Materials Data on Li2FeF4 by Materials Project

Abstract

Li2FeF4 crystallizes in the orthorhombic Pna2_1 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 distorted LiF4 trigonal pyramids that share corners with five equivalent FeF6 octahedra and corners with two equivalent LiF4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 38–79°. There are a spread of Li–F bond distances ranging from 1.89–1.95 Å. In the second Li1+ site, Li1+ is bonded in a 4-coordinate geometry to six F1- atoms. There are a spread of Li–F bond distances ranging from 1.89–2.70 Å. Fe2+ is bonded to six F1- atoms to form FeF6 octahedra that share corners with four equivalent FeF6 octahedra and corners with five equivalent LiF4 trigonal pyramids. The corner-sharing octahedral tilt angles are 39°. There are a spread of Fe–F bond distances ranging from 2.07–2.15 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 3-coordinate geometry to one Li1+ and two equivalent Fe2+ atoms. 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 in a 5-coordinate geometry to three Li1+ and two equivalent Fe2+ atoms. In the fourth F1- site, F1- is bonded to three Li1+ and one Fe2+ atom to form distorted corner-sharing FLi3Fe tetrahedra.