Materials Data on KFeSn3O8 by Materials Project
KFeSn3O8 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. K1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 3.09–3.18 Å. Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four SnO6 octahedra, edges with two equivalent FeO6 octahedra, and edges with two equivalent SnO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Fe–O bond distances ranging from 2.00–2.13 Å. There are three inequivalent Sn4+ sites. In the first Sn4+ site, Sn4+ is bonded to six O2- atoms to form SnO6 octahedra that share corners with four SnO6 octahedra, edges with two equivalent FeO6 octahedra, and edges with two equivalent SnO6 octahedra. The corner-sharing octahedra tilt angles range from 50–51°. There are a spread of Sn–O bond distances ranging from 2.06–2.11 Å. In the second Sn4+ site, Sn4+ is bonded to six O2- atoms to form SnO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with two equivalent SnO6 octahedra, and edges with four SnO6 octahedra. The corner-sharing octahedra tilt angles range from 50–52°. There are a spread of Sn–O bond distances ranging from 2.06–2.16 Å. In the third Sn4+ site, Sn4+ is bonded to six O2- atoms to form SnO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with two equivalent SnO6 octahedra, and edges with four SnO6 octahedra. The corner-sharing octahedra tilt angles range from 51–52°. There are a spread of Sn–O bond distances ranging from 2.00–2.15 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent K1+, one Fe3+, and two equivalent Sn4+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent K1+, two equivalent Fe3+, and one Sn4+ atom. In the third O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent K1+ and three Sn4+ atoms. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent K1+ and three Sn4+ atoms. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to one Fe3+ and two equivalent Sn4+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Sn4+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three Sn4+ atoms. In the eighth O2- site, O2- is bonded in a trigonal planar geometry to two equivalent Fe3+ and one Sn4+ atom.