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.