Li6Sr3Ta2O11 crystallizes in the orthorhombic Pmma space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(4), one O(5), and two equivalent O(3) atoms to form distorted LiO4 tetrahedra that share corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra,  a cornercorner with one Li(3)O5 trigonal bipyramid, corners with two equivalent Ta(1)O5 trigonal bipyramids, and  an edgeedge with one Li(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 14°. In the second Li site, Li(2) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(3)O5 trigonal bipyramids, corners with two equivalent Ta(1)O5 trigonal bipyramids,  an edgeedge with one Ta(2)O6 octahedra, and  an edgeedge with one Li(2)O4 tetrahedra. In the third Li site, Li(3) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form distorted LiO5 trigonal bipyramids that share  a cornercorner with one Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra,  a cornercorner with one Ta(1)O5 trigonal bipyramid, edges with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Li(1)O4 tetrahedra, and  an edgeedge with one Li(3)O5 trigonal bipyramid. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(5), two equivalent O(1), and two equivalent O(4) atoms to form TaO5 trigonal bipyramids that share corners with four equivalent Li(1)O4 tetrahedra, corners with four equivalent Li(2)O4 tetrahedra, and corners with two equivalent Li(3)O5 trigonal bipyramids. In the second Ta site, Ta(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form TaO6 octahedra that share corners with four equivalent Li(1)O4 tetrahedra, edges with two equivalent Li(2)O4 tetrahedra, and edges with four equivalent Li(3)O5 trigonal bipyramids. There are five inequivalent O sites. In the first O site, O(4) is bonded in a 6-coordinate geometry to one Li(1), one Li(3), one Sr(1), two equivalent Sr(2), and one Ta(1) atom. In the second O site, O(5) is bonded in a trigonal planar geometry to two equivalent Li(1) and one Ta(1) atom. In the third O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Li(2), two equivalent Sr(2), and one Ta(1) atom. In the fourth O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Li(3), one Sr(1), two equivalent Sr(2), and one Ta(2) atom. In the fifth O site, O(3) is bonded to one Li(1), one Li(2), one Li(3), one Sr(1), one Sr(2), and one Ta(2) atom to form a mixture of distorted corner, edge, and face-sharing OSr2Li3Ta octahedra. The corner-sharing octahedral tilt angles range from 0-70°.
Li6Sr3Ta2O11 crystallizes in the orthorhombic Pmma space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(4), one O(5), and two equivalent O(3) atoms to form distorted LiO4 tetrahedra that share corners with two equivalent Ta(2)O6 octahedra,  a cornercorner with one Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra,  a cornercorner with one Li(3)O5 trigonal bipyramid, corners with two equivalent Ta(1)O5 trigonal bipyramids, and  an edgeedge with one Li(3)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 14°. The Li(1)-O(4) bond length is 2.06 Å. The Li(1)-O(5) bond length is 1.82 Å. Both Li(1)-O(3) bond lengths are 1.99 Å. In the second Li site, Li(2) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(3)O5 trigonal bipyramids, corners with two equivalent Ta(1)O5 trigonal bipyramids,  an edgeedge with one Ta(2)O6 octahedra, and  an edgeedge with one Li(2)O4 tetrahedra. Both Li(2)-O(1) bond lengths are 2.04 Å. Both Li(2)-O(3) bond lengths are 2.09 Å. In the third Li site, Li(3) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form distorted LiO5 trigonal bipyramids that share  a cornercorner with one Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra,  a cornercorner with one Ta(1)O5 trigonal bipyramid, edges with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Li(1)O4 tetrahedra, and  an edgeedge with one Li(3)O5 trigonal bipyramid. The Li(3)-O(4) bond length is 2.12 Å. Both Li(3)-O(2) bond lengths are 2.11 Å. Both Li(3)-O(3) bond lengths are 2.24 Å. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. Both Sr(1)-O(2) bond lengths are 2.50 Å. Both Sr(1)-O(4) bond lengths are 2.77 Å. All Sr(1)-O(3) bond lengths are 2.55 Å. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Sr(2)-O(1) bond lengths are 2.55 Å. Both Sr(2)-O(2) bond lengths are 2.81 Å. Both Sr(2)-O(3) bond lengths are 2.57 Å. Both Sr(2)-O(4) bond lengths are 2.72 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(5), two equivalent O(1), and two equivalent O(4) atoms to form TaO5 trigonal bipyramids that share corners with four equivalent Li(1)O4 tetrahedra, corners with four equivalent Li(2)O4 tetrahedra, and corners with two equivalent Li(3)O5 trigonal bipyramids. The Ta(1)-O(5) bond length is 1.88 Å. Both Ta(1)-O(1) bond lengths are 2.01 Å. Both Ta(1)-O(4) bond lengths are 1.94 Å. In the second Ta site, Ta(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form TaO6 octahedra that share corners with four equivalent Li(1)O4 tetrahedra, edges with two equivalent Li(2)O4 tetrahedra, and edges with four equivalent Li(3)O5 trigonal bipyramids. Both Ta(2)-O(2) bond lengths are 2.01 Å. All Ta(2)-O(3) bond lengths are 2.03 Å. There are five inequivalent O sites. In the first O site, O(4) is bonded in a 6-coordinate geometry to one Li(1), one Li(3), one Sr(1), two equivalent Sr(2), and one Ta(1) atom. In the second O site, O(5) is bonded in a trigonal planar geometry to two equivalent Li(1) and one Ta(1) atom. In the third O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Li(2), two equivalent Sr(2), and one Ta(1) atom. In the fourth O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Li(3), one Sr(1), two equivalent Sr(2), and one Ta(2) atom. In the fifth O site, O(3) is bonded to one Li(1), one Li(2), one Li(3), one Sr(1), one Sr(2), and one Ta(2) atom to form a mixture of distorted corner, edge, and face-sharing OSr2Li3Ta octahedra. The corner-sharing octahedral tilt angles range from 0-70°.