DOE OSTI2020
Li6B4O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are six inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to five O2- atoms to form LiO5 trigonal bipyramids that share corners with three LiO5 trigonal bipyramids, edges with two equivalent LiO4 tetrahedra, and edges with three LiO5 trigonal bipyramids. There are a spread of Li–O bond distances ranging from 1.98–2.34 Å. In the second Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.96–2.02 Å. In the third Li1+ site, Li1+ is bonded to five O2- atoms to form distorted LiO5 trigonal bipyramids that share a cornercorner with one LiO4 tetrahedra, corners with three LiO5 trigonal bipyramids, and edges with four LiO5 trigonal bipyramids. There are a spread of Li–O bond distances ranging from 1.99–2.41 Å. In the fourth Li1+ site, Li1+ is bonded to five O2- atoms to form LiO5 trigonal bipyramids that share corners with three equivalent LiO4 tetrahedra, corners with two equivalent LiO5 trigonal bipyramids, edges with two equivalent LiO4 tetrahedra, and an edgeedge with one LiO5 trigonal bipyramid. There are a spread of Li–O bond distances ranging from 2.05–2.22 Å. In the fifth Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share corners with four LiO4 tetrahedra and edges with two equivalent LiO5 trigonal bipyramids. There are a spread of Li–O bond distances ranging from 1.96–2.00 Å. In the sixth Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with four LiO4 tetrahedra, corners with four LiO5 trigonal bipyramids, and edges with two equivalent LiO5 trigonal bipyramids. There are a spread of Li–O bond distances ranging from 1.92–2.01 Å. There are four inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.34–1.42 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.36–1.45 Å. In the third B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.35–1.44 Å. In the fourth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.35–1.41 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to four Li1+ and one B3+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to four Li1+ and one B3+ atom. In the third O2- site, O2- is bonded in a 5-coordinate geometry to four Li1+ and one B3+ atom. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to four Li1+ and one B3+ atom. In the fifth O2- site, O2- is bonded to four Li1+ and one B3+ atom to form a mixture of distorted edge and corner-sharing OLi4B trigonal bipyramids. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to one Li1+ and two B3+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+ and two B3+ atoms. In the eighth O2- site, O2- is bonded to four Li1+ and one B3+ atom to form a mixture of distorted edge and corner-sharing OLi4B trigonal bipyramids. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+ and two B3+ atoms.