Materials Data on Li4FeF8 by Materials Project

Abstract

Li4FeF8 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Li sites. In the first Li site, Li is bonded to six F atoms to form LiF6 octahedra that share corners with three equivalent LiF6 octahedra, corners with four equivalent FeF6 pentagonal pyramids, and edges with five LiF6 octahedra. The corner-sharing octahedra tilt angles range from 5–66°. There are a spread of Li–F bond distances ranging from 2.04–2.14 Å. In the second Li site, Li is bonded to six F atoms to form LiF6 octahedra that share corners with three equivalent LiF6 octahedra, corners with two equivalent FeF6 pentagonal pyramids, edges with five LiF6 octahedra, and an edgeedge with one FeF6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 6–55°. There are a spread of Li–F bond distances ranging from 1.90–2.17 Å. Fe is bonded to six F atoms to form distorted FeF6 pentagonal pyramids that share corners with twelve LiF6 octahedra and edges with two equivalent LiF6 octahedra. The corner-sharing octahedra tilt angles range from 26–70°. There are a spread of Fe–F bond distances ranging from 1.96–2.01 Å. There are five inequivalent F sites. In the first F site, F is bonded in a rectangular see-saw-like geometry to three Li and one Fe atom. In the second F site, F is bonded to three Li and one Fe atom to form a mixture of edge and corner-sharing FLi3Fe trigonal pyramids. In the third F site, F is bonded in a trigonal planar geometry to two equivalent Li and one Fe atom. In the fourth F site, F is bonded in a trigonal non-coplanar geometry to two equivalent Li and one Fe atom. In the fifth F site, F is bonded in a rectangular see-saw-like geometry to four Li atoms.