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DOE OSTI2020

Materials Data on Fe3O4 by Materials Project

Fe3O4 is Spinel-derived structured and crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are seven inequivalent Fe+2.67+ sites. In the first Fe+2.67+ site, Fe+2.67+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–59°. There is one shorter (1.90 Å) and three longer (1.94 Å) Fe–O bond length. In the second Fe+2.67+ site, Fe+2.67+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are two shorter (2.09 Å) and four longer (2.15 Å) Fe–O bond lengths. In the third Fe+2.67+ site, Fe+2.67+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. All Fe–O bond lengths are 2.06 Å. In the fourth Fe+2.67+ site, Fe+2.67+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are two shorter (2.07 Å) and four longer (2.16 Å) Fe–O bond lengths. In the fifth Fe+2.67+ site, Fe+2.67+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are four shorter (2.05 Å) and two longer (2.07 Å) Fe–O bond lengths. In the sixth Fe+2.67+ site, Fe+2.67+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.05–2.13 Å. In the seventh Fe+2.67+ site, Fe+2.67+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 55–58°. There is three shorter (1.92 Å) and one longer (1.96 Å) Fe–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.67+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.67+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.67+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.67+ atoms. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe+2.67+ atoms. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3O4 by Materials Project

Fe3O4 is Spinel-derived structured and crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. there are seven inequivalent Fe+2.67+ sites. In the first Fe+2.67+ site, Fe+2.67+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. All Fe–O bond lengths are 2.04 Å. In the second Fe+2.67+ site, Fe+2.67+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are four shorter (2.14 Å) and two longer (2.18 Å) Fe–O bond lengths. In the third Fe+2.67+ site, Fe+2.67+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are four shorter (2.04 Å) and two longer (2.06 Å) Fe–O bond lengths. In the fourth Fe+2.67+ site, Fe+2.67+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are four shorter (2.15 Å) and two longer (2.16 Å) Fe–O bond lengths. In the fifth Fe+2.67+ site, Fe+2.67+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Fe–O bond distances ranging from 1.91–1.94 Å. In the sixth Fe+2.67+ site, Fe+2.67+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 53–60°. There are a spread of Fe–O bond distances ranging from 1.91–1.95 Å. In the seventh Fe+2.67+ site, Fe+2.67+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.07–2.12 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.67+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.67+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.67+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.67+ atoms. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.67+ atoms. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe2O3 by Materials Project

Fe2O3 crystallizes in the trigonal P3 space group. The structure is three-dimensional. there are eight inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to four O2- atoms to form distorted FeO4 trigonal pyramids that share corners with two FeO6 octahedra, corners with six equivalent FeO4 trigonal pyramids, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 18–49°. There are a spread of Fe–O bond distances ranging from 1.80–2.03 Å. In the second Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with four FeO6 octahedra, corners with six equivalent FeO4 tetrahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 20–63°. There are a spread of Fe–O bond distances ranging from 1.91–2.02 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO4 tetrahedra, edges with six FeO6 octahedra, and a faceface with one FeO6 octahedra. There are three shorter (2.10 Å) and three longer (2.11 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 six FeO6 octahedra, corners with three equivalent FeO4 trigonal pyramids, edges with three equivalent FeO4 trigonal pyramids, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 48–51°. There are three shorter (2.04 Å) and three longer (2.17 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 three equivalent FeO4 tetrahedra, edges with three equivalent FeO4 tetrahedra, and a faceface with one FeO6 octahedra. There is three shorter (1.80 Å) and three longer (2.10 Å) Fe–O bond length. In the sixth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO6 octahedra, corners with three equivalent FeO4 tetrahedra, and edges with six FeO6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are three shorter (2.05 Å) and three longer (2.10 Å) Fe–O bond lengths. In the seventh Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO6 octahedra, corners with three equivalent FeO4 tetrahedra, and edges with six FeO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are three shorter (2.08 Å) and three longer (2.09 Å) Fe–O bond lengths. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO4 trigonal pyramids and a faceface with one FeO6 octahedra. There is three shorter (1.85 Å) and three longer (1.97 Å) Fe–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a see-saw-like geometry to four Fe3+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe3+ atoms. In the third O2- site, O2- is bonded to four Fe3+ atoms to form a mixture of distorted edge and corner-sharing OFe4 trigonal pyramids. In the fourth O2- site, O2- is bonded in an L-shaped geometry to two Fe3+ atoms. In the fifth O2- site, O2- is bonded in a see-saw-like geometry to four Fe3+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe8O9 by Materials Project

Fe8O9 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Fe+2.25+ sites. In the first Fe+2.25+ site, Fe+2.25+ 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 0–10°. There are a spread of Fe–O bond distances ranging from 2.15–2.23 Å. In the second Fe+2.25+ site, Fe+2.25+ 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 0–13°. There are a spread of Fe–O bond distances ranging from 2.13–2.25 Å. In the third Fe+2.25+ site, Fe+2.25+ 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 4–12°. There are a spread of Fe–O bond distances ranging from 2.06–2.11 Å. In the fourth Fe+2.25+ site, Fe+2.25+ 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 0–13°. There are a spread of Fe–O bond distances ranging from 2.12–2.26 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to five Fe+2.25+ atoms to form OFe5 square pyramids that share corners with two OFe6 octahedra, corners with seven OFe5 square pyramids, edges with four OFe6 octahedra, and edges with four OFe5 square pyramids. The corner-sharing octahedral tilt angles are 3°. In the second O2- site, O2- is bonded to five Fe+2.25+ atoms to form OFe5 square pyramids that share corners with two equivalent OFe6 octahedra, corners with seven OFe5 square pyramids, edges with five OFe6 octahedra, and edges with three OFe5 square pyramids. The corner-sharing octahedra tilt angles range from 5–9°. In the third O2- site, O2- is bonded to six Fe+2.25+ atoms to form OFe6 octahedra that share a cornercorner with one OFe6 octahedra, corners with five OFe5 square pyramids, edges with four OFe6 octahedra, and edges with eight OFe5 square pyramids. The corner-sharing octahedral tilt angles are 8°. In the fourth O2- site, O2- is bonded to five Fe+2.25+ atoms to form OFe5 square pyramids that share corners with three OFe6 octahedra, corners with six OFe5 square pyramids, edges with three OFe6 octahedra, and edges with five OFe5 square pyramids. The corner-sharing octahedra tilt angles range from 6–10°. In the fifth O2- site, O2- is bonded to six Fe+2.25+ atoms to form OFe6 octahedra that share corners with two equivalent OFe6 octahedra, corners with four OFe5 square pyramids, edges with four equivalent OFe6 octahedra, and edges with eight OFe5 square pyramids. The corner-sharing octahedral tilt angles are 8°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe14O15 by Materials Project

Fe14O15 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. there are five inequivalent Fe+2.14+ sites. In the first Fe+2.14+ site, Fe+2.14+ 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 0–13°. There are a spread of Fe–O bond distances ranging from 2.07–2.22 Å. In the second Fe+2.14+ site, Fe+2.14+ 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 0–13°. There are a spread of Fe–O bond distances ranging from 2.07–2.22 Å. In the third Fe+2.14+ site, Fe+2.14+ 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 0–13°. There are a spread of Fe–O bond distances ranging from 2.07–2.22 Å. In the fourth Fe+2.14+ site, Fe+2.14+ 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 3–13°. There are a spread of Fe–O bond distances ranging from 2.13–2.22 Å. In the fifth Fe+2.14+ site, Fe+2.14+ 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 0–3°. There are a spread of Fe–O bond distances ranging from 2.02–2.14 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to five Fe+2.14+ atoms to form OFe5 square pyramids that share corners with five OFe6 octahedra, corners with four equivalent OFe5 square pyramids, and edges with eight equivalent OFe6 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the second O2- site, O2- is bonded to six Fe+2.14+ atoms to form OFe6 octahedra that share corners with four equivalent OFe6 octahedra, corners with two OFe5 square pyramids, edges with seven OFe6 octahedra, and edges with five OFe5 square pyramids. The corner-sharing octahedra tilt angles range from 1–8°. In the third O2- site, O2- is bonded to six Fe+2.14+ atoms to form OFe6 octahedra that share corners with six OFe5 square pyramids, edges with eight equivalent OFe6 octahedra, and edges with four equivalent OFe5 square pyramids. In the fourth O2- site, O2- is bonded to five Fe+2.14+ atoms to form OFe5 square pyramids that share corners with three OFe6 octahedra, corners with six OFe5 square pyramids, edges with seven OFe6 octahedra, and an edgeedge with one OFe5 square pyramid. The corner-sharing octahedra tilt angles range from 7–10°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe23O32 by Materials Project

Fe23O32 is beta indium sulfide-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twenty-three inequivalent Fe+2.78+ sites. In the first Fe+2.78+ site, Fe+2.78+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Fe–O bond distances ranging from 1.86–1.97 Å. In the second Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.91–2.03 Å. In the third Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.00–2.06 Å. In the fourth Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.14 Å. In the fifth Fe+2.78+ site, Fe+2.78+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–61°. There is one shorter (1.88 Å) and three longer (1.94 Å) Fe–O bond length. In the sixth Fe+2.78+ site, Fe+2.78+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–63°. There is two shorter (1.90 Å) and two longer (1.95 Å) Fe–O bond length. In the seventh Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.92–2.02 Å. In the eighth Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.08–2.10 Å. In the ninth Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.02–2.21 Å. In the tenth Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.99–2.05 Å. In the eleventh Fe+2.78+ site, Fe+2.78+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–59°. There are a spread of Fe–O bond distances ranging from 1.89–1.96 Å. In the twelfth Fe+2.78+ site, Fe+2.78+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–61°. There are a spread of Fe–O bond distances ranging from 1.85–1.98 Å. In the thirteenth Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–1.99 Å. In the fourteenth Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.08 Å. In the fifteenth Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.07 Å. In the sixteenth Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.09–2.18 Å. In the seventeenth Fe+2.78+ site, Fe+2.78+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–62°. There are a spread of Fe–O bond distances ranging from 1.89–1.98 Å. In the eighteenth Fe+2.78+ site, Fe+2.78+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–62°. There are a spread of Fe–O bond distances ranging from 1.91–1.94 Å. In the nineteenth Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.07–2.12 Å. In the twentieth Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.07–2.19 Å. In the twenty-first Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.13 Å. In the twenty-second Fe+2.78+ site, Fe+2.78+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.92–2.02 Å. In the twenty-third Fe+2.78+ site, Fe+2.78+ is bonded to four O2- atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–64°. There are a spread of Fe–O bond distances ranging from 1.88–1.97 Å. There are thirty-two inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe+2.78+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe+2.78+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to three Fe+2.78+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe+2.78+ atoms. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the tenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the eleventh O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to four Fe+2.78+ atoms. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe+2.78+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the seventeenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the nineteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the twenty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the twenty-third O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the twenty-fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the twenty-fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the twenty-sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the twenty-seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the twenty-eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe+2.78+ atoms. In the twenty-ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the thirtieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the thirty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms. In the thirty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.78+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeO by Materials Project

FeO is Molybdenum Carbide MAX Phase-like structured and crystallizes in the hexagonal P-62c space group. The structure is three-dimensional. Fe2+ is bonded to six O2- atoms to form a mixture of edge, corner, and face-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 45–49°. There are a spread of Fe–O bond distances ranging from 2.14–2.29 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to six equivalent Fe2+ atoms to form a mixture of distorted edge and corner-sharing OFe6 pentagonal pyramids. In the second O2- site, O2- is bonded in a 6-coordinate geometry to six equivalent Fe2+ atoms. In the third O2- site, O2- is bonded to six equivalent Fe2+ atoms to form a mixture of distorted edge and corner-sharing OFe6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeO2 by Materials Project

FeO2 is Rutile structured and crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Fe is bonded to six equivalent O atoms to form a mixture of corner and edge-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There is four shorter (1.94 Å) and two longer (2.02 Å) Fe–O bond length. O is bonded in a trigonal planar geometry to three equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe32O35 by Materials Project

Fe32O35 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are thirty-two inequivalent Fe+2.19+ sites. In the first Fe+2.19+ site, Fe+2.19+ 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 1–18°. There are a spread of Fe–O bond distances ranging from 1.95–2.22 Å. In the second Fe+2.19+ site, Fe+2.19+ 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 2–18°. There are a spread of Fe–O bond distances ranging from 2.04–2.39 Å. In the third Fe+2.19+ site, Fe+2.19+ 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 0–25°. There are a spread of Fe–O bond distances ranging from 2.06–2.37 Å. In the fourth Fe+2.19+ site, Fe+2.19+ 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 1–5°. There are a spread of Fe–O bond distances ranging from 2.03–2.27 Å. In the fifth Fe+2.19+ site, Fe+2.19+ 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 1–5°. There are a spread of Fe–O bond distances ranging from 2.06–2.30 Å. In the sixth Fe+2.19+ site, Fe+2.19+ 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 4–5°. There are a spread of Fe–O bond distances ranging from 1.97–2.15 Å. In the seventh Fe+2.19+ site, Fe+2.19+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 2–24°. There are a spread of Fe–O bond distances ranging from 1.98–2.40 Å. In the eighth Fe+2.19+ site, Fe+2.19+ 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 2–12°. There are a spread of Fe–O bond distances ranging from 2.01–2.12 Å. In the ninth Fe+2.19+ site, Fe+2.19+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 0–23°. There are a spread of Fe–O bond distances ranging from 2.00–2.40 Å. In the tenth Fe+2.19+ site, Fe+2.19+ 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 4–13°. There are a spread of Fe–O bond distances ranging from 2.11–2.26 Å. In the eleventh Fe+2.19+ site, Fe+2.19+ 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 1–25°. There are a spread of Fe–O bond distances ranging from 2.07–2.27 Å. In the twelfth Fe+2.19+ site, Fe+2.19+ 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 3–9°. There are a spread of Fe–O bond distances ranging from 2.00–2.35 Å. In the thirteenth Fe+2.19+ site, Fe+2.19+ 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 3–4°. There are a spread of Fe–O bond distances ranging from 2.02–2.27 Å. In the fourteenth Fe+2.19+ site, Fe+2.19+ 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 1–13°. There are a spread of Fe–O bond distances ranging from 2.08–2.22 Å. In the fifteenth Fe+2.19+ site, Fe+2.19+ 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 6–11°. There are a spread of Fe–O bond distances ranging from 2.14–2.26 Å. In the sixteenth Fe+2.19+ site, Fe+2.19+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 1–24°. There are a spread of Fe–O bond distances ranging from 2.01–2.36 Å. In the seventeenth Fe+2.19+ site, Fe+2.19+ 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 1–23°. There are a spread of Fe–O bond distances ranging from 2.02–2.33 Å. In the eighteenth Fe+2.19+ site, Fe+2.19+ 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 2–9°. There are a spread of Fe–O bond distances ranging from 2.07–2.30 Å. In the nineteenth Fe+2.19+ site, Fe+2.19+ 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 5–6°. There are a spread of Fe–O bond distances ranging from 2.15–2.27 Å. In the twentieth Fe+2.19+ site, Fe+2.19+ 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 3–7°. There are a spread of Fe–O bond distances ranging from 2.05–2.33 Å. In the twenty-first Fe+2.19+ site, Fe+2.19+ 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 3–5°. There are a spread of Fe–O bond distances ranging from 1.97–2.13 Å. In the twenty-second Fe+2.19+ site, Fe+2.19+ 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 5–7°. There are a spread of Fe–O bond distances ranging from 2.13–2.24 Å. In the twenty-third Fe+2.19+ site, Fe+2.19+ 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 3–9°. There are a spread of Fe–O bond distances ranging from 2.11–2.24 Å. In the twenty-fourth Fe+2.19+ site, Fe+2.19+ 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 1–19°. There are a spread of Fe–O bond distances ranging from 2.07–2.35 Å. In the twenty-fifth Fe+2.19+ site, Fe+2.19+ 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 1–25°. There are a spread of Fe–O bond distances ranging from 2.08–2.28 Å. In the twenty-sixth Fe+2.19+ site, Fe+2.19+ 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 3–25°. There are a spread of Fe–O bond distances ranging from 2.08–2.34 Å. In the twenty-seventh Fe+2.19+ site, Fe+2.19+ 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 1–7°. There are a spread of Fe–O bond distances ranging from 2.09–2.28 Å. In the twenty-eighth Fe+2.19+ site, Fe+2.19+ 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 2–7°. There are a spread of Fe–O bond distances ranging from 2.04–2.30 Å. In the twenty-ninth Fe+2.19+ site, Fe+2.19+ 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 2–5°. There are a spread of Fe–O bond distances ranging from 2.00–2.17 Å. In the thirtieth Fe+2.19+ site, Fe+2.19+ 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 3–6°. There are a spread of Fe–O bond distances ranging from 2.13–2.33 Å. In the thirty-first Fe+2.19+ site, Fe+2.19+ 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 1–7°. There are a spread of Fe–O bond distances ranging from 2.13–2.26 Å. In the thirty-second Fe+2.19+ site, Fe+2.19+ 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 4–19°. There are a spread of Fe–O bond distances ranging from 1.96–2.24 Å. There are thirty-five inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe+2.19+ atoms. In the second O2- site, O2- is bonded to six Fe+2.19+ atoms to form OFe6 octahedra that share corners with four OFe6 octahedra, corners with two equivalent OFe5 square pyramids, edges with nine OFe6 octahedra, and an edgeedge with one OFe5 square pyramid. The corner-sharing octahedra tilt angles range from 2–9°. In the third O2- site, O2- is bonded to five Fe+2.19+ atoms to form OFe5 square pyramids that share corners with four OFe6 octahedra, a cornercorner with one OFe5 square pyramid, corners with two equivalent OFe4 trigonal pyramids, edges with six OFe6 octahedra, and edges with two equivalent OFe5 square pyramids. The corner-sharing octahedra tilt angles range from 11–17°. In the fourth O2- site, O2- is bonded to six Fe+2.19+ atoms to form OFe6 octahedra that share corners with four OFe6 octahedra, corners with two equivalent OFe5 square pyramids, edges with nine OFe6 octahedra, an edgeedge with one OFe5 square pyramid, and edges with two equivalent OFe4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 2–6°. In the fifth O2- site, O2- is bonded to six Fe+2.19+ atoms to form OFe6 octahedra that share corners with four OFe6 octahedra, a cornercorner with one OFe4 trigonal pyramid, edges with eight OFe6 octahedra, and edges with four OFe5 square pyramids. The corner-sharing octahedra tilt angles range from 1–4°. In the sixth O2- site, O2- is bonded to six Fe+2.19+ atoms to form OFe6 octahedra that share corners with four OFe6 octahedra, corners with two OFe4 trigonal pyramids, edges with eight OFe6 octahedra, and edges with four OFe5 square pyramids. The corner-sharing octahedral tilt angles are 1°. In the seventh O2- site, O2- is bonded to four Fe+2.19+ atoms to form distorted OFe4 trigonal pyramids that share corners with four OFe6 octahedra, corners with four OFe5 square pyramids, corners with two equivalent OFe4 trigonal pyramids, and edges with five OFe6 octahedra. The corner-sharing octahedra tilt angles range from 3–14°. In the eighth O2- site, O2- is bonded to six Fe+2.19+ atoms to form OFe6 octahedra that share corners with two OFe6 octahedra, corners with two equivalent OFe5 square pyramids, corners with two equivalent OFe4 trigonal pyramids, edges with eight OFe6 octahedra, an edgeedge with one OFe5 square pyramid, and edges with three OFe4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 1–5°. In the ninth O2- site, O2- is bonded to five Fe+2.19+ atoms to form OFe5 square pyramids that share corners with four OFe6 octahedra, a cornercorner with one OFe5 square pyramid, corners with four OFe4 trigonal pyramids, edges with six OFe6 octahedra, and edges with two equivalent OFe5 square pyramids. The corner-sharing octahedra tilt angles range from 17–19°. In the tenth O2- site, O2- is bonded to six Fe+2.19+ atoms to form OFe6 octahedra that share corners with four OFe6 octahedra, corners with two equivalent OFe5 square pyramids, edges with nine OFe6 octahedra, an edgeedge with one OFe5 square pyramid, and edges with two equivalent OFe4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 2–6°. In the eleventh O2- site, O2- is bonded to six Fe+2.19+ atoms to form OFe6 octahedra that share corners with two OFe6 octahedra, corners with two equivalent OFe5 square pyramids, corners with two equivalent OFe4 trigonal pyramids, edges with eight OFe6 octahedra, an edgeedge with one OFe5 square pyramid, and edges with three OFe4 trigonal pyramids. The corner-sharing oc

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeO2 by Materials Project

FeO2 is Cyanogen Chloride-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is zero-dimensional and consists of two iron dihydroxide molecules. Fe is bonded in a linear geometry to two equivalent O atoms. Both Fe–O bond lengths are 1.59 Å. O is bonded in a single-bond geometry to one Fe atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeO2 by Materials Project

FeO2 is trigonal omega-like structured and crystallizes in the monoclinic P2_1/m space group. The structure is two-dimensional and consists of two FeO2 sheets oriented in the (0, 0, 1) direction. there are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form edge-sharing FeO6 octahedra. There is three shorter (1.92 Å) and three longer (1.93 Å) Fe–O bond length. In the second Fe site, Fe is bonded to six O atoms to form edge-sharing FeO6 octahedra. There is four shorter (1.92 Å) and two longer (1.93 Å) Fe–O bond length. There are three inequivalent O sites. In the first O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the second O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the third O site, O is bonded in a distorted T-shaped geometry to three Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeO2 by Materials Project

FeO2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of four iron dihydroxide molecules. Fe is bonded in a distorted linear geometry to two equivalent O atoms. Both Fe–O bond lengths are 1.32 Å. O is bonded in a single-bond geometry to one Fe atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeO2 by Materials Project

FeO2 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. there are two inequivalent Fe sites. In the first Fe site, Fe is bonded to four O atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–55°. There is two shorter (1.82 Å) and two longer (1.88 Å) Fe–O bond length. In the second Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six equivalent FeO4 tetrahedra and edges with two equivalent FeO6 octahedra. There is two shorter (1.90 Å) and four longer (2.03 Å) Fe–O bond length. There are two inequivalent O sites. In the first O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the second O site, O is bonded in a bent 120 degrees geometry to two Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe2O3 by Materials Project

Fe2O3 crystallizes in the orthorhombic Cmcm 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 octahedral tilt angles are 0°. There are a spread of Fe–O bond distances ranging from 1.91–2.15 Å. In the second Fe3+ site, Fe3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Fe–O bond distances ranging from 1.83–2.53 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to six Fe3+ atoms to form distorted OFe6 octahedra that share corners with four equivalent OFe5 square pyramids, edges with two equivalent OFe6 octahedra, and edges with six equivalent OFe5 square pyramids. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Fe3+ atoms. In the third O2- site, O2- is bonded to five Fe3+ atoms to form distorted OFe5 square pyramids that share corners with two equivalent OFe6 octahedra, edges with three equivalent OFe6 octahedra, and edges with four equivalent OFe5 square pyramids. The corner-sharing octahedral tilt angles are 9°. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe5O7 by Materials Project

Fe5O7 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are three inequivalent Fe+2.80+ sites. In the first Fe+2.80+ site, Fe+2.80+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are a spread of Fe–O bond distances ranging from 1.92–2.13 Å. In the second Fe+2.80+ site, Fe+2.80+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are two shorter (2.16 Å) and four longer (2.18 Å) Fe–O bond lengths. In the third Fe+2.80+ site, Fe+2.80+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Fe–O bond distances ranging from 1.83–2.29 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Fe+2.80+ atoms. In the second O2- site, O2- is bonded to five Fe+2.80+ atoms to form a mixture of edge and corner-sharing OFe5 square pyramids. In the third O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Fe+2.80+ atoms. In the fourth O2- site, O2- is bonded to five Fe+2.80+ atoms to form a mixture of edge and corner-sharing OFe5 square pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeO2 by Materials Project

FeO2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twelve inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with four FeO4 tetrahedra and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.85–2.05 Å. In the second Fe site, Fe is bonded to four O atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 49–57°. There are a spread of Fe–O bond distances ranging from 1.78–1.87 Å. In the third Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with three equivalent FeO4 tetrahedra and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.86–1.98 Å. In the fourth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with four FeO4 tetrahedra and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.85–2.05 Å. In the fifth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with two equivalent FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.03 Å. In the sixth Fe site, Fe is bonded to four O atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–56°. There are a spread of Fe–O bond distances ranging from 1.78–1.87 Å. In the seventh Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with six FeO4 tetrahedra and edges with two equivalent FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.03 Å. In the eighth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with five FeO4 tetrahedra and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.88–2.17 Å. In the ninth Fe site, Fe is bonded to four O atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Fe–O bond distances ranging from 1.83–1.90 Å. In the tenth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with five FeO4 tetrahedra and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.89–2.17 Å. In the eleventh Fe site, Fe is bonded to four O atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–57°. There are a spread of Fe–O bond distances ranging from 1.79–1.94 Å. In the twelfth Fe site, Fe is bonded to four O atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 54–59°. There are a spread of Fe–O bond distances ranging from 1.88–1.97 Å. There are twenty-four inequivalent O sites. In the first O site, O is bonded in a water-like geometry to two Fe atoms. In the second O site, O is bonded in a distorted trigonal planar geometry to three Fe atoms. In the third O site, O is bonded in a water-like geometry to two Fe atoms. In the fourth O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the fifth O site, O is bonded in a bent 120 degrees geometry to two Fe atoms. In the sixth O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the seventh O site, O is bonded in a distorted trigonal planar geometry to three Fe atoms. In the eighth O site, O is bonded in a bent 120 degrees geometry to two Fe atoms. In the ninth O site, O is bonded in a bent 120 degrees geometry to two Fe atoms. In the tenth O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the eleventh O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the twelfth O site, O is bonded in a bent 120 degrees geometry to two Fe atoms. In the thirteenth O site, O is bonded in a bent 120 degrees geometry to two Fe atoms. In the fourteenth O site, O is bonded in a distorted trigonal planar geometry to three Fe atoms. In the fifteenth O site, O is bonded in a bent 120 degrees geometry to two Fe atoms. In the sixteenth O site, O is bonded in a bent 120 degrees geometry to two Fe atoms. In the seventeenth O site, O is bonded in a water-like geometry to two Fe atoms. In the eighteenth O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the nineteenth O site, O is bonded in a distorted trigonal planar geometry to three Fe atoms. In the twentieth O site, O is bonded in a bent 120 degrees geometry to two Fe atoms. In the twenty-first O site, O is bonded in a rectangular see-saw-like geometry to four Fe atoms. In the twenty-second O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the twenty-third O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the twenty-fourth O site, O is bonded in a trigonal planar geometry to three Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeO2 by Materials Project

FeO2 crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are two inequivalent Fe sites. In the first Fe site, Fe is bonded to four O atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 57–59°. There is three shorter (1.91 Å) and one longer (1.93 Å) Fe–O bond length. In the second Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with three equivalent FeO4 tetrahedra and edges with four equivalent FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.87–2.11 Å. There are four inequivalent O sites. In the first O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the second O site, O is bonded in a distorted rectangular see-saw-like geometry to four Fe atoms. In the third O site, O is bonded in a distorted T-shaped geometry to three equivalent Fe atoms. In the fourth O site, O is bonded in a water-like geometry to two equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeO2 by Materials Project

FeO2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twelve inequivalent Fe sites. In the first Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share a cornercorner with one FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.81–2.09 Å. In the second Fe site, Fe is bonded to six O atoms to form edge-sharing FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.89–2.04 Å. In the third Fe site, Fe is bonded to six O atoms to form edge-sharing FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.88–2.10 Å. In the fourth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share a cornercorner with one FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.88–2.15 Å. In the fifth Fe site, Fe is bonded to six O atoms to form edge-sharing FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.88–2.04 Å. In the sixth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share a cornercorner with one FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.81–2.12 Å. In the seventh Fe site, Fe is bonded to six O atoms to form edge-sharing FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.85–2.00 Å. In the eighth Fe site, Fe is bonded to six O atoms to form edge-sharing FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.94–2.10 Å. In the ninth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.92–2.08 Å. In the tenth Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.99–2.07 Å. In the eleventh Fe site, Fe is bonded to six O atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra and edges with five FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.06 Å. In the twelfth Fe site, Fe is bonded to four O atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–60°. There are a spread of Fe–O bond distances ranging from 1.87–1.94 Å. There are twenty-four inequivalent O sites. In the first O site, O is bonded in a water-like geometry to two Fe atoms. In the second O site, O is bonded in a water-like geometry to two Fe atoms. In the third O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the fourth O site, O is bonded in a water-like geometry to two Fe atoms. In the fifth O site, O is bonded in a 3-coordinate geometry to three Fe atoms. In the sixth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms. In the seventh O site, O is bonded in a rectangular see-saw-like geometry to four Fe atoms. In the eighth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms. In the ninth O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the tenth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms. In the eleventh O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the twelfth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms. In the thirteenth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms. In the fourteenth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms. In the fifteenth O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the sixteenth O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the seventeenth O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the eighteenth O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the nineteenth O site, O is bonded in a distorted T-shaped geometry to three Fe atoms. In the twentieth O site, O is bonded in a 3-coordinate geometry to three Fe atoms. In the twenty-first O site, O is bonded in a trigonal planar geometry to three Fe atoms. In the twenty-second O site, O is bonded in a distorted trigonal planar geometry to three Fe atoms. In the twenty-third O site, O is bonded in a distorted trigonal non-coplanar geometry to three Fe atoms. In the twenty-fourth O site, O is bonded in a trigonal planar geometry to three Fe atoms.

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