Materials Data on Li2FeF4 by Materials Project

Li2FeF4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a distorted see-saw-like geometry to four F1- atoms. There are a spread of Li–F bond distances ranging from 1.86–2.22 Å. In the second Li1+ site, Li1+ is bonded to five F1- atoms to form LiF5 square pyramids that share corners with three equivalent FeF6 octahedra, edges with two equivalent FeF6 octahedra, and an edgeedge with one LiF5 square pyramid. The corner-sharing octahedra tilt angles range from 29–66°. There are a spread of Li–F bond distances ranging from 1.92–2.11 Å. Fe2+ is bonded to six F1- atoms to form distorted FeF6 octahedra that share corners with two equivalent FeF6 octahedra, corners with three equivalent LiF5 square pyramids, an edgeedge with one FeF6 octahedra, and edges with two equivalent LiF5 square pyramids. The corner-sharing octahedral tilt angles are 51°. There are a spread of Fe–F bond distances ranging from 2.04–2.26 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted rectangular see-saw-like geometry to two Li1+ and two equivalent Fe2+ atoms. In the second F1- site, F1- is bonded in a T-shaped geometry to two Li1+ and one Fe2+ atom. In the third F1- site, F1- is bonded in a distorted see-saw-like geometry to three Li1+ and one Fe2+ atom. In the fourth F1- site, F1- is bonded to two Li1+ and two equivalent Fe2+ atoms to form distorted corner-sharing FLi2Fe2 trigonal pyramids.