Materials Data on Na6Fe2B4AsO16 by Materials Project
Na6Fe2B4AsO16 crystallizes in the cubic Fd-3 space group. The structure is three-dimensional. Na is bonded to six O atoms to form distorted NaO6 octahedra that share corners with eight equivalent NaO6 octahedra, edges with two equivalent FeO6 octahedra, and an edgeedge with one AsO4 tetrahedra. The corner-sharing octahedra tilt angles range from 60–87°. There are a spread of Na–O bond distances ranging from 2.45–2.56 Å. Fe is bonded to six equivalent O atoms to form FeO6 octahedra that share edges with six equivalent NaO6 octahedra. All Fe–O bond lengths are 2.02 Å. B is bonded in a trigonal planar geometry to three equivalent O atoms. All B–O bond lengths are 1.38 Å. As is bonded to four equivalent O atoms to form AsO4 tetrahedra that share edges with six equivalent NaO6 octahedra. All As–O bond lengths are 1.73 Å. There are two inequivalent O sites. In the first O site, O is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na, one Fe, and one B atom. In the second O site, O is bonded to three equivalent Na and one As atom to form edge-sharing ONa3As trigonal pyramids.