–2.03 Å. In the fourth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with three FeO4 tetrahedra, corners with three ZnO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.09–2.13 Å. In the fifth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with three FeO4 tetrahedra, corners with three ZnO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.06–2.14 Å. In the sixth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six FeO4 tetrahedra, edges with two equivalent ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.07–2.18 Å. In the seventh Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with two equivalent ZnO4 tetrahedra, corners with four FeO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.08–2.14 Å. In the eighth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six FeO4 tetrahedra, edges with two equivalent ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.07–2.17 Å. In the ninth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share a cornercorner with one ZnO4 tetrahedra, corners with five FeO4 tetrahedra, edges with two equivalent ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.01–2.20 Å. In the tenth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share a cornercorner with one ZnO4 tetrahedra, corners with five FeO4 tetrahedra, edges with two equivalent ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.02–2.19 Å. There are forty inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe3+ atoms. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to three Fe3+ and one Zn2+ atom. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the nineteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the twenty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the twenty-third O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the twenty-fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the twenty-fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the twenty-sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the twent

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Be(FeO2)2 by Materials Project

BeFe2O4 is Ilmenite-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are four inequivalent Be2+ sites. In the first Be2+ site, Be2+ is bonded to four O2- atoms to form BeO4 tetrahedra that share corners with six FeO6 octahedra and edges with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of Be–O bond distances ranging from 1.59–1.70 Å. In the second Be2+ site, Be2+ is bonded to four O2- atoms to form BeO4 tetrahedra that share corners with six FeO6 octahedra and edges with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of Be–O bond distances ranging from 1.59–1.71 Å. In the third Be2+ site, Be2+ is bonded to four O2- atoms to form BeO4 tetrahedra that share corners with six FeO6 octahedra and edges with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of Be–O bond distances ranging from 1.59–1.70 Å. In the fourth Be2+ site, Be2+ is bonded to four O2- atoms to form BeO4 tetrahedra that share corners with six FeO6 octahedra and edges with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 58–61°. There are a spread of Be–O bond distances ranging from 1.59–1.71 Å. There are eight inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four FeO6 octahedra, corners with two BeO4 tetrahedra, edges with four FeO6 octahedra, and edges with two BeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Fe–O bond distances ranging from 2.03–2.06 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four FeO6 octahedra, corners with two BeO4 tetrahedra, edges with four FeO6 octahedra, and edges with two BeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–60°. There are a spread of Fe–O bond distances ranging from 2.03–2.06 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with eight FeO6 octahedra, corners with four BeO4 tetrahedra, edges with two FeO6 octahedra, and an edgeedge with one BeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–60°. There are a spread of Fe–O bond distances ranging from 2.01–2.15 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with eight FeO6 octahedra, corners with four BeO4 tetrahedra, edges with two FeO6 octahedra, and an edgeedge with one BeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–60°. There are a spread of Fe–O bond distances ranging from 2.01–2.15 Å. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four FeO6 octahedra, corners with two BeO4 tetrahedra, edges with four FeO6 octahedra, and edges with two BeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 53–61°. There are a spread of Fe–O bond distances ranging from 2.02–2.06 Å. In the sixth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four FeO6 octahedra, corners with two BeO4 tetrahedra, edges with four FeO6 octahedra, and edges with two BeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Fe–O bond distances ranging from 2.02–2.06 Å. In the seventh Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with eight FeO6 octahedra, corners with four BeO4 tetrahedra, edges with two FeO6 octahedra, and an edgeedge with one BeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–61°. There are a spread of Fe–O bond distances ranging from 2.01–2.15 Å. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with eight FeO6 octahedra, corners with four BeO4 tetrahedra, edges with two FeO6 octahedra, and an edgeedge with one BeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–61°. There are a spread of Fe–O bond distances ranging from 2.01–2.15 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Be2+ and three Fe3+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Be2+ and three Fe3+ atoms. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to one Be2+ and three Fe3+ atoms. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Be2+ and three Fe3+ atoms. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Be2+ and three Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Be(FeO2)2 by Materials Project

BeFe2O4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Be2+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.52 Å) and two longer (1.56 Å) Be–O bond length. There are two 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 54–62°. There are a spread of Fe–O bond distances ranging from 1.97–2.13 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 54–62°. There are a spread of Fe–O bond distances ranging from 2.05–2.09 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe3+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Be2+ and two equivalent Fe3+ atoms. In the third O2- site, O2- is bonded to one Be2+ and three Fe3+ atoms to form distorted corner-sharing OBeFe3 tetrahedra. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Be2+ and three Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd(FeO2)2 by Materials Project

CdFe2O4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two 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 49–58°. 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 six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–58°. There are a spread of Fe–O bond distances ranging from 2.01–2.09 Å. Cd2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Cd–O bond distances ranging from 2.39–2.65 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent Fe3+ and two equivalent Cd2+ atoms to form distorted edge-sharing OCd2Fe3 square pyramids. In the second O2- site, O2- is bonded in a 5-coordinate geometry to three equivalent Fe3+ and two equivalent Cd2+ atoms. In the third O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Cd2+ atoms. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Cd2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti(FeO2)2 by Materials Project

Fe2TiO4 is Spinel-like structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent TiO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.90–2.10 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent TiO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.97–2.01 Å. There are three inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ 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 TiO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.11–2.20 Å. In the second Fe2+ site, Fe2+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six TiO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–66°. There are three shorter (2.04 Å) and one longer (2.06 Å) Fe–O bond lengths. In the third Fe2+ site, Fe2+ 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 TiO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.09–2.24 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ti4+ and three Fe2+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ti4+ and two Fe2+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ti4+ and three Fe2+ atoms. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two Ti4+ and two Fe2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(FeO2)2 by Materials Project

CaFe2O4 crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Ca2+ is bonded in a body-centered cubic geometry to eight O2- atoms. All Ca–O bond lengths are 2.47 Å. Fe3+ is bonded in a square co-planar geometry to four O2- atoms. All Fe–O bond lengths are 1.92 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca2+ and two equivalent Fe3+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca2+ and two equivalent Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al(FeO2)2 by Materials Project

AlFe2O4 is Spinel structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent AlO4 tetrahedra and edges with six FeO6 octahedra. All Fe–O bond lengths are 2.11 Å. In the second Fe+2.50+ site, Fe+2.50+ is bonded to six equivalent O2- atoms to form FeO6 octahedra that share corners with six equivalent AlO4 tetrahedra and edges with six equivalent FeO6 octahedra. All Fe–O bond lengths are 2.07 Å. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–55°. There is one shorter (1.79 Å) and three longer (1.82 Å) Al–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe+2.50+ and one Al3+ atom. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three equivalent Fe+2.50+ and one Al3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(FeO2)2 by Materials Project

YFe2O4 is Spinel structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Y3+ is bonded to four O2- atoms to form YO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–61°. There are one shorter (2.11 Å) and three longer (2.16 Å) Y–O bond lengths. There are two inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent YO4 tetrahedra and edges with six FeO6 octahedra. All Fe–O bond lengths are 2.14 Å. In the second Fe+2.50+ site, Fe+2.50+ is bonded to six equivalent O2- atoms to form FeO6 octahedra that share corners with six equivalent YO4 tetrahedra and edges with six equivalent FeO6 octahedra. All Fe–O bond lengths are 2.08 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to one Y3+ and three Fe+2.50+ atoms to form a mixture of distorted corner and edge-sharing OYFe3 trigonal pyramids. In the second O2- site, O2- is bonded to one Y3+ and three equivalent Fe+2.50+ atoms to form a mixture of distorted corner and edge-sharing OYFe3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(FeO2)2 by Materials Project

ZnFe2O4 is Spinel structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent ZnO4 tetrahedra and edges with six FeO6 octahedra. There are two shorter (2.03 Å) and four longer (2.05 Å) Fe–O bond lengths. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent ZnO4 tetrahedra and edges with six FeO6 octahedra. There are four shorter (1.99 Å) and two longer (2.01 Å) Fe–O bond lengths. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent ZnO4 tetrahedra and edges with six FeO6 octahedra. There are two shorter (2.02 Å) and four longer (2.05 Å) Fe–O bond lengths. Zn2+ is bonded to four O2- atoms to form ZnO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 57–59°. There is one shorter (1.97 Å) and three longer (2.01 Å) Zn–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form a mixture of distorted corner and edge-sharing OZnFe3 trigonal pyramids. In the second O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form a mixture of distorted corner and edge-sharing OZnFe3 trigonal pyramids. In the third O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form a mixture of distorted corner and edge-sharing OZnFe3 trigonal pyramids.

36 MATERIALS SCIENCE↗