DOI: 10.17188/1294940
title: Materials Data on Li8Fe(O2F)2 by Materials Project

description: Li8Fe(O2F)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are eight inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to three O2- and one F1- atom to form LiO3F tetrahedra that share a cornercorner with one FeO4F2 octahedra, corners with seven LiO3F tetrahedra, an edgeedge with one FeO4F2 octahedra, and edges with two LiO3F tetrahedra. The corner-sharing octahedral tilt angles are 13°. There is two shorter (1.95 Å) and one longer (2.00 Å) Li–O bond length. The Li–F bond length is 1.99 Å. In the second Li1+ site, Li1+ is bonded in a distorted see-saw-like geometry to three O2- and one F1- atom. There are one shorter (1.98 Å) and two longer (2.03 Å) Li–O bond lengths. The Li–F bond length is 2.24 Å. In the third Li1+ site, Li1+ is bonded to three O2- and one F1- atom to form distorted LiO3F tetrahedra that share a cornercorner with one FeO4F2 octahedra, corners with five LiO3F tetrahedra, and edges with four LiO3F tetrahedra. The corner-sharing octahedral tilt angles are 59°. There are two shorter (2.00 Å) and one longer (2.07 Å) Li–O bond lengths. The Li–F bond length is 1.93 Å. In the fourth Li1+ site, Li1+ is bonded in a distorted rectangular see-saw-like geometry to two O2- and two F1- atoms. There is one shorter (1.87 Å) and one longer (1.93 Å) Li–O bond length. There are one shorter (1.98 Å) and one longer (2.10 Å) Li–F bond lengths. In the fifth Li1+ site, Li1+ is bonded to three O2- and one F1- atom to form distorted LiO3F tetrahedra that share a cornercorner with one FeO4F2 octahedra, corners with eight LiO3F tetrahedra, an edgeedge with one FeO4F2 octahedra, and edges with two LiO3F tetrahedra. The corner-sharing octahedral tilt angles are 30°. There are two shorter (1.90 Å) and one longer (2.22 Å) Li–O bond lengths. The Li–F bond length is 1.97 Å. In the sixth Li1+ site, Li1+ is bonded to three O2- and one F1- atom to form LiO3F tetrahedra that share a cornercorner with one FeO4F2 octahedra, corners with five LiO3F tetrahedra, and edges with four LiO3F tetrahedra. The corner-sharing octahedral tilt angles are 45°. There is two shorter (1.93 Å) and one longer (1.97 Å) Li–O bond length. The Li–F bond length is 1.97 Å. In the seventh Li1+ site, Li1+ is bonded to two O2- and two F1- atoms to form LiO2F2 tetrahedra that share a cornercorner with one FeO4F2 octahedra, corners with seven LiO3F tetrahedra, an edgeedge with one FeO4F2 octahedra, and edges with two LiO3F tetrahedra. The corner-sharing octahedral tilt angles are 34°. There is one shorter (1.91 Å) and one longer (1.96 Å) Li–O bond length. There is one shorter (1.90 Å) and one longer (1.98 Å) Li–F bond length. In the eighth Li1+ site, Li1+ is bonded to three O2- and one F1- atom to form a mixture of distorted edge and corner-sharing LiO3F tetrahedra. There are a spread of Li–O bond distances ranging from 1.97–1.99 Å. The Li–F bond length is 2.04 Å. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to four O2- and two equivalent F1- atoms to form distorted FeO4F2 octahedra that share corners with ten LiO3F tetrahedra and edges with six LiO3F tetrahedra. There are two shorter (1.97 Å) and two longer (2.44 Å) Fe–O bond lengths. Both Fe–F bond lengths are 2.50 Å. In the second Fe2+ site, Fe2+ is bonded in a distorted square co-planar geometry to four O2- atoms. There are two shorter (1.94 Å) and two longer (2.37 Å) Fe–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to five Li1+ and one Fe2+ atom to form a mixture of distorted edge and corner-sharing OLi5Fe octahedra. The corner-sharing octahedral tilt angles are 0°. In the second O2- site, O2- is bonded in a 7-coordinate geometry to six Li1+ and one Fe2+ atom. In the third O2- site, O2- is bonded in a 7-coordinate geometry to six Li1+ and one Fe2+ atom. In the fourth O2- site, O2- is bonded to five Li1+ and one Fe2+ atom to form a mixture of distorted edge and corner-sharing OLi5Fe pentagonal pyramids. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a 6-coordinate geometry to five Li1+ and one Fe2+ atom. In the second F1- site, F1- is bonded in a 5-coordinate geometry to five Li1+ atoms.