Na4Ti5O12 is Spinel-like structured and crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form NaO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, and corners with four equivalent Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-68°. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. In the third Na site, Na(3) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form NaO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, and corners with four equivalent Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-67°. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form TiO6 octahedra that share corners with two equivalent Na(3)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra, edges with two equivalent Ti(2)O6 octahedra, and edges with two equivalent Ti(3)O6 octahedra. In the second Ti site, Ti(2) is bonded to one O(2), one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form TiO6 octahedra that share corners with two equivalent Na(3)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra,  an edgeedge with one Ti(1)O6 octahedra,  an edgeedge with one Ti(2)O6 octahedra, and edges with three equivalent Ti(3)O6 octahedra. In the third Ti site, Ti(3) is bonded to one O(1), one O(3), one O(4), one O(5), and two equivalent O(6) atoms to form distorted TiO6 octahedra that share corners with two equivalent Na(3)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra,  an edgeedge with one Ti(1)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra, and edges with three equivalent Ti(2)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Ti(1), and one Ti(3) atom to form distorted ONa2Ti2 trigonal pyramids that share corners with two equivalent O(5)NaTi3 tetrahedra, corners with three equivalent O(6)NaTi3 tetrahedra,  a cornercorner with one O(4)Na2Ti2 trigonal pyramid, corners with two equivalent O(1)Na2Ti2 trigonal pyramids, corners with three equivalent O(2)Na2Ti2 trigonal pyramids,  an edgeedge with one O(2)Na2Ti2 trigonal pyramid, and  an edgeedge with one O(4)Na2Ti2 trigonal pyramid. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Ti(1), and one Ti(2) atom to form distorted ONa2Ti2 trigonal pyramids that share corners with two equivalent O(6)NaTi3 tetrahedra, corners with three equivalent O(5)NaTi3 tetrahedra,  a cornercorner with one O(4)Na2Ti2 trigonal pyramid, corners with two equivalent O(2)Na2Ti2 trigonal pyramids, corners with three equivalent O(1)Na2Ti2 trigonal pyramids,  an edgeedge with one O(1)Na2Ti2 trigonal pyramid, and  an edgeedge with one O(4)Na2Ti2 trigonal pyramid. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Na(3), one Ti(1), one Ti(2), and one Ti(3) atom. In the fourth O site, O(4) is bonded to one Na(2), one Na(3), one Ti(2), and one Ti(3) atom to form distorted ONa2Ti2 trigonal pyramids that share corners with three equivalent O(5)NaTi3 tetrahedra, corners with three equivalent O(6)NaTi3 tetrahedra,  a cornercorner with one O(1)Na2Ti2 trigonal pyramid,  a cornercorner with one O(2)Na2Ti2 trigonal pyramid, corners with two equivalent O(4)Na2Ti2 trigonal pyramids,  an edgeedge with one O(1)Na2Ti2 trigonal pyramid, and  an edgeedge with one O(2)Na2Ti2 trigonal pyramid. In the fifth O site, O(5) is bonded to one Na(1), one Ti(3), and two equivalent Ti(2) atoms to form distorted ONaTi3 tetrahedra that share  a cornercorner with one O(6)NaTi3 tetrahedra, corners with two equivalent O(1)Na2Ti2 trigonal pyramids, corners with three equivalent O(2)Na2Ti2 trigonal pyramids, corners with three equivalent O(4)Na2Ti2 trigonal pyramids,  an edgeedge with one O(5)NaTi3 tetrahedra, and edges with two equivalent O(6)NaTi3 tetrahedra. In the sixth O site, O(6) is bonded to one Na(1), one Ti(2), and two equivalent Ti(3) atoms to form distorted ONaTi3 tetrahedra that share  a cornercorner with one O(5)NaTi3 tetrahedra, corners with two equivalent O(2)Na2Ti2 trigonal pyramids, corners with three equivalent O(1)Na2Ti2 trigonal pyramids, corners with three equivalent O(4)Na2Ti2 trigonal pyramids,  an edgeedge with one O(6)NaTi3 tetrahedra, and edges with two equivalent O(5)NaTi3 tetrahedra.
Na4Ti5O12 is Spinel-like structured and crystallizes in the monoclinic C2/c space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form NaO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, and corners with four equivalent Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-68°. The Na(1)-O(1) bond length is 2.25 Å. The Na(1)-O(2) bond length is 2.26 Å. The Na(1)-O(5) bond length is 2.28 Å. The Na(1)-O(6) bond length is 2.21 Å. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. Both Na(2)-O(1) bond lengths are 2.29 Å. Both Na(2)-O(2) bond lengths are 2.27 Å. Both Na(2)-O(4) bond lengths are 2.53 Å. In the third Na site, Na(3) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form NaO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, and corners with four equivalent Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-67°. Both Na(3)-O(3) bond lengths are 2.19 Å. Both Na(3)-O(4) bond lengths are 2.19 Å. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form TiO6 octahedra that share corners with two equivalent Na(3)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra, edges with two equivalent Ti(2)O6 octahedra, and edges with two equivalent Ti(3)O6 octahedra. Both Ti(1)-O(1) bond lengths are 1.97 Å. Both Ti(1)-O(2) bond lengths are 1.99 Å. Both Ti(1)-O(3) bond lengths are 2.00 Å. In the second Ti site, Ti(2) is bonded to one O(2), one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form TiO6 octahedra that share corners with two equivalent Na(3)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra,  an edgeedge with one Ti(1)O6 octahedra,  an edgeedge with one Ti(2)O6 octahedra, and edges with three equivalent Ti(3)O6 octahedra. The Ti(2)-O(2) bond length is 1.86 Å. The Ti(2)-O(3) bond length is 1.96 Å. The Ti(2)-O(4) bond length is 1.86 Å. The Ti(2)-O(6) bond length is 2.14 Å. There is one shorter (2.14 Å) and one longer (2.20 Å) Ti(2)-O(5) bond length. In the third Ti site, Ti(3) is bonded to one O(1), one O(3), one O(4), one O(5), and two equivalent O(6) atoms to form distorted TiO6 octahedra that share corners with two equivalent Na(3)O4 tetrahedra, corners with four equivalent Na(1)O4 tetrahedra,  an edgeedge with one Ti(1)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra, and edges with three equivalent Ti(2)O6 octahedra. The Ti(3)-O(1) bond length is 1.89 Å. The Ti(3)-O(3) bond length is 2.29 Å. The Ti(3)-O(4) bond length is 1.98 Å. The Ti(3)-O(5) bond length is 1.89 Å. There is one shorter (1.97 Å) and one longer (2.08 Å) Ti(3)-O(6) bond length. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Ti(1), and one Ti(3) atom to form distorted ONa2Ti2 trigonal pyramids that share corners with two equivalent O(5)NaTi3 tetrahedra, corners with three equivalent O(6)NaTi3 tetrahedra,  a cornercorner with one O(4)Na2Ti2 trigonal pyramid, corners with two equivalent O(1)Na2Ti2 trigonal pyramids, corners with three equivalent O(2)Na2Ti2 trigonal pyramids,  an edgeedge with one O(2)Na2Ti2 trigonal pyramid, and  an edgeedge with one O(4)Na2Ti2 trigonal pyramid. In the second O site, O(2) is bonded to one Na(1), one Na(2), one Ti(1), and one Ti(2) atom to form distorted ONa2Ti2 trigonal pyramids that share corners with two equivalent O(6)NaTi3 tetrahedra, corners with three equivalent O(5)NaTi3 tetrahedra,  a cornercorner with one O(4)Na2Ti2 trigonal pyramid, corners with two equivalent O(2)Na2Ti2 trigonal pyramids, corners with three equivalent O(1)Na2Ti2 trigonal pyramids,  an edgeedge with one O(1)Na2Ti2 trigonal pyramid, and  an edgeedge with one O(4)Na2Ti2 trigonal pyramid. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Na(3), one Ti(1), one Ti(2), and one Ti(3) atom. In the fourth O site, O(4) is bonded to one Na(2), one Na(3), one Ti(2), and one Ti(3) atom to form distorted ONa2Ti2 trigonal pyramids that share corners with three equivalent O(5)NaTi3 tetrahedra, corners with three equivalent O(6)NaTi3 tetrahedra,  a cornercorner with one O(1)Na2Ti2 trigonal pyramid,  a cornercorner with one O(2)Na2Ti2 trigonal pyramid, corners with two equivalent O(4)Na2Ti2 trigonal pyramids,  an edgeedge with one O(1)Na2Ti2 trigonal pyramid, and  an edgeedge with one O(2)Na2Ti2 trigonal pyramid. In the fifth O site, O(5) is bonded to one Na(1), one Ti(3), and two equivalent Ti(2) atoms to form distorted ONaTi3 tetrahedra that share  a cornercorner with one O(6)NaTi3 tetrahedra, corners with two equivalent O(1)Na2Ti2 trigonal pyramids, corners with three equivalent O(2)Na2Ti2 trigonal pyramids, corners with three equivalent O(4)Na2Ti2 trigonal pyramids,  an edgeedge with one O(5)NaTi3 tetrahedra, and edges with two equivalent O(6)NaTi3 tetrahedra. In the sixth O site, O(6) is bonded to one Na(1), one Ti(2), and two equivalent Ti(3) atoms to form distorted ONaTi3 tetrahedra that share  a cornercorner with one O(5)NaTi3 tetrahedra, corners with two equivalent O(2)Na2Ti2 trigonal pyramids, corners with three equivalent O(1)Na2Ti2 trigonal pyramids, corners with three equivalent O(4)Na2Ti2 trigonal pyramids,  an edgeedge with one O(6)NaTi3 tetrahedra, and edges with two equivalent O(5)NaTi3 tetrahedra.