Na3Ti8O16 is beta indium sulfide-derived structured and crystallizes in the orthorhombic Pmmn space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1) and two equivalent O(5) atoms to form NaO4 tetrahedra that share corners with two equivalent Ti(2)O6 octahedra, corners with two equivalent Ti(4)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, and corners with four equivalent Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 60-63°. In the second Na site, Na(2) is bonded to one O(6), one O(7), and two equivalent O(3) atoms to form NaO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra, corners with three equivalent Ti(3)O6 octahedra, and corners with four equivalent Ti(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-62°. There are four 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(1)O4 tetrahedra, corners with two equivalent Na(2)O4 tetrahedra, edges with two equivalent Ti(1)O6 octahedra, 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(1), one O(6), two equivalent O(3), and two equivalent O(4) atoms to form TiO6 octahedra that share  a cornercorner with one Na(1)O4 tetrahedra, corners with three equivalent Na(2)O4 tetrahedra,  an edgeedge with one Ti(2)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and edges with two equivalent Ti(4)O6 octahedra. In the third Ti site, Ti(3) is bonded to one O(2), one O(7), two equivalent O(3), and two equivalent O(5) atoms to form TiO6 octahedra that share corners with two equivalent Na(1)O4 tetrahedra, corners with three equivalent Na(2)O4 tetrahedra,  an edgeedge with one Ti(2)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and edges with two equivalent Ti(4)O6 octahedra. In the fourth Ti site, Ti(4) is bonded to one O(4), one O(5), two equivalent O(6), and two equivalent O(7) atoms to form TiO6 octahedra that share  a cornercorner with one Na(1)O4 tetrahedra, corners with four equivalent Na(2)O4 tetrahedra, edges with two equivalent Ti(2)O6 octahedra, edges with two equivalent Ti(3)O6 octahedra, and edges with two equivalent Ti(4)O6 octahedra. There are seven inequivalent O sites. In the first O site, O(5) is bonded to one Na(1), one Ti(4), and two equivalent Ti(3) atoms to form a mixture of edge and corner-sharing ONaTi3 tetrahedra. In the second O site, O(6) is bonded to one Na(2), one Ti(2), and two equivalent Ti(4) atoms to form a mixture of distorted edge and corner-sharing ONaTi3 tetrahedra. In the third O site, O(7) is bonded to one Na(2), one Ti(3), and two equivalent Ti(4) atoms to form a mixture of edge and corner-sharing ONaTi3 tetrahedra. In the fourth O site, O(1) is bonded to one Na(1), one Ti(2), and two equivalent Ti(1) atoms to form a mixture of edge and corner-sharing ONaTi3 tetrahedra. In the fifth O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ti(3) and two equivalent Ti(1) atoms. In the sixth O site, O(3) is bonded to one Na(2), one Ti(1), one Ti(2), and one Ti(3) atom to form a mixture of edge and corner-sharing ONaTi3 tetrahedra. In the seventh O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Ti(4) and two equivalent Ti(2) atoms.
Na3Ti8O16 is beta indium sulfide-derived structured and crystallizes in the orthorhombic Pmmn space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1) and two equivalent O(5) atoms to form NaO4 tetrahedra that share corners with two equivalent Ti(2)O6 octahedra, corners with two equivalent Ti(4)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra, and corners with four equivalent Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 60-63°. Both Na(1)-O(1) bond lengths are 2.14 Å. Both Na(1)-O(5) bond lengths are 2.16 Å. In the second Na site, Na(2) is bonded to one O(6), one O(7), and two equivalent O(3) atoms to form NaO4 tetrahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra, corners with three equivalent Ti(3)O6 octahedra, and corners with four equivalent Ti(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-62°. The Na(2)-O(6) bond length is 2.17 Å. The Na(2)-O(7) bond length is 2.15 Å. Both Na(2)-O(3) bond lengths are 2.15 Å. There are four 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(1)O4 tetrahedra, corners with two equivalent Na(2)O4 tetrahedra, edges with two equivalent Ti(1)O6 octahedra, 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 2.01 Å. Both Ti(1)-O(2) bond lengths are 2.03 Å. Both Ti(1)-O(3) bond lengths are 2.02 Å. In the second Ti site, Ti(2) is bonded to one O(1), one O(6), two equivalent O(3), and two equivalent O(4) atoms to form TiO6 octahedra that share  a cornercorner with one Na(1)O4 tetrahedra, corners with three equivalent Na(2)O4 tetrahedra,  an edgeedge with one Ti(2)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and edges with two equivalent Ti(4)O6 octahedra. The Ti(2)-O(1) bond length is 2.02 Å. The Ti(2)-O(6) bond length is 2.02 Å. Both Ti(2)-O(3) bond lengths are 2.05 Å. Both Ti(2)-O(4) bond lengths are 2.00 Å. In the third Ti site, Ti(3) is bonded to one O(2), one O(7), two equivalent O(3), and two equivalent O(5) atoms to form TiO6 octahedra that share corners with two equivalent Na(1)O4 tetrahedra, corners with three equivalent Na(2)O4 tetrahedra,  an edgeedge with one Ti(2)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and edges with two equivalent Ti(4)O6 octahedra. The Ti(3)-O(2) bond length is 1.96 Å. The Ti(3)-O(7) bond length is 2.08 Å. Both Ti(3)-O(3) bond lengths are 2.02 Å. Both Ti(3)-O(5) bond lengths are 2.02 Å. In the fourth Ti site, Ti(4) is bonded to one O(4), one O(5), two equivalent O(6), and two equivalent O(7) atoms to form TiO6 octahedra that share  a cornercorner with one Na(1)O4 tetrahedra, corners with four equivalent Na(2)O4 tetrahedra, edges with two equivalent Ti(2)O6 octahedra, edges with two equivalent Ti(3)O6 octahedra, and edges with two equivalent Ti(4)O6 octahedra. The Ti(4)-O(4) bond length is 1.99 Å. The Ti(4)-O(5) bond length is 2.05 Å. Both Ti(4)-O(6) bond lengths are 2.04 Å. Both Ti(4)-O(7) bond lengths are 2.01 Å. There are seven inequivalent O sites. In the first O site, O(5) is bonded to one Na(1), one Ti(4), and two equivalent Ti(3) atoms to form a mixture of edge and corner-sharing ONaTi3 tetrahedra. In the second O site, O(6) is bonded to one Na(2), one Ti(2), and two equivalent Ti(4) atoms to form a mixture of distorted edge and corner-sharing ONaTi3 tetrahedra. In the third O site, O(7) is bonded to one Na(2), one Ti(3), and two equivalent Ti(4) atoms to form a mixture of edge and corner-sharing ONaTi3 tetrahedra. In the fourth O site, O(1) is bonded to one Na(1), one Ti(2), and two equivalent Ti(1) atoms to form a mixture of edge and corner-sharing ONaTi3 tetrahedra. In the fifth O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Ti(3) and two equivalent Ti(1) atoms. In the sixth O site, O(3) is bonded to one Na(2), one Ti(1), one Ti(2), and one Ti(3) atom to form a mixture of edge and corner-sharing ONaTi3 tetrahedra. In the seventh O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Ti(4) and two equivalent Ti(2) atoms.