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DOE OSTI2020

Materials Data on Ca(FeO2)2 by Materials Project

CaFe2O4 is Spinel structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–64°. There are two shorter (2.18 Å) and two longer (2.20 Å) Ca–O bond lengths. There are four 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 CaO4 tetrahedra and edges with six FeO6 octahedra. There are two shorter (2.02 Å) and four longer (2.09 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 CaO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.05–2.08 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent CaO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.99–2.18 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent CaO4 tetrahedra and edges with six FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.04–2.09 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ca2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra. In the second O2- site, O2- is bonded to one Ca2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra. In the third O2- site, O2- is bonded to one Ca2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra. In the fourth O2- site, O2- is bonded to one Ca2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

MgFe2O4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 pentagonal pyramids that share corners with six FeO6 octahedra, edges with six FeO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 3–17°. There are a spread of Mg–O bond distances ranging from 2.09–2.26 Å. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form distorted MgO6 pentagonal pyramids that share corners with twelve FeO6 octahedra, edges with two equivalent MgO6 pentagonal pyramids, and faces with two FeO6 octahedra. The corner-sharing octahedra tilt angles range from 44–53°. There are a spread of Mg–O bond distances ranging from 2.14–2.23 Å. There are six inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with five MgO6 pentagonal pyramids, edges with six FeO6 octahedra, an edgeedge with one MgO6 pentagonal pyramid, and a faceface with one MgO6 pentagonal pyramid. There are a spread of Fe–O bond distances ranging from 2.00–2.17 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with five MgO6 pentagonal pyramids, edges with six FeO6 octahedra, an edgeedge with one MgO6 pentagonal pyramid, and a faceface with one MgO6 pentagonal pyramid. There are a spread of Fe–O bond distances ranging from 2.00–2.18 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent MgO6 pentagonal pyramids, edges with six FeO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 1.99–2.08 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent MgO6 pentagonal pyramids, edges with six FeO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 1.99–2.08 Å. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent MgO6 pentagonal pyramids, edges with six FeO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 2.00–2.08 Å. In the sixth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four equivalent MgO6 pentagonal pyramids, edges with six FeO6 octahedra, and edges with two equivalent MgO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 2.00–2.08 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Fe3+ atoms. In the fifth O2- site, O2- is bonded to two Mg2+ and three Fe3+ atoms to form a mixture of edge and corner-sharing OMg2Fe3 trigonal bipyramids. In the sixth O2- site, O2- is bonded to two Mg2+ and three Fe3+ atoms to form a mixture of edge and corner-sharing OMg2Fe3 trigonal bipyramids. In the seventh O2- site, O2- is bonded to two Mg2+ and three Fe3+ atoms to form a mixture of edge and corner-sharing OMg2Fe3 trigonal bipyramids. In the eighth O2- site, O2- is bonded to two Mg2+ and three Fe3+ atoms to form a mixture of edge and corner-sharing OMg2Fe3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(FeO2)2 by Materials Project

ZnFe2O4 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are four inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to five O2- atoms to form distorted FeO5 square pyramids that share corners with four FeO6 octahedra, corners with four ZnO5 trigonal bipyramids, edges with two equivalent FeO5 square pyramids, and an edgeedge with one ZnO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 51°. There are a spread of Fe–O bond distances ranging from 1.92–2.07 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four FeO5 square pyramids, corners with four ZnO5 trigonal bipyramids, edges with four FeO6 octahedra, and a faceface with one ZnO5 trigonal bipyramid. There are a spread of Fe–O bond distances ranging from 1.94–2.20 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four FeO5 square pyramids, corners with four ZnO5 trigonal bipyramids, edges with four FeO6 octahedra, and a faceface with one ZnO5 trigonal bipyramid. There are a spread of Fe–O bond distances ranging from 1.95–2.20 Å. In the fourth Fe3+ site, Fe3+ is bonded to five O2- atoms to form distorted FeO5 square pyramids that share corners with four FeO6 octahedra, corners with four ZnO5 trigonal bipyramids, edges with two equivalent FeO5 square pyramids, and an edgeedge with one ZnO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 50–51°. There are a spread of Fe–O bond distances ranging from 1.92–2.07 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to five O2- atoms to form ZnO5 trigonal bipyramids that share corners with four FeO6 octahedra, corners with four FeO5 square pyramids, an edgeedge with one FeO5 square pyramid, edges with two equivalent ZnO5 trigonal bipyramids, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 42–59°. There are a spread of Zn–O bond distances ranging from 2.06–2.12 Å. In the second Zn2+ site, Zn2+ is bonded to five O2- atoms to form ZnO5 trigonal bipyramids that share corners with four FeO6 octahedra, corners with four FeO5 square pyramids, an edgeedge with one FeO5 square pyramid, edges with two equivalent ZnO5 trigonal bipyramids, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 42–59°. There are a spread of Zn–O bond distances ranging from 2.06–2.12 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form distorted corner-sharing OZnFe3 tetrahedra. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe3+ atoms. In the fourth O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form distorted corner-sharing OZnFe3 tetrahedra. In the fifth O2- site, O2- is bonded in a square co-planar geometry to two equivalent Fe3+ and two equivalent Zn2+ atoms. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Zn2+ atoms. In the seventh O2- site, O2- is bonded in a square co-planar geometry to two equivalent Fe3+ and two equivalent Zn2+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Zn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

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

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(FeO2)2 by Materials Project

ZnFe2O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. 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 three ZnO6 pentagonal pyramids, edges with six FeO6 octahedra, and an edgeedge with one ZnO6 pentagonal pyramid. There are a spread of Fe–O bond distances ranging from 1.93–2.04 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three ZnO6 pentagonal pyramids, edges with six FeO6 octahedra, and an edgeedge with one ZnO6 pentagonal pyramid. There are a spread of Fe–O bond distances ranging from 1.92–2.16 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three ZnO6 pentagonal pyramids, edges with six FeO6 octahedra, and an edgeedge with one ZnO6 pentagonal pyramid. There are a spread of Fe–O bond distances ranging from 1.93–2.04 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three ZnO6 pentagonal pyramids, edges with six FeO6 octahedra, and an edgeedge with one ZnO6 pentagonal pyramid. There are a spread of Fe–O bond distances ranging from 1.93–2.18 Å. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share edges with six FeO6 octahedra and edges with two ZnO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 1.93–2.00 Å. In the sixth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share edges with six FeO6 octahedra and edges with two ZnO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 1.92–2.00 Å. In the seventh Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share edges with six FeO6 octahedra and edges with two ZnO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 1.92–2.00 Å. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share edges with six FeO6 octahedra and edges with two ZnO6 pentagonal pyramids. There are a spread of Fe–O bond distances ranging from 1.93–2.01 Å. There are four inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to six O2- atoms to form distorted ZnO6 pentagonal pyramids that share corners with six FeO6 octahedra and edges with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 1–20°. There are a spread of Zn–O bond distances ranging from 2.09–2.28 Å. In the second Zn2+ site, Zn2+ is bonded to six O2- atoms to form distorted ZnO6 pentagonal pyramids that share corners with six FeO6 octahedra and edges with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 1–20°. There are a spread of Zn–O bond distances ranging from 2.09–2.27 Å. In the third Zn2+ site, Zn2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Zn–O bond distances ranging from 2.09–2.30 Å. In the fourth Zn2+ site, Zn2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Zn–O bond distances ranging from 2.08–2.30 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the second O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form distorted OZnFe3 trigonal pyramids that share corners with four OZn2Fe3 trigonal bipyramids, corners with five OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and an edgeedge with one OZnFe3 trigonal pyramid. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the fourth O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form distorted OZnFe3 trigonal pyramids that share corners with four OZn2Fe3 trigonal bipyramids, corners with five OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and an edgeedge with one OZnFe3 trigonal pyramid. In the fifth O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form OZnFe3 trigonal pyramids that share corners with four OZn2Fe3 trigonal bipyramids, corners with three OZnFe3 trigonal pyramids, and edges with four OZn2Fe3 trigonal bipyramids. In the sixth O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form OZnFe3 trigonal pyramids that share corners with four OZn2Fe3 trigonal bipyramids, corners with six OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and an edgeedge with one OZnFe3 trigonal pyramid. In the seventh O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form OZnFe3 trigonal pyramids that share corners with four OZn2Fe3 trigonal bipyramids, corners with three OZnFe3 trigonal pyramids, and edges with four OZn2Fe3 trigonal bipyramids. In the eighth O2- site, O2- is bonded to three Fe3+ and one Zn2+ atom to form OZnFe3 trigonal pyramids that share corners with four OZn2Fe3 trigonal bipyramids, corners with six OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and an edgeedge with one OZnFe3 trigonal pyramid. In the ninth O2- site, O2- is bonded to three Fe3+ and two Zn2+ atoms to form distorted OZn2Fe3 trigonal bipyramids that share corners with five OZn2Fe3 trigonal bipyramids, corners with three OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and edges with two OZnFe3 trigonal pyramids. In the tenth O2- site, O2- is bonded to three Fe3+ and two Zn2+ atoms to form OZn2Fe3 trigonal bipyramids that share corners with five OZn2Fe3 trigonal bipyramids, corners with three OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and edges with four OZnFe3 trigonal pyramids. In the eleventh O2- site, O2- is bonded to three Fe3+ and two Zn2+ atoms to form OZn2Fe3 trigonal bipyramids that share corners with five OZn2Fe3 trigonal bipyramids, corners with three OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and edges with two OZnFe3 trigonal pyramids. In the twelfth O2- site, O2- is bonded to three Fe3+ and two Zn2+ atoms to form OZn2Fe3 trigonal bipyramids that share corners with five OZn2Fe3 trigonal bipyramids, corners with three OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and edges with four OZnFe3 trigonal pyramids. In the thirteenth O2- site, O2- is bonded to three Fe3+ and two Zn2+ atoms to form distorted OZn2Fe3 trigonal bipyramids that share corners with five OZn2Fe3 trigonal bipyramids, corners with three OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and edges with two OZnFe3 trigonal pyramids. In the fourteenth O2- site, O2- is bonded to three Fe3+ and two Zn2+ atoms to form OZn2Fe3 trigonal bipyramids that share corners with five OZn2Fe3 trigonal bipyramids, corners with three OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and edges with four OZnFe3 trigonal pyramids. In the fifteenth O2- site, O2- is bonded to three Fe3+ and two Zn2+ atoms to form OZn2Fe3 trigonal bipyramids that share corners with five OZn2Fe3 trigonal bipyramids, corners with three OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and edges with two OZnFe3 trigonal pyramids. In the sixteenth O2- site, O2- is bonded to three Fe3+ and two Zn2+ atoms to form OZn2Fe3 trigonal bipyramids that share corners with five OZn2Fe3 trigonal bipyramids, corners with three OZnFe3 trigonal pyramids, edges with four OZn2Fe3 trigonal bipyramids, and edges with four OZnFe3 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(FeO2)2 by Materials Project

ZnFe2O4 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are eight 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 49–64°. There are two shorter (1.94 Å) and four longer (2.08 Å) Fe–O bond lengths. 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 50–60°. There are a spread of Fe–O bond distances ranging from 1.93–2.03 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–60°. There are a spread of Fe–O bond distances ranging from 1.93–2.02 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–62°. There are a spread of Fe–O bond distances ranging from 1.94–2.14 Å. In the fifth 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 49–60°. There are a spread of Fe–O bond distances ranging from 1.94–2.13 Å. In the sixth 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 49–60°. There are a spread of Fe–O bond distances ranging from 1.93–2.12 Å. In the seventh Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–64°. There are a spread of Fe–O bond distances ranging from 1.99–2.06 Å. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–62°. There are a spread of Fe–O bond distances ranging from 1.94–2.01 Å. There are four inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded in a 6-coordinate geometry to eight O2- atoms. There are a spread of Zn–O bond distances ranging from 2.18–2.70 Å. In the second Zn2+ site, Zn2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Zn–O bond distances ranging from 2.22–2.63 Å. In the third Zn2+ site, Zn2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Zn–O bond distances ranging from 2.22–2.60 Å. In the fourth Zn2+ site, Zn2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Zn–O bond distances ranging from 2.20–2.35 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Zn2+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Zn2+ atoms. In the third O2- site, O2- is bonded to three Fe3+ and two equivalent Zn2+ atoms to form a mixture of distorted edge and corner-sharing OZn2Fe3 trigonal bipyramids. In the fourth O2- site, O2- is bonded to three Fe3+ and two equivalent Zn2+ atoms to form a mixture of distorted edge and corner-sharing OZn2Fe3 trigonal bipyramids. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two Zn2+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Fe3+ and two Zn2+ atoms. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three Fe3+ and one Zn2+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to three Fe3+ and two Zn2+ atoms. In the ninth O2- site, O2- is bonded to three Fe3+ and two equivalent Zn2+ atoms to form distorted edge-sharing OZn2Fe3 trigonal bipyramids. In the tenth O2- site, O2- is bonded to three Fe3+ and two equivalent Zn2+ atoms to form distorted edge-sharing OZn2Fe3 trigonal bipyramids. In the eleventh O2- site, O2- is bonded to three Fe3+ and two equivalent Zn2+ atoms to form a mixture of distorted edge and corner-sharing OZn2Fe3 trigonal bipyramids. In the twelfth O2- site, O2- is bonded to three Fe3+ and two equivalent Zn2+ atoms to form a mixture of distorted edge and corner-sharing OZn2Fe3 trigonal bipyramids. In the thirteenth O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Zn2+ atoms. In the fourteenth O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Zn2+ atoms. In the fifteenth O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Zn2+ atoms. In the sixteenth O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Zn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

MgFe2O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with four FeO6 octahedra, corners with four FeO5 trigonal bipyramids, an edgeedge with one FeO5 trigonal bipyramid, edges with two equivalent MgO5 trigonal bipyramids, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 39–61°. There are a spread of Mg–O bond distances ranging from 2.03–2.08 Å. In the second Mg2+ site, Mg2+ is bonded to five O2- atoms to form MgO5 trigonal bipyramids that share corners with four FeO6 octahedra, corners with four FeO5 trigonal bipyramids, an edgeedge with one FeO5 trigonal bipyramid, edges with two equivalent MgO5 trigonal bipyramids, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 39–61°. There are a spread of Mg–O bond distances ranging from 2.03–2.08 Å. There are four inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to five O2- atoms to form distorted FeO5 trigonal bipyramids that share corners with four FeO6 octahedra, corners with four MgO5 trigonal bipyramids, an edgeedge with one MgO5 trigonal bipyramid, and edges with two equivalent FeO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 50–53°. There are a spread of Fe–O bond distances ranging from 1.92–2.08 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four MgO5 trigonal bipyramids, corners with four FeO5 trigonal bipyramids, edges with four FeO6 octahedra, and a faceface with one MgO5 trigonal bipyramid. There are a spread of Fe–O bond distances ranging from 1.95–2.18 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four MgO5 trigonal bipyramids, corners with four FeO5 trigonal bipyramids, edges with four FeO6 octahedra, and a faceface with one MgO5 trigonal bipyramid. There are a spread of Fe–O bond distances ranging from 1.95–2.19 Å. In the fourth Fe3+ site, Fe3+ is bonded to five O2- atoms to form distorted FeO5 trigonal bipyramids that share corners with four FeO6 octahedra, corners with four MgO5 trigonal bipyramids, an edgeedge with one MgO5 trigonal bipyramid, and edges with two equivalent FeO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 50–52°. There are a spread of Fe–O bond distances ranging from 1.92–2.08 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to one Mg2+ and three Fe3+ atoms to form distorted OMgFe3 tetrahedra that share corners with two equivalent OMgFe3 tetrahedra, a cornercorner with one OMg2Fe3 trigonal bipyramid, and edges with two equivalent OMg2Fe3 trigonal bipyramids. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Fe3+ atoms. In the fourth O2- site, O2- is bonded to one Mg2+ and three Fe3+ atoms to form distorted OMgFe3 tetrahedra that share corners with two equivalent OMgFe3 tetrahedra, a cornercorner with one OMg2Fe3 trigonal bipyramid, and edges with two equivalent OMg2Fe3 trigonal bipyramids. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Mg2+ and two equivalent Fe3+ atoms. In the sixth O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form distorted OMg2Fe3 trigonal bipyramids that share a cornercorner with one OMgFe3 tetrahedra, edges with two equivalent OMgFe3 tetrahedra, and edges with four OMg2Fe3 trigonal bipyramids. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to two equivalent Mg2+ and two equivalent Fe3+ atoms. In the eighth O2- site, O2- is bonded to two equivalent Mg2+ and three Fe3+ atoms to form distorted OMg2Fe3 trigonal bipyramids that share a cornercorner with one OMgFe3 tetrahedra, edges with two equivalent OMgFe3 tetrahedra, and edges with four OMg2Fe3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(FeO2)2 by Materials Project

CaFe2O4 is Spinel structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with twelve FeO6 octahedra. The corner-sharing octahedra tilt angles range from 60–61°. All Ca–O bond lengths are 2.20 Å. There are two 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 CaO4 tetrahedra and edges with six FeO6 octahedra. There are four shorter (2.08 Å) and two longer (2.09 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 CaO4 tetrahedra and edges with six 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 Ca2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra. In the second O2- site, O2- is bonded to one Ca2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

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

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Zn(FeO2)2 by Materials Project

ZnFe2O4 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 50–61°. There are a spread of Fe–O bond distances ranging from 1.97–2.10 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 50–61°. There are a spread of Fe–O bond distances ranging from 1.92–2.03 Å. Zn2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Zn–O bond distances ranging from 2.22–2.63 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Zn2+ atoms. In the second O2- site, O2- is bonded to three equivalent Fe3+ and two equivalent Zn2+ atoms to form a mixture of distorted edge and corner-sharing OZn2Fe3 trigonal bipyramids. In the third O2- site, O2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Zn2+ atoms. In the fourth O2- site, O2- is bonded to three equivalent Fe3+ and two equivalent Zn2+ atoms to form a mixture of distorted edge and corner-sharing OZn2Fe3 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg(FeO2)2 by Materials Project

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

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y(FeO2)2 by Materials Project

YFe2O4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Y3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.39–2.44 Å. There are two inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.95 Å) and two longer (2.02 Å) Fe–O bond length. In the second Fe+2.50+ site, Fe+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.95 Å) and two longer (2.03 Å) Fe–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Y3+ and two Fe+2.50+ atoms to form a mixture of distorted edge and corner-sharing OY2Fe2 tetrahedra. In the second O2- site, O2- is bonded to two equivalent Y3+ and two Fe+2.50+ atoms to form a mixture of distorted edge and corner-sharing OY2Fe2 tetrahedra.

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 twelve 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 ZnO4 tetrahedra, corners with four FeO4 tetrahedra, edges with three FeO6 octahedra, and edges with three ZnO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.08 Å. In the second 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 55–58°. There are a spread of Fe–O bond distances ranging from 1.92–1.96 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, 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 2.01–2.09 Å. In the fourth 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 three FeO6 octahedra, and edges with three ZnO6 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 six FeO4 tetrahedra, edges with two equivalent FeO6 octahedra, and edges with four ZnO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.04–2.07 Å. In the sixth 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 54–58°. There are a spread of Fe–O bond distances ranging from 1.91–1.96 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 ZnO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.03–2.07 Å. In the eighth 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 three FeO6 octahedra, and edges with three ZnO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.08 Å. In the ninth 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 55–58°. There are a spread of Fe–O bond distances ranging from 1.92–1.97 Å. In the tenth 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 three FeO6 octahedra, and edges with three ZnO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.01–2.08 Å. In the eleventh 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 55–58°. There are a spread of Fe–O bond distances ranging from 1.92–1.97 Å. In the twelfth 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 56–59°. There are a spread of Fe–O bond distances ranging from 1.88–2.07 Å. 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 ZnO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–60°. There are a spread of Zn–O bond distances ranging from 1.99–2.03 Å. In the second Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six FeO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.10–2.16 Å. In the third 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, an edgeedge with one ZnO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.09–2.18 Å. In the fourth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six FeO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.10–2.16 Å. In the fifth Zn2+ site, Zn2+ is bonded to six O2- atoms to form ZnO6 octahedra that share corners with six FeO4 tetrahedra, edges with two ZnO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.10–2.15 Å. In the sixth 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, an edgeedge with one ZnO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Zn–O bond distances ranging from 2.09–2.16 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 Fe3+ and two Zn2+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. 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 three Fe3+ and one Zn2+ atom. 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 rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. 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 three Fe3+ and one Zn2+ atom. 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 in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. 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 two Fe3+ and two Zn2+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Fe3+ and two Zn2+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the nineteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. 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 distorted trigonal pyramidal geometry to four Fe3+ atoms. 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 distorted rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom. In the twenty-fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Fe3+ and one Zn2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(FeO2)2 by Materials Project

CaFe2O4 is Spinel-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are six inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–68°. There are a spread of Ca–O bond distances ranging from 2.18–2.26 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.27–2.34 Å. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four FeO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.22–2.33 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.28–2.33 Å. In the fifth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.27–2.32 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.25–2.31 Å. There are twelve 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 CaO4 tetrahedra, corners with four FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.17 Å. In the second Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–60°. There are a spread of Fe–O bond distances ranging from 1.91–2.05 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.20 Å. In the fourth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.25 Å. In the fifth 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 CaO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.05–2.18 Å. In the sixth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 48–60°. There are a spread of Fe–O bond distances ranging from 1.90–2.02 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 CaO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.05–2.16 Å. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.98–2.22 Å. In the ninth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–61°. There are a spread of Fe–O bond distances ranging from 1.90–2.04 Å. In the tenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.34 Å. In the eleventh Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 50–61°. There are a spread of Fe–O bond distances ranging from 1.90–2.04 Å. In the twelfth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Fe–O bond distances ranging from 1.94–2.13 Å. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Fe2 trigonal pyramids. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the third O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted edge and corner-sharing OCa2Fe2 trigonal pyramids. In the fourth O2- site, O2- is bonded to one Ca2+ and three Fe3+ atoms to form a mixture of distorted edge and corner-sharing OCaFe3 trigonal pyramids. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the eleventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the seventeenth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form corner-sharing OCa2Fe2 tetrahedra. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the nineteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ 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 Ca2+ and three Fe3+ atoms. In the twenty-third O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-fourth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(FeO2)2 by Materials Project

CaFe2O4 is Spinel-like structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 56–69°. There are a spread of Ca–O bond distances ranging from 2.17–2.26 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with three CaO4 tetrahedra, corners with three FeO4 tetrahedra, and edges with six FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.25–2.30 Å. In the third Ca2+ site, Ca2+ is bonded to four O2- atoms to form CaO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–69°. There are a spread of Ca–O bond distances ranging from 2.17–2.23 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four FeO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.23–2.32 Å. In the fifth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.28–2.31 Å. In the sixth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.27–2.34 Å. In the seventh Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, an edgeedge with one CaO6 octahedra, and edges with five FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.24–2.30 Å. In the eighth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.28–2.34 Å. There are sixteen inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three CaO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.23 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.20 Å. In the third Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three CaO4 tetrahedra, corners with three FeO4 tetrahedra, edges with two equivalent CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.96–2.21 Å. In the fourth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–60°. There are a spread of Fe–O bond distances ranging from 1.91–2.06 Å. In the fifth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.94–2.18 Å. In the sixth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–60°. There are a spread of Fe–O bond distances ranging from 1.94–2.10 Å. In the seventh Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–61°. There are a spread of Fe–O bond distances ranging from 1.90–2.02 Å. In the eighth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent CaO4 tetrahedra, corners with four FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.95–2.18 Å. In the ninth 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 CaO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.04–2.18 Å. In the tenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 49–61°. There are a spread of Fe–O bond distances ranging from 1.90–2.03 Å. In the eleventh 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 CaO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.05–2.18 Å. In the twelfth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.20 Å. In the thirteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share a cornercorner with one CaO4 tetrahedra, corners with five FeO4 tetrahedra, edges with three CaO6 octahedra, and edges with three FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.20 Å. In the fourteenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six CaO6 octahedra and corners with six FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–60°. There are a spread of Fe–O bond distances ranging from 1.90–2.04 Å. In the fifteenth Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with three equivalent CaO4 tetrahedra, corners with three equivalent FeO4 tetrahedra, edges with two CaO6 octahedra, and edges with four FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.97–2.19 Å. In the sixteenth Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three CaO6 octahedra and corners with nine FeO6 octahedra. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of Fe–O bond distances ranging from 1.94–2.13 Å. There are thirty-two inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the second O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the third O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the sixth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the ninth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCa2Fe2 trigonal pyramids. In the tenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the eleventh O2- site, O2- is bonded to one Ca2+ and three Fe3+ atoms to form a mixture of distorted corner and edge-sharing OCaFe3 trigonal pyramids. In the twelfth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the thirteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the fourteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the fifteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the sixteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the seventeenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the eighteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the nineteenth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twentieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-third O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-fourth O2- site, O2- is bonded to two Ca2+ and two Fe3+ atoms to form corner-sharing OCa2Fe2 tetrahedra. In the twenty-fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-seventh O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the twenty-eighth O2- site, O2- is bonded in a rectangular see-saw-like geometry to two Ca2+ and two Fe3+ atoms. In the twenty-ninth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Fe3+ atoms. In the thirtieth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the thirty-first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms. In the thirty-second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Ca2+ and three Fe3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li(FeO2)3 by Materials Project

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

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li3(FeO2)5 by Materials Project

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

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaSr(FeO2)4 by Materials Project

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

36 MATERIALS SCIENCE↗