Li6Tb2O7 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted LiO4 tetrahedra that share corners with five equivalent Tb(1)O6 octahedra,  a cornercorner with one Li(3)O5 trigonal bipyramid, corners with three equivalent Li(2)O5 trigonal bipyramids,  an edgeedge with one Tb(1)O6 octahedra,  an edgeedge with one Li(1)O4 tetrahedra,  an edgeedge with one Li(2)O5 trigonal bipyramid, and edges with two equivalent Li(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 8-79°. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form LiO5 trigonal bipyramids that share corners with three equivalent Li(1)O4 tetrahedra, corners with three equivalent Li(2)O5 trigonal bipyramids, corners with four equivalent Li(3)O5 trigonal bipyramids, edges with four equivalent Tb(1)O6 octahedra,  an edgeedge with one Li(1)O4 tetrahedra, and edges with two equivalent Li(3)O5 trigonal bipyramids. In the third Li site, Li(3) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form LiO5 trigonal bipyramids that share  a cornercorner with one Li(1)O4 tetrahedra, corners with three equivalent Li(3)O5 trigonal bipyramids, corners with four equivalent Li(2)O5 trigonal bipyramids, edges with four equivalent Tb(1)O6 octahedra, edges with two equivalent Li(1)O4 tetrahedra, and edges with two equivalent Li(2)O5 trigonal bipyramids. Tb(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form TbO6 octahedra that share corners with three equivalent Tb(1)O6 octahedra, corners with five equivalent Li(1)O4 tetrahedra,  an edgeedge with one Tb(1)O6 octahedra,  an edgeedge with one Li(1)O4 tetrahedra, edges with four equivalent Li(2)O5 trigonal bipyramids, and edges with four equivalent Li(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-28°. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Li(2), one Li(3), two equivalent Li(1), and two equivalent Tb(1) atoms to form OLi4Tb2 octahedra that share corners with six equivalent O(2)Li3Tb2 trigonal bipyramids, edges with two equivalent O(1)Li4Tb2 octahedra, edges with two equivalent O(4)Li4Tb2 octahedra, edges with four equivalent O(3)Li5Tb octahedra, and  an edgeedge with one O(2)Li3Tb2 trigonal bipyramid. In the second O site, O(2) is bonded to one Li(1), one Li(2), one Li(3), and two equivalent Tb(1) atoms to form distorted OLi3Tb2 trigonal bipyramids that share  a cornercorner with one O(3)Li5Tb octahedra, corners with six equivalent O(1)Li4Tb2 octahedra, corners with two equivalent O(2)Li3Tb2 trigonal bipyramids,  an edgeedge with one O(1)Li4Tb2 octahedra, edges with two equivalent O(4)Li4Tb2 octahedra, and edges with three equivalent O(3)Li5Tb octahedra. The corner-sharing octahedral tilt angles range from 4-79°. In the third O site, O(3) is bonded to one Li(1), two equivalent Li(2), two equivalent Li(3), and one Tb(1) atom to form OLi5Tb octahedra that share corners with three equivalent O(4)Li4Tb2 octahedra,  a cornercorner with one O(2)Li3Tb2 trigonal bipyramid,  an edgeedge with one O(4)Li4Tb2 octahedra, edges with two equivalent O(3)Li5Tb octahedra, edges with four equivalent O(1)Li4Tb2 octahedra, and edges with three equivalent O(2)Li3Tb2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-22°. In the fourth O site, O(4) is bonded to two equivalent Li(2), two equivalent Li(3), and two equivalent Tb(1) atoms to form OLi4Tb2 octahedra that share corners with six equivalent O(3)Li5Tb octahedra, edges with two equivalent O(3)Li5Tb octahedra, edges with four equivalent O(1)Li4Tb2 octahedra, and edges with four equivalent O(2)Li3Tb2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-22°.
Li6Tb2O7 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form distorted LiO4 tetrahedra that share corners with five equivalent Tb(1)O6 octahedra,  a cornercorner with one Li(3)O5 trigonal bipyramid, corners with three equivalent Li(2)O5 trigonal bipyramids,  an edgeedge with one Tb(1)O6 octahedra,  an edgeedge with one Li(1)O4 tetrahedra,  an edgeedge with one Li(2)O5 trigonal bipyramid, and edges with two equivalent Li(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 8-79°. The Li(1)-O(2) bond length is 1.98 Å. The Li(1)-O(3) bond length is 1.99 Å. There is one shorter (2.02 Å) and one longer (2.04 Å) Li(1)-O(1) bond length. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form LiO5 trigonal bipyramids that share corners with three equivalent Li(1)O4 tetrahedra, corners with three equivalent Li(2)O5 trigonal bipyramids, corners with four equivalent Li(3)O5 trigonal bipyramids, edges with four equivalent Tb(1)O6 octahedra,  an edgeedge with one Li(1)O4 tetrahedra, and edges with two equivalent Li(3)O5 trigonal bipyramids. The Li(2)-O(1) bond length is 2.16 Å. The Li(2)-O(2) bond length is 2.31 Å. The Li(2)-O(4) bond length is 2.32 Å. There is one shorter (2.12 Å) and one longer (2.16 Å) Li(2)-O(3) bond length. In the third Li site, Li(3) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form LiO5 trigonal bipyramids that share  a cornercorner with one Li(1)O4 tetrahedra, corners with three equivalent Li(3)O5 trigonal bipyramids, corners with four equivalent Li(2)O5 trigonal bipyramids, edges with four equivalent Tb(1)O6 octahedra, edges with two equivalent Li(1)O4 tetrahedra, and edges with two equivalent Li(2)O5 trigonal bipyramids. The Li(3)-O(1) bond length is 2.31 Å. The Li(3)-O(2) bond length is 2.39 Å. The Li(3)-O(4) bond length is 2.33 Å. There is one shorter (2.02 Å) and one longer (2.04 Å) Li(3)-O(3) bond length. Tb(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form TbO6 octahedra that share corners with three equivalent Tb(1)O6 octahedra, corners with five equivalent Li(1)O4 tetrahedra,  an edgeedge with one Tb(1)O6 octahedra,  an edgeedge with one Li(1)O4 tetrahedra, edges with four equivalent Li(2)O5 trigonal bipyramids, and edges with four equivalent Li(3)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 0-28°. The Tb(1)-O(3) bond length is 2.24 Å. The Tb(1)-O(4) bond length is 2.22 Å. There is one shorter (2.30 Å) and one longer (2.36 Å) Tb(1)-O(1) bond length. There is one shorter (2.20 Å) and one longer (2.21 Å) Tb(1)-O(2) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Li(2), one Li(3), two equivalent Li(1), and two equivalent Tb(1) atoms to form OLi4Tb2 octahedra that share corners with six equivalent O(2)Li3Tb2 trigonal bipyramids, edges with two equivalent O(1)Li4Tb2 octahedra, edges with two equivalent O(4)Li4Tb2 octahedra, edges with four equivalent O(3)Li5Tb octahedra, and  an edgeedge with one O(2)Li3Tb2 trigonal bipyramid. In the second O site, O(2) is bonded to one Li(1), one Li(2), one Li(3), and two equivalent Tb(1) atoms to form distorted OLi3Tb2 trigonal bipyramids that share  a cornercorner with one O(3)Li5Tb octahedra, corners with six equivalent O(1)Li4Tb2 octahedra, corners with two equivalent O(2)Li3Tb2 trigonal bipyramids,  an edgeedge with one O(1)Li4Tb2 octahedra, edges with two equivalent O(4)Li4Tb2 octahedra, and edges with three equivalent O(3)Li5Tb octahedra. The corner-sharing octahedral tilt angles range from 4-79°. In the third O site, O(3) is bonded to one Li(1), two equivalent Li(2), two equivalent Li(3), and one Tb(1) atom to form OLi5Tb octahedra that share corners with three equivalent O(4)Li4Tb2 octahedra,  a cornercorner with one O(2)Li3Tb2 trigonal bipyramid,  an edgeedge with one O(4)Li4Tb2 octahedra, edges with two equivalent O(3)Li5Tb octahedra, edges with four equivalent O(1)Li4Tb2 octahedra, and edges with three equivalent O(2)Li3Tb2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-22°. In the fourth O site, O(4) is bonded to two equivalent Li(2), two equivalent Li(3), and two equivalent Tb(1) atoms to form OLi4Tb2 octahedra that share corners with six equivalent O(3)Li5Tb octahedra, edges with two equivalent O(3)Li5Tb octahedra, edges with four equivalent O(1)Li4Tb2 octahedra, and edges with four equivalent O(2)Li3Tb2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-22°.