Materials Data on K2Fe4O7 by Materials Project
K2Fe4O7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.90–3.07 Å. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with six equivalent FeO6 octahedra and a cornercorner with one FeO4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. There is one shorter (1.90 Å) and three longer (1.93 Å) Fe–O bond length. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent FeO4 tetrahedra and edges with three equivalent FeO6 octahedra. All Fe–O bond lengths are 2.07 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent K1+ and three Fe3+ atoms. In the second O2- site, O2- is bonded in a linear geometry to six equivalent K1+ and two equivalent Fe3+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent K1+ and three Fe3+ atoms.