Li8TbO6 crystallizes in the trigonal R-3 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 3-coordinate geometry to three equivalent O(1) atoms. In the second Li site, Li(2) is bonded to four equivalent O(1) atoms to form LiO4 tetrahedra that share corners with two equivalent Tb(1)O6 octahedra, corners with six equivalent Li(2)O4 tetrahedra,  an edgeedge with one Tb(1)O6 octahedra, and edges with three equivalent Li(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-55°. Tb(1) is bonded to six equivalent O(1) atoms to form TbO6 octahedra that share corners with twelve equivalent Li(2)O4 tetrahedra and edges with six equivalent Li(2)O4 tetrahedra. O(1) is bonded in a 6-coordinate geometry to one Li(1), four equivalent Li(2), and one Tb(1) atom.
Li8TbO6 crystallizes in the trigonal R-3 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 3-coordinate geometry to three equivalent O(1) atoms. All Li(1)-O(1) bond lengths are 2.14 Å. In the second Li site, Li(2) is bonded to four equivalent O(1) atoms to form LiO4 tetrahedra that share corners with two equivalent Tb(1)O6 octahedra, corners with six equivalent Li(2)O4 tetrahedra,  an edgeedge with one Tb(1)O6 octahedra, and edges with three equivalent Li(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-55°. There are a spread of Li(2)-O(1) bond distances ranging from 1.91-2.03 Å. Tb(1) is bonded to six equivalent O(1) atoms to form TbO6 octahedra that share corners with twelve equivalent Li(2)O4 tetrahedra and edges with six equivalent Li(2)O4 tetrahedra. All Tb(1)-O(1) bond lengths are 2.28 Å. O(1) is bonded in a 6-coordinate geometry to one Li(1), four equivalent Li(2), and one Tb(1) atom.