Materials Data on KFe3(SO7)2 by Materials Project
KFe3(SO7)2 crystallizes in the trigonal R3m space group. The structure is three-dimensional. K is bonded to twelve O atoms to form KO12 cuboctahedra that share corners with six SO4 tetrahedra and faces with six equivalent FeO6 octahedra. There are a spread of K–O bond distances ranging from 2.89–3.18 Å. Fe is bonded to six O atoms to form FeO6 octahedra that share corners with four equivalent FeO6 octahedra, corners with two SO4 tetrahedra, and faces with two equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 40–46°. There are a spread of Fe–O bond distances ranging from 1.84–2.11 Å. There are two inequivalent S sites. In the first S site, S is bonded to four O atoms to form SO4 tetrahedra that share corners with three equivalent KO12 cuboctahedra and corners with three equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There is one shorter (1.45 Å) and three longer (1.51 Å) S–O bond length. In the second S site, S is bonded to four O atoms to form SO4 tetrahedra that share corners with three equivalent KO12 cuboctahedra and corners with three equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 55°. There is one shorter (1.45 Å) and three longer (1.50 Å) S–O bond length. There are six inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one S atom. In the second O site, O is bonded in a single-bond geometry to one S atom. In the third O site, O is bonded in a 2-coordinate geometry to one K, one Fe, and one S atom. In the fourth O site, O is bonded in a 2-coordinate geometry to one K, one Fe, and one S atom. In the fifth O site, O is bonded in a distorted bent 150 degrees geometry to one K and two equivalent Fe atoms. In the sixth O site, O is bonded in a distorted bent 120 degrees geometry to one K and two equivalent Fe atoms.