Li6Ti2O7 crystallizes in the monoclinic C2 space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form LiO5 square pyramids that share corners with two equivalent Li(3)O5 square pyramids, corners with three equivalent Li(2)O5 square pyramids, corners with four equivalent Li(1)O5 square pyramids, edges with four equivalent Ti(1)O6 octahedra, edges with two equivalent Li(2)O5 square pyramids, and edges with two equivalent Li(3)O5 square pyramids. In the second Li site, Li(2) is bonded to one O(1), one O(4), one O(5), and two equivalent O(3) atoms to form LiO5 square pyramids that share corners with two equivalent Li(3)O5 square pyramids, corners with three equivalent Li(1)O5 square pyramids, corners with four equivalent Li(2)O5 square pyramids, edges with four equivalent Ti(1)O6 octahedra, edges with two equivalent Li(1)O5 square pyramids, and edges with two equivalent Li(3)O5 square pyramids. In the third Li site, Li(3) is bonded to one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted LiO5 square pyramids that share corners with three equivalent Ti(1)O6 octahedra, corners with two equivalent Li(1)O5 square pyramids, corners with two equivalent Li(2)O5 square pyramids, corners with two equivalent Li(3)O5 square pyramids, edges with three equivalent Ti(1)O6 octahedra,  an edgeedge with one Li(3)O5 square pyramid, edges with two equivalent Li(1)O5 square pyramids, and edges with two equivalent Li(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 3-13°. Ti(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form TiO6 octahedra that share corners with three equivalent Ti(1)O6 octahedra, corners with three equivalent Li(3)O5 square pyramids,  an edgeedge with one Ti(1)O6 octahedra, edges with three equivalent Li(3)O5 square pyramids, edges with four equivalent Li(1)O5 square pyramids, and edges with four equivalent Li(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 1-3°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Li(1), two equivalent Li(2), and two equivalent Ti(1) atoms to form OLi4Ti2 octahedra that share corners with six equivalent O(3)Li5Ti octahedra, edges with two equivalent O(2)Li4Ti2 octahedra, edges with two equivalent O(5)Li4Ti2 octahedra, edges with two equivalent O(3)Li5Ti octahedra, and edges with four equivalent O(4)Li4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 1-17°. In the second O site, O(2) is bonded to two equivalent Li(1), two equivalent Li(3), and two equivalent Ti(1) atoms to form OLi4Ti2 octahedra that share corners with six equivalent O(4)Li4Ti2 octahedra, edges with two equivalent O(1)Li4Ti2 octahedra, edges with two equivalent O(4)Li4Ti2 octahedra, edges with two equivalent O(5)Li4Ti2 octahedra, and edges with four equivalent O(3)Li5Ti octahedra. The corner-sharing octahedral tilt angles range from 8-20°. In the third O site, O(3) is bonded to one Li(3), two equivalent Li(1), two equivalent Li(2), and one Ti(1) atom to form OLi5Ti octahedra that share corners with three equivalent O(1)Li4Ti2 octahedra,  an edgeedge with one O(1)Li4Ti2 octahedra, edges with two equivalent O(2)Li4Ti2 octahedra, edges with two equivalent O(5)Li4Ti2 octahedra, edges with two equivalent O(3)Li5Ti octahedra, and edges with four equivalent O(4)Li4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 1-17°. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), two equivalent Li(3), and two equivalent Ti(1) atoms to form OLi4Ti2 octahedra that share corners with three equivalent O(2)Li4Ti2 octahedra, corners with three equivalent O(5)Li4Ti2 octahedra,  an edgeedge with one O(2)Li4Ti2 octahedra,  an edgeedge with one O(5)Li4Ti2 octahedra, edges with two equivalent O(1)Li4Ti2 octahedra, edges with two equivalent O(4)Li4Ti2 octahedra, and edges with four equivalent O(3)Li5Ti octahedra. The corner-sharing octahedral tilt angles range from 6-20°. In the fifth O site, O(5) is bonded to two equivalent Li(2), two equivalent Li(3), and two equivalent Ti(1) atoms to form OLi4Ti2 octahedra that share corners with six equivalent O(4)Li4Ti2 octahedra, edges with two equivalent O(1)Li4Ti2 octahedra, edges with two equivalent O(2)Li4Ti2 octahedra, edges with two equivalent O(4)Li4Ti2 octahedra, and edges with four equivalent O(3)Li5Ti octahedra. The corner-sharing octahedral tilt angles range from 6-18°.
Li6Ti2O7 crystallizes in the monoclinic C2 space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form LiO5 square pyramids that share corners with two equivalent Li(3)O5 square pyramids, corners with three equivalent Li(2)O5 square pyramids, corners with four equivalent Li(1)O5 square pyramids, edges with four equivalent Ti(1)O6 octahedra, edges with two equivalent Li(2)O5 square pyramids, and edges with two equivalent Li(3)O5 square pyramids. The Li(1)-O(1) bond length is 2.03 Å. The Li(1)-O(2) bond length is 2.07 Å. The Li(1)-O(4) bond length is 2.11 Å. Both Li(1)-O(3) bond lengths are 1.97 Å. In the second Li site, Li(2) is bonded to one O(1), one O(4), one O(5), and two equivalent O(3) atoms to form LiO5 square pyramids that share corners with two equivalent Li(3)O5 square pyramids, corners with three equivalent Li(1)O5 square pyramids, corners with four equivalent Li(2)O5 square pyramids, edges with four equivalent Ti(1)O6 octahedra, edges with two equivalent Li(1)O5 square pyramids, and edges with two equivalent Li(3)O5 square pyramids. The Li(2)-O(1) bond length is 2.04 Å. The Li(2)-O(4) bond length is 2.08 Å. The Li(2)-O(5) bond length is 2.08 Å. There is one shorter (1.98 Å) and one longer (2.00 Å) Li(2)-O(3) bond length. In the third Li site, Li(3) is bonded to one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted LiO5 square pyramids that share corners with three equivalent Ti(1)O6 octahedra, corners with two equivalent Li(1)O5 square pyramids, corners with two equivalent Li(2)O5 square pyramids, corners with two equivalent Li(3)O5 square pyramids, edges with three equivalent Ti(1)O6 octahedra,  an edgeedge with one Li(3)O5 square pyramid, edges with two equivalent Li(1)O5 square pyramids, and edges with two equivalent Li(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 3-13°. The Li(3)-O(2) bond length is 2.08 Å. The Li(3)-O(3) bond length is 1.96 Å. The Li(3)-O(5) bond length is 2.05 Å. There is one shorter (2.14 Å) and one longer (2.24 Å) Li(3)-O(4) bond length. Ti(1) is bonded to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form TiO6 octahedra that share corners with three equivalent Ti(1)O6 octahedra, corners with three equivalent Li(3)O5 square pyramids,  an edgeedge with one Ti(1)O6 octahedra, edges with three equivalent Li(3)O5 square pyramids, edges with four equivalent Li(1)O5 square pyramids, and edges with four equivalent Li(2)O5 square pyramids. The corner-sharing octahedral tilt angles range from 1-3°. The Ti(1)-O(1) bond length is 2.13 Å. The Ti(1)-O(2) bond length is 2.03 Å. The Ti(1)-O(3) bond length is 1.84 Å. The Ti(1)-O(5) bond length is 2.03 Å. There is one shorter (1.96 Å) and one longer (2.00 Å) Ti(1)-O(4) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Li(1), two equivalent Li(2), and two equivalent Ti(1) atoms to form OLi4Ti2 octahedra that share corners with six equivalent O(3)Li5Ti octahedra, edges with two equivalent O(2)Li4Ti2 octahedra, edges with two equivalent O(5)Li4Ti2 octahedra, edges with two equivalent O(3)Li5Ti octahedra, and edges with four equivalent O(4)Li4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 1-17°. In the second O site, O(2) is bonded to two equivalent Li(1), two equivalent Li(3), and two equivalent Ti(1) atoms to form OLi4Ti2 octahedra that share corners with six equivalent O(4)Li4Ti2 octahedra, edges with two equivalent O(1)Li4Ti2 octahedra, edges with two equivalent O(4)Li4Ti2 octahedra, edges with two equivalent O(5)Li4Ti2 octahedra, and edges with four equivalent O(3)Li5Ti octahedra. The corner-sharing octahedral tilt angles range from 8-20°. In the third O site, O(3) is bonded to one Li(3), two equivalent Li(1), two equivalent Li(2), and one Ti(1) atom to form OLi5Ti octahedra that share corners with three equivalent O(1)Li4Ti2 octahedra,  an edgeedge with one O(1)Li4Ti2 octahedra, edges with two equivalent O(2)Li4Ti2 octahedra, edges with two equivalent O(5)Li4Ti2 octahedra, edges with two equivalent O(3)Li5Ti octahedra, and edges with four equivalent O(4)Li4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 1-17°. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), two equivalent Li(3), and two equivalent Ti(1) atoms to form OLi4Ti2 octahedra that share corners with three equivalent O(2)Li4Ti2 octahedra, corners with three equivalent O(5)Li4Ti2 octahedra,  an edgeedge with one O(2)Li4Ti2 octahedra,  an edgeedge with one O(5)Li4Ti2 octahedra, edges with two equivalent O(1)Li4Ti2 octahedra, edges with two equivalent O(4)Li4Ti2 octahedra, and edges with four equivalent O(3)Li5Ti octahedra. The corner-sharing octahedral tilt angles range from 6-20°. In the fifth O site, O(5) is bonded to two equivalent Li(2), two equivalent Li(3), and two equivalent Ti(1) atoms to form OLi4Ti2 octahedra that share corners with six equivalent O(4)Li4Ti2 octahedra, edges with two equivalent O(1)Li4Ti2 octahedra, edges with two equivalent O(2)Li4Ti2 octahedra, edges with two equivalent O(4)Li4Ti2 octahedra, and edges with four equivalent O(3)Li5Ti octahedra. The corner-sharing octahedral tilt angles range from 6-18°.