DOI: 10.17188/1305221
title: Materials Data on Li2FeF4 by Materials Project

description: Li2FeF4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to five F1- atoms to form distorted LiF5 square pyramids that share corners with two equivalent LiF5 square pyramids, corners with five FeF5 trigonal bipyramids, an edgeedge with one LiF5 square pyramid, and an edgeedge with one LiF5 trigonal bipyramid. There are a spread of Li–F bond distances ranging from 1.93–2.30 Å. In the second Li1+ site, Li1+ is bonded to five F1- atoms to form LiF5 square pyramids that share corners with two equivalent LiF5 square pyramids, a cornercorner with one LiF5 trigonal bipyramid, corners with three FeF5 trigonal bipyramids, an edgeedge with one LiF5 square pyramid, an edgeedge with one LiF5 trigonal bipyramid, and edges with two equivalent FeF5 trigonal bipyramids. There are a spread of Li–F bond distances ranging from 1.91–2.06 Å. In the third Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six F1- atoms. There are a spread of Li–F bond distances ranging from 2.00–2.51 Å. In the fourth Li1+ site, Li1+ is bonded to five F1- atoms to form distorted LiF5 trigonal bipyramids that share a cornercorner with one LiF5 square pyramid, corners with five FeF5 trigonal bipyramids, edges with two LiF5 square pyramids, and an edgeedge with one LiF5 trigonal bipyramid. There are a spread of Li–F bond distances ranging from 1.87–2.45 Å. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to five F1- atoms to form FeF5 trigonal bipyramids that share corners with three LiF5 square pyramids, corners with two equivalent FeF5 trigonal bipyramids, corners with four equivalent LiF5 trigonal bipyramids, and edges with two equivalent LiF5 square pyramids. There are a spread of Fe–F bond distances ranging from 1.97–2.15 Å. In the second Fe2+ site, Fe2+ is bonded to five F1- atoms to form FeF5 trigonal bipyramids that share corners with five LiF5 square pyramids, a cornercorner with one LiF5 trigonal bipyramid, and corners with two equivalent FeF5 trigonal bipyramids. There are a spread of Fe–F bond distances ranging from 1.95–2.14 Å. There are eight inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted see-saw-like geometry to three Li1+ and one Fe2+ atom. In the second F1- site, F1- is bonded in a 4-coordinate geometry to three Li1+ and one Fe2+ atom. In the third F1- site, F1- is bonded to two equivalent Li1+ and two equivalent Fe2+ atoms to form a mixture of distorted edge and corner-sharing FLi2Fe2 trigonal pyramids. In the fourth F1- site, F1- is bonded in a distorted see-saw-like geometry to two equivalent Li1+ and two equivalent Fe2+ atoms. In the fifth F1- site, F1- is bonded to three Li1+ and one Fe2+ atom to form distorted edge-sharing FLi3Fe trigonal pyramids. In the sixth F1- site, F1- is bonded in a distorted trigonal non-coplanar geometry to two Li1+ and one Fe2+ atom. In the seventh F1- site, F1- is bonded in a 5-coordinate geometry to four Li1+ and one Fe2+ atom. In the eighth F1- site, F1- is bonded in a trigonal non-coplanar geometry to two Li1+ and one Fe2+ atom.