Materials Data on Li2FeF4 by Materials Project

Abstract

Li2FeF4 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four F1- atoms to form LiF4 tetrahedra that share corners with four LiF4 tetrahedra and corners with four equivalent FeF5 trigonal bipyramids. There are a spread of Li–F bond distances ranging from 1.89–1.93 Å. In the second Li1+ site, Li1+ is bonded to four F1- atoms to form LiF4 tetrahedra that share corners with four LiF4 tetrahedra, corners with four equivalent FeF5 trigonal bipyramids, and an edgeedge with one FeF5 trigonal bipyramid. There are a spread of Li–F bond distances ranging from 1.86–2.02 Å. Fe2+ is bonded to five F1- atoms to form distorted FeF5 trigonal bipyramids that share corners with eight LiF4 tetrahedra, an edgeedge with one LiF4 tetrahedra, and an edgeedge with one FeF5 trigonal bipyramid. There are a spread of Fe–F bond distances ranging from 1.94–2.40 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a trigonal planar geometry to two equivalent Li1+ and one Fe2+ atom. In the second F1- site, F1- is bonded in a trigonal planar geometry to two 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 corner and edge-sharing FLi2Fe2 tetrahedra. In the fourth F1- site, F1- is bonded in a trigonal planar geometry to two Li1+ and one Fe2+ atom.