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.

MgFe₂O₄结晶于三斜晶系P-1空间群。该晶体结构为三维框架结构。存在两个不等价的Mg²⁺位点。在第一个Mg²⁺位点中，Mg²⁺与六个O²⁻原子配位，形成畸变的MgO₆五棱锥，该五棱锥与六个FeO₆八面体共享顶点、与六个FeO₆八面体共享棱，同时与两个等价的MgO₆五棱锥共享棱。共顶八面体的倾斜角范围为3°~17°，Mg–O键长分布区间为2.09~2.26 Å。在第二个Mg²⁺位点中，Mg²⁺与六个O²⁻原子配位，形成畸变的MgO₆五棱锥，该五棱锥与十二个FeO₆八面体共享顶点、与两个等价的MgO₆五棱锥共享棱，同时与两个FeO₆八面体共享面。共顶八面体的倾斜角范围为44°~53°，Mg–O键长分布区间为2.14~2.23 Å。存在六个不等价的Fe³⁺位点。在第一个Fe³⁺位点中，Fe³⁺与六个O²⁻原子配位，形成FeO₆八面体，该八面体与五个MgO₆五棱锥共享顶点、与六个FeO₆八面体共享棱、与一个MgO₆五棱锥共享一条棱、与一个MgO₆五棱锥共享一个面，Fe–O键长分布区间为2.00~2.17 Å。在第二个Fe³⁺位点中，Fe³⁺与六个O²⁻原子配位，形成FeO₆八面体，该八面体与五个MgO₆五棱锥共享顶点、与六个FeO₆八面体共享棱、与一个MgO₆五棱锥共享一条棱、与一个MgO₆五棱锥共享一个面，Fe–O键长分布区间为2.00~2.18 Å。在第三个Fe³⁺位点中，Fe³⁺与六个O²⁻原子配位，形成FeO₆八面体，该八面体与四个等价的MgO₆五棱锥共享顶点、与六个FeO₆八面体共享棱、与两个等价的MgO₆五棱锥共享棱，Fe–O键长分布区间为1.99~2.08 Å。在第四个Fe³⁺位点中，Fe³⁺与六个O²⁻原子配位，形成FeO₆八面体，该八面体与四个等价的MgO₆五棱锥共享顶点、与六个FeO₆八面体共享棱、与两个等价的MgO₆五棱锥共享棱，Fe–O键长分布区间为1.99~2.08 Å。在第五个Fe³⁺位点中，Fe³⁺与六个O²⁻原子配位，形成FeO₆八面体，该八面体与四个等价的MgO₆五棱锥共享顶点、与六个FeO₆八面体共享棱、与两个等价的MgO₆五棱锥共享棱，Fe–O键长分布区间为2.00~2.08 Å。在第六个Fe³⁺位点中，Fe³⁺与六个O²⁻原子配位，形成FeO₆八面体，该八面体与四个等价的MgO₆五棱锥共享顶点、与六个FeO₆八面体共享棱、与两个等价的MgO₆五棱锥共享棱，Fe–O键长分布区间为2.00~2.08 Å。存在八个不等价的O²⁻位点。在第一个O²⁻位点中，O²⁻以类矩形跷板式配位几何与一个Mg²⁺和三个Fe³⁺原子成键；第二个至第四个O²⁻位点的配位环境与第一个完全一致。在第五个O²⁻位点中，O²⁻与两个Mg²⁺和三个Fe³⁺原子成键，形成兼具共棱和共顶特征的OMg₂Fe₃三角双锥结构；第六个至第八个O²⁻位点的配位环境与第五个完全一致。