Materials Data on Li2Fe3F8 by Materials Project

Abstract

Li2Fe3F8 crystallizes in the tetragonal I4_1/a space group. The structure is three-dimensional. Li1+ is bonded to six F1- atoms to form distorted LiF6 octahedra that share corners with two equivalent LiF6 octahedra, corners with two equivalent FeF4 tetrahedra, and an edgeedge with one LiF6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Li–F bond distances ranging from 1.95–2.35 Å. There are three inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded in a 7-coordinate geometry to seven F1- atoms. There are a spread of Fe–F bond distances ranging from 2.05–2.55 Å. In the second Fe2+ site, Fe2+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are four shorter (2.11 Å) and four longer (2.53 Å) Fe–F bond lengths. In the third Fe2+ site, Fe2+ is bonded to four equivalent F1- atoms to form FeF4 tetrahedra that share corners with eight equivalent LiF6 octahedra. The corner-sharing octahedra tilt angles range from 62–72°. All Fe–F bond lengths are 1.97 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to one Li1+ and three Fe2+ atoms. In the second F1- site, F1- is bonded to two equivalent Li1+ and two Fe2+ atoms to form a mixture of distorted corner and edge-sharing FLi2Fe2 tetrahedra. In the third F1- site, F1- is bonded in a 4-coordinate geometry to one Li1+ and three Fe2+ atoms. In the fourth 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.