Materials Data on Li3AlF6 by Materials Project
Li3AlF6 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are five inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to six F1- atoms to form distorted LiF6 octahedra that share corners with two equivalent AlF6 octahedra, corners with two equivalent LiF4 tetrahedra, corners with two equivalent LiF5 trigonal bipyramids, and edges with two equivalent AlF6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are a spread of Li–F bond distances ranging from 2.01–2.12 Å. In the second Li1+ site, Li1+ is bonded to four F1- atoms to form LiF4 tetrahedra that share a cornercorner with one LiF6 octahedra, corners with four AlF6 octahedra, a cornercorner with one LiF5 trigonal bipyramid, and an edgeedge with one LiF4 tetrahedra. The corner-sharing octahedra tilt angles range from 48–66°. There are a spread of Li–F bond distances ranging from 1.87–1.91 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 1.92–2.49 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 LiF6 octahedra, corners with three equivalent AlF6 octahedra, a cornercorner with one LiF4 tetrahedra, an edgeedge with one AlF6 octahedra, and an edgeedge with one LiF5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 46–79°. There are a spread of Li–F bond distances ranging from 1.88–2.23 Å. In the fifth 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 1.92–2.56 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share corners with two equivalent LiF4 tetrahedra, edges with two equivalent LiF6 octahedra, and edges with two equivalent LiF5 trigonal bipyramids. There are a spread of Al–F bond distances ranging from 1.81–1.84 Å. In the second Al3+ site, Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share a cornercorner with one LiF6 octahedra, corners with three equivalent LiF4 tetrahedra, and corners with three equivalent LiF5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 46°. There are a spread of Al–F bond distances ranging from 1.82–1.86 Å. There are nine inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to three Li1+ and one Al3+ atom. In the second F1- site, F1- is bonded to three Li1+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing FLi3Al trigonal pyramids. In the third F1- site, F1- is bonded in a 4-coordinate geometry to three Li1+ and one Al3+ atom. In the fourth F1- site, F1- is bonded in a trigonal planar geometry to two Li1+ and one Al3+ atom. In the fifth F1- site, F1- is bonded in a distorted trigonal planar geometry to two Li1+ and one Al3+ atom. In the sixth F1- site, F1- is bonded in a 4-coordinate geometry to three Li1+ and one Al3+ atom. In the seventh F1- site, F1- is bonded to three Li1+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing FLi3Al tetrahedra. In the eighth F1- site, F1- is bonded in a distorted rectangular see-saw-like geometry to three Li1+ and one Al3+ atom. In the ninth F1- site, F1- is bonded in a trigonal planar geometry to two Li1+ and one Al3+ atom.